All,

My 91 died on the way to work. Misfired like crazy, coasted to the side of the highway and was towed to work.

Car would not restart, all plug wires were still connected, checked some other stuff on the side of the road before the truck came.

Now, I had a few minutes to mess with it at work. Took the dist. cap off, rotor was not broken, so I put it all back together. The rotor was spinning slowly when I took the cap off and cranked the car. The car turns over fine, just does not run or even hint at it.

Checked for codes, and I have H32 , H34 , H36 , H38 . What do these mean? My manual is at home and I am trying to get this fixed today.

Pulled the MAP sensor, and pushed in the schrader valve on the fuel rail (tester is at home also)...Gas came out, but it didn't seem like 40 psi. Had a slow burst then dribbled out. I remember getting sprayed in the face last time I tested it. FWIW...The pump was replaced with the 255 l/hr racetronix pump back in March. You can hear it run for the 2 seconds with key on, it builds pressure, but without a guage I can only assume it is not enough.

My main issue is how do those codes coincide with a hurting fuel pump?

Also, when cranking the car, SYS flashes on the dash occasionally. I checked out all fuses inside the passenger door, and they are all still good.

Any and all opinions/info are much appreciated because I'd like to get this fixed by 3:30 so I can drive it home. If not, I'll get a ride home and tow it home tomorrow or later in the week.

Thanks,

Mike

 

I would suspect either the injectors, fuel pump, or ignition module. Of course, you'll really need some tools to check this stuff out. First, I would verify if you have spark by attaching a timing light to a plug wire and watching for the flash. If no flash, then I would first suspect the ignition module. Check for 12v at the cap connection.
Check for proper fuel pressure with your guage and make sure that it holds around 40 psi without dropping off. Check the injectors with an ohm scale to make sure that they all read near 13 ohms or so. If one reads really low then it is shorting the whole bank. Unplugging the bad one will make it run again. Probably not good to do that for long though. Sorry that I can't think of any Macgyver tricks since you don't have tools with you. Maybe you could catch a ride and bring the above tools with you tomorrow.

 

Update:

Just checked codes again after cranking it...

H31 H33 H35 H37

I am beginning to think my ECM is shot...

Mike

 

Sivek,

I am getting a ride home today, but tomorrow I'll drive my truck in and bring tools with me. Planning on getting my FP guage, timing light, and multimeter.

Injectors are the Blue Bosch ones, 24#'s...Relatively new. Fuel Pump was new in March. Coil and ICM were new just over two years ago, but I bought them from Autozone like a complete MORON.

So...If the timing light shows spark, and the fuel pressure guage shows 40psi, and the injectors ohm out ok...what does that lead me to??? Hopefully I will have spark, and FP will be like 15psi, so I know what my problem is. I know what running out of fuel feels like, but that was not what happened. This was an instant misfire/shudder/engine stalled rather than a hesitation than gradual loss of potential throttle opening.

I've poked around, and the H32,33,34,35,36,37,38 codes all seem to go with a low battery, which at this point, it's kinda close due to the amount of cranking I have tried.

The ECM is a REMAN for sure. I'd like to try a new one but they will not accept returns on electrical stuff which is completely understandable.

Thanks for you help and all is considered and appreciated.

Mike

 

I highly suspect the Autozone ICM without further info. There is some magic about that part being GM or else. I have gone through countless ignition modules on other cars because they weren't GM.

 

Agree.

The engine may restart when cold. Maybe install the old ICM to get home.

Edit: Have jumper cables? Suggest charging the battery with the truck. Electronic ignitions refuse to fire when cranking voltage is below 8v.

 

What were symptoms of the icm?

I'd like to check for fuel pressure and spark before i buy any parts.

If i have spark, does that mean the icm is good at least when it's cold?

Thanks all

Mike

 

If you find no spark at the plug wires and 12v at the cap, then the ICM is likely bad.

 

So with the key on i should have 12 volts at the pink wire which clips into the batt terminal on the dist cap?

If I have that, but no spark, the icm is shot. What about the coil? That was durajunk installed at the same time.

Sorry for the q's...but trying to be as efficient as possible as my time is limited at work to mess around with this car.

Thanks

Mike

 

The coil would be a possibility but I would leann toward the ICM. It would be preferrable to replace both as a set if funds allow. Definitely check for spark on the plug wires. If no spark, check for 12v at distributor batt connection with ignition on as you describe above. Also check internal distributor wiring visually. If you replace ICM, be sure to use grease supplied with new module.

 

Ok, was able to test some stuff this AM.

Fuel pressure hold steady at 38 psi.

Pink wire at teh distributor with the key on showed 10.8 volts, battery measured out at 11.0 volts. I am charging up the battery now.

Cranked it over with the timing light, and while the motor turned over slowly because of the low battery, I did not see any spark. I am going to repeat this test this afternoon when the battery is up to snuff.

What could be the issue at this point? Coil, ICM, ECM?

Thanks All.

Mike

 

should have had spark at that voltage. ICM, Coil, pickup coil are suspect. ECM does not produce spark, only timing of the advance -also uses ref pulses from distributor to fire injectors.

I have read where service techs found def ICM ten to one, whatever, to either coils. no way to verify ICM on the vehicle, and it's a $20 item. any of the 3 are common failures.

joe

*** just noticed the codes. L98 does not have all of those codes, except 32, 33, 34. are you in the ECM codes, or CCM? Is this L98? those look like SRC codes.

 

I agree. At this point, I would consider buying the ICM and coil from GM as a set. I am amazed that a Duralast ICM has lasted this long.

 

All,

the codes were likely from a low battery...I am ignoring them at this point unless the ECM is junk.

I just ordered an ICM made by AC Delco from rockauto. 52.00 shipped to my door. Dealers wanted 90 and 110. 90 is MSRP, and the dealer selling at 110 sells above MSRP. Scumbags.

This is not my DD and I have my truck, so I am no rush to fix this...If I need to pick up a coil or a pickup coil, i'll do that locally or order them online again. Taking the distributor cap off takes under 5 minutes as I have made labels for my plug wires at this point.

I understand the replacing the coil and ICM with delco parts at the same time, but if I can save 50.00 and ICM's are more likely to suck, then I am going to try it first.

I'm hoping to get it going Friday when everything comes in.


Thanks,


Mike

 

Be sure to use the packet of grease that comes with the module. It helps to transfer heat to the base plate.

 

Update, new icm didn't fix, pulled the coil and it was junk. Replaced it with a napa part, fired right up, died 20 mins later on the highway ....any more ideas?

What's the chance the coil or icm died again?

Mike

 

do you have spark?

how did you conclude the coil was junk? unless there are broken wires, it has to be tested with a meter.

not likely that either part died again. did you check the pickup resistance while you were in there? if not, spark starts at the pickup. if you have fsm, chart C-4 is the place to begin.

 

It could be the pickup or internal wiring. Perhaps moving a wire made it run for a while. Perhaps a distributor rebuild is in order.

 

Pickup ohm'd out 980. Spec is 500-1500.

Coil ohm'd out at .7 ohms. Spec is very low/zero

 

What's the chance the alt is over charging and frying parts?