Fuel Pressure tester

[akty]

OK, I hooked up a fuel pressure guage today to see if it holds pressure. Turned the key, heard the pump(walbro) cycle and then jumped out to check the pressure. It was falling quickly. went back to 0psi in about 15 seconds.
Started the truck and watched the pressure guage again. Stayed at around 38 psi until I shut it off and fell to 0 again. Bummer....
Getting my KB AFPR installed Wednesday and going to see if the injectors are leaking.
Any thoughts on this current problem? Remember I was getting a code 45 with rough idle and spitting and sputtering with throttle response for two minutes until the check engine light came on and then things kinda smoothed out.
Thanks,
Pete

 

[smeagol]

The service manual has a test to determine what area is leaking.

Basically you put clamps/vise grips at the flexible hoses, then based on if the pressure leaks down or not, you can find your leak source.

Build pressure, clamp at the flexible line after the regulator (at the transfercase area is easiest) - if fuel pressure drops after building pressure & clamping - the possible leak areas are - injectors, pulsator/pump.

Build pressure, clamp the flexible line BEFORE the fuel rail (feed line) at the transfercase- if fuel pressure drops after building pressure & clamping - the possible leaks areas are - injectors, FPR

Do those tests I'd say, if it leaks on both, you may have a leaky injector. You might be coordinated enough (or have enough people) to build pressure, then clamp both the feed & return line near the transfercase - if it leaks down after that, it's injectors (barring a massive fuel leak).

You can refer to the manual for the specifics of the test...this is from memory & basic reasoning.

 

[Falco]

Pete,

Do what Brian said. He has a good memory, that's exactly what the manuals suggests to do. A few things. Handle the flexible hose with care, you don't want to destroy them with the vise grips. If you suspect a faulty injector after the tests, you can do an injector balance test to see which one is leaking.

And finally maybe the most important thing. Check your pressure gauge first. Make sure you don't introduce the leak with the gauge. That sucks, belive me. You can troubleshoot a completely perfect fuel systems for days this way. :x

Peace,