all together-still wont start....HELP

[mykal41]

I recently pulled my pump to rebuild it due to the front seal falling out. I rebuilt the pump, it went smooth no problems.(no left over parts)

I also ran 6an from the piston lift pump to a baldwin seperator then to a regulator then to theIP.

When I prime the piston pump pressure goes to 15lbs but fall to 0 in about 4 seconds.

I dont get good fuel at the injectors while trying to bleed them.

while cranking pressure maintains 12psi.

[cummins king]

you have air some where, i had the same problem, and i had a air leak

[mykal41]

If I run a line from the lift pump to a pail of fuel, that would eliminate the old lines. I willl try that.

How about the pump assembley. I am 99% positive its fine.

[cummins king]

were does the return from your regulator go to, you have air some were if you want my opionon, start from from the first thing you modified right to the last thing, put tape on it pipe tread glue, evrything, i had the exact same problem, also did you change the pickup in the tank, do u have a check valve in it the setup some where

[mykal41]

no i only did from the lift pump foward. And no, I assumed the check valve in the lift pump would work..

[cummins king]

oh ya,

[DTanklage]

...put tape on it pipe tread glue, evrything...

i never use tape where it could possibly get into the system and cause a blockage or partial blockage

i dont use it at all really, there are so many good 'liquid' sealers now

[cummins king]

i dont every use tape but if thats all he has its an option, thats all

[mykal41]

I checked the system and it holds presure in the line. I capped the 6an line off at the pump and it holds 15psi on the gauge. I hook the line to the pump, prime the lift pump it hits 15psi and then bleedes down to 0psi.

Like I said I rebuilt the pump a while ago. Does anyone have any sugestions.....

[bgilbert]

Simple stuff like pulling the shutdown/run solenoid, gutting it, reinstall the solenoid, this way you eliminate that from not allowing full fuel to injectors. Throttle indexed properly? Try cranking with throttle wide open? Ether?

[cummins king]

well theres only a few places it could be going to then

A its leaking between the pump and the pump head, so take the pump head of make sure the seal is in right and re install
B its leaking some were else like around the pump head or maby out of the front seal if not installed corectly, i dont know if the second one is posible though
C flowing out of the return (unlikely)

[DTanklage]

I checked the system and it holds presure in the line. I capped the 6an line off at the pump and it holds 15psi on the gauge. I hook the line to the pump, prime the lift pump it hits 15psi and then bleedes down to 0psi.

mine doesnt hold pressure in the inlet either

are they supposed to?

then again, mine has an electric pump

[cummins king]

if it doent ist going to suck air and then you will need to prime the injectors

[DTanklage]

where does the air come from?

wouldnt it get pressure again as soon as you start to crank and the piston pump (or diaphram) creates pressure again?

if i dont turn on my electric pump mine will still start

and run for a little while

[mykal41]

Thats what I originally though. I figured that as soon as the pump built pressure it would be fine.

However the truck wont run. I am going to pull the pump tonight and go through my rebuild. Is there a way to pressure test the pump on the bench. These pumps are not that complicated.......... I feel like an idiot. I have an extra rebuild kit.