I just installed a Westach fuel pressure gauge from Genos Garage. and it works great until I floor it (WOT) ???It runs around 14 psi idle and 12 psi at 70mph, but when I floor it the gauge just shuts off, and goes to 0 psi. I hooked up my trusty mechanical gauge and the pressure never drops below 10 psi. So I know that its the gauge thats screwing up... what could be the problem with it.. I have the gauge and the sending unit grounded to the same location, and the voltage to the gauge stays steady at 14V... Any Ideas...


Thanks
Chris

 

Are you sure the mechanical gauge is correct?

 

ya it Reads the same as the electronic gauge untell WOT... Its a big jump from 0 psi and 10 psi... Right now I have them both hooked up to check it... the mechanical reads maybe .25 psi off the electronic one ???

 

Hey Chris,
Where do you have the gauges hooked up at? I think your 98.5 is like my 99 in that it has the 1/8npt test ports on the top of the filter housing. I have the Westach sending unit hooked to the post-filter test port via an 18" grease gun hose and a mechanical hooked to the pre-filter test port. Are you taking both readings off of the same line (either post or pre filter) or are they on seperate sides of the filter?
If nothing else, I would contact Westach, I've heard they have pretty good customer service from what I have read. I know that I have read of some sending unit failures due to vibration or mounting the sender right off the VP-44.

 

I have the sending unit hooked up to post-filter and the mechanical hooked up to pre-filter

 

Chances are it's the sender. From what I've been told, you need to have a needle valve in line with the sender to help isolate the sender from the vibrations of the VP-44. I thought my Holley pump was putting out over 30 psi at idle (it's rated at 15 psi MAX). So I replaced it with a PE4200. Had the same problem (so I thought). Hooked up a mechanical gauge for fun. 22 PSI at idle. I need to get a longer hose to see what it is at at WOT, but it holds a solid 22 at idle. Point of the story, it was the sender from the beginning.

 

I think it might be a Vibration issue... my Friend taped on the sender while the truck was at Idle and the pressure on the gauge started to go down I checked all the connections and they are tight. I am going to try to remotely mount it away from the filter housing and see if that helps

 

I remotley mounted the sending unit to the fire wall, that fixed the problem ;D it never drops below 9.5 psi at WOT ;D

 

Good deal Chris! ;D
That's why I used the 18" grease-gun hose when I installed mine. ;D After reading where some folks were having trouble when they mounted it directly to the filter housing, I went out and got the stuff to mount it remotely before the guage ever arrived in the mail.
Glad to hear that was the problem and not the lift pump.