I suspect my fuel pump might be weak, so I want to test the pressure.

Is this an easy thing to do, what do I need and where do I test.

Also what values should I be looking for?


(86, auto).

 

Schrader valve (looks like tire valve) on fuel rail. Gauge should be capable of reading at least 50 lbs.

Reading should be above 35 lbs, less than 39

[edit] to correct fuel pressure figures....

 

1.) Fuel pressure gauge.
2.) Connect at the Schrader valve on the fuel rail.
3.) Proceedure and values available in the Factory Service manual available from www.helminc.com.

RACE ON!!!

 

Hook up fp guage to Schrader valve. Key on, engine off....pressure should hold to spec (may take several cycles of the key to max out) record pressure.....start car...pressure should drop a little within spec. For spec....someone will jump in with them or like said above, check your Helms.

 

Thanks guys!

Can I get a fuel pressure guage from anywhere (autozone for instance)?

 

Yep. I just bought a new one from Checker Auto for about $40. It comes with a GM sized fitting on the end, and adaptors for Ford, etc.

I would advise that before hooking it up, you pull the fuel pump fuse and crank the car. If it starts, let it run until it dies. If you go to attach the gauge with full pressure, it will spray fuel until you get it screwed all the way down. Once the gauge is connected, put the fuse back in.

Turn the key to run (not start) and the fuel pump will run for about 2 seconds. Note what pressure it builds. Start the engine....any change?

If you have a no-start condition, you can jump the fuel pump terminal on the ALDL connector so the pump runs continually. Note any changes in fuel pressure from just the 2 second "key on" test.

Disconnect the jumper wire and turn the key off. It should hold pressure (with little loss) for at least a few minutes before "bleeding down". If it drops substantially within a few seconds, it could be a leaking injector, fuel pressure regulator, or check valve in the pump. Pinching off the return line will eliminate the regulator. If you suspect a leaking injector, pull the plugs and look for one that is fuel fouled. If it isn't the regulator or a leaking injector, then the check valve in the pump is at fault.

Why do you suspect the fuel pump is weak? Do you have a no-start condition, or is the car running poorly?

Fuel pressure test is an excellent place to start diagnosing. If you do have a problem, it can help narrow down whether it is fuel, ignition, or timing related.

 

I suspected the fuel pump because I get poor throttle response.

 

It definitely could be the pump.....The fuel pressure test will either confirm it or rule it out. Let us know what you have.

 

The fuel pressure test could reveal a lack of fuel and/or pressure with several possible causes. One IS the fuel pump. Others include bent or crimped fuel lines, or even a clogged fuel filter.

RACE ON!!!

 

I'd recommend one of the guages that have a built-in pressure relief button and drain tube. I got one of these from Pep Boys and I recall the price was about $30 to $40.