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Just wanted to give you guys a heads up on the mechanical fuel pumps on the market. I had rebuilt the top end of the motor a few months back and also rebuilt my carburetor. I kept chasing problems with the carburetor and would up switching between 3 different ones. Finally I built one good one out of all three. Unfortunately I still had problems. I checked the fuel pressure on what was supposed to be a new fuel pump and found it running at 8 psi. That's more than double the pressure it should be. I already had a 2.5-4 psi @ 30 gpm electric fuel pump that I bought for the lawnmower. So far so good.
This isn’t a question to question your decision but what’s wrong with using the mechanical fuel pump?
It was running 8 psi. That's way too high and causes the carburetor to be unstable. Random high idle speeds as he fuel gets pushed by the metering rod.
Oh my bad, glanced over that part while my morning coffee was still kicking in! I thought you replaced one electrical with another. I had a 22R but never bothered to get in running on gas, went straight to propane!
No, that fuel pump does not look like it belongs there.
You shouldn't have a problem with a factory replacement pump. The Aisan carburetors use a little higher fuel pressure than most aftermarket carburetors such as a Weber.
A lot of people use an external pressure regulator bc its so hard to find a pump with proper psi. But maybe thats just for electric pumps?
Looks great!
I looked at installing a regulator on the mechanical pump but they were $50-75. I wasn't spending that money when I had an electric fuel pump sitting on the shelf. I bought that mechanical pump back in June of 2019 and it has less than 1000 miles on it. So back to AAP it goes for a new one. I'll keep it for a backup. After I test it.
Originally Posted by old87yota
No, that fuel pump does not look like it belongs there.
You shouldn't have a problem with a factory replacement pump. The Aisan carburetors use a little higher fuel pressure than most aftermarket carburetors such as a Weber.
I think it looks great bubble buster!
What's a little higher? Where did you get a design from? I don't remember seeing anything for a design on the Aisan's. The only thing I can find is listed on the new mechanical pumps at Rockauto and they state 3.5-4.5 psi @ 20 gph (1,800 rpm).
08-14-2020, 12:07 PM
