Magnum 18, fuel in crankcase

[Shaner]

I have a magnum 18 I put in my 782 to replace the kt17. I had a problem with the mechanical fuel pump on the kt17 filling the crankcase full of fuel. I removed the mechanical fuel pump and used the nipple that attaches to it to use a vacuum style pump which has worked well. I used the carb and intake manifold off the kt17 on this m18 but now I got a crankcase full of fuel again. I rebuilt the carburetor twice, set my float level as to how Matt G did in his tutorial but it still floods the block. I tried using two different floats, bought a new needle and seat but still dumps it into the block. I can't use the walbro carb and intake manifold because the choke levers actuate backwards than the kt17 carter carb.


Does anyone have any insight on what I might be missing? I'd really love to get this tractor back to service.

[dvogtvpe]

Are you sure the vacuum fuel pump didn't take a dump and is putting fuel in the crankcase through the vacuum line?

[_DX3_]

I had to install a manual fuel shut off valve on my KT17 to keep that from happening.

[ford4150]

Put the floats in a container of water and see if they float. I know you tried two different floats, but stuff happens.

[timbo2]

My 1872 did that. I bypassed the pump and went gravity feed with a shutoff valve. I also rebuilt the carb (leaky float) but I wanted to get it in running mode. Eventually I will leave the shutoff valve open and monitor the oil. If that does the trick I'll reattach the pump and monitor again.

Goodluck

[Cannon51]

I'm late to this topic but I have had the same problem with 2 different CV single engines. I got a green tractor off craigslist this week that had a mechanical fuel pump and a crankcase full of gas. I hooked an old fuel pressure gauge to the pump outlet and ran the engine of a gravity feed tank and got a little over 3 psi of fuel pressure. What little I could find on the web says .5 to 2 psi and that more than that can overpower the float needle. I can't find any reference to rebuild or adjustment of these pumps.
Cannon

[Group_44]

With what the ethanol in the gasoline is doing to all the rubber elsewhere in the fuel system it wouldn't surprise me if the problem isn't traced back to rubber diaphragm in the pump or the rubber tip on the float needle being eaten up. So much of the material that was OK before the introduction of ethanol is turning to mush now the alcohol concentration is hovering around 10%.

[J-Mech]

Originally Posted by Cannon51

I'm late to this topic but I have had the same problem with 2 different CV single engines. I got a green tractor off craigslist this week that had a mechanical fuel pump and a crankcase full of gas. I hooked an old fuel pressure gauge to the pump outlet and ran the engine of a gravity feed tank and got a little over 3 psi of fuel pressure. What little I could find on the web says .5 to 2 psi and that more than that can overpower the float needle. I can't find any reference to rebuild or adjustment of these pumps.
Cannon

SO....... what's your question? 3PSI is fine. If you have fuel in the crankcase, either the carb is leaking or the pump. Rebuild the carb, replace the pump. Problem solved.

[Cannon51]

I assumed 3 psi was to much based on what I had read elsewhere.
Cannon

[J-Mech]

Originally Posted by Cannon51

I assumed 3 psi was to much based on what I had read elsewhere.
Cannon

No, it's fine. It takes at least 8PSI to overcome the float. If not more.... IF the float is set right, and the needle valve is good.