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njdpo

Kohler K321S - Fuel pump replacement problem

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Hi all,

Im working on a Kohler K321s and the fuel pump needed replacing ( rubber diaphragm was torn ) . I ordered a replacement pump which is a bit different from the original as it is plastic, and has a rubber gasket channeled into the mounting flange, etc..

The paperwork that came with the pump says – if there is gasket material on the motor remove it. Instead - decided I would leave in on. Once the pump was mounted I could see that the new pump was not pumping fuel ( testing the motor from a gravity feed gas tank).

I know the new pump is functional and working properly - and yes – I did confirm I was running gas into the INLET side of the pump ...

Turns out I needed to remove that gasket afterall – with the pump actuator arm going in a little further (and touching the cam a tiny bit) the pump was now BARELY dribbling gas out of the outlet side of the pump. Certainly not enough to run the engine.

So I took the actuator arm of the pump and I bent it slightly and mounted it back onto the block – and now I have a “marginally acceptable†flow rate to the carb...

Not pleased with the effort – but …

After running the tractor around the yard – Ive noticed a different sound to the engine (like a hissing noise) and suspected it was the new pump... and after about 10 minutes I looked down and saw the mower deck was wet! Oil leaking from around the new pump...

It seems that gasket – which was removed is needed – as the hole in the block is a bit too big for this new replacement pump and its integrated rubber gasket. Great …

Before I go any further and get myself a new gasket – I want to talk others on the forum and come up with a firm plan...

Questions:

If I put a gasket back on this block Im pretty sure Im going to need to bend that actuator arm a bit more... Or not – but I just cant see another way to adjust accordingly... Your advice on how to do this right is appreciated.

Also – In the pump kit there were various parts (large and small fuel hose fittings, and a large steel snap ring)... What the heck is the snap ring for ?

Your advice appreciated

Thanks - Dave

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Sounds like you may have an incorrect pump.

The "O" ring seal is all that you need. It is meant to make surface to surface contact. The paper gasket must be removed. The thickness of the paper gasket is not enough to affect the placement of the arm. Be sure that the arm is on top of the cam and not under it. If the pump is installed properly, and the arm is not making sufficient contact with the cam to provide proper pumping, then I suspect you have the wrong pump.

The large snap ring is used as a tool to remove and install the various input and output fittings that come with or are available for the pump. There should have been an instruction sheet with the pump to show you how to use the tool.

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The snap rings are to install & remove the fittings from the pump. You can damage the orings on the fittings if you do not use the snap rings. Should show in the directions how to do it. You may have cut one or both of the orings and that could be a problem. Also I have installed these pumps on my K341's with no problems. I have always removed the old gasket from the block with no leaks. As far as the problem with pumping if not the orings I would see if you can return the pump & get another. In the last month at work I have gotten one new rotor that was out of round & two new inner tie rod ends that would not take grease. You may have a bad pump right out of the box. My :twocents-02cents:

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You didn't install the pump upside down, did you I've seen that before, and getting the pump arm on the wrong side of the cam, or it could be a bad pump.

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if the pump doesnt cover the existing hole in the block then i would think you have the wrong pump,i would hold the 2 pumps side by side and compare body size and arms,you can put a small peice of hose on with the new pump not on the motor,put the hose in a small container of fuel and pump the arm manually,you will see if its pumping before it goes on the motor

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OK - so the whole pump thing has turned out to be a total fiasco...

Here's where I'm at ...

With a little work - the diaphragm from the new pump had been moved into the old pump... The assembled unit has great vacuum and works like a champ.

Placing the old pump back onto the block with a new gasket - I am seeing that their is very little gas coming from the outlet fuel line (which goes to the carb).

Idling the tractor is possible - but running it (under load with the mower deck ) shows that there is simply not enough output to the carb - and under load she will run out of gas.

If I remove the gasket and remount the pump to the block - there is a better amount of fuel coming from the pump, but I'm back to the oil leakage from the block. Still I would expect to see a better flow from the pump ... Manually operating it - the pump shoots gas from the outlet side 2 feet... so I know its working well.

and no the pump has not been mounted up-side down.

At this point I have looked at the cam surface (through the pump access hole in the block) and it looks to be in nice shape - no scars are wear.

I am very close to trying to bending the actuator arm (slightly) on the old housing to boost the volume on this pump.

Before I do this - I want to see if anyone has any ideas or questions.

Thanks - Dave.

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I had almost the exact same senario happen to me and my C-160. Pump will push all kinds of fuel when you work it by hand. Hardly anything will come out when cranking. I've felt the cam lobe and It feels like it's all there but who knows. If I run the tractor out of gas I have a heck of a time getting fuel back to the carb. If I take the fuel line off of the carb inlet and fill the bowl I can get it running. Once it's running ,the pump seems to pump enough to keep it going. I had a vapor lock problem last week after mowing for awhile and then shutting it off and letting it heat soak. If it happens again I'm just going to put an electric pump on like Brian Miller suggests.

http://gardentractorpullingtips.com/carbfuel.htm

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I am also thinking of an electric pump ... I bent the actuator arm (little by little ) on the other pump and I started to see good volume from the pump.

As it is the pump pushes barely enough to keep the tractor running - put it under load - and your going to run out of gas.

I was very careful about checking the distance of the amount I bent the arm on the first pump - by taking the pump off the engine. placing the flange side of the pump against a piece of wood - and tracing the edge of the arm with a pencil on the wooden block... then I could compare the amount I bent the arm - by placing the pump back against the wooden block after I bent the arm.

As it is - I know I dont want to bend the arm too much otherwise Ill cause excesive wear on the cam.

I also know that with the gasket OOF the engine - I saw a "better" amount of volume from the pump... but still not that good (that gasket is about 1/32 thick... ) but I know im on the right path...

So if I can bend the arm about 3/32-1/8 of an inch I'll have good flow to the carb.

This time I will pull the actuator arm from the pump - heat it with a torch and tap it lightly so as to not crack the arm.

Last arm I tapped while it was cold - and fatigued cracked the arm - I wasnt willing to put it in the block - and risk the chance of it breaking off and laying waste to a complete engine.

If this doent work - Im going down the electric fuel pump road ...

Im under the impression I should try an get an electric fuel pump with a low amp draw to it

I dont want too much pressure - and I dont want to sap the charging system running a high draw pump either .

Ill keep the group posted with the way the story ends ...

Dave

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well I installed a low pressure Facet electric fuel pump this weekend - the engine starts quick and runs strong.

Any idea where I can find a block off plate for the old mechanical fuel pump ?

( Kohler K321S )

I want to remove it entirely, its leaking oil - it needs to go. )

Thanks - Dave

******

NOTE: Started a new thread : " Kohler K321S mechanical fuel pump - block off plate."

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Ok - so the electric fuel pump has been on for several months now and im not real happy with it.

I like the way it will prime the carb before I turn the engine over - thats real nice.

But - I frequently need to charge the battery. I think the pump is drawing more than the 14 HP Kohler puts out. Im sure having the lights on pushes the charging system past its limits ... I run my tractors about 1/3 -2/3 throttle, if im about 2/3 open most times I can restart the tractor. I dont always need 2/3 throttle - while im grabbing a cart of wood I idle my machines down...

Question - will the mechanical fuel pump from a 10HP Kohler K fit on the 14hp K block ?

Without my spectacles on, theses pumps look roughly the same.

If the mech pump doesnt fit - I may try a vacuum pump. I guess I could drill and tap into the block off plate .

Your thoughts and ideas welcome on the matter.

Thanks - Dave.

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Mr. Kirk has them. I have tried to fix or replace old pumps and decided the electrics are a good way to go for a working tractor.

Scroll down if needed. He has some nice upgrades.

http://www.kirkengines.com/

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