Fuel pump not pumping

[John76]

18 hours ago, Stevenc22 said:

Buy an electric pump and bypass the machinal pump.

Or consider an electric booster pump in tandem with the mechanical.

On 11/11/2023 at 2:21 PM, nodoi said:

I'm thinking of putting a check valve between the fuel pump and the carb.

The mechanical pump has a built-in check valve. You can test by blowing into the pump outlet ... should not blow.

Are you using a fuel return valve?  This will keep a small amount of fuel constantly circulating back to the tank to help prevent vapor lock. Also, the addition of a check valve at the fuel tank helps keep the line full in case the fuel pump check valve leaks and siphons gas back to the tank.

 

 

[TodB]

I added a check valve per John76 which worked for a few days but anything longer than that and I'm back to "self priming". I just installed a booster priming pump (and removed the check valve though I could have left in in) as in the diagram above and per Dick R with a push button engage. I only use it for cold start priming and it works great. The mechanical pump is still the primary and pulls fuel through the priming pump. 

[nodoi]

It's running! I pulled the pump and checked if I could blow through the outlet and I could. I think someone said that the pump has an internal check valve, so I'm assuming mine isn't working. So I ordered an inline check valve. I tried it between the pump and the carb, but that didn't work. Switched it to before the pump and now it's pumping gas better than ever! So I'm going to say that my problem was the crumbled o-ring along with it needing an in-line check valve. I might actually make it to the 2002 coffee meetup tomorrow!

 

Edited November 18, 2023 by nodoi

['76mintgrün'02]

10 minutes ago, nodoi said:

I pulled the pump and checked if I could blow through the outlet and I could. I think someone said that the pump has an internal check valve, so I'm assuming mine isn't working. 

 

Yes, that was just two posts ago.  I'd say John earned a click of the "solution" button!

 

On 11/13/2023 at 10:51 AM, John76 said:

The mechanical pump has a built-in check valve. You can test by blowing into the pump outlet ... should not blow.

 ... Also, the addition of a check valve at the fuel tank helps keep the line full in case the fuel pump check valve leaks and siphons gas back to the tank.

 

[nodoi]

I actually drove to the meetup and made it home. Noticed a strong fuel smell and saw a puddle of fuel below the accelerator pump in the intake manifold. Also, the car was running on after turning the key off, so I was questioning my adjustments for mixture and timing (and everything). I suspected a leaky accelerator pump gasket, so ordered a rebuild kit for the carb. When it came in I did a quick rebuild on it. The quality of the kit was not great, the supplied gaskets were folded as everything came in a plastic bag. I replaced the needle and checked the floats and everything looked pretty good, but I've had a hard time figuring out how to get it running.
Then today after researching choke settings, I finally think I have the carb adjusted well. I started it up and it sounded great, I looked under the dash and gas started spitting out of the overflow! I shut it down, and now I'm wondering what's up.

I'm actually kind of stoked that I found the issue, it feels like I can solve this one. Would like to take the right next steps to fix this new/ related(?) problem.

The carb is a weber 32/36. Pump is stock mechanical. Check valve installed pre-pump. No connected return line.

The question:
What would allow too much gas to be pumped into the carb?

I'd appreciate your input.

 

[John76]

3 hours ago, nodoi said:

What would allow too much gas to be pumped into the carb?

Possibly a wrong float level due to miss adjustment or a bad float.

Or ... wrong fuel pressure or lack of a fuel return valve.