Yet Another Lift Pump Question ??

[beartrace]

I just changed the fuel filter and tested lift pump with BHopper guage.



1. The Lift Pump will only run 3 sec when I cycle it with the ignition switch. (It used to run 15 secs). ????



2. At the test port on the filter, idle-12, cruise-13, WOT-7 to 8. At the test port on the injection pump, idle-12, cruise-12, WOT 4.



3. At what location should I be connected for the correct reading?



4. Why is there a big difference in WOT between the two test ports?



5. Do I need to be concerned at this point with this situation?.

 

[Archive]

Beartrace. . I'm going to sneek in here with another question...

My readings were about 1-2psi lower than yours. . about 2. 5-3 driving at WOT... My question is... is the spec of 8 psi under a load driving at WOT????

I just had mine at the dealer today to check the lift pump. . they said the psi was 7 at 3000... and it is as long as you are not moving. . I pulled out of the dealership and stomped it and it went to 0 !!!!! I saw a tech there checking a LP (he had just replaced) sitting in the service bay... he said it was 11psi at WOT. . (I never see 11psi... except when the truck is NOT running. . )(reminds me of someone checking a battery. . Yup, its got 12V's, but it still won't start. . )

I just checked my pre-filter and it was about 5psi loaded at WOT. . I guess we are on our own..... :{



Looks like its time to BOMB the fuel system, too

Bryan

 

[Idaho CTD]

Finally got mine replaced today

I wanted the dealer to replace mine before I put in a helper pump. My FP @ idle was 9, @75mph was 5-6, and wot was 0. All these were taken at the injection pump. When I originally took it in they tested it at the filter. It read 10psi and they said that was within spec's. I told them it would go to 0 @ wot on this trip and said the needed to contact the star hotline. They finally did and presto a new pump. Now at idle I'm at 14 and wot with stage II injectors and PM3 box on 9 it wont go below 5-6.



Beartrace,

I would change your fuel filter and test it again. You are only suppose to see 1- 1 1/2psi drop through your filter. 4psi is a lot. In my personal opinion pre-filter pressure is only useful to check your filter condition. Your vp-44 is what needs the pressure.



Nathan