Magnum 10hp fuel pump

[Dreamcatcher 102]

Good morning all,

My 310-8 was experiencing long crank sessions to start and eventually stopped starting.  I decided to replace the tank valve/grommet and all of the fuel lines.  After it was all put back to gether, I cranked for a total of several minutes pausing after every 20 seconds.  It seems that the problem is that the fuel pump doesn't pump anymore.  

I'm not confident the cheapo pump off amazon is going to last and I know the kohler pumps are super expensive.  I think many of you have switched over to a fuel pump from NAPA?  Can someone provide a part number?  Thanks for your help.

[Achto 28,777]

4 minutes ago, Dreamcatcher said:

Can someone provide a part number? 

 

This pump says Holley on it but it is a Facet pump. 1.5 - 2 psi.

 

https://www.amazon.com/Holley-12-426-Mighty-Might-Electric/dp/B00JS18DXS/ref=asc_df_B00JS18DXS/?tag=hyprod-20&linkCode=df0&hvadid=312031441854&hvpos=&hvnetw=g&hvrand=12929618323902156113&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9019446&hvtargid=pla-571975630257&psc=1

 

With the Facet name on it & the Facet part number.

https://www.amazon.com/Facet-FEP304SV-Posi-Flo-Fuel-1-2-5/dp/B07SYCDH5T/ref=sr_1_18_sspa?hvadid=580742775563&hvdev=c&hvlocphy=9019446&hvnetw=g&hvqmt=e&hvrand=12754356096268143947&hvtargid=kwd-324062412145&hydadcr=5740_13191233&keywords=facet+electronic+fuel+pump&qid=1690897436&sr=8-18-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGZfbmV4dA&psc=1

[Gasaholic 257]

Fuel pump can be serviced, and if it worked before and does not leak (Check your oil for presence of gas in oil, if there is, you got a ruptured diaphragm) - But without leaks, then I would suspect there is either a bit of debris holding a check valve open, or equally as common, a check valve popped loose from its seat - pop pump off, remove 4 screws (Take care to pay attention to orientation of the inlet and outlet relative to lower pump body) and separate the two (carefully, try to avoid tearing gaskets/diaphragms) and check the check valves in upper half of pump body - If they look to be in the right place (check valve disk will be facing you on the outlet side, and center nub facing you on inlet side)  you can tap the pump body check valve side down and see if the valves pop loose and fall out. If they do end up rattling around you can make sure they are clear with no debris holding a check valve disk open, and reinstall (As noted above for direction) - a 14mm 12 point thinwall socket , if I recall correctly can *just* fit to press them back in place (Care to make sure gasket rings don't get damaged) and then a center punch can be used on the small flat spot of body on either side of check valve to stake them in place. That can often be all you need to do, assuming you don't have damaged gaskets or diaphragms. (about 75% of the time)  Otherwise, you may luck across a rebuild kit (Haven't seen one in ages)   but I believe Kohler still has (as of 2019) service replacement fuel pumps for relatively low cost. 

 

All the above is assuming you refer to the mechanical fuel pump....   Lastly, I have in the past also put on a fuel pump cover plate , drill out the plate for a barbed hose nipple, and use that for a pulse port to operate a pancake fuel pump as commonly found on Briggs, Kawasaki, Honda engines.. (Just have to fabricate a bracket to bolt the pump to somewhere) , and other than that , can bypass with an electric fuel pump (But use care to not get a high pressure pump that will push fuel past the float needle in carb) 

 

 

[Bill D 2,088]

I make a mounting plate and use impulse pumps.  Never going back to mechanical pumps

[Alex M 0]

Bill D, thank you so much for posting the picture of your fuel pump setup.  I was planning to use an impulse pump on my 314 and had gone through a bunch of designs in my head on how to mount it to the engine like you did.  Everything I came up with was more complicated and I really like the simplicity of the way you did yours.  Much appreciated.  

[Bill D 2,088]

12 hours ago, Alex M said:

Bill D, thank you so much for posting the picture of your fuel pump setup.  I was planning to use an impulse pump on my 314 and had gone through a bunch of designs in my head on how to mount it to the engine like you did.  Everything I came up with was more complicated and I really like the simplicity of the way you did yours.  Much appreciated.  

You're welcome.  Here are some additional pictures to help you with your build.  I used  stainless steel plate for my build.  No need to paint, won't rust.  I used red loctite on the screws that fasten the coupling nuts to the plate.  

[Alex M 0]

Thanks again for sharing.  I really appreciate it.  

[Matkal 34]

On 8/1/2023 at 9:55 AM, Gasaholic said:

Fuel pump can be serviced, and if it worked before and does not leak (Check your oil for presence of gas in oil, if there is, you got a ruptured diaphragm) - But without leaks, then I would suspect there is either a bit of debris holding a check valve open, or equally as common, a check valve popped loose from its seat - pop pump off, remove 4 screws (Take care to pay attention to orientation of the inlet and outlet relative to lower pump body) and separate the two (carefully, try to avoid tearing gaskets/diaphragms) and check the check valves in upper half of pump body - If they look to be in the right place (check valve disk will be facing you on the outlet side, and center nub facing you on inlet side)  you can tap the pump body check valve side down and see if the valves pop loose and fall out. If they do end up rattling around you can make sure they are clear with no debris holding a check valve disk open, and reinstall (As noted above for direction) - a 14mm 12 point thinwall socket , if I recall correctly can *just* fit to press them back in place (Care to make sure gasket rings don't get damaged) and then a center punch can be used on the small flat spot of body on either side of check valve to stake them in place. That can often be all you need to do, assuming you don't have damaged gaskets or diaphragms. (about 75% of the time)  Otherwise, you may luck across a rebuild kit (Haven't seen one in ages)   but I believe Kohler still has (as of 2019) service replacement fuel pumps for relatively low cost. 

 

All the above is assuming you refer to the mechanical fuel pump....   Lastly, I have in the past also put on a fuel pump cover plate , drill out the plate for a barbed hose nipple, and use that for a pulse port to operate a pancake fuel pump as commonly found on Briggs, Kawasaki, Honda engines.. (Just have to fabricate a bracket to bolt the pump to somewhere) , and other than that , can bypass with an electric fuel pump (But use care to not get a high pressure pump that will push fuel past the float needle in carb) 

 

 

I have a new to me 312-8 with an M12, do you know if this rebuild kit will fit my fuel pump?

https://www.amazon.com/Carbhub-Rebuild-Tractor-Generator-Replaces/dp/B07LCG2DBC/ref=sr_1_1_sspa?crid=17YF1K9KA5MU6&keywords=kohler+m12+fuel+pump+rebuild+kit&qid=1691785451&sprefix=kohler+m12+fuel+pump+rebuild+kit%2Caps%2C100&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1

Thanks

Edited August 11, 2023 by Matkal

[Gasaholic 257]

5 minutes ago, Matkal said:

I have a new to me 312-8 with an M12, do you know if this rebuild kit will fit my fuel pump?

https://www.amazon.com/Carbhub-Rebuild-Tractor-Generator-Replaces/dp/B07LCG2DBC/ref=sr_1_1_sspa?crid=17YF1K9KA5MU6&keywords=kohler+m12+fuel+pump+rebuild+kit&qid=1691785451&sprefix=kohler+m12+fuel+pump+rebuild+kit%2Caps%2C100&sr=8-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1

Thanks

It should , long as your only problem is diaphragm - OEM Kohler kits also included the 2 check valves (and gaskets for them) which were usually the more common issue for us to deal with. - the stamped steel ones would rust away or corrode or warp , so were often being replaced even without needing a diaphragm. Then they started making them with a pressed metal & plastic composite which fared better, but liked to fall out of place when engine got hot (different rates of expansion of aluminum vs the pressed metal) so those we could often pop apart and if the gaskets were not shredded, we could put them back in place and then stake around the pump body to hold the check valves in place better (worked on the plastic body fuel pumps too)  Even then, the repair kit was only available through Kohler, and has long since been obsoleted/NLA (I think they stopped making the kits entirely in the middle 2000's)  Aftermarket kits don't seem to ever have the check valves, so the choice then is either a new fuel pump or retro-fit for a pancake vacuum pump. (Or, install a 12v electric fuel pump, which you had to be watchful of the PSI output of the pump or it'd flood the carburetor if too much pressure) 

[Matkal 34]

16 minutes ago, Gasaholic said:

It should , long as your only problem is diaphragm - OEM Kohler kits also included the 2 check valves (and gaskets for them) which were usually the more common issue for us to deal with. - the stamped steel ones would rust away or corrode or warp , so were often being replaced even without needing a diaphragm. Then they started making them with a pressed metal & plastic composite which fared better, but liked to fall out of place when engine got hot (different rates of expansion of aluminum vs the pressed metal) so those we could often pop apart and if the gaskets were not shredded, we could put them back in place and then stake around the pump body to hold the check valves in place better (worked on the plastic body fuel pumps too)  Even then, the repair kit was only available through Kohler, and has long since been obsoleted/NLA (I think they stopped making the kits entirely in the middle 2000's)  Aftermarket kits don't seem to ever have the check valves, so the choice then is either a new fuel pump or retro-fit for a pancake vacuum pump. (Or, install a 12v electric fuel pump, which you had to be watchful of the PSI output of the pump or it'd flood the carburetor if too much pressure) 

Thank you. The check valves appear to be in good working order, I'll pop them out for a better look and stake them in. If that doesn't work I'll probably go with an electric pump

 

[Gasaholic 257]

17 minutes ago, Matkal said:

Thank you. The check valves appear to be in good working order, I'll pop them out for a better look and stake them in. If that doesn't work I'll probably go with an electric pump

 

Carefully - Couple things: the gaskets under the check valves are relatively delicate and if your check valves are still in place and you can't knock them out by rapping the pump body into palm of your hand, I would recommend leaving them well enough alone  Check valve gaskets are even harder to find than the check valves. - If they are working properly you can hook a short piece of hose to the hose nipples (even if pump is not put together) and test if you can blow through  - On inlet side, you should be able to blow through, but not be able to suck air back through, and on the outlet side, you should be able to suck air through but not blow back through.  That would save you the headache of trying to remove them without damage (which is easy to damage them trying to pry them out... we used a 12-point  thinwall 14mm snap-on socket , or a 14mm craftsman socket that we ground the O.D.  to seat them in place. ) I'd suggest using the tubing "breathalyzer" test before trying to remove or service check valves, because if they are working right, there'd be no real reason to remove them. 

 

If the valves are seated tightly and don't pop out easily, I would not bother staking them. Staking was only a solution for when they wanted to pop out by themselves (rap the body flat on a workbench, if they don't pop out they should stay put)  - In other words, if it ain't broke, don't fix it.  If the pump isn't pumping, it's often either the valves, or the diaphragm totally failed (Or the T of the diaphragm got out of place on the lever fork somehow) ... only other symptom to replace diaphragm was if it was leaking gas into the crankcase. 

 

Check valves can sometimes be cleaned/flushed out without removing them, wasn't uncommon to get bits of debris trapped in the valve (even an animal hair that made it through fuel filter) , so a flush and re-test can sometimes fix the problem... an otoscope and tweezers were handy tools to have (or at least a magnifying glass)  for fuel pumps & carburetor work. 

 

 

 

Edited August 11, 2023 by Gasaholic

[Matkal 34]

I gently tried to pop them out and they weren't moving so I am letting them be and will try the breathalyzer test. LOL

The diaphragm has small cracks in it. I'll replace the diaphragm if it passes the breathalyzer, otherwise I'll just go electric.  Again, thank you for taking the time!