high idle sputter (video)

[Randy]

hey what do you guys think the cause may be? only happens when i keep it high idle. fuel pump? fuel supply? timing? its a 92'
https://www.youtube.com/watch?v=yINKleIXDwg&list=UUTxAPHp56BjqOfCZi3c0wPQ

[fatty]

Why on earth would you ever have it revving like that in neutral?? If that's the only time it does it you should quit doing it.

[Randy]

It happens while driving as well. Not only in neutral.

[Remps]

Does it do it with heavy throttle or just light throttle? If it only does it light throttle high rpm just don't drive it like that. My guess is a piece of your fuel shutoff in one of the delivery valves.

[fatty]

Try bumping the timing up an 1/8" or so.

[RCCUMMINS89]

Either timing, or the lift pump is sucking air at a certain point. I could see where the lift pump is too weak... the ip is over riding the lift pump at that high of a level and then sucking air, due to a vacuum through a bad lift pump.

[Randy]

That's one of the possibilities I thought of. Upon further investigation - on the fuel tank is a rubber seal/grommet fits in between the plastic tank and the metal fill tube - that seal is broken, badly. I put one on order(5-7days out), however not sure if that is the cause/could be the cause.
I'm only going to be running it for teating/troubleshooting purposes as running a pump dry can cause internal failure.

[RCCUMMINS89]

Run a hose from a 5 gallon tank of diesel straight to the injection pump. Do the neutral thing and see if it goes away.

A VE CAN RUN WITH ZERO FUEL PRESSURE... AS IT HAS AN INTERNAL SUPPLY PUMP.

[Randy]

Okay, I'll post results.

[AHineman]

When's the last time you changed your fuel filter?

[Randy]

Clogged fuel filter. I purchased this truck around a month ago, previous owner claimed all filters had recently been changed (guess he doesn't know what recent means)
Replaced filter, but going to do an annual pmcs just to be safe.
Thanks for the posts everyone.

[Randy]

Also very possible that dust and dirt where able to come into the fuel tank through that broken seal, shortening the life of the filter drastically.

[DodgeFreak]

Why on earth would you ever have it revving like that in neutral?? If that's the only time it does it you should quit doing it.

I haven't watched the vid....but the way these engines are ...you can run them at wot against the gov with out problems for testing and what not....to check fuel pressure on Internationals we would do an idle fuel and a wot fuel test...