cub lowboy no start

mdm1

Member
Location
Onalaska,WI
My Dad has a cub that he uses for his mowing tractor. It has started and run just fine all summer. He went to mow on Sat and it wouldn't start. Turns over just fine good battery. I went with him today and here is what we did. Cleaned points, cap, rotor. Checked spark coming off the cap and at the end of a spark plug wire. Had plenty of spark to start it. Cleaned filter bowl and checked flow out of tank. Was good flow and we had good flow to the carb. One thing was if we tightened the bowl just a little bit no gas would come out of the tank. Loosen the bowl and it flowed great. Took gas cap off and still no start. Held my hand over the air inlet and intake manifold and had good suction. Pulled and checked the carb and it seemed to be clean and the float working. But when we pulled a spark plug it was dry as a bone. So do I pull the carb again and soak it and blow it out. It just appears that no gas is getting pulled into the cylinders. You don't smell or see any sign of gas coming out the exhaust. Any help is greatly appreciated.
 
If the carb is not getting fuel it won't run. so my suggestion is to pull the carb drain (bottom of bowl) and wactch the flow into a clean can. If flow slows and stops within 10 seconds, there is a obstruction in the fuel line. The fact that you needed to let air out of the sediment bowl is an indication that it is reduced or no flow. There is a screen filter where the fuel line attaches to the carb. it is often the actual issue. Jim
 
Oops sorry I did remove the plug at the bottom of the carb and had good flow. The air in the bowl makes a lot sense leading to a blockage.
 
(quoted from post at 14:12:07 10/23/23) Oops sorry I did remove the plug at the bottom of the carb and had good flow. The air in the bowl makes a lot sense leading to a blockage.


What is "good" flow????
 
Size of a pencil. It did come out very good. I am going to pull the carb and bring it home. Should have done that right away. It's at his cabin.
 
When you get it back together hopefully it runs for
you. If not I would pull a couple plugs and dump a
couple of teaspoons of gas in each. Then screw them
back in to see if it fires then. If not you are going to
need to check the timing. Something may have
happened like a pin came out or stripped.
 
U say no fuel comes out when u tighten the bowl. That is
normal when the carb is full of gas. Pull the carb drain
and then see if it flows. Which it will if the line and
screens are clean.and the needle is not stuck closed.
And to check if it is a fuel problem prime it. Either by
squiring some in the cylinders or removing the carb
intake hose and crank it over while misting some gas in
with a spray bottle. The needle is most likely stuck in the
carb not letting fuel in.
 
If you have spark and you obviously have gas it should start and run for at least a few seconds even if gas flow is horrible. The next question is - is the spark hitting at the tight time to combust the
fuel?


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May not be your problem, but here are a couple of issues that can sneak up on you.
* Like Used Red MN says, distributor drive gear pin sheared. Had it happen more than once. Check the timing.
* What I have seen on 154 Lo-Boy is a low battery. After sitting through the winter come spring and it cracks over just fine, but no fire. Put a charger on for 5 minutes and it fires right off.
I concluded it takes very little battery to crank the little C60, but not enough to fire the plugs. Experienced more than once on more than one 154.
You said you have cleaned the points. To verify point function, connect a test light to the distributor terminal and chassis. While cranking, the light should flash brightly on and off. If the light does not go off or only dims, it indicates the points are not making good contact.
 
the inlet on the sediment bowl is probably plugged remove the bowl and blow
with someair should clean it up look it ran in the past so the only thing now
is getting gas to the carb
 
A condenser that is going bad can produce
enough spark to fool you, but not enough
to make a tractor run. We have chased
'carb issues ' for hours. Someone on this
site suggested a condenser, quick swap and
it fired right up
cvphoto165153.jpg

Good napa part numbers on my shop wall.
 
I'd just spray some ether in while cranking if it stats and runs it is fuel if not then electrical. As for the sediment bowl not filling if it is tight that just means that the air can't get out and the gasket is sealing fine. Crack the line at the carb and see if you get fuel there, if not then you found the fuel problem. If so the nit has to be further down stream so to speak.
 
A shot of starter fluid would confirm if it is a carb issue or a stark issue.

When in college a friend rebuilt an Austin Healey 3000. It had spark but it wouldn't run. He Sold it.
The new owner discovered he had the timing wrong. The spark was 360 degrees out.
 
I don't ever use starting fluid, but I have a little bottle with a 1/4 tube coming out, with 50-1 mixed gas in it. I can squirt a little in the throat of a
carburetor to troubleshoot, I can ever run and engine without a functioning carburetor by dribbling just the right amount, it's great for troubleshooting. I use
mixed gas because cranking on a dead engine dries out the cylinders and the oil improves compression.
 
I pulled the carb off today. Opened the fuel shut off and had really good flow from the fuel line to the carb end. The battery is good. I do have a blue streak condenser up there. I had that problem with my 2 AC G's earlier. I didn't mention that because I got beat up pretty good if I mentioned a bad condenser again on a forum. Most of the time that's what the problem was. I'm going to clean the carb and go from there. Again thanks for all the help. Mike
 
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