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95 c2500 6.5 td
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Discussion Starter · #1 ·
I have a 95 c2500 and a little while ago it started bucking randomly as it got warmer it got better then recently it started not running right at all bucking under load at idle seems like it’s miss firing also when it bucks it puts out a little puff of black smoke no smoke otherwise it does take a minute to start up which is a new issue as well I have changed the lift pump, fuel filter, and deleted the vacuumed pump for the waste gate(I kept it under 15psi) I just ordered new injectors and a new cdr valve. My pmd is moved to the bumper also straight pipe new exhaust manifolds any ideas are welcome I am about out of them thanks guys I hope with your help I can keep this beauty on the road
 

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I have a 95 c2500 and a little while ago it started bucking randomly as it got warmer it got better then recently it started not running right at all bucking under load at idle seems like it’s miss firing also when it bucks it puts out a little puff of black smoke no smoke otherwise it does take a minute to start up which is a new issue as well I have changed the lift pump, fuel filter, and deleted the vacuumed pump for the waste gate(I kept it under 15psi) I just ordered new injectors and a new cdr valve. My pmd is moved to the bumper also straight pipe new exhaust manifolds any ideas are welcome I am about out of them thanks guys I hope with your help I can keep this beauty on the road
Any codes with the issue?

Open your fuel cap. Do you hear a large "Whoosh" sound? If so, then you have a restriction and need to modify your fuel cap.
 

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95 c2500 6.5 td
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Discussion Starter · #3 ·
What do you mean modify fuel cap please elaborate on the modification and I will go check that right now And the only code I’ve ever been able to pull off of there was 78 wastegate solenoid And what kind of a restriction are you talking about if I hear that wash would it be better to replace my fuel sender unit or something
 

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Look at the top of this forum....the 6.5 FAQ section....look up FUEL CAP....there are instructions on how to modify it. The whoosh is excess vacuum in the tank caused by faulty fuel cap. I had a code 78...turned out to be a weak vacuum pump not allowing the wastegate solenoid to operate properly. I would put a vacuum gauge on your pump to see if it is going out before replacing the WG solenoid.
 
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What do you mean modify fuel cap please elaborate on the modification and I will go check that right now And the only code I’ve ever been able to pull off of there was 78 wastegate solenoid And what kind of a restriction are you talking about if I hear that wash would it be better to replace my fuel sender unit or something
It refers to the fuel cap not allowing adequate ventilation into the tank. When the fuel cap is restricted, a vacuum forms that can prevent the lift pump from doing its job correctly and the fuel tank can collapse on itself.
See this link; Fuel cap
 
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I see now that he has already deleted his vacuum pump. Probably the reason for the DTC 78....
 
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95 c2500 6.5 td
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Discussion Starter · #7 ·
No whoosh but while I was examining that I did find a rust hole in my fill line So I don’t think there’s any problem getting airflow but that being said there’s a rust hole where my fuel goes in
 

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No whoosh but while I was examining that I did find a rust hole in my fill line So I don’t think there’s any problem getting airflow but that being said there’s a rust hole where my fuel goes in
Install a piece of clear fuel line on the return side of the injection pump to help locate any air in fuel issues ( as shown in this link) .
 

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95 c2500 6.5 td
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Discussion Starter · #9 ·
Bingo air in the fuel thank you everybody trucks running good as she ever was still going to do the new injectors and everything just cause I already have them ordered them
 

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Bingo air in the fuel thank you everybody trucks running good as she ever was still going to do the new injectors and everything just cause I already have them ordered them
When it comes time for the injector install it is best to do one bank first then start and run the engine to purge any air in the fuel lines then change out the second bank and start and run to purge air.
It lessens the chance for hard starts after the full change over.
 

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95 c2500 6.5 td
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Discussion Starter · #11 ·
When it comes time for the injector install it is best to do one bank first then start and run the engine to purge any air in the fuel lines then change out the second bank and start and run to purge air.
It lessens the chance for hard starts after the full change over.
Thank you any tips on modifying a socket to not damage the injectors I read bad reviews on the otc one and 100 after shipping for the snap on one is a lot
 

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Discussion Starter · #13 ·

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Thank you that is a great thread still wondering about modifying my own 30mm instead of buying one though am I correct that I just have to grind down the inside a bit so it doesn’t bend the nipples
As long as you presoak the injectors with Kroil and use the socket without over-forcing things you should not damage the injector
 

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Discussion Starter · #15 ·
As long as you presoak the injectors with Kroil and use the socket without over-forcing things you should not damage the injector
Ha I’m gonna have to give that stuff a shot I’ve always used PB blaster But I have yet to have bad advice on this website I’ll give it a whirl
 
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