New carb on Big foot

[9.3]

I have a 2000 Bigfoot 18 hp vanguard motor. I purchased a new replacement carb from Argo Adventure and had it installed at dealer. Now the machine continues to surge even when sitting. If you try to hold the throttle to maintain even speed it will rev up then back to normal. It got worse as I tried to get it out of the bush. It worked ok around the yard before I took it. Any ideas?

[Laird]

Surging USUALLY occurs with a dirty carb but as yours is new that shouldn't be the problem. Being changed at the dealers I would have to assume there was a new filter etc. Surging also occurs when there is water present in the fuel. I have heard of surging if the carb springs are not at the right tension. An engine can rev slightly if it is going lean before running out of fuel. This is more common on 2 strokes like chainsaws but my JD rider with a Briggs will rev a little higher just before it runs out of fuel. You may have an issue with the fuel pump, which are known to give problems. And you could have a defective carb or dirt was introduced into the new carb somehow. What was the reason for the carb replacement?

[9.3]

The old carb was pouring gas into the crank case and the dealer could not locate a new needle The old needle had a small crack in the tefelon tip. I could only find a replacement carb that they installed. During the problem with the original carb they replace fuel filter, drained tank, new oil and filters. I thought perhaps it is getting air from a line or from new carb install.

[9.3]

Up date.... I found a rebuild kit from the US and had it installed. Argo works perfect now. The new carb is back in the box. That was a waist of $100.

[Laird]

I am glad a rebuild kit worked for you. Sometimes they work, sometimes they don't. Cheapest kit I could find for my engine was 150 bucks. New original Briggs carb from the Argo dealer was 495. Amazon had one pt.no. 808626 which my engine, 380447, calls for ,for 320 plus tax. Do I spend 150 for non returnable item with no warranty or bite the bullet and bolt on a new carb? If the carb is defective I can return it. Open a carb kit and you own it. I cleaned mine twice, both times through an ultrasonic cleaner, set the carb to run at an idle and high speed. Worked fine for 10 minutes at home. Got back in the swamp and wondered if I could make it home. I had pulled the tank, drained it, cleaned it, new lines, filter, fresh fuel. I am pretty sure the carb is pooched. I guess I will find out. Carb is supposed to be here Sunday.

[msafi65]

If you haven’t replaced your fuel line from tank to carb do it. The line from the pump to carb is usually the first to decompose internally. The little black pieces I find in the carbs are usually fuel line. Many times you never even see the piece causing the problem.

[Laird]

You are totally correct about the fuel line. Ethanol kills fuel systems. Knowing this I ran new line, tank to carb. Carb keeps loading up the cylinders at a low rpm. Works fine at an idle, low to midrange is boggy from excess fuel, midrange to wide open, cleans up. Plugs have black residue like you were running with the choke on which it isn't. If I lean it out for the boggy part, then the top end is boggy from lack of fuel. This is where the FI engines are nice. But then you can run into even more expensive problems and the engines are a lot more pricey to begin with. I can't complain too loud about the repairs. With the purchase of the 23hp, new head gasket for it, a brand new carb and after selling the 16 hp that was in it, I have a grand total of $160 engine wise. The engine came out of a skid steer from a farm unit. I tore the engine down and checked the ring gap, rods and crank. Compression is 170 and 165, has new coils, new fuel pump, valves are adjusted right, so in my mind that leaves the carburator. 90% of small engine problems are fuel related, 80% of fuel related problems are the carb.

[Laird]

Update on the carb situation. Bolted the new carb on, seemed a little better, so headed for the bush. Worked ok but was not super impressed. Went out hunting with a buddy, got back in the swamp ok but coming out... the carb started flooding out severely. This is 7 at night. It is dark, snowing, raining, and we wanted to get out. Ended up pulling the vacum line off the pump, clearing the cylinders and running till the carb ran out of fuel which got us a couple hundred feet. Hook up the vacum hose, fill the carb, pull the hose off, run couple hundred feet. Got home , pulled the carb, got hold of the seller, they sent me a shipping label for the return, and replaced the carb with another new one. This one works really good. Made a big difference. To make matters worse coming out, l had gotten a small doe, shotgun season, which seemed pretty big by the time we got to the argo. And we still had half mile to the truck. Some of the spots on the way in had the argo swimming. My buddy and I are pretty close to 70 so it would have been quite an experience.