18HP Twin Vanguard, Horizontal shaft motor. Uneven surging issue

[XTwarrior1985]

I have a Cub Cadet 2166 I got from an auction for a steal. I am getting it in running order, and at this point it is running, cutting, and moving well. I do however have an odd motor issue.

The motor seems to have a 'miss' at any RPM. This miss is accompanied with a momentary loss of power. Whenever the motor requires more fuel (going up a hill, engaging the mower deck PTO) the miss/loss of power is more noticeable. Sometimes, this miss goes completely away after the motor warms up. Other times, like today, the miss stays when the motor is completely warm. This miss also seems to not have a set pattern, meaning it might go 5 second for one, then 10 for the next, then 7 for the next, etc. I have a video showing it clearly, but I need to find a site that will let me host the 35 second clip/MB size. EDIT: Uploaded it to my Youtube channel, if this is allowed. It is just a clip of the mower running:

At first I thought it was the carb, but the thing starts fine, and when the miss goes away, the motor throttles up and down with no issues. I then noticed today that the in-line fuel filter was basically empty. I have used various in-line filters, so I know they can work fine with some air in the bulb, but this was next to nothing in the filter. The fuel runs from under the frame, up next to the engine, and then to the top where it enters the fuel pump.

Anyone run into this before?

 

[XTwarrior1985]

So I went ahead and disconnected the fuel line from the in line filter to the fuel pump. I poured some fresh gas into a small container and ran the motor on that. The motor ran the same with the same miss, so I'm thinking maybe fuel pump.

At the same time, when I disconnected the line and placed it in the container, some black material, probably line varnish, came out and settled on the bottom. I went ahead and ordered 10 feet of 30R14 carb line with a new fuel filter and B&S fuel pump. I'll replace everything between the fuel tank and the carb.

 

[Scrubcadet10]

i think you're on the right track

 

[bertsmobile1]

That is an old mower so those fuel lines are probably well past their replacement dates
Take the carb off,pull it down and give it a good clean
Check that the fule solenoid is working properly and if it is then pull the kill wires off the coils and see it that ends the problem.
At that age you get chaffing of the kill wires that can give a similar sort of random surging
When I get one of these to diagnose , Ir remove the hood then fir a pair of red in line spark testers so I can see them when mowing and do a test mow after dark ( so I can see the red flashes )
When running full speed they should glow constant red
If they flash as the engine surges then I know it is a coil problem so then I disconnect the kill wires to see if it is the coils or the wiring.
A bit of a job but as you know it is a big job to get the blower housing off one of these to access the wires so the extra time diagnosing is well worth doing .
When I suspect the fuel supply I run an external fuel tank directly to the carb, directly to the fuel filter then directly to the fuel pump.
The mechanical fuel pumps are very reliable but they do wear out so when buggered I do an impulse pump conversion as was done on the latter models

 

[XTwarrior1985]

i think you're on the right track

That is an old mower so those fuel lines are probably well past their replacement dates
Take the carb off,pull it down and give it a good clean
Check that the fule solenoid is working properly and if it is then pull the kill wires off the coils and see it that ends the problem.
At that age you get chaffing of the kill wires that can give a similar sort of random surging
When I get one of these to diagnose , Ir remove the hood then fir a pair of red in line spark testers so I can see them when mowing and do a test mow after dark ( so I can see the red flashes )
When running full speed they should glow constant red
If they flash as the engine surges then I know it is a coil problem so then I disconnect the kill wires to see if it is the coils or the wiring.
A bit of a job but as you know it is a big job to get the blower housing off one of these to access the wires so the extra time diagnosing is well worth doing .
When I suspect the fuel supply I run an external fuel tank directly to the carb, directly to the fuel filter then directly to the fuel pump.
The mechanical fuel pumps are very reliable but they do wear out so when buggered I do an impulse pump conversion as was done on the latter models

Thanks for the info and tips!

The mower sat for a bit before the auction, based on some of the way the dirt and the tires looked. The lines being done in makes a lot of sense, it doesn't look like they were ever replaced.

For the carb cleaner, can I just use spray can carb/choke cleaner? I usually have CRC brand stuff on hand. I'll admit to not being good with carbs, but a simple remove and clean can't be that hard.

For the fuel solenoid, I am not sure my mower has one? I checked the Cub Cadets parts diagram and did not see one in the tank or in line. https://www.partstree.com/models/2166-13a-214g100-cub-cadet-garden-tractor All I have is the black and round fuel pump on the side of the engine. My Motor is the B&S Vanguard 18, which seems like it was not original. Everything I find points me at a Kohler motor.

I do have a spark plug in-line tester I will test with.

 

[Scrubcadet10]

Yep, you can use spray can carb/choke cleaner.
The fuel solenoid will be on the Carburetor bowl, if it has one. The proper name is "anti afterfire valve". There is a rubber plunger on the solenoid that when the key is in the off position (you turn the mower off) it blocks the main jet passage to prevent that big B A N G, if raw fuel gets drawn into the engine and passed into the muffler/exhaust as the engine is winding down.

 

[XTwarrior1985]

Yep, you can use spray can carb/choke cleaner.
The fuel solenoid will be on the Carburetor bowl, if it has one. The proper name is "anti afterfire valve". There is a rubber plunger on the solenoid that when the key is in the off position (you turn the mower off) it blocks the main jet passage to prevent that big B A N G, if raw fuel gets drawn into the engine and passed into the muffler/exhaust as the engine is winding down.

Ahh ok, the mechanic I had this with when I brought it home from the Auction actually disabled this. At the time of the Auction the mower ran only on Starting fluid. He said as soon as he disabled this, the mower ran on it's own fuel. Could this being disconnected cause this surging maybe?

EDIT - Found a cleaning video, might try this when I replace the lines and Fuel pump.

Or I will just make a delete screw to go into the carb

 

[Scrubcadet10]

When there is no power to the solenoid (unplugged) it is in the state of blocking fuel. If they fail and the customer doesn't want them replaced, i just cut or grind the plunger off flush with the top of the threads and screw it back in.
and i wrap the + wire up in electrical tape and fold it up out of the way on the mower.

 

[bertsmobile1]

The solenoids very rarely fail
The just get gummed up
You spray them with your CRC then work the plunger in and out till it all evaporates and repeat till the needle clicks back when pressed down
The carb will need an ultrasonic bath clean or a boil with a couple of dish washer tablets Plain powder does not work as good to remove the built up varnish , tar, gum
Outdoorpowerinfo.com has detailed photo instructions on pulling down your carb

 

[StarTech]

Or just clean those the fuel solenoids in USC.