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doc724

C101 Fuel Problem-what have I missed?

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doc724

A year and a half ago, I mentored a teen down the street to  restore a C101.  At that time I did rebuild and clean the carb.  The machine ran flawlessly until about a week ago when it would not start. I have diagnosed the problem as a fuel problem as I have visually confirmed spark and it runs for a few seconds when a bit of gas is put in the spark plug hole or when stater fluid is sprayed into the carb.

 

I disconnected the carb fuel inlet line and cranked the engine and fuel was expelled from the fuel pump, but it was not like it shot several inches, although not a dribble either.  So my diagnosis was that the fuel pump (it is a mechanical pump) was probably tired.  So I bought a new aftermarket pump (Kohler pricing was prohibitive) and installed it today.  Still nothing.

 

I have confirmed that the tank shutoff is not blocked by removing the fuel line at the tank and opening the shutoff.  Fuel runs out easily both with and without the gas cap installed.

I removed the fuel line from the in-line filter and fuel readily flows from the tank out the fuel line so I know that it not blocked.  Tank was cleaned and fuel lines and filter were all replaced when we did the restore.

 

I did not confirm that the fuel line from the filter to the fuel pump is clear but I am hard pressed to believe that it could be blocked either.  The fuel filter does not look to be damaged or have sediment inside.  When the engiine was running properly, the fuel filter never completely filled with gas, but this appears to be normal as my C141 (K321) does not fill either.

 

With the new pump installed, I again removed the fuel line from the carb and cranked the engine and NO fuel comes out of the pump at all.  Put the old pump back on and now no fuel comes out of that one either.  I know the cam in the engine is on the correct side of the pump mechanism since I can see where the chromate plating on the new one has started to wear off.  So at this point, I have concluded that both the new and old fuel pumps are bad.  Has anyone else had a new pump be bad?

 

My next step is to take a fuel pump from a K301 sitting in my garage that I know runs and try it.

 

So for all you experts out there:  What have I missed?  Gas is definitely not getting to the carb (or is it?) and could the carb itself be somehow blocked thus preventing the fuel from getting into the needle valves? 

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953 nut

Has the engine been using non-ethanol gas? There have been lots of posts on here about the crap that shows up in a fuel system from the ethanol fuel breaking down rubber components and from the ethanol itself decomposing during layup periods. I would suggest replacing the fuel line and filter and rebuild the carburetor. It was good to go a year and a half ago, but that may not be the case today.

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Jerry77

I did get one brand new fuel pump for a 314-8 that I had years ago that was bad out of the box...so it does happen - put a hose on the inlet and move the tab on the pump with the hose in gas - it should shoot a stream several feet if it is good..:twocents-02cents:

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skrusins

I would try an electric fuel pump. The gas that we are using today evaporates quickly with heat. 

 

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doc724
2 hours ago, 953 nut said:

Has the engine been using non-ethanol gas? There have been lots of posts on here about the crap that shows up in a fuel system from the ethanol fuel breaking down rubber components and from the ethanol itself decomposing during layup periods. I would suggest replacing the fuel line and filter and rebuild the carburetor. It was good to go a year and a half ago, but that may not be the case today.

Unfortunately here in the northeast, it is almost impossible to buy gas without ethanol.  For my own machines I use 93 octane and Sea Foam.  I have had no problems and my machines typically only get 15 hours use per year (since I have 4 to share all the duties).  I do not know what my protege used in his although I told him 93 octane plus Sea Foam.  Most likely whatever his Dad puts in his (Dad's) Craftsman.  The C101 is in way better condition than the Craftsman and the kid knows it too! :-)

 

Pulling the carb and rebuild may be my last resort, although everything you buy today is supposedly suitable for 10% ethanol and that is all that is available here (unlike corn producing states where you can get up to 85% ethanol

 

 

2 hours ago, Jerry77 said:

put a hose on the inlet and move the tab on the pump with the hose in gas - it should shoot a stream several feet if it is good..:twocents-02cents:

I will try this when I pull the pump from the K301.  The quantification of shooting several feet is kinda the input I was looking for.

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Ed Kennell
4 hours ago, doc724 said:

 

 

With the new pump installed, I again removed the fuel line from the carb and cranked the engine and NO fuel comes out of the pump at all.  Put the old pump back on and now no fuel comes out of that one either 

  No need to rebuild a carb till this is resolved.      Fill the tank to be sure the fuel level is above the fuel pump and try cranking again with the carb line off.

These pumps have very little suction capacity.   The pump intake must be below the fuel level.   These tractors with the tank under the seat can have a fuel delivery problem if the pump is less than perfect.   If the inlet valve does not seal perfectly, they will not suck fuel into the pump.

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JC 1965

I would get an electric fuel pump.  (  1 to 4 PSI  )     :twocents-02cents:

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Elkskin's mower junkyard

also make sure its primed. i take and put gas line down towards grond into a container then turn fuel on wait til it starts flowing cap it off with my finger and quickly reinstall. has i have had issues with pumps priming in past

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doc724
On 10/30/2016 at 5:55 PM, Jerry77 said:

I did get one brand new fuel pump for a 314-8 that I had years ago that was bad out of the box...so it does happen - put a hose on the inlet and move the tab on the pump with the hose in gas - it should shoot a stream several feet if it is good..:twocents-02cents:

I tried jerry's suggestion today on the original fuel pump that I thought was bad.  A couple of inches of gas in a soup can and a 10-12 inch section of hose.  A few movements of the actuator and it was pumping 12-18 inches.  So I am rethinking the my original hypothesis that the line from the filter to the pump is NOT blocked.  Wednesday is the next time I have to work on this so the ideal is to get that section of hose off, determine it is is blocked and then replace it.  If it is blocked, I guess I can put that into my "did I learn anything new today" library of facts.

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doc724

I finally got the tractor running today.  I confirmed with a bench test that the "new" fuel pump was not working at all, so the original pump was reinstalled.  There was NO blockage of the fuel line but I replaced the short portion that went from the fuel filter to the pump (the one that routes under the engine).  The lines filled easily with fuel but it took some time for the pump to spurt some fuel out and it was not anywhere near as powerful as when tested on the bench.  I wonder if you can get more motion on the actuator with your hand than the cam in the engine provides?  It took three shots of starting fluid down the carb to get it to run consistently and then it ran fine.  Never did get to root cause and that is troubling because if you cannot turn the problem on and off, it is bound to come back.

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Ed Kennell

Always good to hear them run again.    I think you could definitely get more pumping by hand with full stroke of the lever.

Could the cam be worn?

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doc724
11 hours ago, Ed Kennell said:

I think you could definitely get more pumping by hand with full stroke of the lever.

Could the cam be worn?

With 1150 hours on the engine I suppose anything is possible.  However I would assume the cam is case hardened and the pump lever is mild steel.  The finish on the pump lever is gone in the contact area but there is no measurable wear.

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midpack
5 minutes ago, doc724 said:

With 1150 hours on the engine I suppose anything is possible.  However I would assume the cam is case hardened and the pump lever is mild steel.  The finish on the pump lever is gone in the contact area but there is no measurable wear.

My KT17 did the same thing. the cam lobe was worn. I put a cheepo electric pump on (~ $12) a couple years ago and no more fuel problems :)

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doc724
11 hours ago, midpack said:

My KT17 did the same thing. the cam lobe was worn. I put a cheepo electric pump on (~ $12) a couple years ago and no more fuel problems

If the problem comes back, I will probably take your suggestion and be done with it.

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BESTDOGEVER

Another thing I have found in these pumps is the diaphragm can get dried out and that affects its ability to prime. A little bit of oil in the inlet works to solve that for a considerable amount of time. 

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953 nut

An electric pump is not a bad option, I used one on my GT-14 because it is nearly impossible to replace the mechanical pump without taking a half day's work removing the nose and replacing it. They cost less and in most cases can be installed quickly.

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can whlvr

I completely agree with ed,these pumps are a abear to prime sometimes,a good trick is to use a spray bottle with gas in it and spray into the carb till she runs,i know its a bit dangerous but does seem to help the old pumps prime up,i have a spare tank that I use to hold over an engine to see if it runs,you don't need a pump if the tank is above the engine,some guys pressureize the gas tank also to push fuel along,buy I like the spray bottle,works everytime

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formariz
On 10/30/2016 at 9:56 PM, Ed Kennell said:

  No need to rebuild a carb till this is resolved.      Fill the tank to be sure the fuel level is above the fuel pump and try cranking again with the carb line off.

These pumps have very little suction capacity.   The pump intake must be below the fuel level.   These tractors with the tank under the seat can have a fuel delivery problem if the pump is less than perfect.   If the inlet valve does not seal perfectly, they will not suck fuel into the pump.

 

Correct indeed! The stock mechanical pump in this system with tank under seat has a lot to work against it specifically gravity . With fuel tank full level is about even with pump, however as it lowers even with a new pump its hard work for it. On my c-125 anything less than full tank at full throttle under load there was always fuel starvation. It was also very easy to see what was happening by paying attention to the fuel level inside the clear inline fuel filter.

Switched to a Faccet electric pump and tractor runs so much better. Starting it is pretty much instant, once it turns over it fires.

 

Another change I made was to eliminate strainer inside tank. Somehow unlike other systems, with tank under seat, garbage always gets in the tank. Strainer gets blocked real easy and clearing it is just a pain. I opted to have an additional clear inline filter right outside tank. I can see how much debris is in it all the time and it is easy to change keeping tank also clean this way.

 

So, I have a small clear inline filter outside tank, a filter right before pump (supplied with pump) and I also have a large clear inline filter in the engine bay. This last filter I found at Auto Zone and unlike most, fuel enters through top and also exits through top. Filter stands up straight acting like a sediment bowl. If there is water in the system it actually separates it from fuel and you can see water on bottom of it.

 

All sounds a little excessive but for the last two years I never had to clean carburetor, adjust it or any other fuel related problem.

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