Hi My 94 f150 with a 5.8 has very low fuel pressure and I was told 35-45lbs is normal for my truck. With a gauge hooked up it reads 17lbs at idle and the highest it will go to when warmed up a bit is 22 to 25 lbs[once I seen 28lbs] when reved. Now I have replaced the electric fuel pump and filter sock and the fuel regulator[a new regulator raised it 5lbs]but still have low pressure. I replaced the inline fuel filter less than 2 years ago and don't think that's bad. I will take it out and check it when the rain stops around here. I had the tank out a couple of times now and that was perfectly clean. I was wondering about other things that might cause low fuel pressure. Has anyone ever had problems with the gas tank selector valve? That's it just behind the intake right? I see that the gas line curves up behind the intake and some kind of valve is there. Could the tank selector valve be stuck half open? Anyone had problems like this or any other things to look for? Thanks

 

Does this truck have dual tanks and if so same reading from either tank?

Just to be clear what did you replace as the fuel regulator?

As highlighted above first you suggest you replaced it but then down further you ask about the tank selector valve just behind the intake.

There is no fuel selector valve on your model year and the part you see at the back of the intake is the fuel pressure regulator.

So if you haven't change that part you might want to start with that, but before leap ahead to fast, first answer the question about number of fuel tanks your truck has please.

 

Leaking injectors.

Also double check your gauge with another known good one.

 

There is no fuel selector valve on a gas engine 1994 truck.

Are you experiencing an issue? If not I suspect a faulty pressure gauge.

 

I replaced what I thought was the fuel regulator. IT was on the back of fuel rail was held on two small torx bolts had a single vacuum line going to center of it. Autozone gave me one that looked just like what I described when I asked for a regulator. The truck has two tanks but I only use the rear tank as the front one has a bad pump in it.

 

my fuel pressure gauge is from Harbor freight and maybe defective, I've wondered about it and have thought about renting one from autozone. The Truck might have bad injectors, it has 230,000 miles on it and gets very bad gas mileage [10 mpg]. I have one of those pressurized fuel injector cleaner units and was going to do a tune up,replace the ox. sensor,and clean the injectors. Maybe replacing the injectors might be a better idea.

 

That right there is one of the more likely sources of your problem. When was the last time you checked the fuel level in that tank? You could have the very common fuel transfer problem where half your fuel is going into the other tank as your drive and overflowing out the filler tube once the tank is full. Have you ever noticed a raw fuel smell right after parking the truck?

Dirty or stuck open fuel injectors are another cause, with this problem you will see fuel pressure drop to zero immediately after shutting the motor off and one or more spark plugs would be wet.

 

So can you tell me how to test for a fuel transfer problem? Is there a overflow hose on the front tank that the fuel would come out of ? I guess with 230,000 miles on my truck it's too late to have ford fix it free under a recall. Can anyone confirm I did replace the fuel pressure regulator, Some of you made it sound like I replaced something other than it.