So I've had the Fass on there for a while now (4+ years). For about the 1st 2 years the FP read 15 (WOT, Idle, and everything in between).

Now it drops down to 10. Needle bounces around a little then jumps back up to 15, then to 10, sometimes to 7 or 8 for a split second. Sometimes it'll be at 15 like normal when I leave the house, but 20 min later it's bouncing around from 7- 12. Then the next day it'll be fine - 15 regardless of what I do. Some days it even reads 18-20.

WHAT IS GOING ON?

I've put new filters in....

What else should I be looking at? Relays?

Help!

Thanks in advance.

 

just went throught this with mine the spring and ball are weak next thing happen the motor quit ,shorted out motor was done I called fass there was still warrenty on the pump had sent it back and they rebuilt it for free but you need to call and get an rma number

 

Are you sure it's not your gauge? Is your gauge electric or mechanical? I use a Walbro lift pump and are experiencing the same issue as you. I have a electic gauge and I'm not sure if I trust the gauge. I'm in the process of adding a test port back to my system to be able to test with a mechanical test gauge. After that I'm planning to replace my electric gauge with a mechanical gauge. I think I could trust a mechanical gauge over a electric gauge.

 

That's what I'm trying to determine...

I am thinking it might not be the gauge because somedays it does stay right at 15. And then other times it doesn't. I think the gauge is reading correctly (which is why I'm trying to figure this out prior to ruining a VP$$)...

 

My fuel pressure acts the same way.But only does it in the winter time. The fuel pressure numbers on my edge will jump around.If the OAT is above about 60 F it holds steady at 16 psi.

 

My Autometer fuel gauge requires a buffer to stop the pulses that the VP44 generates or the gauge gets beat up and eventually fails.

 

So was the problem your gauge or FASS? thanks