I've had an occasional P0300 code and the truck has died on me and won't start for about 10 min of sitting after dying. I noticed that it usually happened when warm/hot out and has been running/driving for a while, or driving a lot during the day. I finally was able to get a fuel pressure gauge on it when not starting, it was just above half tank and noticed that when running ok, was around 61-66 psi, but when it was not starting it was only at about 33 psi and pressure bled off quickly bled off after turning off the key. Once it sat for a few minutes pressure was normal again, it started right up and I filled up the tank, no problem since and if I keep at least 2/3 tank it seems to run ok. Would this scenario pretty much rule out everything but the fuel pump?

Also does anyone have a good write up or tips on replacing the pump?

 

normal fuel pres. psi. should be around 60-66 psi. it should hold pressure for i'd say a good 5-10 min. without any drastic press. loss. if so then the fuel is bleeding off somewhere (injector, regulator, leaky line, filter etc.) the low press. at start up could be from this leak down or restriction in fuel system. check fuel filter 1st. a weak fuel pump would also give you low press. you would have to do a fuel volume test when acting up.

 

Well when it's running fine, pressure is ok at 61-66 psi., and holds the pressure well, it's only when it acts up does the pressure bleed off and show low psi. It has never acted up in the morning or after sitting for a while, only when outside temp is warm/hot and has been running for a while and 2/3 of tank or less.

 

Follow the diagnostic procedure oultined in this post and let us know what you find.