Fuel pressure issues and poor gas mileage

[rickmorgan2005]

Was on a slight road trip car was running fine and then on our way back home it started cutting out off and on and then it slowly got worse I couldn't get over 50 miles an hour and then it got so bad when I was going into the mountains going up hills I would lose all power and it would die and I would have to back up with a trailer and had no power steering
I have done a fuel pressure test the fuel pump was changed about 8 months ago what a strange it will show 4446 PSI at best with the key on but soon after that it will start losing pressure we also had terrible gas mileage on the way home what is y'all suggestions

 

[S33k3r]

If possible, get a code reader on it to see what is wrong. That said, what brand of fuel pump did you use? There is at least one brand that does fall in the first year.

 

[SnowDrifter]

Sounds like what happened when my fuel pump went out

It would only act up when it got hot. After an hour or more of driving

Need to diag if it's the fuel pump, or depending on what year your vehicle is - the fuel pressure regulator or fuel pump control module

 

[rockola1971]

If possible, get a code reader on it to see what is wrong. That said, what brand of fuel pump did you use? There is at least one brand that does fall in the first year.

There are no codes tied directly to a fuel pump nor the fuel pressure. Sure there are misfire and what not which COULD lead to bad fuel pump.

 

[rockola1971]

Typically a fuel pump rarely just dies without any warning whatsoever. The usual warning which could last a week, month or even well over a year is having to crank the engine multiple times to get it started every start. The "not going over 50mph" leads me to believe fuel filter is clogged up and needs changed but the "horrible gas mileage on the way back" leads me toward a leaky fuel injector(s) flooding the engine. Could be both or one or the other. If filter hasnt been changed I would do that first since it needs to be done anyway and should always be done when the fuel pump is replaced.

 

[Mudsport96]

What year and is it flex fuel? If it is flex maybe the ethanol content sensor is going bad and signaling to add fuel.

 

[rickmorgan2005]

Typically a fuel pump rarely just dies without any warning whatsoever. The usual warning which could last a week, month or even well over a year is having to crank the engine multiple times to get it started every start. The "not going over 50mph" leads me to believe fuel filter is clogged up and needs changed but the "horrible gas mileage on the way back" leads me toward a leaky fuel injector(s) flooding the engine. Could be both or one or the other. If filter hasnt been changed I would do that first since it needs to be done anyway and should always be done when the fuel pump is replaced.

Here's little update
Went out to shop at 530 yesterday morning to work on it,when fuel pressure test,key on,it would go to 46psi,but rapidly fall.losing pressure.i decided that if it's a injector it would eventually flood a cylinder correct? So I was going to cycle turn off cycle turn off several times to try to get a spark plug wet then I was going to remove each spark plug one by one and find out which injectors leaking well when I started that process the more I mess with the car then the fuel pressure went up to like 50 and it held so I left it alone and it held pressure for like two and a half hours then I went started the car cycle the key a few times then it started losing pressure again so it's like it fixed itself and then it f***** itself up what do y'all think?

 

[swathdiver]

Fuel Pressure Regulator? Not sure how your trucks are configured.

 

[rickmorgan2005]

I took off vacuum line to pressure regulator,it was dry

 

[Fless]

When you do the vacuum line test, one should wait and watch several minutes to verify that fuel isn't in the vacuum line; it takes time. Also, that's only one test and doesn't tell if the FPR is actually regulating the pressure.

Help us help you -- tell us a little about your truck. Year, engine, flex fuel or not, etc. There are unique properties of different years and engines.