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stalling

Did you do some diagnostics before parts swapping? Anymore a new part seems just as likely to bad, as an un-diagnosed part on the truck.

Have you tired running with the fuel cap loose?

Have you tried running with the lift pump jumpered?

Have you run with a fuel pressure gauge?

Have you checked for voltage at the lift pump with the truck running?

If your OPS is putting out any volts while the truck is running, do the lift pump relay upgrade - you can most often do that upgrade and leave the bad OPS right where it is. At that time the OPS only needs to put out enough juice to trigger the relay.

I have been running "bad" OPS's in at least 2 vehicles for many years. The other vehicle I sold, so I do not know if it is still running with a bad OPS

Have you run 1/2 gallon of fuel or so out the drain T with the lift pump jumpered and timed how long it took?

Last thing to try is to open the T valve with the truck running and see if it dies.
 
Did the t valve while running. Kept running.
The only new parts are the OPS and the harness from Leroy.
It wouldn't start with the new harness or the AC Delco OPS.
Does the PMD need to be grounded to work?
When the truck was running. I swapped the PMD when it was running and it made no difference.
I swapped it while it wouldn't start, no difference.
Thanks.
 
The Borg Warner OPS is just as good as any other OPS IMHO having sold many and not a single warranty.
There probably all made in the same plant somewhere? ;)
With my relay harness its a mute point anyway.
 
Could possibly be a wiring issue, ground issue or even an ignition switch.

I just reread the thread and I didn't see anything about checking/adding grounds or battery cables.

I always add grounds. Especially to the stud on the back of the engine that everything goes to. I have seen that stud lose connection more than once. I add grounds to the frame, to the Injection pump, to the battery box bolt and from the heater blower ground to the dash mount bolt just a few inches away.

You must have a ground to the injection pump

These trucks are very fussy about being grounded.

I have also been changing my engine wiring harnesses as I work on these old things. In my opinion the harnesses are exceeding their life expectancy.

I have had to replace the ignition switch on all of my 6.5's except the 94's. Our 95 Tahoe and 96 Suburban haD SIMILAR issues as yours and new ignition switches cured both

I'm not big on throwing parts at things without doing any diagnostics, but the wiring harness and the ignition switch are things I would try on your 95.

I would do the wiring harness first. Just as a matter of routine maintenance.

A plugged or plugging injection pump return line can cause no run issues, but that does not sound like what you have.

If you have the optic sensor filter harness on your Burb, take it off, throw it away and plug directly into the injection pump

Change out the short harness that plugs into the PMD - that harness also has the ground that runs to the injection pump
 
jrsavoie said:
If you have the optic sensor filter harness on your Burb, take it off, throw it away and plug directly into the injection pump
Click to expand...
That's the first I've heard of the optic sensor?? Where and what does it do?

I'm going to spend tomorrow working on the truck.
I'm retired but manage to work on a LOT of things for everyone but myself??
Working on 3 junk riding mowers trying to make 1 junk mower, a 98 200hp Johnson(broken shift rod and a 25hp Johnson(seized drive shaft) and more and more and more.
 
I did a code scan again. 29/36/49/57/62/91????
I search the motor for loose wires and questionable grounds!!!
I found some but not positive they were actually loose. Maybe ???
I removed and replaced the connectors anyway.
Tried to start and nothing.
Then from the diagnostic tests the first thing I did was disconnect the optical sensor and tried to start it.
Started right up.
Plugged the sensor back in and it still runs????
I deleted the codes.
Started and let it run, shut down, started again.

Did another code check.
Found 12/12/12????
Not positive the problem is fixed but how can you tell if there is a problem if it runs and doesn't show codes??

Anyone want to buy a burb? :)
 
I have not been back through the whole thread however, I had a similar problem and diagnostics kept going back to PMD. I changed many times.. I knew they where good so finally changed IP ran great for 3 weeks or so and started again, long story short and a number of long talks with shop the I bought IP from he warrantied it for me changed again, ran great for 3 weeks or so and started all over.... the answer was a bad extension harness on PMD one connection inside was not crimped or soldered. had it not been for a "beeping" ohm meter and my son, I would still be looking or running a mechanical!
 
On the 94 I had a similar experience. I thought it was the PMD from the got go. I tried 3 PMD's, at least 3 extension harnesses.

I checked for power off the plug that the PMD plugs into and everything showed good. The harness on the engine that the extension cable plugs into was the issue.

I checked for continuity on the extension harnesses, but never checked that end for proper voltage until after the truck started. By then I had things pretty well narrowed down. At least your working in a better climate than I was that winter.

I didn't figure everything out until I made a test harness out of a spare harness that I had not tried yet. I plugged it in to test for volts in the start position. Cindy hit the key and to our amazement the truck started. After more close looking and testing I figured out which pin was giving me an issue. If you find my thread from a couple of Decembers ago, there are links to directions on how to test the pins on a PMD and Harness.

I also periodically pull the IP return line and run Sea Foam through the Injection pump. Probably a wasted effort to clean the optic sensor. Don't know if it actually does any good or harm, but it makes me feel like I'm doing something. I also run a bowl full through every time I change the fuel filter.
 
Jerryjerry05 said:
I did a code scan again. 29/36/49/57/62/91????
I search the motor for loose wires and questionable grounds!!!
I found some but not positive they were actually loose. Maybe ???
I removed and replaced the connectors anyway.
Tried to start and nothing.
Then from the diagnostic tests the first thing I did was disconnect the optical sensor and tried to start it.
Started right up.
Plugged the sensor back in and it still runs????
I deleted the codes.
Started and let it run, shut down, started again.

Did another code check.
Found 12/12/12????
Not positive the problem is fixed but how can you tell if there is a problem if it runs and doesn't show codes??

Anyone want to buy a burb? :)
Click to expand...

How fairly good shape is it in? How much do you want for it?
 
Went for a ride around the neighborhood(afraid to go far) did ok for the first five min.
Then shut off like someone hit the key.
But started right back up.
1 min later died again, got out and turned on the LP switch(from Leroy's harness) that I installed.
Got home and was too hot to mess with(not overheating)(already tried the pulling the sensor off the thermo)
I'm gonna try to replace the OS filter(have a spare from a motor I bought)then go for a ride.
That filter's in there DEEP. Gonna have to take part of the intake off.
Then I'm gonna change the PMD to a known good one.
 
I replaced it (OSF)and it stalled again.
Then I removed it completely and it ran and ran and ran.
Gonna take it out today(sat) and see if I can get towed back again.

Thanks all for the hints and help!!!!!!
 
It could still possibly be a bad harness issue. I've seen where you move a harness around and things get just right so a connection is made, Later on things can jiggle and connection be lost again.

Hopefully you've cured your woes
 
I repaired or redid the grounds??? Still wouldn't start.
Tried starting with the replacement OSF no start.
Took it out and it started.
Let it idle for 45min.
Took it for a short ride yesterday 1-2mi. NP
Again today 5 mi. NP
Recap: Tank full and clean, LP working as it should.
Stalled and I changed the OPS started and ran a short while.
Did that again, changed and started , ran for a short while.
Installed the relay and harness from Leroy's Diesel. No difference.
Used AC Delco OPS. and a Borg Warner. No difference.
When it was cool it would start. Then shut down when warm(not overheating).
Then changed the OSF and still nothing??
Took it out and left it out and it runs!!!
I also tried a second PMD mounted under the front bumper.
The old wouldn't come off so I drilled and tapped holes next to the old to supply a good mount.
Now I have 2 mounted in case one goes bad.
Hopefully this will run for another year??

Changed the OSF and no difference, removed it and it starts.
 
Throw the osf as far as you possibly can. Then run over and smash it with a hammer and throw the scrap parts as far as you can. If you go buy another one, bring the hammer with you and smash it in the parts store before bringing it home- to throw as far as you can. New parts do not mean good parts. You dont need that thing, at least leave it in the glove box for a month or two and deal with the am radio interferance until your truck has some miles on it without problems.

After that, do you get the no start issue? If so jiggle the wire harness while someone is cranking like your trying to give it shaken baby syndrome. I'm talking homer simpson choking bart here.

You did mount the pmds onto heat sinks, which are mounted to the bumper, right? Not just onto the bumper?

Is it only when hot the truck wont start?

If shaken harness syndome has no effect on no start, next pull an injector line off an injector and watch to see if fuel is being supplied while the no start is occuring.
You might be fighting more than one issue.

I feel for you. Bobbie Martin wrote this book...
 
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