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Problems With Fuel Pressure Gauge

3468 Views 8 Replies 3 Participants Last post by  jrglenni
I've been having problems with my fuel pressure gauge every since I installed it. The reading bounces around all the way from 0-100psi for no apparent reason. Sometimes its while I'm cruising, other times it's when I accelerate, sometimes it's when I let off the gas. Every now and then it seems to say steady at approximately the right pressure, right around 38psi. I checked the wiring and I'm pretty sure it's ok. I have a Zex wet nitrous kit so I put the electronic sending unit in between the fuel feed line and the NMU, which I assume should be fine.

I sent the manufacturer an e-mail and they didn't give me much to go on but said that the gauge wouldn't work on a return-less style fuel system. Has anyone heard of that before? It seems like the gauge should work no matter what type of system it's on. I'm thinking it might be the sending unit or the gauge itself. Anyone have any idea what might be wrong?
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Really? That's a bummer... what do people usually do for fuel pressure sensors on the stock fuel system? Does it have to be a mechanical gauge? I guess the other option is to replace it with an aeroforce gauge that reads the pressure from the ECU through the OBD port but that's not a good fit for my install. I'm mainly only concerned with fuel pressure when the nitrous system is flowing, should I expect to see stable readings when the fuel solenoid opens and fuel is flowing through the line?
Just hooked the gauge up to my air compressor and same behavior. Either I need a new sending unit or a new gauge.
So Glowshift called me back once my gauge was sent back, apparently the sending unit was junk which was what I had expected. The guy said that the return-less fuel systems leave pressure in the lines even after the car is shut off, which degrades the diaphragm in the sending unit much more quickly. I don't think the unit ever functioned properly, so my guess is that the diaphragms in those units are just junk regardless of what type of fuel system the car has.

He gave me 3 options though; return it for a full refund, exchange it for another one that he said would probably fail within a few months, or upgrade to their Elite 10 color series gauge which is a different style and shouldn't have any problems. I picked option 3 as I had originally though about going with that gauge since my nitrous pressure is the same style, and they gave me 10% off of it and I just had to pay the difference.

Got the new gauge in last night. This sending unit looks much more stout, identical looking to the sending unit for the nitrous pressure gauge. It doesn't use a diaphragm and uses a chip apparently. The crappy thing is that the wiring harness is different and although I probably could just cut some wires and use the ones I already ran, I am probably going to just run the new one and pull out the old ones. Wiring fun here I come... Actually this time I am going to drill a hole in the bottom of the defroster vent and run my wires through there, being able to see the wires in the wind shield kind of annoys me.
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Out of curiosity, does the sending unit have a diaphragm or is it completely electronic?
That's cool. I thought about getting the Autometer Cobalt series since blue is my color of choice for my instrument panel, but for the price of the Glowshifts and the good reviews in general, I couldn't justify the autometers. Even with the fuel pressure gauge issues, I'm not regretting the choice. We'll see how they hold up 2 years from now but from other peoples experiences, they seem to be fine. I get a warranty for a year at least *crosses fingers*

I figured some jumping would be normal. With the return-less system, the pressures will spike up and down more than a return style, which is one of the reasons for switching to a return system, so I'm expecting that behavior.
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