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OPS/Lift pump?

T

thr464fuf

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Location
Rochester, MN
Went out and started my 2000 chevy 3500 6.5l turbo diesel yesterday. Started normally. Did a few things while it warmed up. Came back 5-10 mins later and the engine had quit. I just replaced the PMD and relocated it it the bumper a few weeks ago. Also replaced all glow plugs at that time. Truck still won't start. I also now don't get a "wait to start" light when I turn the key. No noise coming from the lift pump and no fuel coming out of the T valve. I pulled the fuel filter and the housing was almost empty. I am guessing the engine quit due to lack of fuel. Bad lift pump? Bad OPS? Both? Any ideas?
 
The PCM or OPS controls the lift pump. The PCM also controls your WTS light and Glo-Plugs. You would have had to have the OPS fail and the PCM or LP relay.

Do you get an SES light with the IGN ON, engine OFF?

Did you check the GP fuse? Do you get any codes?
 
No SES light with ignition on and engine off. I did try to jump the lift pump with 12v and just got a faint click, not pumping. I replaced the fuel pump relay. No change. I do not have a code reader. All fuses are good. checked with continuity tester.
 
Sounds like your PCM failed, or the power to it. Dont buy a new one just yet though.

I dont have the pin out of the ECM for OBDII, and I dont know if it is the same as OBDI for power. Youll need to check its power source when IGN ON and each of the grounds that it is supposed to have.

And youre positive the PCM fuse is good? check continuity through it.
 
thr464fuf said:
No SES light with ignition on and engine off. I did try to jump the lift pump with 12v and just got a faint click, not pumping. I replaced the fuel pump relay. No change. I do not have a code reader. All fuses are good. checked with continuity tester.
Click to expand...

If you jump and there is still no fuel, then the LP is bad and NOT the relay. Change the LP, get a LP for 93 trucks that has a little bit more pressure and volume.
 
Blown ECM fuse. Replaced and it started right up. Fingers crossed that it stays running. Thanks for your help. I owe you a cold one!
 
buddy said:
Sounds like your PCM failed, or the power to it. Dont buy a new one just yet though.
Click to expand...

definately way soon to make that assumption, I'm at work no time to go into detail you might want to have a run through the dignostic list in meantime, your new driver, new or just new to you, you remoted it, your remote or you buy it from somebody.
 
With truck running I opened the T valve to check for fuel. Nothing out of hose. Engine died within 30secs. I tried applying 12v to the lift pump and got nothing. I am assuming that my lift pump is bad and will replace it. Would a bad lift pump cause the ECM fuse to blow or am I looking at other issues?
 
PMD is new out of box Dtech. Attached to heat sink in front bumper with aftermarket extention. Grounded to heat sink and to original ground lug on top of IP.
 
Turbine Doc said:
definately way soon to make that assumption, I'm at work no time to go into detail you might want to have a run through the dignostic list in meantime, your new driver, new or just new to you, you remoted it, your remote or you buy it from somebody.
Click to expand...

Except it was a correct assumption.

No GP light, No SES light, No start says NO PCM power to me.

Now if the LP doesnt work thats another issue to fix. Sounds like its just broke and needs new LP.
 
thr464fuf said:
With truck running I opened the T valve to check for fuel. Nothing out of hose. Engine died within 30secs. I tried applying 12v to the lift pump and got nothing. I am assuming that my lift pump is bad and will replace it. Would a bad lift pump cause the ECM fuse to blow or am I looking at other issues?
Click to expand...

It happens probably when you tried to jump the LP. Your jumper contacted the wrong place. Of course, things can happen in this truck.
Try to troubleshoot the LP and also the OPS that controls the LP before condemning anything. The LP and OPS are another weak point in addition to the PMD. You have made the right decision to move the PMD to the bumper on a heatsink.
 
Replaced LP with new meant for a 93 as mentioned in other threads. Had to use the plug from the old pump but was no big deal. turned key and heard the new pump run. Checked at T valve and had good flow right away. waited for WTS light to go off and truck fired right up. Thanks again for everyone's help. Cold ones for all.:thumbsup:
 
Good deal.

If you want to test the LP, with the truck off, or drain water from the filter assembly there is a red wire in the engine bay, near the fuse/relay center that if you apply 12V to it, it is specifically to test the LP. It connects to the LP relay in the normally closed position (so when its off)
 
buddy said:
Except it was a correct assumption.

No GP light, No SES light, No start says NO PCM power to me.

Now if the LP doesnt work thats another issue to fix. Sounds like its just broke and needs new LP.
Click to expand...


You know what they say about assumptions,

Since I've been playing with 6.5s begining in 2000 at multiple forums, where I can count maybe 1 hand number of times there has been a bad PCM found (some of the guys that mentored me been doing it before 2000 have said similar).

Not saying I am THE expert on this, I have been known to be more right than wrong on these things; but I did not want to scare him into thinking the worst too soon, we needed more info before going into the PCM diagnostics mode. Once when I was purely a mechanic on jet turbines & control systems, I was all about hollering "bad trons" rite off the bat & got proven wrong with that call way to many times to go there now.
 
Turbine Doc said:
You know what they say about assumptions,

Since I've been playing with 6.5s begining in 2000 at multiple forums, where I can count maybe 1 hand number of times there has been a bad PCM found (some of the guys that mentored me been doing it before 2000 have said similar).

Not saying I am THE expert on this, I have been known to be more right than wrong on these things; but I did not want to scare him into thinking the worst too soon, we needed more info before going into the PCM diagnostics mode. Once when I was purely a mechanic on jet turbines & control systems, I was all about hollering "bad trons" rite off the bat & got proven wrong with that call way to many times to go there now.
Click to expand...

I just skip to the real problems :)

If you notice I mentioned that in order for the LP to not work the OPS and PCM/LP relay had to fail, and that if the SES and glo plug lights arent working it is a PCM or PCM power problem. So all signs pointed to a PCM problem. I didnt say the PCM was fried right out, I recommended checking power to it.

He said all the fuses were fine, so I reiterated to check the PCM fuse.
 
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