When I first got my fp gauge it stayed at exactly 15. It didn't move at all except when truck turned off...no bouncing needle. So for the past couple of days the needle has been bouncing from about 10 to 15. Then yesterday on the way home it started bouncing down near 5 and then 10. This is making me worried.

Thoughts on what's going on here?

Driving habits haven't changed anything. Even idling the needle bounces.

P.S. my comp is not tapped, just hooked up as an ez right now.

 

mechanical or electric sender?

 

Not sure, I had it put in when they replaced the injection pump, installed the Fass and rebuilt my trans. How would I tell...?

Thanks for your help...

 

Is it possible the sender is failing? That would be a WHOLE lot better than the Fass pump or the VP44....

Or you think it might just be a clogged filter from bad fuel?

 

I had the same problem but not just in cold weather. I replaced the gauge and it went back to normal but then I also replaced the fass soon after because of weak pressure but I would say it was the gauge.

 

Anyone know what the warranty is on the Fass?

Should I change the filter first? Seems like that could be the problem too???

 

Warranty was 4 year with my first fass. The last one I bought is supposed to be lifetime. You could try the filter first that would be a cheaper fix. Do you have an isolator?

 

I have the same issue in cold weather.My fuel pressure never stays steady when its cold outside.It skips around 12,17,18,16,19,16,13, etc.I've noticed during the summer its steady on 16. My sending unit came from Edge and when I got my fass,I put it in the side of the unit,instead of on the VP44. Dont know if this helps you or not,but I've always figured it was just cold fuel and harder to pump,than in the summer when its warm.

 

Not sure if this is your problem - but if you have an electric sender, I'd do this.

I have an electric sender and it goes erratic every couple years. I clean the contacts with sandpaper and reattach and all is good.

Also, consider a snubber before the sender to minimize pulses from the VP44. I use a needle valve tightened down almost all the way as my snubber.

 

I bet it is the electric sender.
My mechanical gauge stays rock solid regardless of the temperature.