Kohler Engine Swap Issue

[psyc0tic1]

Hi all,

I recently swapped the engine on my Craftsman T3000 mower from Briggs to Kohler. Before you ask why I would swap out the 20hp Briggs with a 13.5 hp Kohler... that stupid little fuel shut-off sylinoid failed and allowed a bunch of gas to leak into the crank case and my son never told me there was an issue... months of running the motor with gas diluted oil has caused the motor to start knocking so I bought a John Deere mower for $100 to snag the engine from.

Here is the issue. The Craftsman mower is a gravity feed fuel system and the Kohler engine has a fuel pump as it came out of a John Deere mower.

When I first fired it up it ran great and I was mowing until it ran out of fuel. Knowing that there might be an issue I ran the fuel line out of the tank (which comes out the bottom of the tank) up high over the tank then down to the pump trying to cut down on the weight of the fuel pushing through the pump. it seemed to work until I ran out of fuel and filled the tank about half way up. Now all it does is flood the engine.

I suspect that I only had a few cups of fuel in the tank before and there wasn't much gravity weight pushing it through the pump.

Anyone know how to make this combination work?

I tried jerry-rigging the setup by strapping the fuel tank all the way at the back down on the hitch plate and running the fuel line uphill to the pump but the problem of flooding still happens.

 

[bertsmobile1]

Firstly, the shut off valve does not prevent the carb from overflowing into the cylinder.
The problem is the float valve does not shut the fuel off so it fills the bowl then overflows out of the air vent and runs down into the engine.
The shut off jambs a plug in the end of the main jet preventing fuel entering the venturi tube thus stopping unburned fuel passing through the engine while it is spinning down with no spark.

Now what you did not mention was weather you swapped the engines complete with carbs this is very important..

This is important because fuel pump carbs are different to gravity feed carbs.
Some use different needles, some use different needle seats to change the closing force on the fuel supply.
Some are convertible other are not
Gravity carbs fed from a pump tend to run rich
Pump carbs fed from gravity tend to run lean

 

[psyc0tic1]

The reason for the failure on the briggs engine is irrelevant at this time.

I swapped engines complete... Carburetor and all.

The question... How can I get the pump engine (and carburetor) to work on my mower that has a fuel tank above the engine?

 

[bertsmobile1]

The reason for the failure on the briggs engine is irrelevant at this time.

I swapped engines complete... Carburetor and all.

The question... How can I get the pump engine (and carburetor) to work on my mower that has a fuel tank above the engine?

IF the pump engine has the pump carb on it then you just hook the fuel line to the pump inlet.
The position of the tank will make no difference.
The two spigots on the side of the pump are the inlet & outlet the one in the middle is the impulse line.
The spigot nearest the impulse spigot is the inlet.
The lonely one all by itself is the outlet.
There is a small vent in the pump with a sintered brass filter in it these can also get clogged and stop the pump working properly.
The outlet should pump fuel at least 4" higher than the top of the tank when the engine is cranking.

You might need to dissasemble the carb and clean it sounds like you have some old gummy fuel in there.
Nice new fuel lines would not hurt either same for the filter.

OTOH no reason to assume that the $ 100 JD fuel pump is actually working to start with.
If it has been left without any tubes on the end small insects seem to like to take residence in there.

The head on the pump will make no difference the pump is a simple diaphragm with a light spring on it.
Crankcase pressure causes the diaphragm to move in & out as the piston goes up & down.
The pressure of the fuel delivery from the pump will not be affected by any head on the supply side
There is a one way valve on the outlet that regulates supply pressure and pump carbs have a stronger closing force on the float needle to account for the extra pressure from the pump.

 

[psyc0tic1]

So the Kohler engine on the John Deere worked perfectly before I did the engine swap... pump and all was fine and I was mowing the grass with it for a couple of months. I just didn't like the 38" cut and it didn't have the bagging attachment that I use on the Craftsman and I like that so I did the swap.

So you are saying that even though the tank is above the engine, it should still work fine? Maybe as you said a little piece of trash may have gotten in the carb causing it to start flooding? Or there could be a piece of trash in the pump causing the check valve to remain open allowing gravity fed fuel to continue flowing into the engine flooding it?

I just wasn't sure if the tank being above the engine would cause the problem since on the John Deere the tank is below the engine way in the back of the mower.

 

[bertsmobile1]

Pump on gravity should work fine.
Other way round causes problems.
Sometimes people swap the entire carbs over because the linkages don't line up which is why I had to check.
If the fuel lines on the craftsman are old, replace them as they can get soft and collapse when hooked up to a pump, yet work fine under gravity.
And a tap is still a good idea .
Belt & braces means you won't get caught bare bummed when you least expect it.

 

[psyc0tic1]

Pump on gravity should work fine.
And a tap is still a good idea .
Belt & braces means you won't get caught bare bummed when you least expect it.

Thank you very much for the clarifications.

I do not know what you mean by a "Tap" and the belt and braces part I do not understand either

 

[bertsmobile1]

Thank you very much for the clarifications.

I do not know what you mean by a "Tap" and the belt and braces part I do not understand either

Tap as an inline fuel shut off tap, put in the fuel line between the fuel tank & fuel pump.
If the filter is also in that length of hose, upstream of the filter so you can shut it off when not in use thus avoiding the same problem happening again.
Also make it easier to replace the filter and clean the carb.

SO the tap is stopping the fuel flow and the needle valve is also stopping the fuel flow

2 things doing the same job

Same as wearing a belt in your trousers and a pair of braces hooked onto your trousers

 

[psyc0tic1]

I understand now.. thank you very much for your helpful information

 

[bertsmobile1]

I understand now.. thank you very much for your helpful information

Probably an age thing
My grandad wore his "firemans braces" to hold his trousers up
Dad regularly wore both a belt & braces.
It was an old saying for doubling up
And if you were really anal it was belt braces & a rope ( total over kill )

Now we have sorted out English USA vs Aust we need to get your mower happening.
Well it's midnight so I need to get the ZZZZZZZ's happening.
See you in the morrow.