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I have a 95 gmc 6.5 turbo 2500 series runs and starts pretty good but it is starting to miss, kind of like a bucking action under a load passing etc. I replaced fuel filter didnt help.Can anybody help me is there anything I could do myself to check for problems? also it has 150,000 miles
 

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HAVE YOU CHECKED YOUR LIFT PUMP?? TRUCK WILL RUN FINE EVEN IF ITS NOT WORKING. BUT WILL BUCK AT YOU FROM FUEL STARVATION. TO TEST IT OPEN BLEEDER VALVE ON FRONT OF ENGINE WHILE ITS RUNNING, IT SHOULD HAVE STEADY STREAM OF FUEL IF ITS WORKING PROPORLY. BUT IF ITS NOT WORKING, THERE WILL BE NO FUEL AND ENGINE WILL DIE AFTER A SEVERAL SECONDS. IF IT DIES LIFT PUMP IS NOT WORKING. WHEN YOU ARE DONE AND IT DIES IT WILL BE HARD TO START,DONT WORRY JUST CLOSE VALVE AND KEEP CRANKING ON IT, IP WILL SLOWLY PRIME ITS SELF AND START. HOPE THIS HELPS OUT
 

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ditto on the lift pump. Likely cause is oil pressure switch as the pump is powered throught the o/p switch, its also cheaper then the lift pump. You may choose to wire the pump up using a relay that the oil pressure switch closes to take the load of the switch.
 

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Buggy69,


I feel your pain. I am having the "exact" same problem with mine. I have actually been through the warranty replacement pump (60,000 ago), a new PMD (20,000 ago) and a new rail pump (2 weeks ago).


Your description is very accurate. It seems to run fine until it warms up........Then it will start bucking and skipping? The condition over the past couple days has been much worse in my case and the truck now is almost impossible to drive once it warms up. It starts jerking like a gasser V8 running on 4 cylinders up to a point....... Then it throws a code or something, the check engine light comes on and it seems to run much better but with reduced power. Today it actually cut off on me while travelling 75 on the interstate (un safe!).





I'm guessing the PMD has died again or the oil pressure switch is messing up?





Any help on this topic is greatly appreciated!





AJ
 

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Pinehead, what year is your truck? '92-'95 will give a code with a wire between A and B Terminals on the ALDL link located under the dash next to the hood release.





'96 up OBDII and you have to have a scantool to read the DTC's (Diagnostic Trouble Codes). Your right to think fuel delivery but on the '94 and newer EFI 6.5L There's sensors that control injection timing and delivery, as well as a timing advance piston that's known for failing due to scoring of its' aluminum housing. Without an enhanced perameter scantool proper diagnosis would be guesswork. It's not a bad Idea to have an extra FSD (Fuel Solenoid Driver). Do you have it remotely mounted? It sure makes it easy to change.Edited by: quantum mechanic
 

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Quantum,


Hello....... Thanks.......





The truck is a 95 Chevy 2500. King Cab, long bed 2 wheel drive with 174,000 miles. It is actually my fathers truck (company truck). The thing really is great when it runs right........ When it does'nt...... It is a nightmare that no local diesel shop can figure out. The dealers are a joke. So we have taken it upon ourselves to try to do so.





Unfortunately I took off the battery terminals to clean them. I have been told that this clears the codes? Are you saying it is possible to read the codes without the scan tool? I also changed the fuel filter and re-oiled the air filter. All were really dirty and it seemed to make a difference. The truck has to be driven a little over 1 hour before it really starts to act up. It seems the hotter it gets...... The more it acts up. I put some pretty serious hours on it every day so I'll see how it does tomorrow.





No........ I do not have the remote mounted PMD. I have already planned to order the remote cooler with the long harness so I can mount it on the firewall. I was looking at that PDC/PMD cooler. I was going to get it tonight....... But I want to be sure before I order it. Of course I want to get the kit anyway. If anything..... Just because it is easier to change and swap it out.





I also plan to rip that snorkel restriction out of the fender tomorrow. Good pics of that on the other thread!





Thanks!





AJ
 

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Yes,


With the '95 you can read the codes. key turned to on, ignition off, put a wire between A and B. The check engine light will flash, and you must count the pulses. They will come in sets of numbers. Three flashes and then five flashes would be 35, the code for injection response too short. www.kennedydiesel.com has all the DTC's listed under the 6.2/6.5 tech tips. Also on the '95 you might have the cast web in the upper intake.


This is what it looks like with no cast web. If you see an aluminum veil,remove it as best you can, as it's a restriction.


I made my own wiring harness remote mount and cooler for about $15 and it's worked excellent. The post with pic's is here on the diesel place.
 

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Hey Quantum;


May I steel your photo of the scanner plug?





hope so ; thanks.
 

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Quantum,





WOW.......... I think the air filter was the problem. It was toatally plugged with dirt and crud. The fuel filter was not too bad. It looked the same as it always does. I removed the restrictive snorkel before I left today......... I drove it all day long.......... Problem resolved!! I cant believe it was that simple (clogged air filter). There is no telling how long it has been like that.


I am still ordering the remote PMD cooler and harness. I also want to check for and or remove the webbing you are talking about. Did you use a Dremel tool or some other to remove? Was it easy?





Thanks again!





AJ
 

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16gasxs,


Steal away.


Pinehead,


I'd keep an eye out, as most problems are compound complex problems(you mentioned a code). I have a cut off tool(air powered) that I score a line around the inside and outside of the cast web, then I gently tap it with a ballpeen hammer to crack it out. I score the whole thing and then break it out a small piece at a time.


I've heard of using a short jigsaw or sawzall blade to cut it. You could drill holes along a breakline and then use the hammer.


I would ask you to consider a 3" downpipe and straight exhaust and make a boost controller. These two things will give you more power than most mods, and if you make your own boost controler you might feel up to making your own wiring harness remote locator and cooler.








This gives you the choice of 6psi, 10 psi at half pot. and 15 at full pot. but do the exhaust or your just turning up the back pressure.
 

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Hey QM,





Where would I get that 3" downpipe? Mine also has a catalytic converter. It was added by a dealer in Canada, I guess it's the rules up there. Anyway, would I obtain a pipe for that from the same place?
 

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Bob;


Down Pipes can be had from a number of sources. BD, Banks, Jardine (that's what I have) Heath Diesel, Kennedy Diesel. Most have the just the down pipes or complete systems.
 

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Wycliff diesel has the '93 6.5L downpipe $155. It's a bullydog pipe though.





Next, I buy a joint of 3" stock and have it expanded at one end and 15 deg. bend at the other.





The result is more power, less back pressure, and a pleasent BB sound. Step on the reostat to hard and it throws your head back.


without actually having had it dynoed, I'd guess 350hp and near 500Tq. I'm going to do a HD friction plate rebuid myself and maybe take the heads off for new valve guides( I see smoke when I start two of the trucks.).





Edited by: quantum mechanic
 

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clean all your ground wires ,my 98 has a ground wire on the passenger top side rear of the head 'very important even if they look clean take them loose and clean them
 

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buggy69 said:
I have a 95 gmc 6.5 turbo 2500 series runs and starts pretty good but it is starting to miss, kind of like a bucking action under a load passing etc. I replaced fuel filter didnt help.Can anybody help me is there anything I could do myself to check for problems? also it has 150,000 miles
Edited by: ken smith
 

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buggy69 said:
I have a 95 gmc 6.5 turbo 2500 series runs and starts pretty good but it is starting to miss, kind of like a bucking action under a load passing etc. I replaced fuel filter didnt help.Can anybody help me is there anything I could do myself to check for problems? also it has 150,000 miles
 

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GREEN95CHEVY said:
HAVE YOU CHECKED YOUR LIFT PUMP?? TRUCK WILL RUN FINE EVEN IF ITS NOT WORKING. BUT WILL BUCK AT YOU FROM FUEL STARVATION. TO TEST IT OPEN BLEEDER VALVE ON FRONT OF ENGINE WHILE ITS RUNNING, IT SHOULD HAVE STEADY STREAM OF FUEL IF ITS WORKING PROPORLY. BUT IF ITS NOT WORKING, THERE WILL BE NO FUEL AND ENGINE WILL DIE AFTER A SEVERAL SECONDS. IF IT DIES LIFT PUMP IS NOT WORKING. WHEN YOU ARE DONE AND IT DIES IT WILL BE HARD TO START,DONT WORRY JUST CLOSE VALVE AND KEEP CRANKING ON IT, IP WILL SLOWLY PRIME ITS SELF AND START. HOPE THIS HELPS OUT



 
 

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GREEN95CHEVY said:
HAVE YOU CHECKED YOUR LIFT PUMP?? TRUCK WILL RUN FINE EVEN IF ITS NOT WORKING. BUT WILL BUCK AT YOU FROM FUEL STARVATION. TO TEST IT OPEN BLEEDER VALVE ON FRONT OF ENGINE WHILE ITS RUNNING, IT SHOULD HAVE STEADY STREAM OF FUEL IF ITS WORKING PROPORLY. BUT IF ITS NOT WORKING, THERE WILL BE NO FUEL AND ENGINE WILL DIE AFTER A SEVERAL SECONDS. IF IT DIES LIFT PUMP IS NOT WORKING. WHEN YOU ARE DONE AND IT DIES IT WILL BE HARD TO START,DONT WORRY JUST CLOSE VALVE AND KEEP CRANKING ON IT, IP WILL SLOWLY PRIME ITS SELF AND START. HOPE THIS HELPS OUT



 
 

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GREEN95CHEVY said:
HAVE YOU CHECKED YOUR LIFT PUMP?? TRUCK WILL RUN FINE EVEN IF ITS NOT WORKING. BUT WILL BUCK AT YOU FROM FUEL STARVATION. TO TEST IT OPEN BLEEDER VALVE ON FRONT OF ENGINE WHILE ITS RUNNING, IT SHOULD HAVE STEADY STREAM OF FUEL IF ITS WORKING PROPORLY. BUT IF ITS NOT WORKING, THERE WILL BE NO FUEL AND ENGINE WILL DIE AFTER A SEVERAL SECONDS. IF IT DIES LIFT PUMP IS NOT WORKING. WHEN YOU ARE DONE AND IT DIES IT WILL BE HARD TO START,DONT WORRY JUST CLOSE VALVE AND KEEP CRANKING ON IT, IP WILL SLOWLY PRIME ITS SELF AND START. HOPE THIS HELPS OUT



 
very very importantto clean all ground wires ,main one is on top of passenger head .i spent $1500.00 to find this out
 

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ken smith said:
buggy69 said:
I have a 95 gmc 6.5 turbo 2500 series runs and starts pretty good but it is starting to miss, kind of like a bucking action under a load passing etc. I replaced fuel filter didnt help.Can anybody help me is there anything I could do myself to check for problems? also it has 150,000 miles
 
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