Hey -

Has anyone ever heard of a worn fuel pump eccentric?

 

I had a hard time believing this was my problem, but there it is .....

 

Yes. on Pontiac V/8 engines.

 

While I've never taken a Pontiac engine apart, I did have the eccentric fail on me on a 389 in the middle of Nevada. Spent 3 days there. It is my understanding that the fuel pump eccentric is bolted to the cam in a Pontiac and can shear itself loose. That's what mine did.

Regardless, I don't believe Snoopy is referring to Pontiac engines. My picture is a Crower cam in an SBC. My failure occurred when I switched to Mobil 1, believing it to be a superior lubricant. I since learned how important additives can be.

 

I have been battling a fuel delivery issue.

I am fairly certain the carb is OK, it rebuilt by Lars a few years ago and only has about 600 miles on it

I replaced the fuel pump

I bought the 'S' hose cause it did not have one, I think there was a bit of a kink in the old hose

I dropped the tank and made sure sediment was not in there, the sock looked good, maybe I should replace it for good measure

I tuned it up

I put in the old distributor

'It appears as though the eccentric is worn but it is hard to see'

I may pull the water pump off and timing cover to check. I might as well check the timing chain while I am there.

 

wouldn't a worn cam fuel pump lobe result in a noise caused by the fuel pump push rod slapping?
how is pulling off the cover going to allow you to see the lobe on the camshaft?
what is the fuel pressure in PSI?

 

So the eccentric is part of the camshaft and does not bolt to the front of the timing chain.

Oh boy

I don't know what the fuel pressure is.

 

The spring in the fuel pump takes up any slack. The lever travels over a smaller and smaller arc and once there is no motion, the wear stops.

That's right, a fix will not be as easy as you are probably thinking. Once you are out of every other easier diagnostic, probably the best thing you can do to diagnose this with minimum pain is to remove the fuel pump and put a dial indicator on the rod. That'll get you an actual measurement of the lobe's eccentricity. If that's too hard attach a magnet to the rod and something else to the magnet that protrudes from the block, hold it in with your finger and watch how much motion you get when somebody cranks it.

I found hard to believe that the car would even run as I got near the point you see, but it did.

Lastly, if this is what has really happened you will either have to install a new cam or an electric pump. The pump is not the greatest option, I would recommend it as a band aid. The cam however, well that's an opportunity

With the new cam, I also installed a pushrod with brass tips and made sure my oil had enough ZDDP. I sent the cam back to the supplier, it might have been competition, I don't remember off the top of my head and they surmised that maybe that lobe had been improperly hardened. but the failure was coincident with the Mobil 1 so who really knows. They did give me a credit on a new cam.

 

I think I will block off the fuel pump and install an electric fuel pump. I will let you know how that works.

 

Lots of guys did that "Back in the Day".

 

Given your car still gets smog'd here in our great state, I guess a new cam might put you in jeopardy with the CARB guys.