Bad FP guage or bad Lift Pump

[TboneMan]

Well, after several emails to Westech trying to trouble shoot my FP guage, I figured I'd check with the "experts".



Here's the situation:

I have installed a Westech FP guage post fuel filter via Ray's banjo bolt and rubber fuel hose (barbed fittings and hose clamps).



Occationally, the guage will read 7 to 9 psi at idle. However, as soon as I head down the road the guage begins to drop (slowly) and then drop below zero where it will stay.



It is almost as if the lift pump doesn't have sufficient pressure to feed the injector pump plus the gauge. Could the injector pump create a vaccum in the guage line if the lift pump is not supplying enought fuel?



Thus far I haven't noticed any significant performance problems.

 

[Doc Tinker]

If you were close to me, I'd loan you my portable gauge. You could plug it in when your pressure drops and see whether or not there really is pressure in there.



Doc

 

[MCummings]

Originally posted by TboneMan

Could the injector pump create a vaccum in the guage line if the lift pump is not supplying enought fuel?

Yes, I've read on the TDR that the Injection pump (VP44) can pull up to -12PSI of vacuum.



If you don't have any BOMBs, just take it to your Dealer and ask them to check your lift pump out. It is supposed to be replaced on their dime if it falls below what I recall somewhere close to 8PSI.



If you have BOMBs just remove your dieing lift pump, and put a good pusher pump by the fuel tank. www.entepriseengine.com has a pusher pump kit for sale, but I have not heard how much $$ it is, I have heard it works great, and is easy to install.



MerrickNJr

 

[Bigsaint]

Tbone, MC is right on in regards to the vaccum. When my first Mallory died, my SPA was reading -11 at idle . If your gauge has been doing this since the install, I kinda doubt it's the sender. Do as stated above and take it to the dealer for a check or find someone with a mechanical gauge and see what you have with that.



Scott W.

 

[RustyJC]

I failed two (2) Westach sending units on my post-filter gauge (none on the pre-filter) before I finally added a gauge snubber at the inlet to the post-filter sending unit. The third sending unit is working with no problems. I wouldn't count out a failed sender - yours sounds like my second failure (the first failure was evidenced by a gauge needle that just went wild from 0 to full scale).



Rusty