Diagnosing a dying fuel pump

[Pube]

On my quest to try and rosolve my 1GGTE pinging issue I have turned to my fuel pump. Another Toymodder I have spoken to said his engine pinged due to a failing fuel pump. So how do I actually determine if my fuel pump is under performing??

So far I have noticed that my fuel pressure falls not long after I shut off the engine. Im using a Walbro in tank pump and have Sard fuel reg with a pressure gauge attached. With the fuel pressure set at 38psi at idle, approximately 15 mins after shutting off the engine, I have zero fuel pressure. My fuel pressure use to stay around 38psi for a long time after shutting down the engine.

Dont fuel pumps have some sort of check valve to stop pressure back flowing through the pump? I have tried testing this by clamping the return line (with the engine off) but the pressure still falls. I have also noticed when you pinch the feed line either with your fingers or a clamp, the pressure rises, however when you pinch the return line, pressure does not change. I guess this is an indication that the fuel regulator is OK.

Could this be an indication that the fuel pump is failing?

[EVOSTi]

clamp the feed line when you turn off the engine and see if it still drops.

[DazbaVBz]

Diagnosing a faulty fuel pump, - make sure you getting proper voltage at your pump, check your fuel filter is clean and in good condition,

Now at idle you should have about 30psi of pressure, when your under boost it should increase,

you were saying that pinching you feed line bumps you pressure seems a bit strange, when you crimp your return to the tank line off your reg the pressure regulator guage should increase, your fuel pump does have a one way valve in it, it should hold pressure at about 15 for a while then slowly drop down but there should always been some pressure in the system to stop fuel in rails boiling and vapourising,

Does your fuel pump sound any different to normal, have you changed fuel stations or fuels or moved your distrubutor or changed anything for ignition timing,

regards
Dale

[The Real Roadrunner]

is the guage in the rail or on the feed line?
do you still have the factory pulsation damper/check valve on the rail? it should hold 30odd psi for a fair while or it may be rooted.

as for testing the pump, the only real way to tell is by being able to see the guage at the point of peak HP and seeing if the pressure has fallen off from where it should be (38psi + whatever boost you run) but it would be nice to have a flow gauge on there also, that way you can tell if the pump is doing a good enough job, ideally you want to have about .5L or more returning back to the tank at all times.

cheers
linden

[IN 05 NT]

take it to unigroup, throw it on the dyno,

they can check you pump, reg, while youre there, and give you ther afr's also!

quickest and easiest way i can recomend!.

[The Real Roadrunner]

well i wasn't going top recommend anyone in particular but they are who i use and its generally the first thing they do unless you go in there saying "ive got a bosch 044 and 600cc injectors with a sard reg and 3/8"lines " then he would probly just throw it on and start tuning but if the numbers seam odd he will stop and run the flow/pressure test.

cheers
linden