Craftsman Rider dies

[Roccus]

Have a small craftsman riding mower with a problem that is beyond me....

Problem: It runs for 10 or 15 minutes then stops running then it wont start. I let it sit for 15 or 20 minutes and it will strat but will only run for another 10 or 15 minutes then stops running

What I did to try to fix? I had thought it must be the coil going bad seemed when it warms up it quits, sits for a bit cools down and it will start again. So I replaced the coil and spark plug still same problem so I turned my attention to the fuel system. Next time it quit I looked at the fuel filter and it was empty. I thought ok must be fuel tank outlet, fuel line plugged, or vent for tank plugged. I drained tank (it looked clean inside tank bottom). I ran a wire down the tank outlet then blew air through the fuel line into the tank. I also thought it may be a vent problem just to be sure I drilled a small hole in the tank cap and put a new fuel filter on. I then put new gas back in and disconnected the fuel line from the carb. Fuel flowed through the fuel line and filter, flow looked good so reattached the fuel line to carb started it up and could see fuel in the filter was dropping, looked like it was sucking gas faster than the fuel from the tank refilled the filter. Sure enough the filter emptied and the motor stopped. Once again I disconnected the fuel line from the carb and gas immediately came pouring out. So no signs of anything plugged.

I thought about this and thought maybe a vent in the carb is plugged and stopping the flow of gas from the tank. So I put a brand new carb on, lower the fuel line to let the filter fill and connected it back to the carb. But this did not help once the fuel filter got empty it died. So I have been through the electrical with new coil, spark plug and fuel system with new carb, fuel filter, blowing fuel line out all the way from just before fuel filter into tank, made sure tank is venting, and verified fuel moves freely through gas line and fuel filter by disconnecting fuel line from carb.

I don't have a clue what else I can do and why fuel does not flow through the line when connected to the carb. After the fuel filter empties out and it dies, by letting it sit fuel drips very slowly from the tank into the filter and it will start till the fuel filter is empty. Any ideas?

 

[Ocean909]

The pros are gonna need your model type and code of your engine and the model # of your rider to really help.

In the meantime, what happens if you delete the fuel filter? Can you replace it with a shut off valve to see how it runs then.

 

[sgkent]

Many engines have a convoluted fuel pump system that is not obvious. They aren't purely gravity fed. Often it is a diaphragm that is part of the carb system which has a flap that helps pump fuel, and that system depends on crankcase pressure differentials. Some engines have a dedicated fuel pump. When there is a fuel shortage, that is one of the first places I look. Bad hoses, debris in the tank or line, all can contribute to a fuel issue. I would start by looking up the engine pictorial and studying it to see if there is a dedicated fuel pump, and I would rebuild the carb and all the diaphragms that go with it, using OEM or factory parts. Good luck. One thing for sure, no one here can put their head to their computer screen and tell you what the defective part is. They can only offer you suggestions and point to common issues.

 

[Bertrrr]

Is this a gravity fed carb ? If not you have a fuel pump in the system and needs to be swapped out, you've done everything I would have - Diaphram fuel pumps go out periodically - basically 2 check valves that can get trash in the seat of one or the other and no flow - I keep an electric fuel pump on hand to help trouble shoot these problems - if it runs with the electric pump it will help you find the problem , I had a similar issue and ended up finding my supply side fuel line was sucking air

 

[StarTech]

Let's start with the basics first. When it shuts down do you have spark or fuel issue?

Yes there is multiple things that can cause the problem so it is a process of eliminating possible causes first to get to the root cause. I have see thing from failing spark plugs to fuel lines collapsing among other things like carburetor problems and remote electrical issues. It can even be a combination of problems.

It does sounds like an ignition coil problem but may just be a mouse bed under the engine shroud blocking air flow. But I have seen fuel collapsing to cause the same symptoms.

Just recently went thru a problem where the customer had set his mower on fire. After I repair the known problems the mower came back a week later with more problems. This time there were multiple causes. One was the fuel he was using as it was destroying the new fuel pumps and then it had fuel line liners collapsing. The fuel issue I believe was the E15 he was getting so had him switch suppliers. The fuel line issue I believe was caused by the initial fire issue he had. I lost two brand new fuel pumps before I found the E15 problem.

 

[Roccus]

Is this a gravity fed carb ? If not you have a fuel pump in the system and needs to be swapped out, you've done everything I would have - Diaphram fuel pumps go out periodically - basically 2 check valves that can get trash in the seat of one or the other and no flow - I keep an electric fuel pump on hand to help trouble shoot these problems - if it runs with the electric pump it will help you find the problem , I had a similar issue and ended up finding my supply side fuel line was sucking air

The fuel line comes out the bottom of the fuel tank outlet then there is a fuel filter then the line goes strait into the carb, so I would say this is a gravity fed carb....

 

[Bertrrr]

Well the Needle / Seat in the carb bowl controls the fuel input, Maybe the float is sticking in the UP position not allowing fuel to flow- I know you swapped the carb but the problem still exists so I'd pull the carb and check the float assembly anyway

 

[Roccus]

Let's start with the basics first. When it shuts down do you have spark or fuel issue?

Yes there is multiple things that can cause the problem so it is a process of eliminating possible causes first to get to the root cause. I have see thing from failing spark plugs to fuel lines collapsing among other things like carburetor problems and remote electrical issues. It can even be a combination of problems.

It does sounds like an ignition coil problem but may just be a mouse bed under the engine shroud blocking air flow. But I have seen fuel collapsing to cause the same symptoms.

Just recently went thru a problem where the customer had set his mower on fire. After I repair the known problems the mower came back a week later with more problems. This time there were multiple causes. One was the fuel he was using as it was destroying the new fuel pumps and then it had fuel line liners collapsing. The fuel issue I believe was the E15 he was getting so had him switch suppliers. The fuel line issue I believe was caused by the initial fire issue he had. I lost two brand new fuel pumps before I found the E15 problem.

It is for sure a fuel problem if you read the original post you can see I had said brand new coil brand new plug when it shuts down still have spark I have narrowed it down to a fuel flow problem I don't see the fuel running into the fuel filter but if I pull the fuel line off the carb, ( that is after the fuel filter) gas pours out of the fuel line as it should. The carb is brand new I just bought it but same problem as the old carb haf so it was not the carb... What is E 15?

 

[Ocean909]

Is your fuel filter one of those paper filters that amazon sells at 15 for 9 bucks? If it were me, I would have no obstruction between the fuel tank and carb and see what happens. It could be as simple as a crappy fuel filter.

 

[Roccus]

Is your fuel filter one of those paper filters that amazon sells at 15 for 9 bucks? If it were me, I would have no obstruction between the fuel tank and carb and see what happens. It could be as simple as a crappy fuel filter.

It's one of those clear generic ones I got from the parts store. I don't think it is the filter as when I disconnect the fuel line from the carb gas pours out no problem, With the old carb I thought maybe there is a vent for the float bowel that may be plugged and could be why gas wont flow. They wanted $55 for a rebuild kit but a brand new complete one was $35 so that is what I got. The carb is exact identical to the one I took off except the electric gas shut off solenoid was a bit to long to clear a belt pully from the motor to the transmission. So I took the one off the original carb and before I put it on cut the valve seat on the solenoid to eliminate that as a potential problem figuring I will just put an inline shut off valve. It's really strange after I put the new carb on I tested the machine out I let it run for near 1/2 hour in the shop and it just purred like a kitten I thought that was good as it would not run for more than 15 before. I then mowed my who;e yard with it I have about an acre and a half of law to mow and it ran good. I did notice the the fuel filter never completely filled however but hey it ran and was able to do my lawn so I call friend and told him it was all set. He came picked it up, took it home and 15 minutes later it quit..... so back to square one doing the same thing it was doing before I did anything to it. Seems I always get myself into messes and screwing myself when ever I try to help someone.