1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Quick question about fuel pumps

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Old 04-08-18, 09:15 PM
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Quick question about fuel pumps

So just rebuilt my carb to fix a major flooding issue, seems to be working well. I have to do a couple more things before I attempt to start it.

I turn the ignition on to make sure the carb doesn't flood like it did before. I'm curious though, does the fuel pump normally stop after the float bowl is full? Mine seems to run kinda indefinitely.
Old 04-08-18, 09:26 PM
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Yes, that is normal. The stock electric fuel pump will always run with ignition. When you can't hear it, that's bad news!

The oem setup is a return style system, it manages a low fuel pressure at the carb. It functions with the return line and the restrictor.

I have not had a Nikki flooding problem but sometimes it can be attributed to aftermarket needle and seats. Also make sure float bowl vent solenoid is working.
Old 04-08-18, 11:43 PM
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Originally Posted by tommyeflight89
Yes, that is normal. The stock electric fuel pump will always run with ignition. When you can't hear it, that's bad news!

The oem setup is a return style system, it manages a low fuel pressure at the carb. It functions with the return line and the restrictor.

I have not had a Nikki flooding problem but sometimes it can be attributed to aftermarket needle and seats. Also make sure float bowl vent solenoid is working.
Floats and needle were fine, but my solenoid wasn't working. Not a huge deal since this is mainly a track car. I decided to shim it open instead and it works great so far. I guess i'll see once I do a full start up. Still a couple small things that I need to address.

So just to clarify, there are 2 hoses going to the stock Nikki carb. You're saying there's a feed line and a return line. So i'm guessing when the float needle closes, it redirects the fuel back through the return line to the tank?

I also know those 2 hoses are different sizes. Big one is feed, small one is return?
Old 04-09-18, 08:00 AM
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Right, except when the float closes it just forces the gas to flow to the return line. Theres no valve or anything. Thats one reason there has to be a restrictor on the return line so that the pressure stays up to the needles. Without the restrictor, the float bowls could starve for fuel at times due to uneven waves of pressure and flow.
The following 2 users liked this post by t_g_farrell:
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