Knocking Fuel Pump

[trollkepr]

I have a 93 2X4 with 300K mi. The fuel pump is making a knocking sound. It sounds like the pump is sitting against the bottom of the tank and vibrates against it.

Is there a typical problem that causes this? Is the pump at the end of the pick-up/float? Is there a reason it would loosen or move so it hits the tank?

The fuel gage works ok so I don't think it has dropped to the bottom of the tank but then again, I have no idea what the set-up is so I have no idea what I am talking about.

Russ

 

[DeRocha]

The fuel pump sits midway between the top of the sender and the pick - up tube as picture below:

 

[dolphans1]

You know I never thought of this, but my Explorer was/is making an intermitent knocking sound and it happened shortly after I changed my fuel pump.

When it first happened I thought my fuel pump was hiccuping and I said oh NO,NO,NO, because I just filled the tank all the way up and I did not want to drop the tank all over again. I then quickly thought to myself, I can't imagine such a small electric fuel pump making or causing so much noise. I believe the pressure is only 3-4lbs is it not? (I read on other post its 30lbs)

Here are my thoughts: When reinstalling the fuel pump/sending unit, I recall there were times the fuel sending unit would bottom out to the bottom of the tank and I would have to slightly turn it one way or the other to get it to go all they way inside. That little screen filter on the bottom of the sending unit has to get pretty close to the bottom of the fuel tank.

Is it possible the screen could have bottomed out against the bottom of fuel tank, thus starving the fuel pump of fuel, and that could cause the fuel pump to starve for more fuel?

Also, no one mentions the grease packet that comes with the fuel sending unit, that you place on all 4 electrodes at the end of the wire that connects to wire harness at the back of left rear frame. Did any of you guys apply this grease? I think its there to prevent corrosion.

Is it really possible for the fuel pump to knock, and if so, would it not do it all the time?

d-1

The fuel pump sits midway between the top of the sender and the pick - up tube as picture below:

 

[dolphans1]

Possible solution?

Trollkeeper, I found this post below, it may be the answer to both of our problems, at least it's worth a try. Read every post, especially the last one.


http://www.explorerforum.com/forums/showthread.php?t=64684&highlight=fuel+pump+knocking


Where is the in line fuel filter located? Anyone know?

d-1

I have a 93 2X4 with 300K mi. The fuel pump is making a knocking sound. It sounds like the pump is sitting against the bottom of the tank and vibrates against it.

Is there a typical problem that causes this? Is the pump at the end of the pick-up/float? Is there a reason it would loosen or move so it hits the tank?

The fuel gage works ok so I don't think it has dropped to the bottom of the tank but then again, I have no idea what the set-up is so I have no idea what I am talking about.

Russ

 

[DeRocha]

Fuel injected vehicles run at 30 psi or better. The thread you have mentioned deals with Engine knock, not specifically a fuel pump area noise. A clogged fuel filter will cause engine knock as it will starve the engine from getting the fuel it needs. The fuel filter is located within the driver's side frame rail (under the driver's seat area).

 

[dolphans1]

DeRocha,

If it were fuel related or starving, I would think the engine would stall or hesitate and the check engine light would come on. It almost sounds like a a loud tick, tick, tick, tick. And its not the rocker arm sort of sound. I drove to shop today and they could not dectect it. It just seems strange that I change the fuel pump and it starts making this sound, but only intermitently, if it makes the sound and I turn the car off and restart it, it stops.

I will keep you posted.

d-1

Fuel injected vehicles run at 30 psi or better. The thread you have mentioned deals with Engine knock, not specifically a fuel pump area noise. A clogged fuel filter will cause engine knock as it will starve the engine from getting the fuel it needs. The fuel filter is located within the driver's side frame rail (under the driver's seat area).

 

[dolphans1]

Any luck troll keeper?

d-1

I have a 93 2X4 with 300K mi. The fuel pump is making a knocking sound. It sounds like the pump is sitting against the bottom of the tank and vibrates against it.

Is there a typical problem that causes this? Is the pump at the end of the pick-up/float? Is there a reason it would loosen or move so it hits the tank?

The fuel gage works ok so I don't think it has dropped to the bottom of the tank but then again, I have no idea what the set-up is so I have no idea what I am talking about.

Russ