3165 with fuel starvation

[tuxedoman]

Well you’ll be happy to know I got my cub back. It took some wrangling but it is happily now in my possession. I see it’s been a year since I’ve been back so I guess it’s time. You folks have had a big hand in keeping this old tractor Running. Now I have a new problem.--

I bought good old cub model 3165 back in the year 2000. It was two or three years old at that time. It has served me greatly. I’ve had many problems over the years but I have always been able to resolve them, but this one I’m not so sure. On a hot day when the engine is in full throttle and I’m mowing the grass the engine begins to sputter. Almost sounds as though the fuel is too rich. It coughs and chokes a couple of times and then it just quits. Also worth noting this usually happens when the tractor is leaning slightly to the right, I am usually able to start it back up for a few minutes and this gives me time to Park it because what happens next is it just plain dies. It also kind of sputters a bit when you Hi, my name is Jeff. I bought good old cub model 3165 back in the year 2000. It was two or three years old at that time. It has served me greatly. I’ve had many problems over the years but I have always been able to resolve them, but this one I’m not so sure. Hot day when the engine is in full throttle and I’m mowing the grass the engine begins to sputter. Almost sounds as though the fuel is too rich. It coughs and chokes a couple of times and then it just quits. I am usually able to start it back up for a few minutes and this gives me time to Park it because what happens next is it just plain dies. After an hour or so it’s usually OK for another 20 minutes or so. I have sprayed carburetor cleaner down the throttle, I have replaced the fuel pump, and I have replaced the fuel filter. If you try to start it after this little episode it’ll just turn over again and again and again with no signs of starting. Let it rest for an hour or so and it usually starts right up again. It be great if somebody had an idea what this might be being caused by. I’ll wait to hear from you guys.--
It also happens if you put a load on the engine when it is acting up. After an hour or so it’s usually OK for another 20 minutes or so. I have sprayed carburetor cleaner down the throttle, I have replaced the fuel pump, and I have replaced the fuel filter. If you try to start it after this little episode it’ll just turn over again and again and again with no signs of starting. Let it rest for an hour or so and it usually starts right up again.
This has done this for the last 8-10 years, but getting to frequent to ignore. I thought it might be a vapor lock???
It be great if somebody had an idea what this might be being caused by. Thanks Jeff I’ll wait to hear from you guys.--
Thanks Jeff

[bugeye]

My tractors are different, but maybe similar.

I have had the problem you described. Fuel starvation under load or when on a slope.

If the fuel tank is full and the cap vented and the fuel system clean and pump working, the engine should run unless an electrical spark problem. When the engine will not start, disconnect fuel tube from the carburetor and crank engine. Capture fuel pumped in a container. Think safety with gas around a hot engine. Fuel should flow as engine is cranked.

I changed the fuel pump with a generic sourced on evil pay or amazon. When I took apart the old fuel pump, the rubber diaphragm check valves were shot with wear.

Also check for debris in the fuel tank shutoff valves.

[Oak]

If you don't have a fuel problem it's probably a spark problem.

There are 2 diodes that isolate the ignition coils. When 1 or both of them fail it will do all kind of strange things with the spark. I had 1 fail on my 3165 and replaced them with these. The Radio Shack part number is 276-1114. These are rated at 1.5 amps/1000 volt and cost around $3.
Mag kill wire - Copy.jpg

Another problem that could exist is your ignition coils could be failing and they are located behind the flywheel if they need replaced.
DSCN1241 - Copy.jpg

I would also check your ignition switch to see if it is failing. My 3165 did that a few years ago and it was acting up like yours. Unplug it and see if the plug is corroded or has any heat damage on any of the terminals.

Good luck and let us know how you make out.

[tuxedoman]

Oh my, don’t mean to seem like a dummy but when you say the ignition switch do you mean where the key is located?

[dieselbob69]

Looking at parts diagrams, doesn't look like this tractor has fuel shut off valve off tank like my 1864 does. Cheapest thing to do is decrease air pressure on regulator of compressor and take the fuel feed line off fuel filter(one that comes from tank), leave gas cap tight, and blow some air into that line gently to see if you can hear air come out of gas cap.Should be a pinhole on top of cap-if you can hear or feel air come out of that hole,cap is ok. Next step is replace the fuel line-your line may be degrading from the inside and getting spongy, collapses when it gets hot and restricts the fuel. Should be either 1/4" or 5/16" fuel line-go to a Napa or similar store and buy some(take a ruler and try to measure all fuel line you see) -runs between $1.50-$2 per foot, just make sure you get enough. I've been looking up parts on Shanks Lawn Equipment site, pretty easy to navigate. Used it to get part#s, and you see what's NLA for your machine....

[Oak]

Originally Posted by tuxedoman

Oh my, don’t mean to seem like a dummy but when you say the ignition switch do you mean where the key is located?

Yes, unplug it from the back and look at the connections checking for any corrosion or signs of heat damage.

Fuel lines are a pain to change but that could also be your problem. You will need to pull the fender pan off (I do) to run a new line.

You may also have a fuel pump issue. For testing you could put one of these in.
https://www.ebay.com/itm/31335418229...oAAOSwl5Bf4gwC

If your fuel cap vent isn't working you can loosen it and try running it that way. Just don't have a full tank of gas sloshing around.

Good luck.

[tuxedoman]

Originally Posted by Oak

Yes, unplug it from the back and look at the connections checking for any corrosion or signs of heat damage.

Fuel lines are a pain to change but that could also be your problem. You will need to pull the fender pan off (I do) to run a new line.

You may also have a fuel pump issue. For testing you could put one of these in.
https://www.ebay.com/itm/31335418229...oAAOSwl5Bf4gwC

If your fuel cap vent isn't working you can loosen it and try running it that way. Just don't have a full tank of gas sloshing around.

Good luck.

No spark or fuel starvation

Well I was able to blow bubbles into the gas tank from behind the fuel filter. Next I looked at the connection behind the ignition key and Shernoff they were corroded terribly. Clean both male and female ends up really good and thought oh this is it! But guess what, it is so I guess now I’m going to try to replace the two diode‘s. If you won going all the way back to the tank was replaced two years ago so I don’t think that’s the problem. Again guys thanks for all your help.

[Ken41]

Originally Posted by Oak

If you don't have a fuel problem it's probably a spark problem.

There are 2 diodes that isolate the ignition coils. When 1 or both of them fail it will do all kind of strange things with the spark. I had 1 fail on my 3165 and replaced them with these. The Radio Shack part number is 276-1114. These are rated at 1.5 amps/1000 volt and cost around $3.
Attachment 108968

Another problem that could exist is your ignition coils could be failing and they are located behind the flywheel if they need replaced.
Attachment 108969

I would also check your ignition switch to see if it is failing. My 3165 did that a few years ago and it was acting up like yours. Unplug it and see if the plug is corroded or has any heat damage on any of the terminals.

Good luck and let us know how you make out.

Couple of questions, are these diodes only on the Briggs engine? And are these diodes in the engine harness?

[Oak]

The diodes are behind the fan shroud. Each coil has its own diode and then they connect together and only one wire exits the shroud.

I'm not 100% sure but I think only the Briggs engines have them.

[ejl6658]

All of the diff lock Kohler Command 3000 series have diodes on the two control lines for the anti backfire solenoid on the carb. The diodes are in the wiring harness behind the flywheel shroud covered by a plastic tube.

https://www.ccpartsnmore.com/cub-cad...ing-schematics