1987 Chevy start and run problem.

bigdaddy1832 · #1 01-19-2005, 07:38 PM

Hey everybody, I have a puzzle with my 87 chevy 4x4. When the motor in cold (like over night cold) it will start up. But it will die in just a few minutes. Then it won't start. I checked to see if it getting fire to the coil and it isn't. The ICM is new and I had it tested and it works fine. The truck as a fresh rebuilt 5.7 motor (6 months ago) and alot of parts were replaced at that time including wires, plugs, cap, rotor button, map sensor, knock sensor, and computer with updated prom just to mention some. What do you think woud make one run just a few minutes when cold and die, then not fire after that. The next morning it will crank again and die. etc.

J-Ri · #2 01-19-2005, 10:31 PM

It may be flooding, the early fuel injection systems weren't as good as the new ones. Next time you start it, keep the engine reved up a bit and see if it keeps running.

bigdaddy1832 · #3 01-20-2005, 06:53 AM

Thanks for your responce. I will try that. Do you know why it would not fire after it dies if it were flooding out?

Fireplug · #4 01-20-2005, 08:39 AM

Do you have spark after it shuts down??? if not look at the ign module in the dist and all the wiring around the dist.

rpreston · #5 01-20-2005, 09:31 AM

Not sure on what model year it started, but if the ECM doesn't get a signal from the oil pressure sensor (back of intake, left of distr.) the ECM will assume no oil pressure and shut off the ignition. You might want to double check the connector on the sensor. I would have thought that it would immediately restart (then fail again) if that were the case, but I don't know for sure.

rpreston · #6 01-20-2005, 09:39 AM

A second thought. You said it dies after running a few minutes. Does it run long enough for the engine to warm up? If it is, it could be possible that the coil is flaky and heats up and dies...

bigdaddy1832 · #7 01-20-2005, 05:09 PM

Well it isn't flooding because it died when I had it running about 1500 rpms. Just cut off, didn't sputter or anything. Just like I turned off the switch. THe Ignition module has been replaced and also has been tested to make sure it is good. The wires around the distributer all seem fine. That is interesting about teh oil pressure sending unit. Does it use the signal from the same one the gadge uses? If so it registers good oil pressure but I will check it. I checked the fire going to the coil from the distributer and there is none going to the coil after it dies. But it cranks when cold and runs good for about 3 to 5 min. then shuts down. Thanks for all your help.

jdr2008 · #8 01-20-2005, 08:44 PM

I,ve noticed that you have replaced several items, and it seems the coil is giving you the problem after the engine warms up, and after it cools down again it will crank and run and do the same thing again, you never said that you replaced the coil, I would try replacing the coil and see if that would help,since you have already replaced and retested the ICM, I dont know how old the coil is, but it could be the problem. heat and time can affect a coil also, causing it to do strange things, hope that is the problem.

bigdaddy1832 · #9 01-21-2005, 06:44 AM

I will replace the coil today and see if that is it. That is the only part I haven't replaced. I had it tested and was told it was ok but I have to get it running. Could there be something wrong with the distributer causing this? Since the ICM is tested good. Once again, thanks everybody.

rpreston · #10 01-21-2005, 08:43 AM

If its the same as my 90, there is a small coil pack in the distributor. You should have seen it when you took out the ICM. If memory serves, it was only a couple of dollars. I had replaced mine when I rebuilt the distributor last summer.

bigdaddy1832 · #11 01-21-2005, 11:22 AM

The coil for mine is seperate from dist and mounted on intake just in front of dist.

New developments, I testtedthe power to the coil from ignition and it has power there so I tested to see if it went out the coil to the module and power does. I had my tester set for 50 volts and thats what it showed. Now when you pull the coil wire off the distributer and check for spark when cranking there is none. Does that mean the coil is bad?

bigdaddy1832 · #12 01-21-2005, 07:09 PM

Next update, I replaced the coil and it didn't help. I even replaced the ICM again just in case but nothing. I still get no spark at plugs and no spark from coil. Help please?

jdr2008 · #13 01-21-2005, 10:51 PM

It may be the pick-up coil inside the distributor, you can replace that yourself, it runs between 10 and 20 dollars, that would be the only other thing I can think of, maybe someone with some better sense than me will get on board and give you a better idea, good luck. the pick-up coil looks like a doughnut with a couple of wires and a connector on the end of it. or you could go with a whole new distributor, but that would be expensive and we dont know for sure yet if thats the problem.

bigdaddy1832 · #14 01-22-2005, 07:26 AM

How would I replace the pickup coil? Do you have to remove the dist?

Fireplug · #15 01-22-2005, 07:47 AM

Dont you think its time to STOP throwing parts and money and still not fix the problem. You need to get q repair manual and use the no start flow chart because I beleve you might have a ecm problem. It starts then dies after a few min. that sounds like the est/esc controls in the ecm a going or have gone south. Pull your ecm and tap on it when the problem happens and see if it keeps running or anything changes in the idle if it does replace the ecm

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