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#915187 - 05/30/17 12:30 PM Cannot keep engine running?????
Northsidedrive Offline
newbie

Registered: 05/06/15
Posts: 28
I have a older John Deer riding tractor, L120. When I pour gas inside the carb. it only runs until that gas I poured in the carb. is used up. How can I check to see is my gas pump working??? This gas pump is a small black piece mounted on the side of the engine, it has one gas line connection on each side and one gas line connection on the bottom. So far I do not see any gas in the gas line plastic filter. Something is keeping gas from getting to the carb. I disconnected the gas host from the carb. and the gas pump, crank the engine and no gas shoots out of the gas pump. What makes the gas pump, pump gas since it is not wired???? I notice the short gas host at the bottom of the gas pump connect from a metal box bolted to the engine with a label OHV on the metal box. This gas host has a cut in it after it extends out of the OHV box, (OHV box appear to be the cover for the engine pistons. Could this cut in this gas host be what keeping the gas pump from pumping gas to the carb. I also took loose the gas line that connects to the gas tank, blew inside the gas tank where the gas line goes to the bottom of the gas tank to be sure it was not stopped up, I blew and saw bubbles inside the tank, so it was not stopped up. What else can I check to see what is causing gas not to getting to the gas filter and the carb>???????

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#915188 - 05/30/17 01:06 PM Re: Cannot keep engine running????? [Re: Northsidedrive]
JasonB Offline
Sharp -Shooter
Carpal Tunnel

Registered: 04/27/04
Posts: 16164
Loc: Cape Spencer, New Brunswick, C...
The fuel pump on a small engine is operated by pressure fluctuations in the engine's internal spaces. In your case, it would appear that yours gets its "pulse" from the overhead valve cover.

Yes, a cut in the pulse line WILL stop the pump from operating. Inside the pump is a diaphragm. Pulse from the engine causes the diaphragm to oscillate, which along with the check valves in the pump, results in fluid flow.

Your first step is to repair that pulse line. If that doesn't solve it, servicing the fuel pump (typically replacing the diaphragm) would be the next.

J
_________________________
er, somethin'....

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#915881 - 06/08/17 11:34 AM Re: Cannot keep engine running????? [Re: Northsidedrive]
Northsidedrive Offline
newbie

Registered: 05/06/15
Posts: 28
I replaced the fuel line from the OHV box to the fuel pump. I also replaced the fuel pump. After cranking the engine several times, I do now see a little gas in the plastic fuel filter that I was not seeing before. But it will still not keep running. The fuel filter is not full of gas, and I believe gas is not getting to the fuel pump, to get in the carb. What to look for or how to check that gas is pumping from the gas tank. Where is the carb for this model?? Is it under the big white filter that sits in the front of the carb.?? If so how to check that there is no issue with the carb???? How to test that gas is pushing out of the tank all the way pass the fuel pump??????

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#915883 - 06/08/17 12:03 PM Re: Cannot keep engine running????? [Re: Northsidedrive]
JasonB Offline
Sharp -Shooter
Carpal Tunnel

Registered: 04/27/04
Posts: 16164
Loc: Cape Spencer, New Brunswick, C...
The carb is where the fuel line ultimately ends... It'll be between the cylinder and the air filter. Judging from your posts, you may be getting over your head, know when to stop if you are.

Fuel filters normally have an air bubble in them. They appear partially full quite commonly. Ignore this.

To verify flow from the tank to the pump, remove the fuel line from the tank at the pump inlet. Should gravity flow when the fuel line is held lower than the fuel level in the tank. Assuming your filter is between the tank and pump, this would also prove the filter to be good. If no-flow, try again upstream the filter. Replace or clean whatever stops the flow, if anything.

To verify a fuel pump is working, I remove the fuel line from the carb, and direct it into a small clear bottle (soda bottle). Have someone crank the engine. Fuel should be pumped into the bottle in a pulsing manner with each engine revolution. If you got fuel to the pump, but the pump doesn't pump, then you service the pump.

I wonder how long it's been since this machine ran. If it's been sitting a good while, it's quite likely that the carb needs to be removed, disassembled and thoroughly cleaned. Old gasoline turns to a varnish that clogs fuel passages. Old pump diaphragms become stiff and don't pump well anymore. These are the usual culprits when an engine that has been idle for several months or more won't start.

When did the machine last run, how did it come not to run (did it quit in use, or is it just out of storage?). A bit of history helps.

J
_________________________
er, somethin'....

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#916525 - 06/14/17 10:33 AM Re: Cannot keep engine running????? [Re: Northsidedrive]
Northsidedrive Offline
newbie

Registered: 05/06/15
Posts: 28
The engine ran last year grass cutting season. Ok at this point I have the engine running and I am back at cutting grass. I replaced the fuel pump, and took off the gas cap, and will drill a larger hole in the cap. Which one was the cause is still a quest. Another issue I want to work with is replacing my engine muffler. also why do my cutting system (precision plus cutting system) at certain times the turning blade stalls and pick back up on it own.

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#916641 - 06/15/17 06:22 AM Re: Cannot keep engine running????? [Re: Northsidedrive]
notnew2diy Offline
Carpal Tunnel

Registered: 08/18/06
Posts: 4167
Loc: harvard, il.
Originally Posted By Northsidedrive
also why do my cutting system (precision plus cutting system) at certain times the turning blade stalls and pick back up on it own.


You might get a better response by starting a new thread on this topic.
I know nothing about your system.
My experience is...
1 - stretched/loose belt
2 - bad or glazed over pulley


HTH...notnew...
_________________________
Thanks to all US military veterans.

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#918874 - 07/14/17 09:29 AM Re: Cannot keep engine running????? [Re: Northsidedrive]
Northsidedrive Offline
newbie

Registered: 05/06/15
Posts: 28
I got the motor running, last week. Cut grass for about an hour. But here again a week later, I try to use the motor again, and it is doing the same thing. I have replaced the fuel pump, and took off the fuel cap. And again it only runs long enough to burn out the gas that I pour down in the carb. What else can I check for that is causing this problem. Could the motor solenoid be causing this problem. How do I test the solenoid????? Would a defected solenoid cause these problem, not letting the fuel pump get gas to the carb. John Deer L-120 model--917276910.

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#918875 - 07/14/17 09:32 AM Re: Cannot keep engine running????? [Re: Northsidedrive]
CabinConnection Offline
Bigfoot
Carpal Tunnel

Registered: 01/20/04
Posts: 49473
Loc: The Indianhead's Left Nostril....
I didn't have time to wade through this whole thread, but what little I did read makes me wonder if your float/needle/seat is sticking in the carb...

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#919502 - 07/22/17 08:41 AM Re: Cannot keep engine running????? [Re: CabinConnection]
Bob_Q Offline

Carpal Tunnel

Registered: 06/28/01
Posts: 17677
Loc: Albany area,New York
This thread has gotten a little muddied up.
To start back at the beginning,even after replacing the pulse pump,an easy way to check it's operation is to remove the fuel line from the carb,place it in a container to catch the fuel,remove the spark plug wire,then turn the engine over several times. If you get plenty of fuel,then the problem lies ahead of that,like maybe the carburetor.
As C.C. suggested, you could have a sticking/inoperative float,or debris somewhere else in the carb,which means R&R.

Let us know what you find or have found since the last post.
_________________________
It must get boring preaching to the choir.

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