Fuel Pressure Leakdown / Rich


New Member
Jun 20, 2002
I am encountering two problems, I was wondering if anyone could give me a quick list of things to check if they've had similar problems. I tried doing a search but most of the fp issues relate to WOT tuning.

I installed a FP guage to see what it was set at, static. Key on it went to ~28-30 p.s.i. line on. Key off, went back to zero in 3 seconds. Vac line off the F.P. was 38 p.s.i.

The regulator has a Bosch 233 part no, however it has a stud with an allen head stud and a nut on the top. I figure this is either the stock fpr or a stock-appearing adjustable. I have a Kenne Bell adjustable- however, diff't problem, the flare nut on the return fuel line does not fit the KB fpr.

The pump setup is two pumps, the stock fuel pump and a loud aftermarket pump above the axle. The car runs without the aftermarket pump connected, so I assume the in-tank pump is hooked up. Plan to ditch the dual pumps for a walbro in the near future.

I am mostly looking for information on how to determine why the rail doesn't hold fuel. The car also seems to run rich (BLM ~115) but as long as they are maxed I'd rather run rich than lean.
Either leaky/stuck open injectors or a bad/leaking FPR return. Sqeeze the return line hose with some visegrips and test pressure. If it holds, injectors are good, AFPR is bad. If it does not hold, injectors are leaking.
May also have to do the test above and using the vise-grips to clamp off the fuel feed hose, could be a bad check valve in pump, allowing the fuel to return to the tank thru the pump.
Energize pump, and while it has pressure, clamp off the fuel feed line...don't clamp the fuel feed line until the pump is off, may need two people to do this test if it is dropping pressure that quickly.

The rubber hoses are under the car right between the rear axle and the tank.