engine noise fuel pump maybe?

Don Jorgensen · Post by **Don Jorgensen** » Sat Jul 14, 2007 2:30 pm

Before I changed out the 3AC, I had what I thought was an exhaust manifold leak. It began about 2,200 rpm and stayed consistant with rpm increase but goes silent at idle.
After the switch to the 4AC I thought I would have gotten it fixed but I've noticed especially with a cold engine the noise is there and is consistant with the previous condition.
I'm beginning to think it may be the fuel pump. I used the same one over. Ceretainly sounds like the vacinity of the noise.
Anyone have experience with this?

Don

Typrus · Post by **Typrus** » Sat Jul 14, 2007 2:41 pm

Out of curiosity... Did you replace the exhaust gasket for the manifold to downtube connection? Mine is bad and gets noisy sometimes. In fact, all 3 of my gaskets are bad.... Nice and fumey. lol.

Don Jorgensen · Post by **Don Jorgensen** » Sat Jul 14, 2007 8:52 pm

yup gaskets new and good and tight!

takza · Post by **takza** » Sun Jul 15, 2007 3:00 am

Take a length of vacuum tubing and use it as a stethoscope?

CASE · Post by **CASE** » Mon Sep 17, 2007 8:21 am

My Schucks Rotor is slightly different shape than the OE in the manual. It works good, but it clacks back and forth just like a broken rocker, or a crappy fuel pump, and it's right on the other side of the firewall from me. There's a chance it's nothing bad, wouldn't that be nice?!

Post by **Petros** » Mon Sep 17, 2007 8:19 pm

if you do not have one of those automotive type stethoscope (not too expensive from Harbor Freight tools), you could use a long screw driver and hold the handle end against your ear, and place the other end in contact with the pump, or what ever else might cause the noise. you will hear it load and clear through the screw driver.

Usually fuel pumps do not make noise when they fail, the diaphragm gets a leak and it stops pumping (no noise). But it is possible.

Good luck.

takza · Post by **takza** » Tue Sep 18, 2007 2:32 am

Petros wrote:Usually fuel pumps do not make noise when they fail, the diaphragm gets a leak and it stops pumping (no noise). But it is possible. Good luck.

My pump sounded like a loose valve and was much louder in cold weather when starting up...it was sticking and not following the cam when cold...still worked though...but not too well cold.

keith · Post by **keith** » Tue Sep 18, 2007 6:00 pm

The arm of the fuel pump rides right next to the distributor gear on the camshaft. Maybe the teeth of the gear is clicking against the side of the arm, possibly one tooth of the gear has a burr that is hitting the fuel pump arm.

Iain · Post by **Iain** » Tue Sep 18, 2007 7:37 pm

takza wrote:My pump sounded like a loose valve and was much louder in cold weather when starting up...it was sticking and not following the cam when cold...still worked though...but not too well cold.

Mine does the same thing...