Fuel system issues...

[txstang84]

Hey guys,

I've been fortunate to not need much assistance lately, but I guess it's about time that I have a problem. I've been having a fuel delivery problem off and on here lately. Here's the deal:

Yesterday morning, while sitting at a stoplight on my way to work the idle dropped from 950-1000 to about 600-650...completely out of nowhere. I proceed on my way to work babying the car cuz it's running like hammered doo doo. I manage to catch a glimpse of my PMS and it shows "0" on both O2 sensors output. My first thought is that I burned up some wires or something. After checking volts at the connectors, I noticed that I have ZERO fuel pressure...again, this happened completely without warning. I've had other fuel pressure problems before; after changing the fuel filter it seemed to go away-the car had been running pretty well. Incidentally, after the filter dried out, I inspected it, and it was clean. So, I try to adjust my FP to no avail...I even changed the FPR thinking the diaphragm had torn or something. Again-no fuel pressure reading on the gage, and the car barely runs.

I can hear the pump running and all seems normal except that the tone of the pump doesn't change (like it used to when the pressure built up). Is it likely that the pump is bypassing internally in the tank? There are no leaks throughout the entire system, the filter is new, the FPR is new...the only thing I can think of is that the pump is Tango Uniform...

Any other ideas? I don't want to drop the tank unless I really have to.

 

[WhiteFox342]

You will most likely have to drop the tank. I think I may know the problem. The fuel pump may be bad, but I suspect the rubber hose that connects the fuel pump to the metal line leaving the tank. I have seen them develope a hole. When the pump tries to pressurize the lines it sprays out the side of the hose. It is like having a big leak, but it is in the tank so you won't see it. to

 

[jrichker]

Fuel pump pressure test
Disconnect the larger of the two fuel lines up by the Schrader valve. It is the return line and does not
have the Schrader valve on it. Find a piece of rubber fuel hose and clamp it on the return line
coming from the regulator. Stick a bolt in the other end of the hose and clamp it. Make sure that
all your connections are tight and leak proof as possible. Be extremely careful that your
test connections have no leaks. There is a definite fire hazard when you do this test.
When this powers up, you don't want fuel squirting everywhere.
Hook up the fuel pressure test gauge to the Schrader valve pressure test port.

Turn the ignition switch on and watch for leaks. You may want to use a helper inside the car
to cut the switch off quickly if you have a leak. To trick the fuel pump into running, find the ECC test
connector and jump the connector in the Upper RH corner to ground.

.
Caution!!! You have blocked the return line for the fuel pump! Pressure will rise very quickly past safe levels with a good pump

If the pressure goes up past 55 PSI, the pump is good and the fuel pressure regulator is bad.
If the fuel pressure does not hit 55PSI or more in a few seconds, the pump is bad or you have electrical problems.