MORE PUMP QUESTIONS

[BIG C]

Okay, these are probably easy questions for the more experienced 12valve mechanics.
My first question is - Are / is there any easy way to tell if the injector pump is starting to fail?
The local rebuilder wants me to pull it so he can put it on his machine to test it.I know that with the smoke screw now turned all the way in and the fuel pin turned about 90degrees the is no difference in power or smoke.
as a matter of fact the truck does not produce any 'black' smoke at all now, which it did 6 months ago.

second question - what should the supply rate or pressure be from the lift pump?

third question - what #'s should I be looking for with a compression test?

THANKS!

[PToombs]

My first question is; Have you changed the fuel filter lately? The simple things are often overlooked. If it hasn't been done, I'd be careful starting it after changeing it, with the fuel screw all the way in. You might be in for a rude and costly surprise!
The fuel pressure should be abot 5-6 after the fuel filter at idle. Much below 3 isn't good, at any speed. I put in my gauge, had 5 psi. Went for a ride, 3 psi driving, at WOT, 0 psi. Not good!
Compression, I don't know! I could look in the book, if I could find it!

[dpuckett]

I dont think you shoot for any given number when testing compression, but check how even stuff is. It's preferrable to have the cylinders a little low, but EVEN, than to have a broader range at higher pressures.

A 7.3IDI I had tested one time had 300-320psi cranking compression.

Signs of an injector packing up to go south include reduced power, harder starting, lower MPG (sometimes not so low, til after the rebuild, and you gain 4-5mpg), erratic idle.

Daniel

[cummins king]

psi to the pump should always be above 1 that means there is alittle bit extra for the pump to use, anything less and it will starve, mine with 1/2 lines will idle at 8ish with mild fuel 10ish and romping time 5ish, more then enough fuel, if you not getting it get a new lift pump or for that mater get a new piston pump

[BIG C]

It has a new filter, I also just put another new lift pump on, made sure all fuel system connections are tight, no leaks found,ok mileage at ~19mpg.
the idle is still low in park, rough idle in gear, and doesn't change when I try to adjust it either.
of course their is no smoke produced when you 'slap' the throttle.
I keep thinking I'm forgeting something very basic here but what?

[cummins king]

check if ur full power srew isn't backing out, if there isnt enough fuel then it will run ruff

[wannadiesel]

When the pump is getting tired the truck will want to die at idle when hot.

[One Big Doofus]

My compression #'s on my 1st gen Ford conversion are between 350 and 380psi(160,000 miles). That's with a home made, gutted out injecter adapter so it increases the combustion chamber a little bit(lower number's),...schrader valve is on the top end of injecter.

I've never seen #'s printed in any cummins manual's

[flashgordon]

I thing it more important to have equal ### then what they are.

On the newer (common rail) truck the compression is supposed to be between 400 and 450.................At 7000 Feet a good compression is any thing above 325.


Flash

[BIG C]

The full power screw is locked down and has not moved, although it has been 'tampered' with by someone. is there a way to tell hjow far it's been adjusted from a 'stock' setting?
A good point for me to make is, when the truck has deen driven a while and it's all warmed up it will barely idle and it seems to have even less power.
Hopefully tonight i'll get to do a compression test.
Unless someone or something steers me in a different direction I'm thinking the injector pump is fading away.
thanks for your help.