Fuel pump kit

[markseven 93]

Wondering if anyone can give me a tip 

On installing a new diaphragm in the old 

Kohler 301 Original pump.

Want to try and do it right so it doesn't fill

The crankcase  with a gallon of gasoline again. 

[Retired Wrencher 6,478]

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Then and now have the best ones I have seen. Sorry i do not now the address or full site name.

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Edited March 5 by Retired Wrencher

[953 nut 64,321]

prior to tightening the screws on the pump body clamp it in a vise and push the plunger rod all the way. This will properly position the diaphragm.

[ri702bill 11,386]

1 hour ago, 953 nut said:

prior to tightening the screws on the pump body clamp it in a vise and push the plunger rod all the way. This will properly position the diaphragm.

Indeed. That pre-stresses the diaphragm to allow movement. Avoid this step & the diaphragm will tear....

[pfrederi 19,955]

https://www.thenandnowautomotive.com/antique-auto-parts-store/Kohler-Fuel-Pump-Kits-c196218002

 

Sorry but for less money you can buy a Carbole electric pump which many people here have used and never have to worry about gas in t crankcase again.  If you want to spend a bit more get a made in USA Facet posiflo.

[sqrlgtr 2,245]

All of the above. I found that the then and now diaphragms are on the thin side, but the only place I have found where you get the internal valves with kit. I started making an extra gasket to go in between pump body and diaphragm to keep them from leaking, even after stoning pump body halves to make flat, they were hard to get to seal up for me. Be aware there were a few different styles of pumps used so make sure you order the right one if you order a whole kit. Just turn diaphragm 90 degrees to remove. I had ordered a few diaphragms from isave tractors before he went out of business, and they were made with a heavier material and sealed up better. I have used the later plastic pumps also and have had good luck with them myself, but others have not.

[peter lena 9,781]

@markseven  BEEN USING  CARBOLE   2-3,5 PSI ELECTRIC PUMPS FOR YEARS added   ADDED A led  dash light to verify  its function , my 3 horses have the same , problem eliminating  set up ? fuel check valve , to hold and verify  fuel to carb , filter  and clear  fuel rated hose to carb , showing you its there , also have filter  just after leaving tank , went after  every  issue spot and eliminated it . try /  test  / verify . regularly make up  something that lets me make a change , (   you already know  what  fails ) often  staring right at you , also  function detail  in the throttle linkage ? is every movement  spot  smooth , easy  moving / sliding ? like throttle / choke cable lubrication slide ? this is baseline stuff for me , that I evolved to  , nothing sarcastic  implied , just  what  I regularly do  , pete  

[WHX?? 55,226]

Glass the halves and don't overtighten the screws is the best advice I can give. 

[AHS 1,597]

I am having trouble with rebuilding my fuel pumps… some work some do not! Ones that i rebuilt, I have had a fuel pump leak right between the halves… does this mean it’s bad? I have not tried the sanding yet. 

On 3/5/2026 at 7:21 AM, 953 nut said:

prior to tightening the screws on the pump body clamp it in a vise and push the plunger rod all the way. This will properly position the diaphragm.

Or this. 

 

I have put it in the vise (rebuilt), hooked a hose with gas in it between the outlet and inlet and pumped it. Kinda pre bleeding it.

[Handy Don 16,013]

1 hour ago, AHS said:

I have not tried the sanding yet. 

Mandatory.

The pump bodies are relatively soft metal alloy and can definitely warp when the screws are overtightened.

Also, “more” is not necessarily “better” in diaphragm thickness. What does matter is flexibility and tear-resistance over the long haul.

Flat pump shell faces, positioning the pump to maximum displacement before tightening screws, and not overtighening are all keys to success. 

Edited 10 hours ago by Handy Don