MTD tractor..

[howie2112]

Hey everyone.

I'm slightly frustrated right now, but i'm hoping you guys can help me out. You have done so many times in the past.

Ok, I have an older MTD tractor...with a 14HP briggs engine in it. Its not a Cub, but this is a tractor i'm fixing up for someone. My Cub actually runs pretty dang good right now.

Point is, lol, that the thing would only run with the choke. It sat for 10 years, so I figured it needed a good carb cleaning. So i did that, and voila, now it doesn't start.

Well it starts and runs, but apparently only with the fuel in the fuel bowl. If i let it fill it will run until its out. I've disassembled it now three times and each time nothing new.

The thing is, it ran fine just yesterday, only with the choke.

The flow to the carb is good, fuel filter new, etc, air cleaner new. This has got me stumped. If i pour gas in the carb it runs until its gone.

This has a fuel pump of some sort, i believe i read its a vacuum pressure or something like that.

Any ideas?
Thanks guys. I do appreciate you reading the long read.

[howie2112]

i'm sitting here trying to think of reasons why it does it. Maybe the float isn't allowing fuel to flow in fast enough? But why....maybe the fuel pump? But i thought that with this vacuum type thing that there's nothing really to go wrong because it uses crankcase pressure?

[LarryW]

There is a diaphragm in the pump that could go bad. Have you tried gravity feeding fuel right to the carb maybe? Is the float adjusted right? Is the fuel line clear of debri or maybe where it enters the carb before the needle valve? Try taking the bowl of if possible and working the float manually and check fuel flow. Just ideas.

[truckntran]

Are there any wires or electrical connectors on the carb? Some MTD's have a solenoid on the main jet that must be energized for them to run.

[howie2112]

hey everyone,
thanks alot for responding, i truly appreciate the help.

LarryW-
yeah actually i took the carb apart today and cleaned it pretty darn well. there was alot of gunk in there, which is why (i assume) i needed the choke to run it yesterday. the float seemed to be operating correctly. its funny you mention gravity feed though. when i held the fuel tank above the carb, gas flowed into the bowl just fine. and when i attached the carb and held the tank above and allowed gas to flow in, it seemed to start and run until the gas was gone, and the tank was below the carb. in fact, one time i let the bowl fully fill up, and i even took a lap around the house with it until it sputtered and died. but when it died the fuel tank was below the carb since i couldn't hold it up and drive the tractor. in fact, for a few seconds there it was running pretty dang well, it idled (something it hadn't done) and i could run it without the choke. but once that fuel supply went, it was done.

also you mentioned using the float manually. i thought of this, but this is one of those carbs that are in two pieces in the sense that i couldn't manually operate the float, since the float is on the top of the carb and the bowl and fuel inlet are on the bottom, if that makes sense. i'm not good at explaining lol but its along those lines. there might be a way, i just couldn't figure it out today.

truckntran-
nope, no wires going to the carb at all.

i'm beginning to think its a problem with the pump. i'm just surprised that it could go bad overnight, but i guess thats how things happen. i'm going to take another look tomorrow, and probably order a pump rebuild kit this week sometime.

EDIT-
just thought of something. to test the fuel pump, maybe i could take the top of the carb off, which has the float, but leave the bottom connected to the vacuum line and the fuel line, and crank the engine over and see if gas comes out of where its supposed to. like i said, gas flows fine when i held the tank above, so i'm guessing there aren't clogs. but if the pump is operating properly, then gas should come out when i crank the engine as well.
its one of these carbs:
http://outdoorpowerinfo.com/repairs/..._twin_carb.asp

[ol'George]

I have a little experience with those combo carb/pumps.
I would say that indeed you are not pumping fuel.
Possibly a diaphragm got damaged or a gasket is torn.
I'm remembering on one I worked on, a little spring
got lost/forgotten and I had to re do it as it would not pump.
I would do a little more online searching for a diagram on the assy of the pump part of that carb.
also make sure nothing is under the little check valves or it will not pump.
Check to make sure the vacuum line to the block is good and not old/cracked/split

[howie2112]

hey everyone.

so, i went outside today and took it all apart again and put it back together. in the process, i lost one of those little springs. lol. but i'm going to get one of those rebuild kits and replace everything in the pump.

however, i went to start it up to see if it worked, and it actually worked. i'm surprised, because one, its missing a spring, and two, yesterday it didn't do this. it just started right up like nothing even happened.

so i don't know what happened yesterday. all i know is i'm getting a kit and rebuilding it properly, altho part of me says just leave it alone...

anyway, ol'George, i checked and nothing was torn, altho i am going to change the vacuum line when i rebuild the pump.

Thanks everyone, you've been very helpful to me this time and many times before. I'll be sure to come back with any more problems! Lol. Hopefully not many more...

Also, thanks mods for moving this to General Talk, i apologize i posted it in the wrong section, i just wasn't sure where to put it.