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1995 GMC Suburban
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That sounds really bad.
Have you measured the fuel pressure?
Did you try another PMD?
Any DTC?
 

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happen to have a spare fuel shutoff solenoid laying around to check? Or remove and test the existing one. Also check voltage to it while running and clean connector.
 
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Check/search for the DieselPro gremlin remover.
 
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other things I would do before swapping the IP with a new one.... troubleshoot optic sensor and also go over grounds with a fine tooth comb. And search this forum using keywords like "stumble" and anything else specific to your situation and read as many threads as you can handle.

Also consider potting the fuel pressure gauge in a tee RIGHT at the inlet to the IP... easy enough and the better place for it imho.
 

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1995 GMC Suburban
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Well, at this point, Doomy may need to put the fuel pressure gauge at different places along the fuel system to see where the issue is.
 

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140k 2000,gmc,k2500 380k 94 chev 1500 n/a
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53 Posts
Discussion Starter · #26 ·
Fuel pressure is 10 at koeo its wired into a fuse tap on a circuit that's on with the key on
As soon as it starts fuel pressure drops to ~5 which is normal for when it was running decent
Its tapped into the bleed bung on top of the ffm
I will move it very much doubt that will change the readings

I have 2 spare pmd's its mounted by the driver side battery with heatsink tried both no change

No codes nothing off with the live data either
Cylinder power balance test all are firing

I have not tested the ffs it was new with the injection pump i think i have a gutted one lying around to throw in(can it please be this one this is easy and a definitive issue)

Gremlin pro is the 3l i6 chevy diesel right like 40k starting price
 

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Fuel pressure is 10 at koeo its wired into a fuse tap on a circuit that's on with the key on
As soon as it starts fuel pressure drops to ~5 which is normal for when it was running decent
Its tapped into the bleed bung on top of the ffm
I will move it very much doubt that will change the readings

I have 2 spare pmd's its mounted by the driver side battery with heatsink tried both no change

No codes nothing off with the live data either
Cylinder power balance test all are firing

I have not tested the ffs it was new with the injection pump i think i have a gutted one lying around to throw in(can it please be this one this is easy and a definitive issue)

Gremlin pro is the 3l i6 chevy diesel right like 40k starting price
I would disconnect the fuel line at the lift pump and connect a line from a jerry can full of Diesel to the LIft Pump and run it. See if conditions improve
 
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this is gremlin remover referred to

You are right, fuel pressure tap location from top of ffm to top of IP probably wont change but it will eliminate a length of hose. Probably not collapsed but who knows.... easy enough.

Hope it is the FSOS... beyond that there are not too many easy options I can think of. dangerously loose pump drive gear? doubt it is the ecm but crazier things have happened. Anyways, please find it and share the solution! I have given all the ideas I can think of.
 

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140k 2000,gmc,k2500 380k 94 chev 1500 n/a
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Discussion Starter · #29 ·
Not FSOS swaped in the gutted one no change
Unplugged optical sensor and it won't run gotta look into that

Still gotta try a pmd without extension harness think I have a spare extension lying around
 

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Discussion Starter · #30 ·
By unplugging the sensor, you put the system into backup mode and the computer relies on information from the crankshaft position sensor. In the very unusual case that both sensors were bad, the truck would not start with the optical sensor disconnected.
So bad crank sensor? Wonder if I can find its output on the live data from the ecm
 

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Discussion Starter · #31 ·
Ecu read crank sensor as good
Volt meter says bad
Got lucky came out in one peice
This guys vid was excellent though I didn't remove the ps pump i just took the whole bracket loose and came in from the driver side wheel well with 3 extensions and a swivel socket
Should be 45 mins or so to put it all back together
Parts stores weren't open by the time I got it out
Also no ac Delco in state gonna order one and put a napa generic in till the other gets here
 

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1995 Chevrolet Silverado Z71 6.5 TD
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Ecu read crank sensor as good
Volt meter says bad
Got lucky came out in one peice
This guys vid was excellent though I didn't remove the ps pump i just took the whole bracket loose and came in from the driver side wheel well with 3 extensions and a swivel socket
Should be 45 mins or so to put it all back together
Parts stores weren't open by the time I got it out
Also no ac Delco in state gonna order one and put a napa generic in till the other gets here
Gremlins could appear
 

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Discussion Starter · #33 ·
Bad crank sensor and a loose or bad optical sensor
Runs with new crank optical unplugged
Swapped in my old optical sensor dies as soon as I clear the code
Old one took a t40 screwdriver and a 12 inch wrench to get off
New Pump on the truck was just hand tight so the scribe line isn't correct
Gotta find the part number for it and a test/set procedure for the optical sensor
 

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Bad crank sensor and a loose or bad optical sensor
Runs with new crank optical unplugged
Swapped in my old optical sensor dies as soon as I clear the code
Old one took a t40 screwdriver and a 12 inch wrench to get off
New Pump on the truck was just hand tight so the scribe line isn't correct
Gotta find the part number for it and a test/set procedure for the optical sensor
Info for TDCO and Optical sensor can be found in the 6.5L FAQ: Info: - The 6.5L FAQ's... The Master List of...
 

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Discussion Starter · #35 ·
Its back home tried adjusting optic sensor 5-6 times each prolly the cause of death on the last pump too
Running in limp on the crank sensor

new reman pump ordered
After the swap I'll warrenty out the old one and have one on the shelf
New freeze plug heater old one didn't work and was leaking
Do not bother with the 600w heaters they suck metal is so thin you can't hold it to keep the orientation right
Broke 2 then had to have the wife make a parts run and bought both local parts store only had the 600w in stock
Left the clear pvc lines on over the manifold till the new pump comes
Gonna remote mount the ffm when it does and go back to rubber on everything but the short return line and keep some spare hose in the truck
 

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Discussion Starter · #36 ·
Is there any way to make it start faster in limp mode with the optical unplugged??
Drained the batterys today at the store trying to re start it
 

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Is there any way to make it start faster in limp mode with the optical unplugged??
Drained the batterys today at the store trying to re start it
Disconnecting the OS will give you longer cranking time but it should still start.
Same goes for the Crank sensor as well.
 

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Discussion Starter · #38 ·
got the new reman pump in(new engine harness run over lower intake) runs and drives now just having issues with the timing, its at ~+5.5 and the tdc is -2.5ish
and it wont relearn timing because the actual and desired ip timing is at 5.5 and 10 so its throwing a p1214
going to move the pump 1mm to the passenger side and tap on the ip timing stepper
stepper does nothing until over 1500 rpm
seams like there's something up with the stepper or I'm too far out of timing adjustment
 

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got the new reman pump in(new engine harness run over lower intake) runs and drives now just having issues with the timing, its at ~+5.5 and the tdc is -2.5ish
and it wont relearn timing because the actual and desired ip timing is at 5.5 and 10 so its throwing a p1214
going to move the pump 1mm to the passenger side and tap on the ip timing stepper
stepper does nothing until over 1500 rpm
seams like there's something up with the stepper or I'm too far out of timing adjustment
Make sure you run the engine up to operating temps (190* +) before you make any timing adjustments. Anything below those temps the timing adjustments will not take
 

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Discussion Starter · #40 ·
Been trying to adjust at 170 thought that was the spec
 
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