Lift pump PSI numbers, are they on par?

[GM Guy]

Hey guys,

We are just now getting ready to christen the 99 into the fleet, as it sat all fall since we got it home in august.

I do remember the LP not working in Salt lake, and at the last fill up in denver area, I do remeber it working

So, it sounds all well and good, but I went ahead and ordered a new one to at least pack in the glovebox, but before switching it, I decided to test it with my Fuel PSI guage (kent moore j-28552A) out of my ebay special used, 2/3 complete J-41550 6.5L kit. (merry christmas to me! )

we first ran some fuel out of the t-valve to flush it, then stuck the guage on, and with the key on, motor off, it read 9 PSI, and fired up at idle, it stayed at about 8 psi, then dad took it to 2K RPM, and it never fell below 6 PSI

Is this good enough to pass, or do we need to test it under load?

 

[JMJNet]

Those are good results.

 

[Crankme69]

Just was checking mine today on the Tahoe 5psi at idle

 

[ak diesel driver]

above avg

 

[GM Guy]

above avg

above average good, or above average inaccurate guage? I hope the first!

 

[ak diesel driver]

I hope so too

 

[Diesel -T]

What make of pump?

 

[GM Guy]

appears to be OEM GM. looks like the new one, but with road crusties.

 

[tanman_2006]

Mine reads 6 psi on my used 2/3 complete Kent Moore Kit. My bet is that you have a good LP. I doubt the guages go bad very often.

 

[GM Guy]

reading the bottom of the guage and seeing it is made in Germany has me convinced that the guage is fine. weee, so I bought a LP for nothing! oh well, I will pack it until I need it

 

[Matt Bachand]

Can't really tell if your only idleing. The amount of fuel used when 'working' is much more. So far reads great though.

 

[Brooklyn Tow]

As Doc always says it could read good at idle....but put a load on it and it'll crap out.....IMO need to check it under driving conditions.

This info is in the stickys somewhere.

 

[WarWagon]

I have had lift pumps rattle away and good pressure at idle but watch the boost drop off at high RPM. It finally failed with 0 PSI at idle 3 weeks and 7000 miles later. The valves fail ESP with commercial 99% bio diesel use. The replacement lift pump had me turn down the boost on the turbomaster...

Run a longer hose and test it under load.

Wiring, relays, fuses including corrosion on fuse blades/contacts, and OPS are suspect for INOP then working on next start.

 

[Turbine Doc]

As Doc always says it could read good at idle....but put a load on it and it'll crap out.....IMO need to check it under driving conditions.

This info is in the stickys somewhere.

Sticky is here in technical reference area http://www.thetruckstop.us/forum/sh...t-Pumps-amp-OPS-operation-and-troubleshooting no lift pressure at idle can lead to hard starting and needs to be checked, but a weak lift leads to low power or sluggishness when loaded or hard acceleration, you need to check both @ idle and under load with most important info IMO is what is lift when at loaded conditions.

As far as unnecessary purchase, 2 options shelve/carry it for a spare, or you could rig in parallel and do a full FTB modification on your truck with selectable pumps one, other, or both on; so 1 dead one would not leave you stranded.

 

[GM Guy]

well, good thing it came with a longer hose in the kit, now I know what it is for!

how do you guys run the hose to get it out of the engine compartment and not pinch it, and not stress the guage with vibration?

also, are the t-valves rebuildable? mine leaks when you open it partially. can this also cause a slightly delayed start? the other 6.x rigs will start quicker than this one, and I am wondering if it gets a little air in.

 

[Brooklyn Tow]

You route it straight over the engine and out the back of the hood and slip it under the drivers wiper....then a strip of duct tape should hold it in place.

 

[D2 Cat]

When you get the gauge to the windshield insert it into a couple of inches of the foam you wrap around pipes. Now worry about vibration to the gauge.