Fuel pump causes engine knock?

[peti]

Can a faulty fuel pump cause engine knock? My 93 Explorer, with 137K knocks something awful on accelleration and has no power. Dealer ran diagnostics and found that fuel pump pressure is 26 instead of 30psi. Wants to install new pump, $380.00 bucks. The pump in the car is only two years old and as far as I can tell it's working just fine. BTW, this is after they charged me $77.00 for a "BG Induction System Clean-Up Service", to clear out carbon deposits in the engine, it made absulately no difference in performance.
Any suggestions?

 

[Opera House]

I suspect

the fuel pressure regulator or a bad electrical connection on the way to the pump which could include bad relay contacts. My FPR failed at only about 140K on my 92. Some of these have springs that are slightly off center and wear only on one side. Aftermarket replacement is only about $60 and takes 10 minutes to change. Two bolts, push on vacuum line and screw off fuel line. You must disconnect battery for 10 minutes to reset the computer when changed. Do this and replace the FPR relay for less than their diagnostic charge. Bad pump sounds bogus if only 2 years old.

 

[peti]

Fuel pump and engine knock.

Thanks Opera House for your suggestions! I'll try replacing the relay first, see if that makes a difference. One thing I forgot to mention in my original post was that just about a year ago I had all the spark plugs replaced(Platinum), the knocking went away for a few months, oh, it was wonderful. In the recent diagnostic check the plugs checked out ok.

 

[TPLYNCH]

Knocking is also caused by a dirty MAS. Try cleaning it too. I highly doubt it's the fuel pump. If your FPR is original, there is a chance that is going as Opera stated.

 

[peti]

Stupid question No.1, what's a MAS?

I'll clean it if you tell me what and where it is.
Thanks.

 

[Opera House]

So do you have a DVM?

You could pull out the fuel pump fuse and measure the current on the 10A range. It should be about 5A at idle. When you pull off the vacuum line to the FPR it should jump up 0.3 to 0.5A higher. Below 3.5A you will have driveability problems. These currents will give you an indication if you have solved the problem rather than having to drive around and guess. I assume you don't have a pressure gauge. With the vacuum line off the pressure should be 39# and about 32# with vacuum line on at idle.

The MAS is the airflow sensor just after the air cleaner. There are some filiment wires like a lamp that can be cleaned with carb cleaner spray. If you really have 26# oressure, this is not your immediate problem but would help performance later.

 

[plrs x45]

I know that you probably did it already but, did you check the fuel filter? Mine knocked and it was the filter clogged and restricting the fuel flow. Good luck!

 

[peti]

Engine knock

Today I removed the Air Flow Sensor, cleaned the little wires with tuner cleaner, replaced it and now it feels like I have a new car. The pinging is completely gone, got a lot more power. How simple! Took ten minutes.
I will be asking the service manager at my dealership how come they don't know about this simple remedy? I suppose they make a lot more money replacing fuel pumps and rebuilding engines.
Thanks for all your help, guys. Peter