Hitman's Pontiac Trans Am Forum
Trans Am Information => Trans Am Tech => Electrical => Topic started by: Silentstrike on February 18, 2009, 05:03:57 PM
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Alright so me and my dad have been working on my car for the past week trying to figure this out. We replaced the carburatuer (sp?) and the distributor coil, the cap and rotor and plugs were new this summer. We're getting a spark but its weak (orange/yellow tint instead of the white) any ideas?
Thanks
Scott
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did you check the control module located in the distributor ? those tend to go bad....and thats your coils brain
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We were just gonna pull that and take it to advance for tests. any other ideas just in case this doesn't work?
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no not really too much else to check after that....maybe a pickup coil....but i doubt that one
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Unless it the distributor battery wire (the red one) is not fully plugged in or is not giving the distributor a full 12 volts. Check the battery wire to the distributor to see if it is indeed giving up the full 12 volts.
Along those lines, about 18 months ago we had a rash of bad ignition switches. Several guys complained of engines running crappy/not starting and it turned out that the ignition switches had fried their contacts and weren't passing a solid +12 VDC. They were getting like 5-7 VDC instead. It was weird -- I bet there were like 3-4 failures in under a week.
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How old are the spark plug wires? Does the car start and run OK? Are you using the correct plugs? Are they gapped correctly?
From what I've experienced with those modules....either they work or they don't. But they're a mystery to me because I've never seen a schematic for a module. The module controls the dwell....that's my total knowledge on those things.
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Well I tore it all down last night and turns our the ignition module was tested good but the flyweights on the distributor itself were about to fall off. We're hoping thats the problem.
Thanks for the advice everyone
Scott
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make sure the coil has the red and white leads on it
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Well I tore it all down last night and turns our the ignition module was tested good but the flyweights on the distributor itself were about to fall off.
Those are the weights that provide your mechanical timing advance. You'll want to pay particular attention to their original shape/weight, or else your mechanical timing will be altered. The springs holding them on are part of the mechanism also.
If they're worn that badly then it's probably time to find a shop with a distributor timing machine and get the distributor recurved. The factory timing curve wasn't all that fine because it was diddled around for emissions considerations and also done on a mass production scale. There may be some free power to be gained by having that done.
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I got a brand new coil with the right leads and we just decided to go with a new distributor period. We figured that would be easier since we don't know any machine shops around here.
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OK -- keep in mind that the mechanical advance curve that will be in it is a generic one. They will use the same kind of weights and springs as were used in the greatest number of factory units, and those aren't necessarily the exact ones you want for optimum spark advance in your car. It will work fine out of the box, but it may well not give you the most power for the fuel you're burning. Tweaking the advance curve is one of those "tuning" things that is required to get the most out of your engine once it is running well and reliably. It's the same thing as picking the right rods, jets, and hangers for the Qjet.
When you get the new distributor, check the end play on the shaft. It shouldn't be more than 0.010" - 0.020" -- the smaller, the better. Excessive end play will result in spark "scatter" as the shaft bounces up and down with the engine running, and that causes the spark to "jump" around because it's driven by the helical gear on the camshaft. It's another "fine touch" item.
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question ? what year is the chassis ? as the early chassis have a resistance lead built into the power wire that the HEI cars didn't have and will also cause this problem .
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question ? what year is the chassis ? as the early chassis have a resistance lead built into the power wire that the HEI cars didn't have and will also cause this problem .
Good catch, stimpy! Yeah if the car originally had points there is a built-in resistor in the wiring.
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Alright this is gonna sound extremely stupid but there is only one bolt that holds in the distributor right? My dad and I removed the bolt we could see and it still won't budge
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One bolt that holds a clamp, which in turn is what secures the distibutor to the block. Years of grime and road crap may have "glued" it into place. Try marking it's location (so you can re-establish rough timing) and then try rotating it to break it free.
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Yeah thats what we thought thanks. It's just held in there so tight that we're taking a punch to the notch and hammering that to turn it back and forth till we can finally get it out
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easy way to turn these is to use a band wrench or take a 1 inch wide leather belt( like the one that hold up your pants ) and wrap it around the base plate of the distributor to spin it .
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We got it out and got the new one in thanks for the advice guys. I'm just hoping once I get the plugs back in and the cap and rotor on she fires
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anyone know if there is a master gear on the distributor it seems to only want to go in place one way
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It should go in at any position that the gear teeth will mesh. It will turn a bit as you drop it in so you have to account for that when you line it up. Otherwise you could end up a tooth or so off. You might need to use a long screw driver to turn the oil pump shaft a little so it will line up.
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I've tried turning the distributor gears in different positions but it seems to only wanna drop to all the way down at ione combination
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I've tried turning the distributor gears in different positions but it seems to only wanna drop to all the way down at ione combination
Then try turning the oil pump shaft in the direction you need the distributor to turn.
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Yeah - I always take the cap off before I pull the distributor. Makes knowing how it goes back in a lot easier vs. being 180 out per Hammer's comment.
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Thanks guys sorry about all the questions I'm 17 and still learning
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Alright - we'll tread lightly. Anything you need to know feel free to ask. There are no dumb questions. Also, if anyone flames you, I'm pretty much the most obnoxious jerk on here so let me know, capice?
(INSIDE VOICE - wait, that was me just repeating what the ex always said - that I was an obnoxious jerk .... I'm still emotionally traumatized by her rantings ...boo-hoo)
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I'm still scratching my head trying to figure out what the problem is. The only thing I can gather is the color of the spark was said to be weak. But, other than that, I have no idea of how the car runs...whether it starts or not, or if it runs poorly. I'm really at a loss as to what problem is being solved.
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also make sure the battery is fully charged , as it will crank the motor but not have enough juice to light the charge and make sure the electrical connections at the starter ar clean as this is where the voltage that supplys the system comes from and a loose or corroded or burnt wire will cause a resistance effect
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Alright so update for today, My car turns over it doesn't start we have the distributor in the spark is now white. We are trouble shooting for other problems but when I crank it it puffs some vapor out of the carbureutor that doesn't smell like burning gas (brand new carbureutor my dad and I were thinking maybe a shelf preservative?) . The top of the fuel pump is wet with gas now so my dad and I are going to see if we're getting gas to the carb but after that we're absolutely stumped. It has a whole new ignition system and carb so any ideas guys? thanks
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Preservative? What's the carb made of that it would spoil on a shelf? LoL ;)
Ok, I'll be serious now. How does it sound when it's turning over? Is it trying to fire? Or is it backfiring? Does the vapor you see smell like coolant steam? Did the plugs look wet when you pulled them?
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That's not how you determine if you're getting the right spark or not. But, try squirting some gas into the carb opening to see if it will begin to fire.
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Its a strong turn over (we thought preservative of some kind so the seals don't dry out) it seems to back fire a bit but not much we were gonna try putting straight gas in tonight when we have the time. The vapor isn't steam or gas it makes you cough and choke but its not exhaust either. And no the plugs were dry when we pulled them
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With minor backfiring it could be something as simple as the timing being off now.
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It doesn't actually fire it only puts out a minior back fire but the engine doesn't run at all
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It's common for them to spit a bit while they're cranking if the timing is off. As you get closer they may also sound like they're barely turning over as the starter "grunts" to keep it going. You pulled the distributor, which totally blew the timing as you are likely many degrees off from where it was originally. Try twisting the distributor around to see if it will catch. If not, and if everything is there (fuel and fire), then you may have to statically time the engine to get it in the ballpark. Let's hope you don't have to go that far because it's kind of a hassle, though.
I'd start by turning the distributor so as to advance the timing because it sounds like it may be firing after top dead center. If it's grunting (barely turning over) that's an indication that it's too far before top dead center, so you need to retard it a little at a time.
Once you get it running you'll need to put a timing light on it to get the fine tuning right.
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Thank you very much I'll try and see
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He could still have the dist 180 out. In the reading I've done on this thread, I read that they got the dist in but I haven't seen anything that would indicate that they have verified that the dist is in correctly and not 180 degrees out. And that's what it sounds like by it not firing and occasionally backfiring.
It's a simple check really. I think this is what Rick was talking about when he mentioned static timing. Take the dist cap off and the number one spark plug out. Also, with HEI, you might want to unplug the coil wire so you don't damage the coil pack if you're cranking it with the key. Someone check me on that. Crank the engine either by hand (with a wrench on the crank shaft) or by turning the key until you can see (with a flash light) the number one piston come up to the top in the cylinder. I think you also need to make sure that it is on the compression stroke when it is up. I just put a finger over the spark plug hole while cranking it. If it's on the compression stroke, the compressed air will push your finger off the hole. Once you get the number one piston at the top of it's travel on the compression stroke, the rotor contact should be pointing at the number one spark plug wire position. Then you're in the ball park.
The dist may still be a tooth or so off but you should be able to turn it enough to compensate for being off that little bit and get it started.
Good luck
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Yes, Randy is describing the static time method. I don't like to have to do that, which is why I go to such great lengths to mark the location of the distributor and the rotor and AVOID "bumping" the engine at all when I have to remove a distributor. But if it comes down to it, that's what you have to do to get the timing back in the ballpark if something does get messed up.
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Well, I'm going under the assumption that he put it back so that it's pointing in the same general direction that it was in before he pulled it and that he didn't try spinning the engine without the distributor in it.
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We pulled it and its pointing the same general direction
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Now it is wanting to start striong spark getting gas but it wont any ideas bad gas maybe it will almost kick but then it will stop
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pull your plugs and if they are wet/damp ( i ussually place them on a pan over a heater to give them some warmth to help evaporate the gas ) let them dry then reinstall them , and if does the same thing very slowly turn the distributor ( with the bolt loosened slightly to prevent it from being pulled by the motor but enough to turn by hand ) as your cranking to see if your still retarded ( turning it clockwise).
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Disconnect the fuel line from the carb and turn it over - does gas go into the bucket ... if yes;
When you work the throttle manually, are you seeing gas? ... if not;
Is the fuel filter old/clogged?
What about dumping gas into the carb directly? You'd said you were going to try that - did you? if so;
Pull the plugs per stimpy - they could be fuel fouled.
Ensure the distributor is on the compression stroke per 78ta
Make sure the rotor would align with the #1 cap/wire when you put the cap back on.
It would be @ 0 degrees timing at that point - do what Rick says about rotating the cap ~5 to 10 degrees
Is the HEI producing spark ...when you pull a wire and turn the engine over, holding it next to the heads, it should produce a spark. (You might feel a slight shock at some point ...)
Firing order is 1-8-4-3-6-5-7-2 ... are you sure that's right?
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Gas goes into bucket
fuel direct into carb won't fire
tested fuel filter its clear
cleaned fouled plugs
on compression stroke
HEI is producing spark
cheacking firing order is that for a 305? and does this car have an EGR on it, could that be a problem?
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#1 is the driver's front cylinder, #7 is driver's rear.
#2 is the passenger front, #8 is the pass rear.
Firing order is counter-clockwise looking down on the distributor.
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What engine are you running? ...
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Firing order is good running a 305 it's the original engine
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Like your thread said - weak spark is what I'm thinking.
You've got the air cleaner assembly off when you're trying to start - it's not choking for air, right?
You're seeing gas enter the airhorn assy with manual movement of the throttle linkage?
It's not -25F in Indiana, right?
HEI has an ignition module in it that can need replacing. There's also the coil ...
I'm assuming you've a new cap & rotor.
Plug wires don't arc in the dark and are otherwise in good condition.
The wires going into the cap - what is it, tach-batt and two other wires are solid/no breaks. Check that all those connections/wires are good.
Battery is good? Turning over at a reputable pace? I'm a little stumped if you've fuel/spark ....
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I just replaced the whole ignition system distributor cap rotor coil plugs wires
the gas I have poured in myself and it just turned 50 today I have no idea what to do my dad thinks we might have gotten a bad carb because thats all thats left we have checked spark over and over
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I'd get a loaner distributor and/or carb from someone.
Find something on Craigslist if you have to and play the substitution game. I've a couple of cars so I can always pull components if something is messing with my head but it sounds like you need some options at this point.
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Yeah we're gonna see if we can take our carb back to the store and get an exchange but we're running out of options and I really don't wanna take this to a shop
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When you test spark ... are you holding it a half inch from the heads/block?
I know HEI has a kick ... if you're not getting that, the PCB board or coil could have issues.
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I just pulled the plug out and put on the wire outside the cylindar so I can see the spark and whether or not it'll light gas and it's fine
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Let's recap for a second -- I just went back and read all 4 pages of this thread...
How was the car running before you started this project? OK? Crappy? Somewhere in between? It was running, right?
There could be some more clues there... ??? ???
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Let's recap for a second -- I just went back and read all 4 pages of this thread...
How was the car running before you started this project? OK? Crappy? Somewhere in between? It was running, right?
There could be some more clues there... ??? ???
I asked that question on the first page and never got an answer. I have no idea what problem was trying to be solved. The only thing I saw was the color of the spark looked weak....so what? That doesn't tell us anything. Now the distributor has been replaced and we have no idea if it was put back in correctly.
It's not necessarily the carb if he poured gas down the intake and it some cylinders didn't fire. But he thinks the carb is bad.
At this point he's just changing parts. It would be nice to know what the symptoms were before he started "fixing" it.
Don't take this as being negative....I'm trying to get the correct information conveyed so the smart people on this forum can correctly diagnosis the problem. We all want to help.
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Don't take this as being negative....I'm trying to get the correct information conveyed so the smart people on this forum can correctly diagnosis the problem. We all want to help.
Yes, that's correct. After 4 pages of posts, it's just time for a little review of the "big picture". It's too easy to get lost in the forest because you can't see beyond the trees. ;)
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I agree with the above post.
After reading all this I am completly confused. Lets start over.
Model and year of firebird
model and year of engine and size
Why did you think you had a problem before you started changing parts.
What were the sympthems?
we never had a clear picture of what you needed besides the spark looked weak.
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Original 305? What model is your car? If you have an original 305 the firing order should be 18436572 but in the clockwise direction. I just skimmed most of the posts on this and thats the only thing I see now that I did not see earlier in the post. Scott
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Alright so I guess I never was that clear on anything.
My car is a 78 firebird 305 motor.
The original problem was that I pulled it out of the driveway a cold winters morning (its my daily driver) and it stalled and wouldn't fire back up.
We knew the carb was on its last leg and were hoping it was just a fuel problem so we changed that.
Then we took a look at the distributor when we noticed the spark was crappy. It turn out the flyweights were extremely loose to the point they would overlap one another. We changed that. We are sure we have the timing the rotor is underneath where I have cylindar one set up the firing order is correct in the clockwise direction.
My dad is reading up on the carb we installed to see if there could be a problem because we are geting a strong spark and have no idea what else it could be.
Later today we are going to check for fuel getting into the cylindars but we're pretty sure it's getting there. We have pulled all the plugs to check for fouling and cleaned the plugs. The whole ignition system is new from the distributor up. I hope I have now been more clear sorry for being dense
I just now saw ricks post about how the car was running before I undertook this, I had been driving this car since last july as my daily driver with only minor problems that were fixed in less than a weekend by me and my father (he is a professional mechanic by trade).
Right now both him and I are stumped so please if you have a suggestion we will try it thank you.
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Ok, sounds like you were jumping around in your method a bit. I think you were on the right track with the carb in the first place causing your cold morning issues. You should try and fix one problem before moving on to another, especially when they overlap like the fuel and ignition systems. Once you got the new carb on did you try and adjust it for your engine? Even if you do have a weak spark, HEIs pump out tens of thousands of volts. If everything else id adjusted right the car should still run.
The way things sit now I think you need to try adjusting the timing while someone turns it over. Turn the dist. slowly first counterclockwise (advancing the timing) until it either fires or starts sounding like the battery is dying. (a too far advanced condition will cause that effect.) Then go back the other way until it turns easier again. That should get you pretty close to the correct timing.
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Yeah, it sounds like there are a couple of things interacting here. Follow Larry's advice and get it running first. When you get it fired up we can look at other stuff, but I'd vary the timing as he describes first. You have to eliminate one problem at a time. If varying the timing by twisting the distributor doesn't get it, raise your hand before you try anything else.
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(raises hand) oooh oooh pick me
all joking aside
We varied the timing till it wants to kick but it just won't it's turning over strong, The carb said it was pretuned from the factory it was marked as direct replacement for my exact engine, My dad didn't wanna mess with it too much, I personally still feel it is the carb or something with it because gas doesn't seem to be getting into the cylindars well.
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At this point, it should pretty well fire up as long as the carb is putting *any* fuel into the engine. At the risk of asking a really stupid question, you don't have it flooded, do you? If you think it might be, you can block the throttle plates open and blow air down the carb into the engine until the gas smell abates a little. A flooded engine can be very difficult to start.
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may I ask how many miles are on the motor ??? and when it died did it make a popping noise ? and was the motor running sluggish at low speed but the performance was good at hiway speed ?( 45-60 )
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I pulled the plugs to make sure they weren't wet and I haven't seen any sign of flooding, There is 178K on my motor but it made no popping noise and ran fine beforehand
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Well, fine and sluggish are relative terms. Especially when talking about a little 305 that's traveled 3/4 of the way to the moon. ;) I know where Stimp's going with this. Has any work been done on the engine? It's possible it didn't pop, but that the timing chain skipped a tooth the last time you shut the engine off.
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Yeah, it's starting to sound like maybe it's timing-chain related. If it's not flooded bad, then it's timing related. You have gas in the engine, and you have spark, so what's left is timing in these circumstances.
The distributor is driven by the camshaft. The camshaft is driven by the crank via a chain (i.e., the timing chain). The crank gear is all metal and pretty durable. The chain stretches over time, but overall it's pretty durable also. The "weak link" in the design is the cam gear. Stock GM cam gears have nylon teeth on them -- that's to make the engine run quieter. Those are only good for about 100,000 miles. With age, mileage, and heat from the engine the factory nylon teeth begin cracking and some can even fall off. As it wears, the timing chain gets looser and looser, and finally the timing chain can slip a few teeth. When that happens all the King's horses and all the King's men can't get the engine started again. Why? Because the timing of the valves opening and closing and the distributor firing is all out of kilter. That stuff all has to happen in a sequence that's dictated by the crank position, and if the timing chain slips it's all screwed up.
It doesn't take much to make that chain slip, either. It can happen just starting the car up. I've had it happen to me just setting at a stoplight, not touching the gas.
If that's the case, then what you need to do is to replace the timing chain. You get a new cam gear, a new timing chain, and a new crank gear -- replace them all as a set. You follow the procedure in the service manual and go from there.
It's not hard to do at all, and it's not very expensive. If your engine has 178K on it and it's either never been opened before then it needs replacement. Even if it was replaced once about 1/2 way through that interval, it's time anyway.
I'd start looking in that direction rather than fooling around with the carb, since the carb is new. Just satisfy yourself that you've done all you can do with the timing/distributor and make sure it's not just flooded badly first.
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Before you pull the timing chain cover (I agree with everyone that it could be the timing chain.....that's exactly what I was thinking) I would measure the voltage at the BAT terminal of the distributor with the engine cranking. Just make sure you have at least 7 volts there. If you do, you've got enough current to give you enough spark. It's a five minute test that will eliminate the ignition switch or bad bulkhead connector from the mix.
If you pull the timing chain cover, you can at that time check your distributor position with the gears at twelve o'clock.
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My father is still stuck on this bad gas thing because it doesn't smell 100% correct do you guys know anyway to check for that? I would check the timeing chain myself but I don't like to get into anything big without my dad backing me up he said we'll do it if we can prove the gas isn't bad
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Pour a little on the ground and see if it lights easily.. I stress little and be careful. Scott
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I can light it with a grill lighter but it burns with more smoke and doesn't seem as hot as regular gas
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Does it light instantly or hard to light. Smoke........... You dont think you put diesel in by accident do you....Scott
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to check the timing chain theres a simple proceedure bring the balancer to the tdc mark on the crank timer , then remove the cap and rotate the crank backwards while watching the rotor and when it starts turning stop! then look at the timer tabs and see how far it moved before the rotro moved if its over 5 degrees its bad .
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To eliminate the gas a a problem, Get your lawn mower gas can and a length of fuel line long enough to go from the gas can to the fuel pump and use that as your source. This ofcoarse assumes the gas in the can is good. Just go put some fresh gas in the can to be sure.
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If you pour a quarter cup of gas in the carb and the engine won't start the timing is OFF!!!!!!!!!!!!!!!
it doesnt matter is the carb is good or not the engine should crank and run about 5 seconds
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Not necessarily. Remember this thread starting with a complaint of weak spark. I still believe it prudent to check the voltage at the bat terminal just to make sure he doesn't have a bad ignition switch.
I've had my car sit in the garage for two years in between starts and the gas was still "good".
But, I tend to agree that the timing chain is suspect. If it were my car, I would pull the timing chain cover just to visually check it. The engine has a lot of miles on it.
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Not necessarily. Remember this thread starting with a complaint of weak spark. I still believe it prudent to check the voltage at the bat terminal just to make sure he doesn't have a bad ignition switch.
I've had my car sit in the garage for two years in between starts and the gas was still "good".
But, I tend to agree that the timing chain is suspect. If it were my car, I would pull the timing chain cover just to visually check it. The engine has a lot of miles on it.
Yeah, but this car hasn't been sitting. It's his daily driver. There was a point made last page that when he tried burning some of the gas from the car it burned with what the OP believes to be more smoke than usual for gas. That could indicate something in the gas that shouldn't be there like diesel. However, that could cause some drivability issues. But I've driven cars from the same era with diesel in the gas and not had this much trouble. So I agree that the chain does need to be checked.
By BAT terminal you mean the power lead at the distributor, right? That's another good idea.
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Thanks to all those who helpedme in this ordeal my bird is back up and running again and no timing change necessary it was after all just bad gas thanks to all of you again
Scott