Wisconsin engine fuel pump M2151

I have a roller that we put an old Wisconsin engine in > when its runs for a while seems like its not getting enough fuel. will stay running if we hold choke. cant fine a replacement M2151 is the tag on pump. do I need another pump?? is is there another issue?

Airtex still sells new pump for many of the air-cooled Wisconsins. Part # 9084.

Have you checked the output of the pump?

There is usually a vent hole on the pump. Any sign of leakage there indicates a bad pump diaphragm.

Assuming this is a cam driven mechanical pump, it should deliver a shot of fuel every other crankshaft revolution. You can check it cranking or disconnect the line, start it up, direct the flow into a clean glass. If the flow is only a dribble, or pumping more air than fuel, something is wrong with the delivery. Best to be ready and check it as soon as the failure occurs.

It can also be a restriction on the suction side of the pump, loose or cracked hose letting it suck air, or a non vented cap causing vacuum in the tank.

If the pump checks good, there may be a screen in the inlet to the carb, or trash in the jets. Look at what was caught in the glass. If contaminated, that will also be in the carb bowl. The carb is simple, don't be afraid to open it up and take a look. Usually they can be cleaned and reassembled without a kit. Work over a clean surface so anything dropped can be found.

Also, have you checked the spark quality? A weak spark, bad plugs, points out of adjustment, failing coil can cause similar symptoms. Again, check it asap upon failure. It should have a strong spark at the plug end of the wire that will jump 1/4" to ground.

Friend has a Bobcat that runs a VH4D Wisconsin motor, he couldn't find a fuel pump so I ordered him an electric, low pressure fuel pump, off E-Bay for less than $10.00. The Wisconsin takes a low pressure pump.

Also if the fuel tank is below engine, manual says ya got to prime the pump, most have a primer rod on the fuel pump. If tank is below engine and no primer rod, ya definitely need an electric pump.