6.5 sputters under load

[350Tacozilla]

I have a 94 k2500 6.5 suburban with 252K on it

at around 200k head gaskets were done along with sleeved water jackets, new injection pump,new remote mounted pmd,heath turbo master,fuel cooler and 3" straight pipe


when i go up the mountain near my house the truck will sputter like its running out of fuel, wont do it all the time only other time is maybe interstate ramp.truck has only stalled once under full throttle then letting off whole way.I only drove the truck once after this happened to test if fuel filter fixed it.

changed fuel filter but no change, lift pump seems loud and only get a drip from drain hose with truck running.

Everyone think its lift pump?

also i see a max of about 12psi is this ok or should i crank spring for bit more, i always heard 15 is safe so i went on cautious side.

also anyone tried the variable resistor trick? http://www.thedieselpage.com/t/fsdresistor.htm

[jhornsby3]

Sounds like the oil pressure switch is in need of replacing.

John

[argo]

I agree. In fact, since the contacts in the oil pressure switch are rather puny, you should use the oil pressure switch to activate a relay that would actually power the fuel lift pump.

[JohnC]

lift pump seems loud and only get a drip from drain hose with truck running.

A noisy lift pump is often a failing lift pump. Can't build any pressure so the plunger just rattles back and forth.


also i see a max of about 12psi is this ok or should i crank spring for bit more, i always heard 15 is safe so i went on cautious side.

Where are you seeing 12 psi? the pressure is determined by the fuel bypass valve in the injection pump. Any pump that meets the delivery requirement (30 gph, IIRC) and can build 4-5 psi will do the trick.

[jhornsby3]

Where are you seeing 12 psi?

I assume he's talking about the boost pressure.

[350Tacozilla]

A noisy lift pump is often a failing lift pump. Can't build any pressure so the plunger just rattles back and forth.



Where are you seeing 12 psi? the pressure is determined by the fuel bypass valve in the injection pump. Any pump that meets the delivery requirement (30 gph, IIRC) and can build 4-5 psi will do the trick.


I assume he's talking about the boost pressure.



yes sorry 12 psi boost is what I was seeing before. I changed the lift pump and found a small air leak in the fuel line from tank. I got the line fixed and all air out of system and sub is running like champ again.

thinking of getting egt gauge then playing with the fuel solenoid resistor and a boost fooler as I can now get 15psi of boost and it cuts power(without adjusting the turbo master from before the problems started). I have cranked my turbo master back a bit to limit boost back to 10-12psi for now though.