[cavalry]

I found this forum from this post.

http://www.hotrodders.com/forum/350-tbi-spark-problem-driving-med-crazy-114225.html

Unfortunately it does not seem resolved. I am having a similar problem.

My 87 GMC (TBI 5.7) will not start.

I have no spark at the coil. Here is the results of my testing. I am just about out of ideas.

-ECM-A,ECM-B,IGN fuses all good
-Have 12v on the pink wire going to distributor.
-Have full voltage on the tach wire (not internally shorted)
-Tested coil according to service manual. Passed but changed it anyway with new.
-Ignition module was changed with GM new. Old one tested OK
-Tested pick up coil. 850 ohms. Pass.
-For giggles changed computer with another 5.7 7747.

The only thing I still have to check is the 4 wires from the distributor to the ECM. I think this is unlikely though.

 

[Torque454]

Did you verify that the distributor is turning while cranking?

 

[cavalry]

Yes the distributor is turning

 

[SS66chevelle]

Yes the distributor is turning

ground issue?

 

[rat0names]

security

was this a year they used a chip in the key to provide spark/fuel at start up, perhaps it's in your colum or key.

 

[crussell85]

I would go for the ground issue. Take a pair of jumper cables and run the ground cable from the battery right to the bolt of the coil. Not to be Mr. Obvious but how about the coil wire.

 

[carsavvycook]

Is your oil pressure switch leaking oil? It should be a 3 prong switch, and part of it's function is to turn on the fuel pump. (there were some longer bed trucks built with too small of a wire going to the fuel pump) There may be a fuel pump relay involved, but, I do not remember it's location on yours.

Are the fuel injectors spraying fuel? They can be checked for battery voltage power with a test light. It is the 'right' side wire to the left injector(looking from the front of the car), this should have battery voltage. The other wire can be checked with a multi-meter set to 'dc' voltage. It will show a 'fluctuations' when it is 'fired' by the ECM.

Check for these, and post back.

Stephen

 

[cavalry]

found the problem! Broken insulation on the white wire from the coil. Wire had corroded inside the insulation and depending on how it was positioned worked or did not

 

[M&M CUSTOM]

I am just now having the exact same problem with my 1987 Chevy 5.0 TBI truck.

Truck sat for more than 2 years not started, just rebuilt known severely plugged and leaking TBI.

Upon cranking, no spark, and no fuel to injectors, left saddle tank sat for unknown time with unknown amount of gas in it, tried to remove as much old gas as possible, added 5 gallons, 16 gallon tank, sender showing just over 1/4 tank and upon turning key on initially or just after cranking fuel pump cycles and turns off normally.

All fuses check out OK with ohm meter, noid light confirms no signal to injectors and spark plug wire to tester shows no spark, haven't had chance to check many things listed above and in the other mentioned thread, 19 degrees and snowing lower your want to be out there working on the truck severely. I also loosened the fuel inlet line and checked for fuel flow to TBI unit, just got a few drops after several key on/off cycles and while cranking, possibly plugged fuel filter here too that will need checked.

 

[crussell85]

I am just now having the exact same problem with my 1987 Chevy 5.0 TBI truck.

Truck sat for more than 2 years not started, just rebuilt known severely plugged and leaking TBI.

Upon cranking, no spark, and no fuel to injectors, left saddle tank sat for unknown time with unknown amount of gas in it, tried to remove as much old gas as possible, added 5 gallons, 16 gallon tank, sender showing just over 1/4 tank and upon turning key on initially or just after cranking fuel pump cycles and turns off normally.

All fuses check out OK with ohm meter, noid light confirms no signal to injectors and spark plug wire to tester shows no spark, haven't had chance to check many things listed above and in the other mentioned thread, 19 degrees and snowing lower your want to be out there working on the truck severely. I also loosened the fuel inlet line and checked for fuel flow to TBI unit, just got a few drops after several key on/off cycles and while cranking, possibly plugged fuel filter here too that will need checked.

The first thing I would do is change the ignition module. Or have it checked at a chinese auto parts store.

 

[carsavvycook]

I had a 1989 Camaro 305 TBI with the same no spark, and no fuel injector pulse width. The pick-up coil to the control module connector had corrosion in the connection. I replaced both parts, and I then had spark, but no fuel injector pulse width.

After further diagnosis, I found a bad EPROM in the ECU. I ordered one from tbichips.com, and it ran perfect. (the one I ordered was a 'stage 1' performance chip, that will still pass our very strict emission testing here)

I had suspected this EPROM as going bad for 5 years before it finally quit. It would set codes, and run like crap infrequently, then it would run normal for various extended periods of times. The most common code was for the 'ignition timing' circuit. (spark timing control)

I hope this helps.

Stephen

 

[M&M CUSTOM]

I found the no fuel problem, and have to get more parts to fix the leaking fuel line running inside the frame rail. THAT problem is going to have to get fixed before further testing, so I can turn the key on and not spray fuel all over the ground, THEN it will be on to the next things to check.

I did install a noid light to each injector pod connector with no signal before finding the fuel leak, with no signal there. will hook the laptop to the ALDL and check to see what all it shows me there too. At least that will tell me if it sees any and all signals it should and if not, quickly narrows it down.

Same thing with the no spark, pull all connectors and verify power where it should be and check for corroded connections.