I recently took the bed off my truck to replace my fuel pressure regulator.but I keep getting check engine light and the code keeps saying it's my fuel pressure regulator does anyone have any idea what it could be.

 

Do you mean fuel pump?

 

No my fuel pressure regulator is located in my fuel pump since it's an 04.03 and under have it in the engine bay

 

what is the actual code. what engine

 

I took it to auto zone and they didnt tell me a code just that its saying my fuel pressure regulator needs changed but I changed it saturday.and it's a 4.8L 2004 but the check engine light came on

 

parts guys diagnosis eh? they read a code and the scan tool provides a list of possible things to check or guess at. You get what you pay for.

did you change the fpr or the entire pump assembly? did you change the fuel filter if you changed the assembly? do you have any symptoms other than the mil? ie no power?

there is no code that says fuel pressure regulator. a p0171 or p0172 sets for fuel trim lean...which is a symptom of low fuel pressure. but if could set for a whole bunch of reasons, not just a bad fpr.

You need to post the code. if the code is the ones I have noted. watch the live fuel trim data on both banks with a scan tool. determine what the fuel trim is at idle and when running the engine at 2500 rpm. normal reading are -+ 10% anything over that is an issue. post back your results.

 

Well I dont have a scan tool myself that's the problem i can go see what codes are being thrown.but other then that the truck runs good but it has like 400,000 miles on it lol

 

The code is p0300 but I recently changed my spark plus,spark plug coils,and wires what else could it be?maybe the throttle body?

 

PO300 is a random miss. My sons truck had that and it turned out to be a bad vacuum hose. Replaced that and the truck ran better and the check engine light went away.

 

Where is that located at?I'm not familiar with that vacuum hose.its a 2004 4.8l