6.5Turbo owner // Chevy 3500 // Travels stopped with issues

[KyleH]

Hi everyone; my name is Kyle & I travel in a short school bus, that’s a Chevy Express 6.5 turbo diesel. I’ve been recently stopped along my way with issues that have me scratching my head. To be honest I wish I would have found this site sooner- because I’m already $1000 in repairs which have yielded no success.

In the past week, I have replaced my injection pump as I assumed that was my issue. I’ve read another thread here with lots of great info on the same subject.. just wanted to see if anyone may be able to respond in real time/ help me trouble shoot.

I am getting fuel from LP & my fuel filter has been replaced brand new.. fuel up to the T valve & pressure ( not sure how much). But No fuel past injection pump to injectors..

New injection pump has PMD mounted; but I have PMD relocated under hood from previous owner.. have read on other forums it’s best to be relocated - so I have it hooked to the old PMD. Perhaps I should hook it to the new one?

All fuses are good- but I really need to find/ check all grounds..the thing is, it’s a short school bus mod & it’s difficult to differentiate which systems control what. I assume everything under the hood is for the mechanics and elsewhere is auxiliary..

My questions are :

What should my pressure be from LP /filter to IP?

What will installing a clear tube in front of the IP tell me? Recirculating fuel within the pump? Bubbles?

& How long should I expect to bleed the lines? I have tried maybe 10 times with no fuel showing yet.

Any help is greatly appreciated! not in the best area and would like to carry on soon. Hopefully this isn’t an inappropriate post in the wrong category. Thank you

 

[ak diesel driver]

Fuel pressure should be 6-8 with factory LP and never go to zero even at full load.
The clear tubing coming out of the return is to check for air, other than a stationary bubble at the top you shouldn't have any bubbles even tiny ones. Big issue here as these rigs get older.
I think the real issue you have is probably a bad PMD. Even on a relocation harness they go bad. Another common issue is the extension cable itself. Try plugging your pmd in directly to the IP without the harness.
Also pull as many glow plugs as you can so you don't kill the starter, you can loosen the injector lines and should see wetness at the injectors when it's primed.

 

[KyleH]

thank you for taking the time to respond.
I have just switched from auxiliary pmd to the one that’s built on the new pump and my service engine light went off.,

Going to try and bleed the lines and get some fuel!

if not looks like I need to get a tool to measure pressure from the other end to make sure.

Fuel pressure should be 6-8 with factory LP and never go to zero even at full load.
The clear tubing coming out of the return is to check for air, other than a stationary bubble at the top you shouldn't have any bubbles even tiny ones. Big issue here as these rigs get older.
I think the real issue you have is probably a bad PMD. Even on a relocation harness they go bad. Another common issue is the extension cable itself. Try plugging your pmd in directly to the IP without the harness.
Also pull as many glow plugs as you can so you don't kill the starter, you can loosen the injector lines and should see wetness at the injectors when it's primed.

 

[KyleH]

Another thing I’d like to add for reference is 2 weeks ago I had it die on me like it had a short or fuel pump went out suddenly., vehicle went silent and coasted to a stop.
Dash said service engine, check gauges & battery... The other day it started right up and I drove around the corner and it died on me the same way & has yet to start again. Not sure this would help at all but.. I suppose PMD or IP can go out suddenly like anything over time?

Also found the T-valve was leaking for some time. Could be why the failure... stumped but I have narrowed it down to no fuel spraying from injectors so I think it’s pretty close..


I’ve also recently messed with some auxiliary wires exchanging a water pump for the inside of the coach.. Pretty sure this is an entirely different system but all tied together somehow.. I thought this maybe to be my problem; but I think a major coincidence.

 

[ak diesel driver]

Classic PMD issue

 

[WarWagon]

Any codes in the ECM?

After you fix it: Underhood heat is worse than fuel cooled on the IP. Get the PMD on the bumper where it can get cool air NOT the 200 degree air coming off the radiator and heat soak when the engine is off.

 

[Will L.]

Follow the above advice. I strongly second the remove glow plugs. It will help a lot in saving the starter from burning up from too much cranking. When you get fuel it will be a mist coming out of the glow plug holes.

Yes the clear is basically to see if bubbles are there. Any bubbles mean there is a leak in the fuel line but instead of leaking out diesel, air gets sucked in and it can run tough to not running at all.


Looks like Van/hummer intake manifold and center mount turbo- The picture was taken with camera right on top of the turbo?

A few more engine pics won’t hurt- maybe we will spot something amiss.

 

[KyleH]

Any codes in the ECM?

After you fix it: Underhood heat is worse than fuel cooled on the IP. Get the PMD on the bumper where it can get cool air NOT the 200 degree air coming off the radiator and heat soak when the engine is off.

No codes. There was service engine light but no codes which was odd. Also check gauges. I connected the PMD on the new pump instead of the remotely mounted old one & the service engine light went off. So I feel this is surely my problem. Having a hard time bleeding tho

 

[KyleH]

Follow the above advice. I strongly second the remove glow plugs. It will help a lot in saving the starter from burning up from too much cranking. When you get fuel it will be a mist coming out of the glow plug holes.

Yes the clear is basically to see if bubbles are there. Any bubbles mean there is a leak in the fuel line but instead of leaking out diesel, air gets sucked in and it can run tough to not running at all.


Looks like Van/hummer intake manifold and center mount turbo- The picture was taken with camera right on top of the turbo?

A few more engine pics won’t hurt- maybe we will spot something amiss.

Just to be clear, remove the glow plugs themselves not just the harness connecting ? And keep the lines to injectors cracked ?

 

[KyleH]

Follow the above advice. I strongly second the remove glow plugs. It will help a lot in saving the starter from burning up from too much cranking. When you get fuel it will be a mist coming out of the glow plug holes.

Yes the clear is basically to see if bubbles are there. Any bubbles mean there is a leak in the fuel line but instead of leaking out diesel, air gets sucked in and it can run tough to not running at all.


Looks like Van/hummer intake manifold and center mount turbo- The picture was taken with camera right on top of the turbo?

A few more engine pics won’t hurt- maybe we will spot something amiss.

I will upload some more pics in the morning. Thank you guys for the guidance

 

[Will L.]

Remove the glow plugs from the heads. Tighten the lines onto the injectors. With no compression the engine will spin over crazy fast and will cycle the injection pump a lot. This will purge the air out of the lines through the injectors and you will see a mist of diesel fuel.
There is a few different “counts” that gm used over the years to not burn up starters. I stick to the tried and true:
30 seconds on, 30 seconds off,
30 seconds on, 30 seconds off,
30 seconds on, 30 MINUTES off.

This gives the starter motor and solenoid time to cool off. Otherwise it cools the components and a new starter gets installed.

Do NOT use starting fluid on this engine. Too little won’t help and one drop too much will destroy the block and heads. If you do get away with the tight amount, Any starting fluid gets on the glowplugs and they form a crystalline structure rendering the plug useless so unplug the relay when desperate and willing to risk the engine becoming scrap weight.

 

[KyleH]

Remove the glow plugs from the heads. Tighten the lines onto the injectors. With no compression the engine will spin over crazy fast and will cycle the injection pump a lot. This will purge the air out of the lines through the injectors and you will see a mist of diesel fuel.
There is a few different “counts” that gm used over the years to not burn up starters. I stick to the tried and true:
30 seconds on, 30 seconds off,
30 seconds on, 30 seconds off,
30 seconds on, 30 MINUTES off.

This gives the starter motor and solenoid time to cool off. Otherwise it cools the components and a new starter gets installed.

Do NOT use starting fluid on this engine. Too little won’t help and one drop too much will destroy the block and heads. If you do get away with the tight amount, Any starting fluid gets on the glowplugs and they form a crystalline structure rendering the plug useless so unplug the relay when desperate and willing to risk the engine becoming scrap weight.

Thankyou! I will give this a try in the morning

 

[BIGR]

Welcome to The Truck Stop, KyleH.

Looks like these guys have already offered some great advice and tips for your truck issues.

Good luck on your troubleshooting and repairs

 

[KyleH]

Ok just an update- maybe you guys can help.
I have an older mechanic helping me currently.. we were going to try bleeding the lines when we realized we should check power to the IP solenoid.. it’s getting ~3.5v

however now the LP is not working.. hmm

 

[KyleH]

Still having issues. The main fuel harness only has 12v supplied to 4 pins out of the 20+... any ideas? LP was working yesterday... feeling stumped .. got to be electrical so chasing .. ugh ... in the photo holding the unhooked harness, my index finger indicates which row is getting voltage .

driving myself crazy. LP was working yesterday..

 

[WarWagon]

Just jumper the lift pump "ON" direct to battery for now. Lots of "maybe it works when" as GM tried a lot of things. Engine running it should be running. Everything else is a "maybe" and depends on year.

In depth left pump:

Lift Pumps & OPS operation and troubleshooting

Okay fuel delivery basics for the 6.5 On the 6.5 you have a fairly simple fuel delivery system. Starts at the tank, a suction strainer, to lift pump, to filter manager, to IP shut off solenoid, to IP, flow is controlled to IP via PCM demand to PMD/FSD. Depending on vintage power to the...

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