Stuart S

86 LG4 - cranks nice and strong - won't start...

Have fuel, have nice spark...not a timing issue...

New plugs, good wires, new coil, pickup, cap, module, etc...

What gives?! Could it be ECM?

Thanks

MRZ28HO

How's the carb? (ie: choke, is it tuned properly, just rebuilt, clean, etc ...) Look down the primaries (not directly) when an assistant tries to start the car, do you see fuel being dumped (you can also try this without trying to start the car)? Have you tried using non-computer controlled stuff? Can you give me a background on the situation (did you rebuild it, was it in storage)?

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George P. Lara
Z28s Owned:
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ede

only 3 things needed for it to start. air/fuel mixture, spark, and compression. if you have fuel, and spark try compression. i know lot enters into having the correct air/fuel mixture and spark at the right time, but that's the basics. if you had a ecm related problem you should have a code set. will it fire on either? that would tell you that the spark is good and the a/f is wrong. compression test will eliminate that as a factor if it's all good.

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Vader

Stuart,

I thought you'd be out running circle around Mousetanks by now.

You have the 305 large-chambered heads with a 4 BBL E4ME, correct?

You have fuel delivery, spark, and plenty of cranking. The only things left in this equation are, air flow, timing, and compression. If you are certain the timing (both ignition and valve timing) is correct, and there are no air restrictions in sthe intake, then there may be a compresion problem.

Unless you've suffered a catastrophic piston or valve loss or sticking on all eight cylinders, there should be compression. The only other thing that can cause no compression is incorrect valve timing. If the valves are not opening on the intake/exhaust stroke and closing on the compression stroke, there will be no compression or air flow.

If you have spark and fuel delivery, there should at least be an occasional backfire or intake popping.

The ECM in your car only controls timing advance and some fuel mixture. The engine should at least start, and would probably run without an ECM. Assuming you have fuel, you fuel pump must be operating. Have you tried priming the engine with a little extra fuel or starting fluid?

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Later,
Vader
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Stuart S

Yes, checked for fuel, and have plenty - tried starter fluid, still nothing...

Timing is fine - its gotta be ignition related - I dunno what to say...

Also right now the car is 5 1/2 hours away at a friends house in MD, and I am back home in NY...so I can't check things right away - makes things worse, I know...

Vader

Stuart,

If you're certain you're getting spark (check it at the plugs) you might have fuel-fouled plugs. Remove a few spark plugs and smell them. Plugs that are wet with raw fuel don't fire very well. If the plugs are new but wet, pull them all and rinsethemn with hot water and allow them to dry. About the time they are dry, you can crank the engine over a few revs to clear out the excess fuel, then reinstall the plugs. You should at least get a pop if there is adequate spark. The ECM may be retarding spark for starting, but won't suppress it completely.

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Later,
Vader
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Stuart S

we'll try that - and yes, we do get an occasional pop - and it sounds like it wants to start but it just wont...

and yes, we have spark at the plugs...

and no, the car has not been in storage...

[This message has been edited by Stuart S (edited December 30, 2000).]

Birmass

Ok, it starts but it won't idle and it runs like crap. I don't think it's because of the timing though because it's been moved around each possibility and the best it runs is where it's at. It sounds like a horrible miss and the exhaust is GLOWING!! Even the intermediate pipe!!! It also revs VERY slow. Could it be a broken spring or something that's letting all that gas into the exhaust to ignite? Any ideas?? Thanks.

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Engineboy

Glowing exhaust is usually an indication of retarded timing/lean cond.

This is a long shot but I just had this happen to a cust. :

Car quit running, wanted to start but wouldn't.

Got it running after playing with the dist but it ran really bad and also had glowing ex.

The dist. roll pin that holds the gear in place had broken and the gear was on there good enough to spin with the dist., just not in the right place.

I know this isn'y very common but it sounds like you have exhausted all common ideas.

I would pull the dist and take a good look.


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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
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GO #3

[This message has been edited by Engineboy (edited December 31, 2000).]

Vader

SS/Birmass,

If the engine is only running weakly, and with such retarded timing that the exhaust is that hot, I would suggest you find TDC on the #1 cylinder, remove the left rocker cover, and check the timing of the valves. You might have slipped a timing chain.

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Later,
Vader
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GMTech

Ditto on the timing chain.

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Birmass

Engineboy - I have had the distributor out many times to replace the pickup coil etc. but I'm sure the pin is fine.

Vader + GM Tech - well, we put a new timing chain in a month ago and it ran fine for while with the new one. I don't think that's it.

Here's the what's going through my mind...

The car will start. It won't idle. There is a very noticable vibration, like a horrible miss. It revs really slowly. Exhaust is glowing and black stuff is coming out. At first I think - timing, but I've moved it around so many times now. I then think back to when Stuart first had this problem. He was driving along and the car was running great. He said he started to pull into a parking spot and the car began vibrating, missing, and the exhaust was glowing. Nothing physically changed with the timing when that happened to his car. His car then wouldn't start. He doesn't remember hearing any odd moises and nothing had physically moved on his car. I've got it started but I'm back to his first problem of the car missing and glowing exhaust. This leads me to believe that it is not timing, or I should atleast have it close enough. His car was running GREAT before and all the sudden it gave us these symptoms. I've replaced the timing chain, cap, rotor, pickup coil, module, coil, plug wires, plugs, and I have the exact same symptoms he had with the missing and glowing exhaust.

Stuart, I'm dropping a 454 in tomorrow...

[This message has been edited by Birmass (edited December 31, 2000).]

Stuart S

Is that a promise or a threat?

Serious guys, please help!

GOLD85

if the car starts, it wont idel, headers are glowing, and it is blowing alot of smoke sounds like your getting to much fuel. eater your intake valves are open, or you carb is dumping to much fuel in. when the secondary needel and seat on my holley was jamed open, the car ran like pooh, wouldnt idel, slow reving and puffed black exhust out. try rebiulding you carb.

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