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JD 115 Riding Mower

Posted by laboyma Texas (My Page) on
Tue, Oct 1, 13 at 19:23

I have checked the float (non-adjustable), changed the neddle, cleaned the carburetor, and it floods badly. I have changed the oil since it was somewhat thinner. If I started with the fuel line connected it will flood (shoots out of the breathing tube) but when I disconnect the fuel line and crank it - it starts and runs fine until the fuel runs out. I have checked the carburetor parts against the JD web site diagrams and I have them in the right location. The fuel cut off valve/selenoid at the bottom of the bowl is working fine. PLS help.
Mike


Follow-Up Postings:

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RE: JD 115 Riding Mower

Does this have a brass float or is it a foam plastic float?
If it is a brass float, it is probably perforated and filled with gasoline, so it's more of a "sinker" than a float.
You can hold the float between a thumb and finger near your best ear and shake the float, you may be able to hear the slight sloshing of the fuel inside.
Was flooding the original problem or did it begin after you went inside the car for other reasons?


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RE: JD 115 Riding Mower

Your choices are the fuel pump or carb. Nikki or Walbro carb?


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RE: JD 115 Riding Mower

the carb was clean and the float is the newer plastic non adjustable type. No holes....check it. The mower was used several times and then I went to use it and the flooding began. It sat unused for about three weeks. Nikki carburetor.
mike


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RE: JD 115 Riding Mower

You should be able to note if the carb is letting fuel through. If not, verify that you don't have fuel entering via the pulse line to the pump. An extra length of fuel line may help. It may be a defect or piece of debris at the float valve, plugged vent etc, Look closely at the diagrams to confirm parts are there and how they go together. On a Nikki, if I do repair- I replace the whole plastic assy inside w/ seal or replace the carb itself.


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RE: JD 115 Riding Mower

I will check the pulse line to the pump. Then, I will add some fuel line and try that. If none of this works - I will have to buy a carburetor. Is there a way to check the fuel pressure coming out of the pump? I do have a gauge.
mike


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RE: JD 115 Riding Mower

It was the original problem. I will try a couple of suggestions today and see what happens. Will keep all of the kind people that have answered my ad posted.


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RE: JD 115 Riding Mower

I have not ever seen any published specifications on these fuel pumps regarding PRESSURE. I presume this is because the little pumps are designed with the idea of lifting fuel only a few inches, and therefore need not produce much pressure.
The real concern regarding a fuel pump's performance is how much VOLUME of fuel it can move.
Generally, the technique used by many members here is to disconnect the fuel delivery hose (that leads from pump to carb) at the pump and replace it with a longer length of hose. Place the open end of the hose into a clear plastic beverage bottle and crank the engine. You should observe spurts of fuel jetting from the hose with each pulse of the pump. 10 to 15 seconds of crank time should deliver at least 1/2 ounce of fuel into the catch bottle.

From your description I really doubt the fuel pump being the culprit as these pumps are simply not capable of producing enough pressure to unseat the needle valve if the float and needle are working correctly.
Couple of other things I thought about. You did not perhaps lose the coiled spring out of the carb bowl during your initial disassembly, did you? That spring presses the center of the plastic fuel transfer tube against the convoluted sealing O-ring. Without this spring the transfer tube will not seal against the O-ring. And the O-ring itself.........is it new and installed correctly?


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RE: JD 115 Riding Mower

I modified your idea and pinched the fuel line with vise grips.....I adjusted the vise grip until the engine was running fine.
Also, I have looked at the diagram with a magnifying glass and it does not show a spring inside the carburetor - at least; not inside where the bowl, needle, cut off solenoid, etc..... is. I am going to extend the fuel line next; it might do the trick.
Mike


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RE: JD 115 Riding Mower

I should have been more specific. The theory on the extra length of fuel line is merely to pull the pump away from the engine, put in a longer piece of line for the pulse line fashioned in a single loop. That way you can easily see if the pump is feeding fuel into the engine.Your single cylinder version is easier to see due to the length of pulse line it has anyways. It sounds like your engine is flooding rather quickly, so hopefully you have been able confirm the source. If you couldn't confirm the carb overflowing by looking down in through the air filter , remove the elbow and it will become more apparent. The spring that Mownie was referring to is not shown on the diagram, but was likely there. It is real fine and easy to bounce itself into oblivion if you don't know it is supposed to be present.


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RE: JD 115 Riding Mower

Spring as shown.


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RE: JD 115 Riding Mower

OKAY....I guess I have a SPRING problem instead of a fuel pump problem. I will try to find me one.....
You guys are great and have taught me a few things already. I hope that I can help someone in the future.
Mike


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RE: JD 115 Riding Mower

Briggs part number for spring is 695422.


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RE: JD 115 Riding Mower

Got the spring...installed it - no change. Added a 3' hose - no change - changed the fuel pump - no change.
I pinched the line with a vise grip and turned it until it ran fine.....and it does.....
I guess that I have a float issue.....I will take it out and submerge it under fuel for a long time....will let you know....
Miguel


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RE: JD 115 Riding Mower

It seems as though you may need to take a step back to work through this problem. Confirm that the carb is overflowing here. It seems from your description that would be the case. Yes, possible that your float is leaking however not very likely. Had you confirmed the passages- especially the vent is not plugged? The vent hole is visible where the elbow attaches from the filter box. I know shops that won't service a Nikki carb on these- they just replace it. Much of the time I do as well. To service this carb, the proper way is to replace the plastic guts and the seals. Think of what would happen if the top plate does to mate to the seal above. Cost wise, determine if the difference is worth it to you or should you replace then carb if it is the culprit. BTW,the extra hose I referred to was a test method and not designed to bring a halt to your issue.


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RE: JD 115 Riding Mower

Okay this is where I am - Besides using it for target practice -
- Changed fuel pumps - no change
- changed carburetors - no change
- pinched the hose with a vise grip from the fuel pump to the carburetor and adjusted the vise grip as needed - runs fairly good
- Pinched the hose before the fuel filter - too difficult to keep running
- Pinched the hose from the rear of the engine to the fuel pump (dont remember the name) - too difficult to keep running
Questions
- The selenoid at the bottom of the carburetor - when activated is supposed to pull away and let the fuel in - Correct?
- The selenoid when disconnected while the motor is running - is supposed to do what? Kill the engine....???
- When I take off the vise grips and let the fuel flow normally; it floods. And, when I disconnect the fuel line; the fuel is flowing quite nicely - I think too much - steady flow - like a water hose - does it supposed to pulsate?
- The line from the back of the engine to the center of the fuel pump supposed to do what?
Sorry for all the troubles but I do enjoy fixing things and tinkering around.....
miguel


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RE: JD 115 Riding Mower

The carb SOLENOID does nothing to control fuel TO the carb.
It controls fuel through the Main Jet.
It has a pin that blocks the Main Jet when OFF and retracts when ON to allow the jet to do its thing.
when the key is turned OFF, the MJ is blocked which is supposed to prevent after fire.

The fuel pump will have-
Inlet hose.
Outlet hose.
Pulse hose. That transmits the fluctuating crankcase pressure to the fuel pump diaphragm.

I have absolutely no idea which engine is on this.


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RE: JD 115 Riding Mower

There is something defective about this carburetor, or something incorrect in the assembly process.
The bottom line here is that the float system, or the needle and seat..........are unable to regulate the fuel level of the carb bowl.
You state that if you pinch off the fuel line going to the carb inlet, the engine will run fine until it depletes the fuel in the bowl.
What you are doing with the pliers is preventing the fuel from continuing to over fill the carb bowl, and in that fashion you are "manually" adjusting the fuel level instead of the float accomplishing that autonomously.
Put a new carburetor on it.


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RE: JD 115 Riding Mower

If you never had children get sick and when they are at the DOC....there is nothing wrong with them.....
I was telling a friend about my problem (he has a lawn business) - turned the key - it started right up. I waited for it to act up and you know the answer.....I do not know what I did or what was the problem. I even mowed part of my yard to see....she is running fine....I called it "Gremlins". Thanks for all your advice...I have learned a few things from you guys....keep up the great work and help to us out here......miguel


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