After fuel gelling problem in extreme cold, no reading on gauge. replaced FASS and stock filters,cleaned out braided line from inj pump to sending unit.no difference. truck runs fine,even at wot with load. bad sending unit or gauge? does line need bled?

 

Is it a mechanical or electrical gauge? If mechanical, did you use an isolator? Isolators are known to give problems. Line doesn't need to be bled.

 

Gauge is electrical. does sending unit work on resistance? Gauge works when air pressure is applied to braided line from pump.Any way to test sending unit?

 

Autometer doesn't recommend using their electric FP gauges on Cummins trucks because engine vibrations and fuel pressure spikes tend to kill the senders.

Even knowing that I still have an Autometer Phantom electric gauge on my truck. To protect the sender, mount it at the end of a rubber fuel hose to diminish vibrations, and use a snubber to protect against pressure spikes form the injection pump. I've had this setup for a year with no sender problems.

Here is where I bought my snubber and hose. I chose snubber PS-8E and it works fine with diesel fuel.

http://www.omega.com/ppt/pptsc.asp?r...ERS&Nav=prec02

http://www.genosgarage.com/prodinfo....mber=VULCAN-FH

 

Not sure how to check your sending unit, but if your sending unit turns out to be shot, you might want to consider just buying a needle valve, fuel hose, fittings, and a mech. gauge. Probably cheaper, and there's really nothing that can go wrong other than the gauge itself.

 

Think I`ll try the snubber and rubber line setup. not real wild about running fuel line into cab with mech. gauge. thanks for the input.I`m new to this site.lots of good stuff!

 

This is why i always start my conversations with dealers and folks on forums with low pressure issues "Do you know the gauge is reading correctly?" We find numerous gauge issues that the FASS/HPFP take the blame for. I personally run a mechanical gauge with a needle valve just cracked open, no isolator. I had to shut the valve down to keep the vibrations from killing my mechanical gauge.........it still buzzes every now and then.....

 

My needle valve is cracked open just a tiny bit. I don't see any oscillations in the gauge needle. I'm surprised you do. It does buzz though...

 

I had to work with mine......and i got the "Tick Hair" measurement on my valve finally set! haha.....BUT the cool thing was to see how vicious the VP is to gauges! WELL not cool really.....but you know…..i just drive with ole Gary P. Nunn a little louder!