Author Topic: Weak Spark please help  (Read 12411 times)

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Offline Silentstrike

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Re: Weak Spark please help
« Reply #45 on: February 25, 2009, 08:35:09 PM »
Firing order is good running a 305 it's the original engine

Offline jphillips3333

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Re: Weak Spark please help
« Reply #46 on: February 25, 2009, 08:43:31 PM »
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 ....

John

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Offline Silentstrike

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Re: Weak Spark please help
« Reply #47 on: February 25, 2009, 08:48:30 PM »
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

Offline jphillips3333

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Re: Weak Spark please help
« Reply #48 on: February 25, 2009, 08:53:48 PM »
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.

John

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Offline Silentstrike

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Re: Weak Spark please help
« Reply #49 on: February 25, 2009, 08:55:10 PM »
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

Offline jphillips3333

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Re: Weak Spark please help
« Reply #50 on: February 25, 2009, 08:59:26 PM »
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.
John

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Offline Silentstrike

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Re: Weak Spark please help
« Reply #51 on: February 25, 2009, 09:01:11 PM »
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

Offline Rick

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Re: Weak Spark please help
« Reply #52 on: February 25, 2009, 09:04:38 PM »
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... ??? ???

Offline ta78w72

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Re: Weak Spark please help
« Reply #53 on: February 25, 2009, 09:38:52 PM »
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.

Offline Rick

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Re: Weak Spark please help
« Reply #54 on: February 25, 2009, 11:42:46 PM »
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. ;)

Offline 72StreetBird

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Re: Weak Spark please help
« Reply #55 on: February 25, 2009, 11:46:19 PM »
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.
Harry 72 Firebird, 78 Trans Am W72 WS6
PRO Edelbrock Fastest Street Car Series 15 second index winner 2003, 2004 Cordova, Il

Offline fireman_033

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Re: Weak Spark please help
« Reply #56 on: February 26, 2009, 08:31:54 AM »
   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

Offline Silentstrike

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Re: Weak Spark please help
« Reply #57 on: February 26, 2009, 08:54:27 AM »
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.
« Last Edit: February 26, 2009, 09:27:08 PM by Hammer »

Offline Joker (§ir£Ğragon)

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Re: Weak Spark please help
« Reply #58 on: February 26, 2009, 09:31:13 AM »
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.
« Last Edit: February 26, 2009, 09:37:24 AM by §ir£Ğragon »
Larry


Offline Rick

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Re: Weak Spark please help
« Reply #59 on: February 26, 2009, 09:44:45 AM »
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.