Mechanical Fuel Pump near Injection Pump

R

RCW

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Recently, someone posted a diagram of a mechanical engine-mounted fuel pump just before the injection pump (IP).

Tried to find the diagram, but couldn't...

Diagram showed a cam-driven lever-operated fuel pump. Reminded me of many I replaced as a young driver 40 years ago. :p

Are the Kubota mechanical fuel pumps similar to the fuel pumps of cars/trucks from the '60's and '70's? I understand they serve a different purpose....

I used to diagnose the failure of those car/truck fuel pumps by a drip, and/or bottom of the pump was clean....does that apply to these Kubota pumps as well?

Not related to my tractor....just trying to understand better....:cool::cool:

Thanks!
 
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North Idaho Wolfman

North Idaho Wolfman

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They are similar but a little different, they are low volume low pressure pumps, that also serve as a one way check valve (this is why you never use air on the system as you will blow / crack / warp the plastic reed valve).

There purpose is to help lift fuel back up to the injection pump, they normally go into real use on a very low tank and usually a hill or steep grade where the level in the tank goes below the injection pump level.

They don't drip like an automotive fuel pump because they do not have a weep hole behind the diaphragm, they will seep fuel into the oil if they are really bad.

You can test a lift pump by removing the fuel line from the injection pump inlet, and on cranking, the fuel will pulse out of the line.

I have run into a ton of bad mechanical lift pumps and 99% of the time you never know it. ;)
 
R

RCW

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Wolfman - -

Appreciate the detailed response.

I understood some of the differences, but the one about their failure is much different than my early cars and trucks, and good to know!

Since I was of very modest means, I used to do some my car repairs in the back yard of a local garage.

Owner would come out and coach me some, and I'd go at it with my tools.

I try to understand how stuff works....

We were in a very rural place, and he'd sometimes order parts with his discount, even though I was out back working in the rain or snow.....(uphill, both ways!!:eek::p:p)

Great guy, while separated by distance for 30 years, I'm friends with him still, but he'd like to retire. His wife gave me a big hug and kiss last year at an auction I saw them at!
 
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