fuel pressure check

January 10, 2009, 03:15:07 AM

My car has been kicking back like im running out of gas at a specific rpm range (1700-2200) and does not do so under heavy loads. I've already basically ruled out ignition as being the source of the problem, and changed my fuel filter to make sure it wasnt clogged. Everyone who I've talked to about it so far, has pointed me toward the fuel pump, and before spending 160$ on a fuel pump assembly, I'd like to make sure thats the cause of the problem, and not something ive simply missed. The compression test kit im going to be borrowing is a craftsman, and it didnt have a fitting for a newer taurus, and the guy im borrowing it from said he doesnt think it has the correct fitting, so... Basically, Im wondering how I would go about checking my fuel pressure (where its at, what exactly my procedure for doing so would be), and what type of fitting i need for a fuel pressure guage i would need.

I'm pretty new to working on cars, and would much appreciate a little more informed guidance.

Thanks
-Steve

fuel pressure check

Reply #1 – January 10, 2009, 04:49:33 AM

Your assuming we know the vehicle your talking about is a taurus and the year is unkown.

the troubleshooting process is going to be the same cookie cutter aproach but knowing the car/year eliminates assumptions on our part.
I was about to ramble into some information when suddenly i saw "taurus".

so are you doing a compression test and a fuel presure test or are you confussing terminology?

Compression test-
-have motor warm
-remove plugs
-install compression tester on cyl 1
-crank engine until needle guage is as high as it will go,
-repeat for all other cylinders
-look for any diviation of 10-15psi.
-a real huge diviation will be obvious

Fuel presure tester
-install hose fitting on the shrader valve (looks like a bike inner tube fitting located along the fuel rail)
-start motor
-shut off motor
-write down the presure (approx 40psi)
-duct tape the guage to the windshield if the hose is long enough
-drive car
-watch guage as you cycle through RPM / Gears
-if your psi drops into the low 20's or teens, bad fuel pump.

Other simple causes
-TPS located on the throttle body where air comes in.
-penetrate the TPS green wire with a stick pin
-connect volt meter red lead to the green wire stick pin
-connect volt meter black lead to ground
-turn on key
-voltage of the tps should be .6-.9vdc.
-manually and slowly open the throttle body butter fly and watch the voltage.
-voltage should increase smoothly and without any jumps.
Its best to use a need type meter for this test (buttstuffog meter) because it will deflect if you have a partially open circuit.

Your symtoms point to a tps because it repeats at an rpm range and duplicates itself based on what you say.
the only moving part that is that consistant and is a part of a probable fault would be the TPS(throttle position sensor).

Have you pulled the codes?

fuel pressure check

Reply #2 – January 10, 2009, 06:57:24 PM

The guage is from sears.com, you can search for "Craftsman compression test kit", and its the first one (I can't post a link or I would).

He said it can check fuel pressure, which is what im trying to do, not a compression test, I understand your confusion after rereading my original post. But for some reason he keeps telling me that he doesn't think that it has the right sized fitting to check the pressure for my car, because it didn't have the one for his mom's Taurus. I'm going on what he has told me thus far. I will check the TPS like you said soon, when it's daylight outside.

What do you mean by pulling the codes?