Code 32 causing no-start & performance issues! 94 k1500 5.7

[Maui_chevyk1500]

Ok so my truck is A ‘94 Chevy k1500 5.7 auto pretty much stock.
I’ll start from the first time I got the code 32
Truck would drive fine on short trips for weeks but as soon as I would take it on any drive with highway speeds for a sustained amount of time, after it was parked it would not want to start again.
I Tried jumping it and checking all the obvious things but it seemed like no fuel or no spark.
Then I would return the next morning and it would start up first crank and run fine all the way home.
I soon read that the ecm takes a test reading after a certain amount of 50mph driving, It Cycles the EGR and waits to see if the difference occurs at 02 sensor. Based on that reading it can throw code 32.
From the beginning I have tried:
-new cap and rotor.
-Tested fuel pressure before the filter came out to around 10 psi.
-Fuel pump is only a few years old
-removed and cleaned EGR valve (it was definitely funky and black).
-replaced my temp sensor because I realized it was broken and unplugged.
- also check & replaced numerous grounds in the engine compartment.
-new spark plugs because it was needed
-checked vacuum system visually to verify correct and not damaged.

After spark plugs it actually seems to idle worse. Idle fluctuates slightly when it didn’t before
Also stalls from time to time at idle.

Basically still not sure if my problem lies with the EGR/MAP or a short to ground/ bad ground somewhere in the harness.
I am not very confident with a multimeter and I don’t want to keep throwing parts at it.
also it’s hard to tell at this point wether I’ve fixed it or not because I am hesitant to take it on a drive long enough to get possibly stranded.
I Would love to be able to positively identify the issue and know for sure it’s fixed.
Sorry for the long post but I hope it’s all helpful information.
Thanks in advance for any input!

 

[someotherguy]

You may have a code 32 but it's not the cause of your intermittent no-start condition. Ignore the 32 for now. Next time it won't start you need to be ready to determine why. Be ready with spark checker and fuel pressure test gauge, because it'll be one or the other, no spark or no fuel.

Richard

 

[Maui_chevyk1500]

thanks for the reply @someotherguy.
Ok so say I determine it’s no fuel or no spark. What would the next step in diagnoses be? And what would either outcome mean?
Also I should add that when it no-starts I can hear the pump priming when I turn the key on but I don’t see any priming spray happening at the TBI with key on or starting.


I should also mention I have long had this common problem of loose wires on the fuel pump relay pigtail connector which I have ordered the new connector and should be installing in the next week.
Of course when the truck leaves me stranded I mess with that connection and it doesn’t make any difference in the no- start like it has at times in the past when it simply wasn’t plugged in well enough and wasn’t making contact.
Anyway I wish I didn’t have to wait until I’m stranded to be able to troubleshoot this issue but it makes sense what u recommended.
Thanks again!

 

[someotherguy]

Injectors don't spray until you actually crank the engine. Just turning the key to the ON position, should be no spray at all. Now you say when you get the no-start: even while cranking, you're not getting spray from the injectors? That's good information.

At that point I would be hooking up the fuel pressure test gauge. IF you have sufficient (9-13 psi) pressure, but no spray, my immediate suspect is the ignition module. They can fail in several ways. No spark, no injector spray, or both. They can be intermittent. Also, the harness connections to the module can fail from age/heat, so if the wiring there looks brittle and damaged, it will need to be addressed.

If you replace the ignition module be sure to clean off the distributor base where it installs, and apply a thin layer of heat sink compound. Choose the correct product here. Some use plain silicone grease (dielectric grease) and the tube for the stuff even says it's good for that application but I disagree. Actual heat sink compound has extra ingredients for better heat transfer.

Richard

 

[L31MaxExpress]

Injectors don't spray until you actually crank the engine. Just turning the key to the ON position, should be no spray at all. Now you say when you get the no-start: even while cranking, you're not getting spray from the injectors? That's good information.

At that point I would be hooking up the fuel pressure test gauge. IF you have sufficient (9-13 psi) pressure, but no spray, my immediate suspect is the ignition module. They can fail in several ways. No spark, no injector spray, or both. They can be intermittent. Also, the harness connections to the module can fail from age/heat, so if the wiring there looks brittle and damaged, it will need to be addressed.

If you replace the ignition module be sure to clean off the distributor base where it installs, and apply a thin layer of heat sink compound. Choose the correct product here. Some use plain silicone grease (dielectric grease) and the tube for the stuff even says it's good for that application but I disagree. Actual heat sink compound has extra ingredients for better heat transfer.

Richard

Tube of the correct stuff is cheap.

https://www.oreillyauto.com/detail/c/standard-ignition/standard-ignition-silicone-grease/std0/sl3

 

[Maui_chevyk1500]

Injectors don't spray until you actually crank the engine. Just turning the key to the ON position, should be no spray at all. Now you say when you get the no-start: even while cranking, you're not getting spray from the injectors? That's good information.

At that point I would be hooking up the fuel pressure test gauge. IF you have sufficient (9-13 psi) pressure, but no spray, my immediate suspect is the ignition module. They can fail in several ways. No spark, no injector spray, or both. They can be intermittent. Also, the harness connections to the module can fail from age/heat, so if the wiring there looks brittle and damaged, it will need to be addressed.

If you replace the ignition module be sure to clean off the distributor base where it installs, and apply a thin layer of heat sink compound. Choose the correct product here. Some use plain silicone grease (dielectric grease) and the tube for the stuff even says it's good for that application but I disagree. Actual heat sink compound has extra ingredients for better heat transfer.

Richard

Yes, when the the no-start was occurring I verified no spray at tbi while cranking it over. I will look into this ignition module because I’m sure it is 28 years and 230k miles old most likely.

On another note, let’s say the fuel pressure is below spec when checked, would low pressure be enough to not allow the priming spray to happen?
Also would the low pressure be caused by a tired fuel pump? Or something else in the wiring possibly?

 

[Komet]

It's not worth your time to worry about every possible no start scenario; the data collected at the time of failure will begin your diagnostic journey. Low fuel pressure is typically a bad pump or something attached to it, but it can also be a physical restriction in the system.

 

[Maui_chevyk1500]

It's not worth your time to worry about every possible no start scenario; the data collected at the time of failure will begin your diagnostic journey. Low fuel pressure is typically a bad pump or something attached to it, but it can also be a physical restriction in the system.

Ok thanks I appreciate the advice, I will try to have my tools ready when it happens next and I’ll report back with my findings…

 

[someotherguy]

Tube of the correct stuff is cheap.

https://www.oreillyauto.com/detail/c/standard-ignition/standard-ignition-silicone-grease/std0/sl3

This particular product is one I'll have to disagree with you on. That's just plain dielectric (silicone) grease. I'd use that on spark plug wire boots and maybe in bulb sockets. For ignition modules, I'd use actual heat sink compound. Yep, it's still a silicone grease, but it's got extra material to improve the heat transfer. Sometimes ceramic powder, zinc oxide, aluminum oxide, etc. Still only a few bucks but IMO a better choice for this application. Can be had at any place that sells computer/electronic parts, and as someone else mentioned a while back, Home Depot and similar places.

I'm sure plenty of people have used plain silicone grease without issue but I'll hedge my bets with something that is more efficient at heat transfer. The main purpose is to bridge the air gap between the two surfaces, but one type of product is shown to do a better job than the other.

Richard

 

[L31MaxExpress]

This particular product is one I'll have to disagree with you on. That's just plain dielectric (silicone) grease. I'd use that on spark plug wire boots and maybe in bulb sockets. For ignition modules, I'd use actual heat sink compound. Yep, it's still a silicone grease, but it's got extra material to improve the heat transfer. Sometimes ceramic powder, zinc oxide, aluminum oxide, etc. Still only a few bucks but IMO a better choice for this application. Can be had at any place that sells computer/electronic parts, and as someone else mentioned a while back, Home Depot and similar places.

I'm sure plenty of people have used plain silicone grease without issue but I'll hedge my bets with something that is more efficient at heat transfer. The main purpose is to bridge the air gap between the two surfaces, but one type of product is shown to do a better job than the other.

Richard

Weird, because that is what comes with the Standard Ignition modules when you buy them from Oreilly or Rockauto. Never used anything but that compound for the last 20 years. I cannot think of a single module I have had fail, save for the one that shorted out when the tachometer shorted out on my old TBI. I have used that on all my TBIs, TPIs and Vortecs when I changed the module and even on the high-performance DUI modules that have more dwell time built into them for a hotter spark.