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GMC 6.5 Dually

WarWagon

Well it hits on 7 of 8...
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Has anybody used Pensacola Diesel for their pumps and parts??
Read the unprintable bad Google reviews. They are a poster child for other modern diesel stuff as they F-UP our antique injection stuff and GOOD LUCK getting warranty or money back. Run Away from them!

You need to check that the lift pump is working, check for air in the return line off the IP, aka Injection Pump, with a clear 1/4 line, and check for codes before throwing parts at it. A PMD is ok to have a spare but a crap China PMD extension cable is trouble. Never EVER run a PMD without a heatsink like the IP or one outside of the underhood heat. (If you did it's likely ruined from overheating.) We like to put them in the front bumper on a USA extension cable.

Again before dropping near $2000 on a new IP be sure it's the problem. New because you can get them not a rebuilt one with a shot worn out head and rotor that won't start hot... That said how many miles used up on the life limited to 100K miles injectors?
 
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Stoney

Lock-n-load
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Out of curiosity..you said you changed pmd and extension cable..1) are you sure there good..a brand new one can be junk... Just cause there new doesn't mean they work. especially if (from china ) brand... assuming there actually good, I'm with AK, IP is good culprit..but app is also a good probability..if I remember right there problematic on our year truck ( mines a 97 also ) believe it or not a bad electrical conection is a possibility..I'm sure Will and others will chime in on the morning personally I'd start with the cheap stuff that could probably use to be changed anyhow...if ip is shot I'd talk to guys about how to convert to manual one..these electronic ones are a P.I.A.
 

FellowTraveler

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Hey Guys I need HELP! Gosh my truck has been running pretty good, Thursday it started doing strange things. At idle it runs good but when I add a little throttle it goes to a high rev like I have it to the floor but I only have a light touch just laying my foot on the pedal. Going down the road I had to feather the throttle to keep going at a safe speed. it's blowing some black smoke and seems like it's starving for fuel (full tank) and all this just out of the blue. I am a pretty good mechanic but I am stumped!!?? Can anyone shed light on this?? Most of my past experience has been with Ford's 7.3 and 6.0. I thought maybe the injector pump might be the issue. Any help would be great-this is my daily driver and rainy season coming to Florida soon. Thanks for the help. Oh I changed the lift pump, fuel filter and PMD.
Wayne
So, you changed a working PMD WHY?
 

Redtruck97

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So, you changed a working PMD WHY?
WOW thanks for all the info, well from reading other forums and asking questions I went with the simple stuff first to try to isolate the issue...New PMD and cable, New lift pump-yes they both work, I also installed the lift pump harness from Leroy diesel which puts a full 12V to the system. So the pedal must have a clock spring like the fords do...I'll check on that. My lift pump and PMD came from New York and I have been looking for more AC Delco items. Do you know of a rebuild kit for my IP? Otherwise I will have to locate a better source for a IP either rebuilt or new. I think the manual IP's had a FIPL sensor on the side. Thanks again and I will be looking for more help.
 

Redtruck97

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WOW thanks for all the info, well from reading other forums and asking questions I went with the simple stuff first to try to isolate the issue...New PMD and cable, New lift pump-yes they both work, I also installed the lift pump harness from Leroy diesel which puts a full 12V to the system. So the pedal must have a clock spring like the fords do...I'll check on that. My lift pump and PMD came from New York and I have been looking for more AC Delco items. Do you know of a rebuild kit for my IP? Otherwise I will have to locate a better source for a IP either rebuilt or new. I think the manual IP's had a FIPL sensor on the side. Thanks again and I will be looking for more help.
OH also the PMD was relocated when I bought the truck, but I installed new cable and relocated to a cooler spot as well.
 

Will L.

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Adding your truck and any modifications to your signature line would REALLY help us here. You mentioning it once in a post that later gets 10 more comments gets easily missed. Then a year later when another question pops up you don’t have to keep explaining every detail of the rig. Plus modifications of other rigs like your Ford- others that own them know to ask you details or knowledge for improving theirs. But gotta distinguish which 7.3 idi vs powerstroke for all the chevy guys here that don’t knkw by year! Haha.

Ok, cooler spot- but still under the hood anywhere is a mistake. These don’t get killed while the truck is running. When the engine shuts off, heat soak gets to it and that is the death nail. That’s why the best place is front bumper. Submerged in water is ok. Hummer best spot is a top batteries but they are outside the engine compartment on them- incase you see that and think about it.

get the clear 1/4” diameter return line on the front of the ip. Cant stress that enough. $5 and 5 minutes to instantly know whatbis going on- best diagnostics move in existence. Look for any bubbles traveling. Look for any discoloration or of course if you see particles float by.

I stress a fuel pressure gauge tapped at the ip inlet. mount the gauge where you see it while driving and treated like an oil pressure gauge. 2 things kill the ip fast- low pressure or water. More expense than clear line but long term will save an ip from early death.

I would suggest these two things to begin with if you own the truck- if a customers then don’t permanently mount the fuel gauge without explanation obviously, or just temp the gauge but still needs knowing before condemning.

Unfortunately you are 90% towards a bad ip- but I can’t stress this enough- you need to do these before swapping- you would be just one more name on a long list to have done new ip with same issues.

Call and talk to forum sponsors listed above about the new ip if it comes to that. (RA is out of that call list btw.) Some of them sell new ones and others are good sources for rebuilding. On ds4 ip, I prefer new.

IF you are thinking of bumping up the power level some- now would be the time to plan it out and talk to Quadstar about options. Nice thing about these engines is you can do a bit more power while improving mpg and burning cleaner emissions all at the same time - efficiency is key.

AFTER this mess is cleaned up- there are things to think about if you haven’t learned yet like - how old is harmonic balancer? It goes out and crank snaps or block cracks. 100,000 miles is due- and only AC Delco or bigger $ for fluidampr. New drive pulley at same time again Delco only unless spending more for the billet one which will last forever from Leroy.
 

DieselAmateur

Diesel or Bust
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If you have access to a scanner, pull codes, maybe something helpful there?

Agree that it sounds like IP is going bad, sorry for your luck

Also check intake/ turbo. I once had a K&N filter collapse under the hood and plug the turbo on my first 6.5, a '99. Truck had no power and was belching black smoke, acting like it was starving for fuel. Air filter had collapsed and was plugging the compressor wheel so it was starving for air. Even if the truck is relatively low miles the GM turbo is most likely spanked and not worth keeping in my opinion. I've been happy with @uniquediesel's towing turbo to hold me over until my CAC and HX35/40 install

And yes STAY AWAY FROM PENSACOLA DIESEL. If staying with DS4 go with Leroy or Quadstar. If you want to eliminate electronic injection issues forever now would be the time to swap to mechanical DB2
 

Redtruck97

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If you have access to a scanner, pull codes, maybe something helpful there?

Agree that it sounds like IP is going bad, sorry for your luck

Also check intake/ turbo. I once had a K&N filter collapse under the hood and plug the turbo on my first 6.5, a '99. Truck had no power and was belching black smoke, acting like it was starving for fuel. Air filter had collapsed and was plugging the compressor wheel so it was starving for air. Even if the truck is relatively low miles the GM turbo is most likely spanked and not worth keeping in my opinion. I've been happy with @uniquediesel's towing turbo to hold me over until my CAC and HX35/40 install

And yes STAY AWAY FROM PENSACOLA DIESEL. If staying with DS4 go with Leroy or Quadstar. If you want to eliminate electronic injection issues forever now would be the time to swap to mechanical DB2
Awesome info and many thanks....I will try to put my info on here, got to try to navigate around the site. I have been in contact with Leroy and have a couple parts from him, I have an A/C harmonic balancer as well. I will try the things you mention and hope I can pinpoint my issue. I sent a mag to Leroy as well and waiting for a response. Thanks again.
 

Redtruck97

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Clean the ground wire terminals at the back of the right side of the engine. Should be three wires connected to a stud back there.
Thank you, I will doing alot of work this weekend to try to isolate my issue, was told by Southeast power equipment here in Tampa (they are a Stanadyne authorized dealer) that Stanadyne no longer makes these pumps and parts are scarce. If I need a pump they have one reman that fits my truck...so the search continues.
 

Redtruck97

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OK, I HAVE CHECKED AND CLEANED ALL THE GROUNDS I CAN FIND, RELOCATED THE NEW STANADYNE PMD, HEAT SINC TO INCLUDE THE NEW WIRE FOR IT AS WELL, TO THE AREA BEHIND THE FRONT LICENSE PLATE BRACKET, INSTALLED A NEW THROTTLE PEDAL AND IT STILL DOES THE SAME THING. NEW LIFT PUMP AND FUEL FILTER AS WELL. I AM HEADED TO GET A SMALL PIECE OF CLEAR TUBING FOR THE RETRUN LINE TO CHECK THE PUMP FOR BUBBLES AND ANY TRASH. OTHER THAN ALL THESE THINGS I AM LOST. SOUTHEAST POWER SYSTEMS SAYS STANADYNE STOPPED MAKING PARTS AND NEW PUMPS BUT HE DID FIND A REMAN ONE FROM 1 OF ONLY 2 REBUILDERS THAT THEY USE....ANY OTHER IDEAS???
 

Redtruck97

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ALSO THE ENGINE STARTS QUICKLY AND IDLES FINE, NO SMOKE AT IDLE, BUT YOU BARELY LAY YOUR FOOT ON ACCELERATOR PEDAL AND IT REVS UP VERY HIGH, IT HAS NO EFFECT TO SLOWLY PUSH PEDAL TO GET RPM'S, IT JUST ZOOMS UP....I REALLY DON'T KNOW????
 

DieselAmateur

Diesel or Bust
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The shop is lying to you about availability of new DS4 injection pumps, see here


Reman from another site vendor


When you say you installed a new throttle pedal, do you mean a new APP sensor (Accelerator Pedal Position)?

If the truck is surging as you say and all other components have been replaced from crank position sensor to PMD, then it must be the IP. Pull codes with a scantool before going full nuclear and putting in a new IP. I'm no expert in this realm but based on what you've done I don't know what else in the system could be the issue outside of IP
 

ak diesel driver

6.5 driver
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One thing to note is there are no hardened parts to use ulsd. The 5521s has the latest updates but unless something snuck past me nothing is hardened.
 

Redtruck97

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Yes it was a new pedal assembly with the (I know it as a clock spring) but it has the new electrics as part of the pedal. Next step...pull codes if any....maybe a scan tool/code reader instead of paying dealer high a$$ price to scan?, maybe...
Surging really isn't a good term, it's not sucking air and idles very well. Maybe one of the parts stores has a code reader and I can get it done free.
I have not replaced crank position sensor because it cranks and runs fine, unless there is some other sensor that deals with acceleration then I don't know. I have tried to search for troubleshooting online but come up empty, most online explanations say it's the PMD. Maybe somebody on here has had an issue like me and can lead me down the path to repair. Thanks for your insight I greatly appreciate it.
 

Redtruck97

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The shop is lying to you about availability of new DS4 injection pumps, see here


Reman from another site vendor


When you say you installed a new throttle pedal, do you mean a new APP sensor (Accelerator Pedal Position)?

If the truck is surging as you say and all other components have been replaced from crank position sensor to PMD, then it must be the IP. Pull codes with a scantool before going full nuclear and putting in a new IP. I'm no expert in this realm but based on what you've done I don't know what else in the system could be the issue outside of IP
Thanks, yeah I have emailed Leroy several times and gotten a couple things from him, I sent him a msg about as well and haven't heard back from him. I don't know about Quadstar but Leroy's price is above my means right now.
 

Redtruck97

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Thanks, yeah I have emailed Leroy several times and gotten a couple things from him, I sent him a msg about as well and haven't heard back from him. I don't know about Quadstar but Leroy's price is above my means right now.
Has anyone had experience with Quadstar?? I looked at their site, they several products for these trucks.
I would have to go with reman over new...the pump is half the price of the truck!!
 
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