View Full Version : Seeking advice on diagnosing fuel pressure problem on 1999 Z28


Mr Ed
06-22-2012, 12:12 PM
I am looking for suggestions on the sequence of things to try in order to diagnose the cause of a fuel pressure problem on my 1999 Z28.

The problem began very suddenly. I had just made three passes which had all been normal (11.7ís or so). Then, on the fourth pass I lost almost all power when I launched. Now, the car idles OK and drives at low speed OK but loses almost all power if I try to accelerate even just a little bit. It is not drivable on the highway and had to be towed home.

The fuel pressure with the motor off and with the key in on position is now 23 lbs. (s/b between 55 and 60). The pressure drops immediately to zero when the pump stops. At idle, I get a constant 23 lbs.

I should note that for the past two or three years the car has been driven only 4 or 5 times a year. So, I assume old fuel gumming up the works is a contributing factor.

Reckless
06-22-2012, 01:27 PM
Easiest thing to try first is the filter. Move on from there. Could be the pump itself as they do give out eventually, especially if you run the fuel low often.

Mr Ed
06-22-2012, 01:46 PM
Easiest thing to try first is the filter. Move on from there.
As you suggest, I will start there. I was considering doing the filter first since I was going to replace it anyway.

I know a bad filter [xx pump XX] can cause low pressure. Can it also, though, cause the system not to HOLD the pressure it has built up?

Could be the pump itself as they do give out eventually, especially if you run the fuel low often.
The car is mostly used for racing and I rarely have more than a quarter tank to keep the weight down. I am kind of expecting that a bad pump will be the end result. Due to the magnitude of the effort to pull the tank and the cost a pump I want to rule out as many other possibilities first.

Thanks

Note: Please note that I have made a correction above. I originally typed in "fuel pump" but meant to say "fuel filter"

Reckless
06-22-2012, 02:20 PM
Well if it is still running, but at limited speed, it should be able to sustain a lower pressure I would think. Injectors could be gummed up as well

Old Geezer
06-22-2012, 08:38 PM
In tank connection is FUBAR???