Vacuum fuel pump (on m14)?

[arrkerr 54]

An 87 414-8 just followed me home.  The previous owner had some trouble keeping it running, had the carb rebuilt and when that didn't help swapped out the fuel pump, which also didn't help.  I know nothing if the level of competence of the person that did the work.

 

At the moment I can get the tractor to run, but it doesn't tend to stay running.  It will run fine with no sputtering or anything to make me think something is wrong w/the block, but then just cut out.  I seem to be able to keep it running if I immediately reduce the throttle and then push it back up again.  It seems to have this problem more at higher speeds vs. idle, but I'm not entirely sure if that is really the case.  Since it just came home, I'm just starting the diagnostics.

 

The owner gave me *two* of the normal crank-driven pumps (one original, one new, both seem just fine - I can move the arm and seem to get good pressure), and currently a vacuum style pump installed on the tractor.

 

This is what it looks like right now (ignore the clip being slid down, I just did that).

 

I'm tempted to start diagnosing this problem by first putting back the original pump, and then tearing in to the carb.  I just wanted to run that by the experts here.  If the vacuum pump is actually something good and worth keeping, I'll leave it on and start troubleshooting with the carb (the pump seems to be pretty nicely installed, etc).  I'm not familiar with this type of pump at all though, so I don't know if I should be worried about its flow rate, etc (as I see mentioned by people doing an electric pump swap).

 

Thanks!

[arrkerr 54]

Well, this will have to remain a mystery.  I put back in the original pump and she runs great.  I'll throw this strange pump in my arsenal of WH parts and, if the time ever comes, figure out if/how it works then :).