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I did a lift pump test today. What do you guys think

gnel

gnel

Member
Messages
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Location
Jalisco,Mexico
of these results.
51/2 engine not running
4.25 @cold idle(90 degrees today)
2 @2000rpm or about 65 mph
1 down to about 1/2 @ hard acceleration
3.6 @ idle (warmed up)

I´m thinking its time for a new pump? Will this damage the IP if I drive it until I can get a new pump? What pump do you all recomend?
Thanks for any replys g
 
First try running power to the LP to see if its not able to get enough current through the OPS. You can run battery voltage to pin F of the OBD DLC to power your LP while the enigne is running and see if pressure improves. If not then you could use a new LP, or there is a resitriction, like the tank sock clogged, or other. Either way you really need to do the OPS relay mod, to get the power off the OPS.
 
Thanks Buddy for the quick reply. I´m extremely electronicaly challenged(spelling too).Do I need to disconnect the ops first? Is there a step by step for that procedure? Can I use a spare battery to fire up the lift pump directly or is pin f better? ? Thanks again g
 
Last edited:
Welcome to the site gnel.

Those numbers aren't to bad. WOT should not drop below zero.

You could use a battery to run the lift pump but pin f is easier. In the stickies there are pictures where you can get power to jump pin f.
 
Yes I got them from the drain valve. Is there a better method? I´m all ears. This is my first 6.5 and I´m trying (with my old brain) to absorb alot of info. I thought I read somewhere that thats the way to test the L/P. Thanks for the reply g
 
No using the drain valve is fine, just wanted to be sure exactly what we were comparing yr pressure readings with.

More experienced folks here then me will chime in, but I believe using the drain valve to measure the LP supply pressures may also reduce yr pressure readings, so you may not be that far off the expected readings with an OEM LP???
 
Wait for more replies before you make any decisions or purchases for that matter.

The issue that I have & can offer is we have no online OEM monitoring for the IP supply pressure while driving our vehicle unless we add a gauge on our own. Even my ole 1990 Ford has an OEM fuel filter delta P idiot light on the dash so at least you have some idea if / when you may be starving the IP...not optimum not an actual IP inlet pressure reading...but better then what GM provided.
 
The drain valve is actually prefilter, so the filter will drop pressure before it gets to the IP, about 25%. So if those numbers were post filter it might not be so bad, but since it is prefilter where the LP has something to build pressure against (the filter) the pressure is a bit low. I would like to see about double what you saw, but I didnt with the stock type, but others do. I do get good pressure with my Walbro LP, so I dont know, my tank sock could be clogged some too that doesnt allow the stock type to hold high pressure that it is spec'd to, or I got two sub par stock type LPs.

It could be a clog though, if you want to try to blow all the fuel lines out first. Disconnect the LP, blow air from behind Filter Manager out to LP exit. Then open the fill tube and blow from LP input back into the fuel tank. Fuel will come if you disconnect the LP, but I find if I have less than half a tank and park the truck nose down it starves for fuel from my 34 gallon tank.
 
buddy said:
First try running power to the LP to see if its not able to get enough current through the OPS. You can run battery voltage to pin F of the OBD DLC to power your LP while the enigne is running and see if pressure improves. If not then you could use a new LP, or there is a resitriction, like the tank sock clogged, or other. Either way you really need to do the OPS relay mod, to get the power off the OPS.
Click to expand...

NVW said:
Welcome to the site gnel.

Those numbers aren't to bad. WOT should not drop below zero.

You could use a battery to run the lift pump but pin f is easier. In the stickies there are pictures where you can get power to jump pin f.
Click to expand...

I thought the ALDL pin to jump for Lp test was pin G.
http://www.thetruckstop.us/forum/sh...-troubleshooting&p=81671&viewfull=1#post81671
 
Anyone else seeing this message when trying to view the page 2 of this post??

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Apache mod_fcgid/2.3.5 mod_auth_passthrough/2.1 mod_bwlimited/1.4 FrontPage/5.0.2.2635 Server at www.thetruckstop.us Port 80
 
Crankme69 said:
Anyone else seeing this message when trying to view the page 2 of this post??

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You don't have permission to access /forum/showthread.php on this server.

Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.
Apache mod_fcgid/2.3.5 mod_auth_passthrough/2.1 mod_bwlimited/1.4 FrontPage/5.0.2.2635 Server at www.thetruckstop.us Port 80
Click to expand...

Fixed now.

When you add "..." (dots) to the end of the thread title it throws this error.
 
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