1967 520 fuel pump questions...

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tiniestgarage
Posts: 2
Joined: Sat Jul 19, 2014 6:39 pm
Car: 1967 520
Location: Bay Area

1967 520 fuel pump questions...

Postby tiniestgarage » Wed Jul 23, 2014 2:28 pm

Hey folks.

First post, new owner! I searched around and wasn't able to find a solid answer.

My little truck started stumbling on acceleration - just the first couple of seconds once you hit the throttle. I gave it a full look through - replaced plugs, wires, cap, rotor and fuel filter as it needed to be done anyhow.

I noticed that I can see the fuel pressure surging in the filter. It fills to 70% full then falls to 50% full over and over again about every 4 seconds. I assume the pump is my problem.

Having no experience with mechanical pumps, does it make sense to convert to electric and move the pump down under the truck on the frame? Can i just leave the old pump sitting there unplugged?

Thanks in advance - I love this little truck!


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Charlie69
Posts: 279
Joined: Sat Nov 08, 2008 6:01 pm
Car: 1966 Datsun 520
Location: Tolleson AZ

Re: 1967 520 fuel pump questions...

Postby Charlie69 » Sat Aug 02, 2014 1:01 am

It sounds like like 1 of 2 problems. First I would disconnect the fuel line from the pump that feeds the pump fuel from the tank dis connect the other end of that fuel line from the tank. Tie or wrap a rag over the tank end of the fuel line. Take some compressed air and blow through the fuel pump end, a couple good blasts. Check rag for debris/rust. If there is a lot of either your need to drain remove the tank and clean it. Always look into the tank through the fill opening and and through the sending unit hole.

If the rag is clean then I would suspect the pump is diaphragm is failing. pull your engine oil dipstick and smell the oil, if it smells like gas the your diaphragm is bad.

These old trucks will have dirty tanks and lines for various reasons.

Good luck and post what you find please.

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tiniestgarage
Posts: 2
Joined: Sat Jul 19, 2014 6:39 pm
Car: 1967 520
Location: Bay Area

Re: 1967 520 fuel pump questions...

Postby tiniestgarage » Tue Aug 05, 2014 9:23 am

Thanks for your advice!

I would be shocked if the tank didn't need cleaning/re-coating. I will blow out the line to check for debris as you describe and see what I see.

I pulled the dipstick and I definitely smell gas. What are your thoughts on upgrading to an electric pump? I'm up to the job, but then how to plug the old pump hole? Are folks fabricating stoppers? Worst case, I see a couple of mechanical pumps on ebay for ~$80-$100.


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