Fuel Pressure drops to zero immediately, HELP!

[cargarci42]

Hi all!

I am new to the forum and appreciate very much any help!

I have a 2001 Ford explorer 4.0 SOHC with the returnless fuel system.

My problem is that the vehicle is;

1. hard to start (takes about 3 to 4 times cranking to start the truck
2. Vehicle hesitates when pressing gas pedal
3. when coming to a stop sometimes revolutions drop to about 500 and jump back again to normal

I changed the fuel filter and no luck. I put a fuel pressure gauge and noticed that with the key in the ignition I have zero pressure. After cranking 3 times the truck starts and then I have 62 psi and stays there until I shut down the truck.

As soon as I shut down the truck the 62psi goes immediately to 0psi.

What can I check or what is suspected here?

I have read some threads and I am trying to avoid droping the fuel tank???

 

[Chikar]

As I understand it there is a check valve on the output of the fuel pump that's designed to keep pressure on the system when the engine is shut down. If that valve is stuck open fuel pressure will drop immediately when the engine is shut off.

When you go out in the morning to start it put the key in the on position, don't start the engine, and you should hear the pump run. Normally it will run for about one second then shut off if the PCM (computer) doesn't detect the engine is cranking. If you do that 3 or 4 times quickly you might be able to build enough pressure in the system to get a faster starter.

I suspect you're going to be stuck with dropping the tank though.

 

[cargarci42]

Is there any write ups on how to lower the fuel tank and replace the check valve?

Thanks for all the help.

 

[gonenuke]

Try this

Tank removal

fuel pump replacement on another site

 

[cargarci42]

Thanks a lot.

Where is the check valve exactly located?

I am looking at pictures where the fuel pump assembly but cannot identify the check valve???

 

[cargarci42]

After looking closely, I have a returnless system and a check valve is not in the path of the fuel delivery but Now in a return system it will make sense that the pressure will be lost with an open valve but not on a returnless system.

CAN ANYONE AGREE ON THIS????

 

[2000StreetRod]

check valve in tank

The check valve on a returnless fuel system is in the tank. Sometimes the hose in the tank splits which could also result in immediate loss of fuel pressure. See this thread: Ford Explorer Ranger Fuel pressure test procedure
. You either have to drop the fuel tank or cut an inspection hole to correct your fuel pressure problem.

 

[cargarci42]

I do get a constant 62psi while engine is running. Thats because I discarded a split hose inside the tank.

Wouldn't this be pointing to a fuel injector leak?

 

[Dono]

I'd think if it were an injector, that's a really serious leak in it. Your motor would be flooding with gas when its running. I'm going with the fuel pump check valve theory.

 

[Chikar]

I noticed in an earlier post you asked how to drop the tank yet later you mentioned you discarded a split hose in the tank. I'm confused...did you actually drop the tank and find the split hose? If you did go to the trouble to drop the tank why did you just discard the hose without finding out what it did?

I also think you have problems not related to the fuel pressure dropping to zero as soon as you shut down the engine.

From your original post:

"My problem is that the vehicle is;

1. hard to start (takes about 3 to 4 times cranking to start the truck
2. Vehicle hesitates when pressing gas pedal
3. when coming to a stop sometimes revolutions drop to about 500 and jump back again to normal"

I don't think the problems quoted are related to the fuel pressure dropping to zero when the engine is turned off. If the fuel pressure stays at 62 PSI when the engine is running and you have these problems something else is responsible for them.

By the way, once the engine is turned off it's normal for the fuel pressure to eventually drop to zero. As in overnight. But it should still start promptly in the morning if everything else is OK. My 99 can sit for several days and still starts immediately.

Can you read and post any trouble codes from the PCM for us?

 

[cargarci42]

Thanks Chikar, The pressure stays at 62psi while the engine is running but it goes immediately to 0psi when you shut the engine off. Putting the key on puts pressure for a second or two and then drops immediately back to zero.

I am going to try to get some codes tomorrow.

 

[cargarci42]

Ok, I went today to Autozone and got them to get the codes for me. Here are the results;

P0113 and P0171.

 

[2000StreetRod]

prioritize

P0113 Intake Air Temperature Circuit High Input
P0171 System too Lean (Bank 1)

I suspect that your fuel pressure may drop for an instant when you rapidly open the throttle plate. I suggest that you fix the rapid fuel pressure drop before other issues.

 

[cargarci42]

The pressure drops for an instant when I open the throtle and that is what I am calling hesitation.

So how do I fix the rapid fuel pressure drop?

 

[2000StreetRod]

Inspect fuel pump assembly

If it were me I would drop the fuel tank, remove the fuel pump assembly and inspect it.

Maybe the fuel pump outlet hose is split reducing the flow capacity to the fuel rail. If not, try to blow air into the outlet pipe. If no back pressure then the check valve is stuck open.