Steve, with no vacuum to pressure regulatorOriginally posted by Steve Wood:
It will read the same at any speed unless it is under boost.
Under boost, the fp should increase 1# for each pound of boost. In other words, if fuel pressure, vacuum hose off, is 40 and you hit 20# of boost, then you should be reading 60# of fp.
My first statement is really not correct, as fp is normally read with the vacuum hose off and when you put the hose on, the pressure will drop a few pounds due to the vacuum lifting the diaphram inside the regulator. The more vacuum the engine generates, the less the fuel pressure you will read if you have your gauge taped to the windshield. When boost comes on, the procedure is reversed.
Confused you, huh?
The pressure with the vac hose hooked up isOriginally posted by Steve Wood:
you have a bad regulator then unless the pump is completely gone.
Take an air hose and apply pressure to the port, the fuel pressure should rise accordingly...say you put 20 # to the port, the pressure should rise 20#.
Does the pressure drop to about 30# when you put the vacuum hose on? Wondering if the line is blocked.....there should be no check valve in the hose to the regulator.
[This message has been edited by Steve Wood (edited December 10, 2001).]
It is the stock pump,the car has 76000. milesOriginally posted by The Radius Kid:
Yup.26 lbs,vacuum on sounds awfully low though.Is that a stock pump?Maybe time for an upgrade;hotwire kit,walbro 340,adjustable FPR.What kind of shape is the fuel filter in?Changed recently?
I am going to drop the tank tomorrow,should IOriginally posted by Steve Wood:
Well, the stock pump is probably shot. Try the fuel volume test that I suggested above.
Also, with the car idling, pull the the hose off the regulator and add pressure to the regulator port. At idle the car should not be using much fuel and if the pump has anything left, it should raise the pressure when you add some pressure to the the port.
I suspect you need a new pump, a hot wire kit to get full voltage back to the tank...and, perhaps, a new regulator. If the regulator is not adjustable, it would be a good buy, anyway.
I did the fuel test and got just under 2Originally posted by Steve Wood:
Don't drop the tank until you run some tests...pull the schrader valve out of the rail and slide a hose over the end...put 12 volts to the pump test lead and see how it flows...
But, it is time for a new pump. If you want to improve performance beyond stock, you will need a new pump anyway....the stock one barely kept up with the stock set up as it was.....
I would suggest a Walbro 340 since I noticed that PTE was selling either the 307 or 340 for, I think, $85 for a special sale. The only difference in the pumps is the pressure relief spring. Either one will do, actually.
For the hot wire...you can either buy a kit, or simply wire it yourself for $10 worth of parts...a 30 amp relay and a 30 amp fuse holder and a piece of ten guage wire long enuf to run from the alternator to the rear of the fuel tank.
There are several adjustable fuel regulators but you can wait on that if the current regulator is good and you are not upgrading chips, etc. With an aftermarket chip you need an adjustable one or, perhaps, the one of the TTA which has a bit higher pressure.
I suspect your 300 mv o2s are from lack of fuel. Your off idle cut out is probably the same.