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Set of problems dating back 2 years

regrind

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Hello all I am new to this site...any advice would be appreciated.

What I have is a 1994 Chevy C2500, L65 engine, 212,500 miles. Purchased in 2012 with 195000 miles. History mostly unknown, previous owner did a PMD and relocated it to the intake plenum. I have had very few problems with the truck in general, had to do shift solenoids but thats all when it comes to actual repairs. PLenty of maintenance-tires brakes oil and fluids.

About 2 years ago I started having a problem where under continuous throttle or sudden hard throttle like trying to merge it would cough and stumble like a gas engine misfiring. No codes displayed when this happens. About 8 months ago I had a long crank and rough start condition. If I restarted the engine after a few seconds the problem would disappear. If I continued driving after the initial start it would run a little rough and the check engine light would remain on. Codes 17 18 and some others which I've forgotten. I believe that episode was a load of bad fuel, after another 10 gallons of fuel in the tank the problem disappeared 4 days later and has not returned since.

So the last couple days I've had time to fix a coolant leak from the timing cover, I did a water pump thermostat and some hoses when i was in there. I returned the injector pump to the exact same place it was before removal (I scribed the pump and cover in 2 places). crank sensor has been plugged back in.

Now the engine starts harder and runs ok, but on my first test drive while i was nearing 40 mph from a stop after driving a couple miles it dropped into limp mode, minimal power, and the check engine light came on. It promptly stalled after about 1/4 mile and i rolled into a side street. Restart the engine, check engine light gone, drives the next 2 miles home fine. Get home and it isn't running as...sharp as it should be. Misses occasionally and the engine jerks around when it does. None of this had happened before the timing cover was removed.

I know the service manual says to re-time the pump when the cover is removed, but I made sure it went on in the same location. I no longer have access to a scan tool of any kind. Jumping the ALDL connector gave me code 18 and some others which I couldnt decipher. I usually would have used a scan tool.

If you are still reading this and see a pattern which I am missing or have any advice at all I would appreciate it. If its anything short of an injector pump or an engine overhaul I will probably do it. I have a new delphi lift pump right here which I need to install. I get the feeling the inj pump has been done, someone has been in there undoing all the hoses and connectors because they're held on with small screw clamps and zip ties. PMD is probably from SS diesel and who knows what else is...it had an SS diesel sticker on it when i bought it. For all I know the whole engine has been done. Just trying to give all the information.

Thank you
 
Leroy won't be back from vacation till the 22nd. I would clean the grounds in the meantime. Don't buy cheap Chinese extension harness off fleabay.
 
Cleaned grounds, while I was in there I noticed there's a ground from the PMD to the heat sink, which is just barely hanging on to the intake. i read somewhere that the PMD needs to be grounded directly to the injector pump would it be a good idea to just take that and ground it directly to the pump with one of the optical sensor screws?
 
"I believe that episode was a load of bad fuel"
Gasoline, bugs, or water contamination? Did you throw away the fuel or force it through the injection system?

Codes are useful - so pull current codes. Post them up here. Video the SES light flashes and post on here if you can't figure them out.

The lift pump thread is a good read as well as looking for air in the fuel system via a 1/4" clear return line off the IP. Any air must be eliminated - note a restriction like a plugged fuel filter, plugged tank sock, or kinked hose can have the IP draw enough vacuum to vaporize diesel looking like air. You can vapor lock a diesel. Bad fuel may have plugged the sock or filter.

The sell a tool to set timing. Scribing a mark is NOT an accurate way to set pump timing. The bolt holes etc. are just too sloppy.

The PMD on the intake "oven" has shortened it's life if not ruined it. Yes, it is a way to make GM's design worse! Front bumper is a cool location not the 210 degree air coming off the fan and then still has heat soak when you shut down. The intake itself can get over 300 degrees under sustained boost. :facepalm: Who's stupid idea was it to sell a kit that goes there? Oh yeah - being cheap and not making a good extension cable to reach anywhere else. Put it back on the pump where fuel cools it while running or put it on the front bumper...
 
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Cleaned grounds, while I was in there I noticed there's a ground from the PMD to the heat sink, which is just barely hanging on to the intake. i read somewhere that the PMD needs to be grounded directly to the injector pump would it be a good idea to just take that and ground it directly to the pump with one of the optical sensor screws?
Yes
 
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