Transfer pump question (the one ON the tractor, not one to fill the tractor)

[Richard]

If you remove the fuel line on the pressure side of the transfer pump....hold your finger over the hose end and then you flip the little flippy lever at the bottom of the pump with your hands.... would:

1. Fuel get squirted past your finger much like a garden hose would spray? Worded differently, does your finger have the strength to hold the pressure back when you are using your hands to operate the pump?
2. Would "nothing" happen because it's very low pressure and your slight finger pressure be enough to prevent it from spraying it out?

Now....what would happen if instead, you cranked the engine?

With the engine cranking over, will it produce MORE pressure than your hands could?

Would it NOW spray out if it didn't before?
Could it STILL be held back (if it could before)??

 

[oldnslo]

What type of vehicle is this on? Most transfer pumps that I have seen are low pressure so you in theory block them with your thumb.

 

[Richard]

It's on a David Brown tractor.

We were indeed, able to block spraying with our fingers. In fact, I didn't perceive any pressure ON my finger (it took zero effort to hold the fuel back)

However....when we cranked the starter, the fuel spurted out about 10" (we could NOT get it to spurt out any at all when we pumped it by hand)

I'm trying to decide if we need to look closer at the transfer pump as an issue. Part of me says no (because it sprayed about 10" when engine cranked) and part of me says yes (because the pressure is virtually zero when HAND operating it)

So not wanting to take the transfer pump apart on my JCB to try....I figure I'd ask and see what the thoughts are!

 

[oldnslo]

Squirting when trying to start it is flow volume related vs pumping by hand. I presume that your David Brown won’t start? Is there a fuel filter between the transfer pump and main pump? If yes do you get fuel through it?

 

[nyone]

Usualy there low pressure. 10psi and below. They pretymuch just need to keep fuel availabe to the injection pump.

 

[Alan W.]

I was thinking the pumps were run off of a cam lobe. If its on the ramp or high of the lobe when you try and hand operate it there will be limited to no fuel pumped because its already partially stroked or on the end of its stroke.

 

[nyone]

For some reason i was thinking electric lift pump. The mechanical ones can have a short stroke if the lobe is in the wrong spot. But its still not a high pressure pump so holding your finger over it may or may not have fuel come out.

 

[Richard]

It's a mechanical lobe type. I was thinking about what if it was already in "pump" position (or whatever it may be called)... we cranked the engine, tried again and had same result.

Came home yesterday and tractor is gone. My guess is it's not passing my brother in laws patience and he's either taking it apart or, just as likely, getting rid of it. (I have no idea yet)

As it happens.....today, I'm heading about six miles down the road to look at a Deere to see how it looks.