Engine/Transmission (1998.5 - 2002) air in my fuel pressure gage...?

[Jim Ross]

I have a DiPricol fuel pressure gage in my '01. The feed line comes off the schrader valve at the inj pump, next in line is an isolator that has a small plastic line filled with anti-freeze that actually runs the gage on the A pillar. I keep getting air (from where? How?) in the feed line from the schrader valve. This causes the gage needle to go crazy. I can bleed out the air at the isolator and the gage returns to normal, but then after a few miles, I have air in the line again.

Any ideas about what is causing this problem? I have had this gage in place for 4-5 yrs with no problems. Dealership replaced my lift pump at 55,000 miles and it was afterwards that the gage problem began... just a coincidence or something else?

 

[Fishin Guide]

Well, unless your lift pump is cavitating and aerating the fuel... .



I really think that your isolator or schrader has a leak somewhere. I would look to the isolator as the diaphrams can rupture and suck air when the pressure is removed. Just a thought. And, if you have a vacuum pump, you cnan test for leak down.



Dave

 

[Jim Ross]

OK, thanks. I'll check out the diaphram in the isolator... . this is the 2nd isolator I have had, the first only lasted about 15 months, but I didn't have these symptoms when it failed... it just quit working. Maybe I should just try switching to an electric gage... . maybe not as accurate, but longer lived?

 

[Fishin Guide]

The primary problem as I see it is the pulses from the VP44. The closer you check pressures to it, the quicker it's gonna waste isolators, gauges, senders. Try adding a snubber (grease gun hose) and or moving the point wher you take your pressures from.



I know everyone wants to monitor pressure at the VP, but it's hard on parts. Now, maybe a liquid filled gauge to dampen those pulses... .



Dave

 

[OL RATLR]

I have a DiPricol fuel pressure gage in my '01. The feed line comes off the schrader valve at the inj pump, next in line is an isolator that has a small plastic line filled with anti-freeze that actually runs the gage on the A pillar. I keep getting air (from where? How?) in the feed line from the schrader valve. This causes the gage needle to go crazy. I can bleed out the air at the isolator and the gage returns to normal, but then after a few miles, I have air in the line again.

Any ideas about what is causing this problem? I have had this gage in place for 4-5 yrs with no problems. Dealership replaced my lift pump at 55,000 miles and it was afterwards that the gage problem began... just a coincidence or something else?

Usually air will help the gauge stop bouncing at least on a mechanical

gauge setup.