Fuel pump replacement

[MalMac 1,331]

I am replacing a original fuel pump on a K241. The new pump is an aftermarket pump. Other than being the now standard plastic it appears to be the right pump. Now for the problem I install it and it won't pump. I can take it off and pump by hand and it has got pump action. When I put it on with the lever riding on the cam it will not pump. I have turned it over like your trying to start it with the fuel lines off, put my fingers over the inlet and outlet with no pumping action taken place. I have replaced several pumps before but have never had this happen. It almost like the pump levers not hitting the cam. I know that it is because the marks thats left on the lever. I am stumped on this one.

[wildman 205]

Is the arm new fuel pump the same as the old one?

[Kelly 1,029]

Didn't put it on upside down? don't ask!!! or the lever under the cam not over it?

[MalMac 1,331]

No, not on upside down but I am about ready to try that. The arm appears to be the same as the original. BUT and I say that lightly to me that can be the only thing that is causing the problem. At first I thought that I put it under the cam. I just wonder if there is just enough difference in the bend of the lever that it's not getting the full throw to pump. When you hold the new one next to the old one the bend in the levers look identical. Maybe trying to save some by trying aftermarket I got bit in th A$$. I have never used aftermarket before I guess now I have been reminded why.

[MalMac 1,331]

Ok I have come to determine that the aftermarket pump is the correct pump just not made to the standards of OEM. The pump lever is just off enough that it's not getting the full throw to activate enough pump action. I guess you get what you pay for. With that said, paying the price for a OEM getting what you pay for I should get a pump that also will do the dishes and sweep the floors correct?

[rmaynard 15,410]

It is critical that both the old pump arm and the new pump arm are exactly the same length and shape. The cam has about 1/4" lift and if the arm is not at the same angle, you will not get the proper action.

But here is another thought. When I got my last plastic pump, the input arrow was on the left, and the output arrow was on the right, just the opposite of what it should have been.

I removed the top and reversed it. All was well after that.

[WH854 44]

P/N for replacement fuel pump is 47-559-11-S Fits these engines.

KOHLER M10 M12 M14 M16 K241 K301 K321 K341

Chas

[halbert 0]

Are you hung up on keeping the engine original? If not, you may want to consider replacing that mechanical pump with an electrically driven pump. Because of a bad experience with a guy I had work on my Onan (crank case vacuum operated fuel pump) I had him replace it with an electric. I really like the new pump better than the old vacuum pump. It isn't necessary to turn the engine over several turns to prime the carb. By the time I hit the starter, the electric pump has already delivered fuel and the engine starts much quicker. Because this "guy"(I won't use the term mechanic) failed to properly tighten the starter I had him replace, I had to go back in and re-set the starter pinion/fly wheel engagement and properly tighten the bolts. In doing so I found that he had failed to re-connect the vacuum line to my original fuel pump. Trust me; a vacuum pump with a disconnected vacuum line will not deliver a drop of gas. I got all that gear properly arranged, but not set up to pump fuel and left the new electric to provide fuel to the carb.

If anyone is interested in going this route, email me and I will be glad to give you what advice I can contribute. An aftermarket electric will most likely cost far less than changing over as the OEM's are far too proud of their hardware and you can see from the above that "will fits" sometimes don't! You will most likely want to select a "low pressure" electric (most manufacturers provide both low and higher pressure pumps) so as not to ovrride the crburator float/needle shutoff. I can give you brand and part number info as well. In any case, good luck.

[MalMac 1,331]

Ok problem solved. Was not the pump, I can not say for sure but I think I had some sort of air lock going on. Anyway thanks for all the suggestions.

[can whlvr 993]

glad u found it,ive had a tough time getting some pumps to prime as well

[gwgdog66 23]

Ok problem solved. Was not the pump, I can not say for sure but I think I had some sort of air lock going on. Anyway thanks for all the suggestions.

I've had the same problem happen to me. Once the air is out of the line it worked.

[dmoore 773]

When I restored my C-101 I decided since everything was new to go ahead and replace the "metal" oem pump with a new Kohler unit which by then was the plastic version...I had run the original engine with the OEM pump a few months prior and it started right up every time.....after installing the new plastic pump I did notice considerably longer start up times.....Today I found that original pump and took it apart....there is a check valve of some sort built into the bottom bowl....I'm thinking of removing the plastic one and installing the metal OEM unit....Anyone else experience this? :thumbs:

[MalMac 1,331]

I did find out from my local dealer that they thought the newer fuel pumps did not have the pressure of the old ones. I tend to agree, I compared the old to the new when cranking and the newer style just seem not to pump near as much fuel. With that said the newer ones must pump enough because the engines that I have them on run fine. I just don't think they have the draw that the old style had to over come some of the air problems that I encountered.

[halbert 0]

That "start up time" is likely the time that the starter has to turn the engine over in order to pump fuel into the carburetor and get it ready for business. Over the life of the engine that is a lot of wear and tear on the starter and associated gearing. I found that the electric pump cuts down on that start up cranking quite a bit. My guess is it cuts out about 60 to 70% of the cranking that I used to experience on a cold start up. The electric pump starts filling the carburetor bowl as soon as you turn on the key. This gives an immediate flow to the fuel jet system and if you have a good hot spark, the engine will roar to life by about the first full turn. Maybe it's just me, but the difference in crank time with my Onan ws almost startling.

The Onan does have a vacuum operated pump which depends on crank case pressure for power. If your engine has a mechanically operated pump then there may be a differene in cranking time if the mechanical pump is quicker at bringing the carburetor to full prime. Either way, I can report that the electric pump has given me much quicker start up response. I've had it in my D160 for only about 6 months and due to other issues I haven't run it a lot since the installation so I can't report long service life, but at under $50.00 for a new pump, the electric beats the socks off most OEM vacuum or mechanical replacements.

[squonk 41,011]

That "start up time" is likely the time that the starter has to turn the engine over in order to pump fuel into the carburetor and get it ready for business. Over the life of the engine that is a lot of wear and tear on the starter and associated gearing. I found that the electric pump cuts down on that start up cranking quite a bit. My guess is it cuts out about 60 to 70% of the cranking that I used to experience on a cold start up. The electric pump starts filling the carburetor bowl as soon as you turn on the key. This gives an immediate flow to the fuel jet system and if you have a good hot spark, the engine will roar to life by about the first full turn. Maybe it's just me, but the difference in crank time with my Onan ws almost startling.

The Onan does have a vacuum operated pump which depends on crank case pressure for power. If your engine has a mechanically operated pump then there may be a differene in cranking time if the mechanical pump is quicker at bringing the carburetor to full prime. Either way, I can report that the electric pump has given me much quicker start up response. I've had it in my D160 for only about 6 months and due to other issues I haven't run it a lot since the installation so I can't report long service life, but at under $50.00 for a new pump, the electric beats the socks off most OEM vacuum or mechanical replacements.

What electric pump did you use?

[halbert 0]

Here's my reply to one of the members who have asked about the electric fuel pump. I have had about four members ask about the pump so out of that amount of interest maybe we'll get some more real-world experience to report on the subject. If I get any feed-back, I'll sure post it here--pro or con:

The electric fuel pump I have on my 16 HP Onan is an Airtex model number E8016S. Airtex makes a boodle of fuel pumps so you want to be especially careful that you get the low pressure unit (2.5 to 4 PSI). A higher pressure pump can generate enough pressure to lift the needle valve in the carb. off its seat and flood the carb. The pump can be found at Autozone for around $46.00. The important thing is that the pump be capable of keeping the carb. fully supplied with fuel. I see no reason that this pump wouldn't work on about any small engine you'd find on machinery like WH tractors. Unless I'm mistaken this one is large enough to supply fuel to a 4 or 6 cylinder automobile engine. It comes with a fuel filter that goes on the inlet side and a mounting bracket. Be especially careful so as not to get any dirt etc. into the inlet side of the pump. The first thing I'd do is mount that filter on the pump. I'd suggest mounting it close to the fuel tank and below fuel tank level to assure a positive prime of the pump. You will want to make the positive side electrical connection into the circuit that supplies current to the ignition. That way it will fire up and fill the carb. as soon as you turn on the ignition switch and, of course, have power while the engine is running. Check out this link: http://www.airtexproducts.com/TSB/TSB-0108-01_ATX.pdf

There are other pumps on the market. Just be careful about quality. Carter is an old and respected brand and probably has a low pressure unit that would do the job. So far, I've been pleased with my Airtex.

If you decide to try one please let me know how it works out.

[47JDG 65]

I read this old thread and just installed this pump on my C-81. It had a newer plastic mechanical fuel pump on it when I bought the tractor, however it looses its prime the longer it runs at high speed, and from sitting a while. I think engine heat eventually affects these newer cheaply made pumps and they just don't perform consistently after awhile. Some last, some don't. The cheapest price I found for a replacement was $40, so I looked up this electric low pressure Airtex pump on Amazon after reading this old thread and found a new one for $23 with free shipping. There are plenty of reviews on Amazon also of guys using them on other small engine applications with great results. I decided to go this route and give it a try. I wired it up to my switch circuit and put a fuse inline. It only draws a couple of amps so no need to install anything else for this application. It's a real clean looking install and mounted nicely. Now it supplies plenty of fuel with the turn of the switch and fires up instantly. I let it run for about 30 minutes at different speeds with no issues at all. Mine measured just 2.8 pounds of pressure so I see no need to add a pressure regulator. I look forward to using it now. I don't like to revive old threads, but I just wanted to give this low pressure pump another thumbs up. For the price I felt it was the way to go on this working tractor. 

[pfrederi 17,635]

I read this old thread and just installed this pump on my C-81. It had a newer plastic mechanical fuel pump on it when I bought the tractor, however it looses its prime the longer it runs at high speed, and from sitting a while. I think engine heat eventually affects these newer cheaply made pumps and they just don't perform consistently after awhile. Some last, some don't. The cheapest price I found for a replacement was $40, so I looked up this electric low pressure Airtex pump on Amazon after reading this old thread and found a new one for $23 with free shipping. There are plenty of reviews on Amazon also of guys using them on other small engine applications with great results. I decided to go this route and give it a try. I wired it up to my switch circuit and put a fuse inline. It only draws a couple of amps so no need to install anything else for this application. It's a real clean looking install and mounted nicely. Now it supplies plenty of fuel with the turn of the switch and fires up instantly. I let it run for about 30 minutes at different speeds with no issues at all. Mine measured just 2.8 pounds of pressure so I see no need to add a pressure regulator. I look forward to using it now. I don't like to revive old threads, but I just wanted to give this low pressure pump another thumbs up. For the price I felt it was the way to go on this working tractor. 

 

Where did you mount the electric pump.  I have one I just bought to put on a C175 but am wondering about the best location.

[47JDG 65]

I mounted it right beside and to the left of the rectifier. I used an existing hole and bolt to mount the bracket so it can be returned to original. I also used the two 90' degree fittings from my old mechanical fuel pump instead of the straight fittings that came with the pump.  I can snap a picture if you would like.

[JackC 617]

A picture would help.  For the C-81, did you cover the port where the old pump mounted or just leave the old pump in place?  I am getting tired of dealing with hard starting due to the old mechanical fuel pumps and the weak vacuum fuel pumps.  I have a C-81 that is hard to start due to a weak pump.  After reading your post, I just bought 2 Airtex E8016S electric fuel pumps from Amazon.  Great deal for $26 per pump plus free shipping.  Thanks for the information.

 

Ethanol is not good for the rubber diaphragms in the older pumps.

Here is a Jay Leno video on the old mechanical pumps and note the comments on ethanol.

 

Edited November 29, 2014 by JackC

[47JDG 65]

JackC, I left the old pump in place and plugged off the inlet and outlet hose. The resistance that is then felt on the pump actuator arm with both lines plugged off is the same as if it were pumping fuel, so I don't believe its adding any unnecessary stress to the cam lob. My pump was really weak, and yours might have more resistance. I thought about removing the arm from the old pump (or just cutting it off) so it no longer contacted the cam, but I just put it back in for now. It's probably not even necessary to plug the fittings off but I did just in case there was a slight leak into the crankcase. I didn't want the pump sucking in dirt and dust and allowing that into the crankcase somehow. I may just make a little cover for the port eventually, but for now I'm not. I will try to snap a couple of pictures later today.

[47JDG 65]

Here are a couple of pictures. I guess it's not going to win any awards for best looking custom install, but I think it looks fine for a working tractor. In the pics it looks like the top fitting may be touching the battery tray, but it isn't. The inlet is on the bottom and the pump comes with that little metal filter already attached to it. The outlet is the top of the pump. You can see why I used my old 90 degree fittings now. I ran it some more today and I am happy with the setup. 

[JackC 617]

47JDG. That looks very neat. Thanks for the pics.  Here is the Kohler mechanical fuel pump port cover that I got from eBay for around $12.00. 

 

 

I sometimes use clear fuel line from the filter to the pump or from the pump to the carburetor so I can get a visual to see if the fuel is flowing when I crank the engine without disconnecting any lines. This is the clear fuel line from the pump to the carburetor on one of my D-160s. That is a check valve before the pump to try to keep the fuel in the line and to keep it from going back to the tank.

 

[47JDG 65]

Those are both good ideas. Thanks for sharing. I think you will be real happy with your new pump when you get it installed. I don't know who you ordered yours from, but mine came within just a couple of days with standard shipping. I was impressed with how fast they were. 

[wheel-mule 46]

One thing to keep in mind on the aftermarket pump is the aftermarket pump does not use the gasket only the odd shaped rubber ring.If the gasket is used the pump will not make as much pressure because it is not hitting cam enough.