3116 / 3126 lift pump issues

[rmllarue91]

Hey hef got my self puzzled got a 950g 3126 with weak transfer pump. Change both check valves piston and barrel. Checked suction line tried from bucket with different line. Didn't have flow meter with me but with it cranking for 30 seconds get very small amount of fuel. If I bypass with electric machine with bleed easy and run good. Was thinking about changing whole governor with a good transfer pump but would really like to know what I messed up. Anyone got any ideas? Was thinking of measuring the lift if cam shaft. I check the Piston and check valves with my mouth the are going the right way and seal good. One wasn't seal to good in housing but I think I got that worked out. It's definitely the transfer pump not suction issues or air in fuel from injectors / cup sealing.

 

[thepumpguysc]

I'm sure this is a dumb question but> are you SURE you put the valve in the right way?
Can you work the plunger on the bench & see/hear if its working??
Do you have access to a manual press?
To be honest> I;ve never seen one but I've worked on thousands of lift/transfer pumps..
Is the spring too stiff to push down by hand??
IF SO.. mount it under a press & work the plunger THAT WAY.
Put fuel in 1 side & see if it squirts out the other.. or check it w/ your finger..
It should pull a vacuum on your finger/thumb..

 

[kshansen]

I'm guessing you have a breakdown of the pump but just to be sure I have one attached from service manual. I only see you mentioned two, any chance you missed one?

I see there are three check valves total inlet, outlet and piston. Also shows a screen on inlet"if included!"

 

[thepumpguysc]

"IF" your JUST going by pictures.. its possible THEY'RE not correct..
I KNOW Bosch instructions are like that.. shows the main valve going THE WRONG WAY..
& its like THAT on every picture.. wrong way..

GOOD flow chart Hansen.. He'll be able to figure it out w/ that..

 

[rmllarue91]

Yes I do have manual and parts info yeah I triple check lol first one prevent drain back piston sucks opening first then forces out the outlet. Either I have a check valve issue or lift of cam is not enough I think ?

 

[rmllarue91]

It pulls weak vacuum and is also small amount of output. this is where it gets weird this one had no screen and was plugged with bark. Cleaned seem likelik bench everything operated normal. put together and pathetic out put. single cylinder gas engine transfer pump puts out twice the fuel. Order all new parts put it back together and not much better. Took it apart couple times and it's still not right. I've seen the out put of these and this one sucks haha but so do I lol worked on it half a day can't firgue out why it's not right. Will get back to machine this week will have flow meter vacuum gauge and such on hand. Thanks

 

[DMiller]

Blockage in the suction line/ IE the Bark supply?

 

[rmllarue91]

Don't think I'll never know machine was sold. The suction line from tank was good. Flowed fuel great with lil pressure in tank. And with output line off it never moved much fuel I can't wait to work on another to take output line off and see how much fuel actually is moved when cranked. I either assembled wrong or the cam was worn. I had it apart a bunch of times couldn't get sh*t flow out even with 10 psi of pressurized fuel supplying it. I really need an excuse to rip one of these transfer pumps apart for my mind's sake. Been really busy and have a few machines with issues that I can't get into but I think about them often and it drives me nuts.

 

[thepumpguysc]

Man oh man.. I remember that feeling.. HATED IT..
Like you said> "drives me nuts"..
Oh well.. Better luck next time..
I'm sure there'll be another "brain teaser" right around the corner..
The satisfaction of figuring out the problem, is a huge reward in itself.. but that Friday paycheck doesn't hurt either..
Maybe you can find out where it went>> & find out what fixed it??