# Murray Lawnmower Problem



## BamaPop (Oct 7, 2008)

I've been trying to get a Murray riding lawnmower going. The gas lines had melted on the inside and some of the melted rubber got into the carb. So I cleaned it real good blowing every hole with the air compressor. Put the carb back on the mower pour a little gas in it and it cranked right up, then died. Repeated several times with the same results (what is the definition of an idiot?). It would never stay running and there is never any gas in the bowl. I happen to check the oil and it seems that's where my gas has been going, in the oil. This is a Brigs Diamond 19hp with the carb on the front. It has the gas line coming into a little diaphram pump and a hose going to the block. I am figuring the gas has been coming into the pump and then going down the hose to the block but why. Has anyone got a cure for this?
Thanks, Gary


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## K-B (Oct 24, 2005)

Sounds like the carb is in dire need of a rebuild, at minimum a new needle valve and possibly a float. It sounds to me like the inlet needle valve is either sticking, damaged/worn or has dirt on the tip, not allowing it to close and shut the gas off, hence the gas overflowing into the crankcase.


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## MrChooks (Apr 19, 2008)

Agree with KB - you almost certainly have a float / needle valve & seat problem. 

When these fail / stick open they allow fuel to flow unchecked into the fuel bowl - flooding the engine then to flow into the engine block.

See if you can get a float needle and seat valve kit and replace and reset and see how you go.


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## Volt-Schwibe (Jan 12, 2003)

he had previously stated that the bowl which contains the float is always empty, so i'm not thinking it's a float/valve problem.

edit: i hadn't read closely enough...

this diaphram, is it torn?


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## MrChooks (Apr 19, 2008)

Volt-Schwibe has a good point regarding the diaphragm - and I didn't read the post properly- re "empty fuel bowl" - many apologies.

If the engine has a mechanical diaphragm fuel pump (like the ones fitted to cars) then a tear in the diaphragm will certainly screw up fuel delivery to the carb and will likely allow fuel to drain into the sump / block.

So you will need to fix any damage to the fuel pump diaphragm 1st. Then once that is fixed you can check that you are getting proper fuel flow to the carb bowl.


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## BamaPop (Oct 7, 2008)

There is not a tear in the diaphram. It all looks ok. If your facing the carb the pump is about 2 inches by 1-1/4 by 1/2 inch thick plastic with the membrane on both side of that with a spring & cap for the spring under the membrane the fuel line comes in from the bottom and the line that goes to the block comes out on the left side of the plastic piece. The spring and that setup is just like on an old auto carb.
I probably need to buy a rebuild kit I was just trying to do it on the cheap.
Thanks for the replies.
(Be on the watch out I'm fixin' to do an old style lawnmower carb with the bowl that's on an old Trojan (I think that's right) chipper. This thing stands about 4' tall. Runs good the carb is just leaking like a sieve.)


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## MrChooks (Apr 19, 2008)

:wave:BamaPop
OK I am not familiar with that particular fuel pump - but something has to be stopping the fuel getting to the carb bowl - it should be about 1/2+ full all the time. So am guessing the fuel pump is suspect. Before you go out and buy a whole heap of parts (& to help doing the job cheap) - see if you can try this:

With fuel in the tank and the plugs out of the engine (so it turns over easily) - disconnect the fuel inlet line from the carb and see if any fuel flows yes?? / no??.

Then try turning over the engine for a bit - if the fuel pump is working it should pick up fuel from its delivery line and squirt it thru the carb fuel delivery line. See if you collect about 1/2 cup full with a few attempts. If yes - then fuel pump may be OK so I would then look very closely at a jambed needle & seat valve.

To check - reconnect the carb fuel line - take the fuel bowl off and give the engine a few turn overs - With the float all the way down - the fuel pump should pump fuel thru the float needle valve. again - see if you can get about 1/2 cup to flow thru - It goes without saying - THESE ARE NO SMOKING JOBS!!:4-thatsba

If you can get fuel to flow to the carb bowl - reassemble and see if it will run as sometimes if you are lucky, this exercising the float / needle and seat can free it up.

If not - then you will at least know where the issue is likely to be and what parts you actually "must have"

Hope this helps


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## k2skier (Sep 30, 2008)

If your fuel pump has 3 screws holding it together you need a carb kit # 694056, if it has 4 screws you need # 693503, both have fuel pumps in the carb kits. From how you described the fuel pump I 'm sure it has 3 screws and uses 694056. Have fun getting all those part lined up, especially those 2 little springs:grin:


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