Erratic fuel pressure -- Ideas??

[wyosteve]

Here's the scenario. Had Westach fuel pressure gauge installed 2 wks. ago. Shop mounted the sender on the side of the engine even though I told them to mount it near fender. Sending unit has grease gun snubber from bottom of fuel filter housing. 68k on truck, 01 ETH. Right after install saw 9-10psi at idle 0 cruising at 70mph. Assumed bad lift pump. Yesterday installed newest and greatest lift pump. 15 psi @ idle, but will drop to 0-3psi running around 70. Seems to drop most around 1800 rpms. Fuel filter was changed about 7k ago and I will put a new one in this weekend, but was wondering if the engine vibration could be causing the fluctuation or if someone has any other ideas. I think for peace of mind, I'll remount the sending unit away from the engine and see if it helps. Any thoughts/suggestions would be appreciated.

 

[DEZLPWR]

I would definitely mount the sending unit remotely!

Several people have had problems with erratic psi readings when mounting the sending unit directly to the engine. My sending unit has been mounted remotely from the get-go with no problems to date...

 

[Jetson]

When I have had problems with my guage, it has been a bad ground. You should try running a separate ground wire to the sending unit.

 

[RustyJC]

The Westach sending unit is not solid-state - it is a potentiometer (resistance) type sender with a (probably) wire-wound resistor and wiper arm. Engine vibration could very well be causing a problem. Both of my senders are remote-mounted on the firewall, and the post-filter sender has a gauge snubber (I failed two post-filter senders before adding the snubber).



Rusty

 

[wyosteve]

Thanks for the thoughts guys. I'll move the sending unit this weekend and see if that helps. I'll post the results.

 

[TNT]

sending unit mod

Here's how I mounted my Dakota Digital senders. One is pre filter, the other is post filter. sender mount 1 sender mount 2 sender mount 3