My Expedition bogs down during normal accelerating but if I floor it, it acts fine. What does a bad fuel pump act like??? Does it just stop working or does it weaken and act up?? I changed the fuel filter in a shop with some other mechanics around. Two of them said the fuel should have sprayed out with about 40lbs of pressure when I disconnected the filter. Instead it just drained out. They said the problem was the fuel pump. Well since the pump itself is $300 I tried a couple of other things first. I changed the fuel filter like I said and then the sparkplugs. I cleaned the mass air flow sensor. I cleaned my air filter. I put in a new camshaft position sensor. I checked the throttle butterfly for sticking. I put 3M fuel injector cleaner in the tank yesterday. It is still hesitating!!!!! Help!!!

 

When fuel pumps are defective they stop working completely, or they don't produce enough volume and pressure which causes problem under load and/or at wot. This is not what you described.

I'm thinking the fuel pressure regulator diaphragm is ruptured causing no vacuum to the regulator which causes high fuel pressure that does not hold in the system upon shut down. The regulator is downstream from the injectors, and basically acts like a relief valve. Hence, high fuel pressure at wot is great but, not so good at part throttle.

Here is a diagram of internal parts: http://cdn.2carpros.com/automotive_p...6999_reg_2.jpg

Notice a fuel inlet, and a fuel outlet (return) going back to the tank.

Pull the vacuum hose off the regulator. You shouldn't see any fuel what so ever present. If you do see gas remove and renew.

 

it might be the fuel regulator on the fuel rail ! pull the hose off and check for gas ! there should be no gas in the vacuum hose, if there is then the injectors are not getting the right amount of gas and pressure ! did you check for any vacuum leaks around the engine ? a vacuum leak can cause a stumble and idling trouble ! when the engine is cold, start it up and spray starting fluid around all vacuum hoses and the intake gasket !

 

I was told today at the parts store that the fuel pressure regulator is located in the fuel pump on this 2005 Expedition Eddie Bauer. Do you now agree with this or what? If its in the pump how could it be checked?? Help!!

 

Fuel pressure regulator is located on the fuel rail attached to the intake manifold.

Here is a pic of the regulator for a 2005 Expedition w/5.4 liter.

http://www.partsgeek.com/assets/dima...mb/1023446.jpg

 

look on the fuel rail under the hood ! there should be a regulator bolted to the fuel rail before the injectors with a vacuum hose going to it ! is the parts store getting the regulator and fuel filter mixed up ! all the ones i saw was the regulator was on the fuel rail

 

JerryF when it's running is there any black smoke coming out of the tailpipe?

 

No black smoke!

 

thexlo8ers you are wrong sir! The 2005 Expedition does not have a fuel pressure regulator but it does have a fuel pressure sensor on the fuel rail.

 

Oh man oh man. The last thing I want to do is post wrong information.

Yeah, not a fuel pressure regulator but a fuel rail pressure sensor. No fuel return line.

There is also a fuel pump drive module located somewhere back by the spare tire.

Here is a link to another forum that may be of some help. Esp. second post in reference to fpdm.

P0191 dtc - Ford F150 Forum - Community of Ford Truck Fans

Doing some research on your complant I also came across some info' that the fuel pump itself has a built in check valve that keeps fuel pressure in the line and rail after shut down. I thought I'd mention that since you stated there was no pressure in the line when you disconnected the fuel filter.

Again, sorry about my mistake. I'm better with older vehicles, and up to the mid to late 90's. By 2005 I'm out of my element.

I don't think this is related to your problem but, I understand now that your truck does not have an EGR valve, but does have a heated PCV. Can you confirm this? I'd be interested to know too if your truck has an electronically controlled throttle body? And is it a flex fuel?