Tried to go see my Dad last week, and the stalling problem has gotten so bad that I had to turn back. Starts happening after the truck is well warmed up. The power will just fade down, and sometimes it will recover, sometimes it won't. Somewhat hard to start afterwards (hurray for two batteries!) but it hasn't just curled up and died. Annoying as all get out, because I need to keep the truck alive.

What are the chances the oil pressure sensor is flaking and that means the fuel pump is cutting out when the sensor does?

I'd change the fuel filter, bleed the fuel system well, then go from there. Eliminate the common first I'd say.

Run the diagnosis checklist at the top of the forum and post your results.

I'd change the fuel filter, bleed the fuel system well, then go from there. Eliminate the common first I'd say.

The fuel filter has been changed recently, (twice, actually) and bled by GM wrench twisters.

Run the diagnosis checklist at the top of the forum and post your results.

Will do.

What I have so far:




0. Truck will occasionally run fine, and will occasionally stall out at constant speed on highway after warm up (approx 30 miles). Looses power, can watch the tach slide down to a stall.

1. engine cranks

1a. engine starts and runs

1b. Wait To Start Light - 9 seconds

1c. Ambient Condition 59 degrees F

1e. stalling - yes

1f. Stalling, down the road

1g. If Stalling, do you notice loss of dash or instruments? idiot lights start activating, tach drops as engine stalls.

2. Service Engine Light while running- off until after stall

2a. Service Engine light does glow during start/cranking/bulb check: Yes

3. 1994

3a. Odometer reading (181826 miles)

3b. Miles on major engine components if been replaced (example Injection pump) 20K on injection pump. Not sure. Less than 1,000 on lift pump and fuel filter

3c. Indicate the model number on the Injection pump (don't know)

4. Have you scanned for engine codes? no - no scanner available

5. List exact results on engine codes:

6. Air Filter condition (clean)

7. Fuel filter condition - recently changed

8. Condition of Battery terminal connections (acceptable)

8a. batteries less than one year old.

8b. batteries are a matched set

8c. Condition of Major Grounds. (acceptable)

9. Upon cold start, does the radiator hose get hard quickly? Not overly hard, but pressure evident.

10. Upon cold start, do you have excessive white smoke? none noted

11. no excessive cranking time on cold starts, yes after stall

12. not a cold starting problem

13. During hard acceleration, do you have excessive black smoke? no

14. no unusual exhaust smoke issues noted

15. Turbo check out - not checked yet.

16. Do you have an EGR on the engine? (S engine code 8th VIN digit)

17. 1500

18. #2 Diesel

19. no fuel additives

20. Texas

21. recent lift pump replacement, filter replacement and tank cleaning by GM mechanics

22. no modifications

23. no vacuum noted after cold start. recent new fuel cap.

24. Location of PMD/FSD - stock

Will be back at it tomorrow.

I've been experiencing the same symptoms over the past few days on my '94, also with a bit over 181K on the clock. I've also noticed that most of the stalling occurs while the temp gauge is between 140 and 180 during the first drive of the day. Once it reaches operating temp, the problem seems to settle down. I strongly suspect the PMD in it's stock location, also my PMD is the earliest version(#30214). I have a more recent incarnation of the PMD(#34583) ready to be remote mounted as soon as I get the extension harness.
After a very rough morning with the truck today(no less than twenty stalls in a 30 minute period) I decided to tear into all the grounds, and clean them up. They were all much worse than they appeared by a quick inspection. Once you get them apart, it's amazing how filthy they can be. Tomorrow morning will be the real test. I'll let you know how it goes. BTW, I also diagnosed that my Vac pump is dead, causing a turbo wastegate fault. I'm fairly certain that is contributing to the problem as well.
One other thing, regarding not having a scanner. You can read the codes with a paper clip. Go to the FAQ's section at the top of the forum page, scroll down to the link that say "OBD I" and you'll find directions there. Post your code results, I'm curious if you have the same ones I do.

I'll check that out. Thanks!

DTC 35 - Injection Pulse Width Error (Time Short)

That's the only code showing

I had stalling/stumbling more of stumbling actually. Never had my engine completely shut off, but I had the code 35. I had a hole in the main fuel line on the pickup/sending unit on top of the tank. The air was getting into the system and causing all kinds of weird stuff. Fixed that and it has been flawless. Might be something to look into.

I had stalling/stumbling more of stumbling actually. Never had my engine completely shut off, but I had the code 35. I had a hole in the main fuel line on the pickup/sending unit on top of the tank. The air was getting into the system and causing all kinds of weird stuff. Fixed that and it has been flawless. Might be something to look into.

I'm going to guess that that's not it, just because Don Davis Chevrolet dropped the tank to clean out the contaminated fuel Texaco sold me. They cleaned it and I trust them to have tested it, but it is something to keep in mind...

Well, my results today are positive. After inspecting, cleaning, and R&R'ing every ground in the truck I could get my paws on yesterday. I had no stalling issues today. Not saying thats absolutley your problem, but might be a good place to start. The ground that was most suspect was the group under the tranny dipstick lug. I'm guessing the PO at one time pulled the dipstick tube out for some reason, and didnt get it fully seated back in place on re-install. There was a 1/4" gap between the grounds, and the bottom side of the D'stick lug. The grounds were just bouncing around in there. Those are the grounds that go down to the frame on the passenger side, just behind the front wheel.

I had three codes, 35, 36 and 78. Thats your problem, but pulse width "short" AND "long", and the turbo WG problem. I cleared the codes, yesterday, and the SES light came on a few times today, but havent had time to check the codes, will do that tomorrow. I'm certain the 78 will re appear, hoping the 35, 36 and the stalling do not. When I get to a week of driving without a stall issue, I may begin to feel confident that the grounds were the problem and consider it handled. I'm still going to remote mount the PMD as soon as possible.

Well, I'll have a look. Grounds appeared to be okay, but...