Fuel pump woes

[Jack90210]

Went out for a quick spin in my Thing and broke down. Diagnosed fuel pump (practically brand new) as defective. PO left me with a good-working spare.

Pulled the old pump and found that it had come apart internally. Further, the shaft that drives the pump had bent.

Bent shaft back to where I could get it out, installed old fuel pump with correct (different) shaft, and still no go. Had to tow home.

Question: What is the shaft driven off of, and is it possible that this got bunged up when the shaft bent?

[glutamodo]

Sounds like a classic mismatch problem!

The shaft is driven off of the disributor drive gear. Those seldom have problems. Now a bent pushrod is not very common to see either. Especially if it's a German one, but new replacement ones I don't think are made of nearly the same strength of metal.

They usually don't get bent unless you use the wrong pushrod/pump combination. Pushrods come in two lengths, about 100mm (4" - originally for alternator engines) and about 108mm (4.25" - generator engines). If you use a long pushrod with the alternator pump, you usually destroy the pump and/or rod. If you use a generator pump with the short pushrod, then it'll just sit there and not pump at all. If you look at the pump, the style needing the longer rod has it's operating arm up inside a few millimeters. The style needing the short rod will have its operating arm protruding from the bottom slightly. Alternator pumps are angled over to clear the larger alternator, but in more recent years they have made generator-length-pushrod style pumps angled similarly so you can't go by that anymore.
-Andy

[bmwloco]

Been there, oh, my.

glutamodo nailed it. Kudos!

[Jack90210]

Thanks Andy, I'll check it out.

Funny thing is that the car ran a few hundred miles before the pump failed, so I doubt that it had the wrong length pushrod to begin with. Hmm.

[Ian Epperson]

[Jack90210]

I'm having a hard time finding a replacement pushrod, does anyone have a good source?

[bmwloco]

There are two available, a long one and a longer one

There's only a little bit of difference. CP1 or jbugs or about anyone like that sells both.

[Jack90210]

[bmwloco]

Got home, looked at where I bought mine. They used to advertise on the Samba with banner lists:

www.bobcostaenterprises.com

Great to deal with, and quick too. Sorry to follow up so late.

[Jack90210]

Still no fuel. What are the chances that the camshaft is damaged?

[bmwloco]

Possible, but doubtful.

Are you getting any fuel? If not, maybe you're using the right pump with the wrong shaft or vice versa.

Good luck!

[glutamodo]

You can check the cam function by taking the fuel pump off, leaving the bakelite base and fuel pump pushrod in place, and turning the engine over by hand while you watch if the rod goes up and down. You can have someone crank the engine over with the key too if you have a helper.