Mechanical Fuel Pump not pumping

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kine8282
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Mechanical Fuel Pump not pumping

Post by kine8282 »

I’ve just rebuilt the mechanical mechanical fuel pump on the R16 that I’m working on. Replaced the diaphragm, valves and other rubber seal that goes on the top. Before putting it on the car I pumped the arm to make sure it was working. I also made sure that the one way valves were in the right places. I put it on the motor and cranked but the pump isn’t pulling or pushing gas. I checked for tears on the diaphragm and I don’t see any tears or obvious issues.

Any advice on what to do or check next? Does this sound like the diaphragm it’s sealed tight enough to create a vacuum?
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Bwk2000
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Re: Mechanical Fuel Pump not pumping

Post by Bwk2000 »

Did you install the pump with the arm above or below the cam? Should be above. I’d double check that first.
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DAC21
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Re: Mechanical Fuel Pump not pumping

Post by DAC21 »

kine8282 wrote: Thu May 25, 2023 7:10 pm I’ve just rebuilt the mechanical mechanical fuel pump on the R16 that I’m working on. Replaced the diaphragm, valves and other rubber seal that goes on the top. Before putting it on the car I pumped the arm to make sure it was working. I also made sure that the one way valves were in the right places. I put it on the motor and cranked but the pump isn’t pulling or pushing gas. I checked for tears on the diaphragm and I don’t see any tears or obvious issues.

Any advice on what to do or check next? Does this sound like the diaphragm it’s sealed tight enough to create a vacuum?
When did the car last run? If some time ago you might consider by-passing the gas tank / hard fuel line to the front of the car and run a hose just before the fuel pump into a small container with a little gas and see if it draws. If no, probably the pump. Yes it draws, you have something clogged between the tank and the pump.
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Nissanman
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Re: Mechanical Fuel Pump not pumping

Post by Nissanman »

Also check for air leaks on the suction side of the pump.
If you are using the glass bowl fuel filter, they are susceptible to warping where the alloy body meets the glass causing an air leak.
Nissanman, just trying to help.
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kine8282
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Re: Mechanical Fuel Pump not pumping

Post by kine8282 »

Thanks everyone. Looks like a solved it (I think). I replaced all the lines with new rubber and SS tubes and what I needed to do was to basically prime the system. I used my reverse pressure bleeder thingy to suck gas until I saw fuel on the inline fuel filter. Reconnected everything and the pump working fine and the motor starts at first attempt.
kine8282
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Re: Mechanical Fuel Pump not pumping

Post by kine8282 »

Thanks everyone. Looks like a solved it (I think). I replaced all the lines with new rubber and SS tubes and what I needed to do was to basically prime the system. I used my reverse pressure bleeder thingy to suck gas until I saw fuel on the inline fuel filter. Reconnected everything and the pump working fine and the motor starts at first attempt.