Hello,

I'm tracking down a problem with my 1995 F150. I've done an engine off fuel pressure test and it was low. (20psi). I've already replaced the fuel filter on the frame rail. This leads to my question. Behind the engine near the firewall are the supply and return fuel lines. There is a pancake shaped metal part about 2.5" in diameter on the supply line. Line in and line out, no other connecting wires or vacuum hoses. There are two numbers on it. 941212B and F2TE-AA. There is a lone V on there as well. It's not clear exactly how to disconnect it. Before I go dropping the tank(s) to check fuel pumps I'd like to know what this is and if it could be restricting the fuel pressure. Any help would be greatly appreciated!

Eddy

 

Hi Eddy, have a question or two. What type of problems are you having and also how long was the engine off before testing fuel pressure?

I agree fuel pressure should be held for a specified period of time after shut down, however, we do need to know what pressure the pump is developing. Lets rememder the pump runs continuously while the engine is running and the regulator prevents over pressure conditions. Lets not attack the pump yet. Get back to us.

 

first I need to know do you have dual tanks? if you have single tank then this is what you need to do fuel pressure should hold steady with very minimal lose over a few hour span. fuel pressure during a leakdown test should accutally increase by approx 5-10 psi.

1. disconnect the return line (small line) at the back of the fuel rail

2. you need to plug of the return on the fuel rail side, cycle the key with your fuel gauge in line watch your pressure it should hold or rise over a period of 3-4 minutes this will test your fuel injectors and your fuel pressure regulator for the ability to hold pressure. if it does not hold pressure then you need to diagnosis further into those two items. (dripping injector, or ruptured diapram in the regulator.

3. if fuel pressure holds.. your problem is the check valve in the fuel pump (fuel pump replacement is the fix).

4. dual tanks is a whole different story it is very difficult to diagnosis this correctly you can perform the same test but do to the selector valve this causes CAN cause false reading as to the witch tank or check vavle is really bad.

 

Thanks Bill!

For a few weeks the engine hasn't been running properly. Check engine lite on and off with periodic loss of power when driving. It's worse when you first start it and try to pull away. Manual trans. On Easter Sunday on the way to parents house I was periodically loosing most of the power. Finally I could barely maintain 50mph going up slight hills on the interstate. I pulled over to check things and it died and never started. I was towed to my parents and later that night it started, but barely. When pressing the gas pedal it hesitates, coughs, and barely wants to rev.

Today I changed the fuel filter on the frame rail. Now it starts and runs better but you can tell there is still a problem. I have a repair manual and bought a fuel pressure tester. Following the directions to jumper the dlc connector to keep the fuel pump on I tested the engine off fuel pressure. Since it was low the manual said to clamp off the return line and the pressure stayed at 20psi. At that point the manual says it's the pump. I tested both tanks. However my rear tank has been problematic since I've owned this truck. It's weak and only really works on the highway. As far as I can tell I'm down to the in tank fuel pump assemblies and this mystery part.

I also pulled the vacuum line from the fuel pressure regulator and saw no gas coming from the nipple. There appeared to be good vacuum and the engine idle increased while off and settled down when I put it back on. I also checked the timing and once it settles down it's close to 10 btdc.

Also the truck appeared to be running rich for you could smell gas. However on another post there was talk of an in tank check valve being able to cause gas to enter a canister in the engine bay as well as low fuel pressure.

I did check the fuel pressure running and it stayed at 20psi on both tanks.

It's my feeling I need to find out what this pancake looking part is since it's in the supply line just before it connects to the fuel rail. I certainly want to do this before looking into the fuel pumps. I spent over an hour searching the part numbers online as well as diagrams but I can't find it. I know the previous two owners and they didn't make any modifications.

I need to get this thing fixed so I can leave the parents house! ha.

Thank you for any assistance.

Eddy

 

I just realized the fuel pressure test I did on the rear tank was engine off only. It will not start when the rear tank is selected. It will start with the front tank selected.

I did notice that there are three lines coming from each tank and each of these lines t's into one of three fuel lines. I can see now how a problem in one tank could cause a problem in another.

However I need to remove my mystery part from the list first.

 

You got a camera?

 

Here are two pictures. I'm sorry I should have done this first.

 

Sorry I don't recognize the part, its appears to be integral to the fuel line, but its unknown to me. Something isn't right if you only produce 20PSI with pump running, range should be 30-40.

Perhaps Sean will recognize the part, he is a pretty sharp boy and has helped alot of people out.

 

that part is called a pulse dampener it's only purpose is to dampen the flow of the initial flow of fuel in the rail (keep down the noise).. never replaced one only comes on the pressure side fuel line..
does your truck have a frame rail mounted fuel pump of just the two in the tank???

 

He has the two in the tank. You of all people should know that, especially if you recognize that part. Me, I have no idea what it is.