Lift Pump Lesson

[phantom309]

Just because the lift pump makes a noise doesen't mean its pumping,.
It,s been low on power,. always has started coughed belched smoke stumbled etc,. then runs fine,.
super hero has listened to the lift pump,. super hero has even jumped the lift pump direct at the aldl connector in the past to see if priming everything would help with starting,.,.
yesterday just for idle (sic) curiosity,. i opened the "t" valve at idle,. by the time i looked underneath she'd quit! Bugger wouldn't go,. so cranked and cranked and finally she fired, coughed, belched, stumbled and then ran fine as usual,.i shut it off,. jumped the lift pump,. its tapping away,. but nothing coming out of the "t".
Bought a new one today,. GM wants over $200,. so i got an airtec for 79.99+ plus taxes.
we'll see if it makes a difference or not,.
kinda explains now why sometimes the truck had power,. and other times kinda doggy,.
still get 21.5+mpg (cdn gal)
So always do the idle test of your fuel pressure,. don't just ASSume because the pump makes noise that its working DOH!! :o

Nick
i also washed the rad out from the fan side and added a new T stat,. runs waay cooler,..

[Robyn]

Oh yessssssssss.

Having the lift pump out of order places a lot of extra stress on the transfer pump in the IP.

It will pull the fuel but its tough on it and over time will wear things out.

Normally during startup, the lift pump primes the IP in the first second or two while the key is in the crank position.

Once the engine fires and the oil pressure builds, the lift pump is operated by either the OPS or in later trucks through the relay (controlled by the ECM)

Glad to hear you got it figured out.


Missy

[phantom309]

Put the aftermarket fuel pump on today,.
yeah baby!!
the old clatterbox now has about 50 more horsies,.
runs right up a steep hill we have and can hold 65mph, Full throttle upshifts are fun again.
i,ve been grinning like a schoolboy,.lesson learned.


Nick