2nd Gen Non-Engine/Transmission Fuel pressure guage,,,,,, or what

[SHobbs]

In Dec. I replaced the L. P, in Mar. a new fuel filter as well as the installation of an ISSPRO fuel pressure guage. In the last two weeks the guage has not been reading right. When I installed it I filled the guage side of the isolator with anti freeze and also opened the bleeder screw on the fuel side after starting the engine to get the air out of the line.



Lately when I start up the truck the guage will only read around 7lbs sometimes only 5lbs at idle. After driving a few miles it seems to go back to where it was for the first week after installation up to 12lbs at idle. Sometimes it goes right to 12lbs and won't move until a few miles are drivin, other times it reads correctly 12lbs@idle and no less than 7 at WOT. It worked fine for about 2 weeks and for the last week or so it started reading funky. Would be nice to get this thing reading right. Any suggestions out there?

 

[Boondocker]

I had some problems with my Westach fuel pressure gauge. I got pretty scared when it dropped to zero, but my fuel pressure warning light didn't come on and i could hear my fuel pump (Air Dog) running.

I removed the electrical connections from the sender, they looked a bit "varnished". I polished them up with nail file till they looked like copper again and re-atached them. Bingo! PSI went right to 15 at idle and 13 at cruise (normal). I've had to do this twice in the last 4 years. Maybe that's routine maintenance.

Hopefully yours is simple like that.

Neil

 

[EKlem]

Since you have an isolator, is it safe to assume that you have a mechanical gauge?



The mechanical gauges tend to be pretty reliable. When it changes readings, is it jerky and quick or does it move smoothly? If it is moving around smoothly and reacting to lots of throttle, the gauge is probably working right. If it goes to one point and stays there until it finally decides to jerk to another place and start working normally, there is probably something sticking in the gauge.



What are you using for a LP? You might be seeing problems there rather than with your gauge.



One thing that you could do is to try another gauge in there if you really think that it is the gauge. Any pressure gauge should work.

 

[SHobbs]

Stock L. P and the gauge moves smoothly. Like I said at first it worked fine, 12lbs at idle and never below 7lbs at WOT. Just that here lately the gauge seems lazy. Today for example I got ready to leave work, fired up the truck and the guage showed 5lbs at idle, it would drop smoothly when I pressed the go pedal. After I drove about 25 miles the guage was at 8lbs at idle. I have another L. P and I will try that as soon as I can. I have checked all the connections for the gauge and all seems ok. Just a little puzzled why it started out ok then started to read low at times.

 

[NoSeeUm]

I am assuming you are still running the Carter OEM (or equivelant)?



I had a LP go bad more or less with the same symptoms you describe. I scratched my head for a long time until the reality dawned on me.



FWIW concerning isolator venting. I don't bleed all the air out of the sensing line quite as well as I used to. I am starting to think a little bit of air in the line helps smooth the pulsations off the diaphram. Allot of posters report isolators failing quite regularly and this may help.



Jim