my truck just started to stumble in the high rpms (2700-3500) which it has never done before. i need gauges i know. no codes have been thrown. so far it seems ok, but i'm guessing the lift pump is dead and/or the vp44 is dying..?


2001 HO stock

 

Sounds like defueling to me , its how the truck is governed for the upper limit on RPMs. at least that would mean no big repair bill.

 

it is the stumbling part that worries me. it never did that. it happens in 2 3 4 and i'm sure 5 and 6 but i don't want to get going that fast down the highway

 

With your truck running in neutral.
Stick your foot the floor!! If it stumbles and puff's white smoke out of the tail pipe your injection pump is going out.

 

I am having the same problem, But at lower rpm's. If I stay at a constant RPM (say 2100 rpm) I feel a hesitation almost like it is defueling and it ticks all throught he rpm range. Also the tone of the motor changes to a rougher tone. I am pulling the injectors tomorrow to see how dirty they are.

 

no smoke or any noticable problems in neutral. oscaroc, mine makes a rougher sound (seems to have gotten louder in the last 2 months) upon acceleration at like 1400-1900rpms. it only stumbles when i floor it any get into high rpms though

 

If I floor it in neutral it blows a puff of white smoke and there is a noticable roughness. I am going to put stock injectors in tomorrow and see if it changes anything. I hope I don't have an injection pump problem

 

Lift pump, injection pump, or fuel filter could all be culprits. My cousins started missing just driving down the road. He changed the fuel filter, and its fine now.

Eric