Help. Engine will only start with full choke then lags

[Rensmith]

When starting my 2005 ranger, it will crank but only catch if the choke is full on. I can adjust it down a bit, but if I take the choke off it dies. I changed the spark plug and it seemed to help for a while, but the problem has returned. Spark plug was really black. Put in a new plug and after a couple of weeks it too had lots of black carbon. It is possible there is water in the gas/engine. (my gas cap broke and the plastic dome is missing - we have had some rain and get a lot of dew at night - maybe dripping water into tank?) I drained the gas and replaced with high test, and also added some water remover to the gas. Still having problem. I changed the fuel filter. Same problem. Help! Any suggestions Ren

[ALAG3]

You could still have some water in the carb. To get this out, take out the air filter, rev the motor pretty high, then close off the carb intake with a rag. It will choke the engine down, but it will also force any water in the bowl through the jets. I did this on a 4-wheeler of mine that was running rough and it fixed the problem.
But I gotta say, if it will only run on full choke, I'm thinking the carb may have a clogged jet. Might be time to pull it off the bike and go through it. They are simple enough that with basic mechanic skills, you could disassemble, clean and reassemble the carb. Good luck!

[Z71]

The choke on could be reason for the black plugs.

Is this SxS used in frequently where condensation can be forming in the fuel system? Then if so, your carb make be gummed up and needs a thorough cleaning.

I know I am hawking a product I sell but AMSOIL recently came out with a fuel system cleaner for small engines that is pretty darn good. I have sold a few bottles to local boater and got some very good comments about it. One of my riding pals has a 2001 Polaris 500 that he was having trouble starting after letting is sit since last fall with the same fuel in it. He says it cured his problems.

I am not guaranteeing your problem is fuel but according to a local repair shop, they are seeing a lot of problems with fuel because of the ethanol being blended in just about all fuels. The problem is really bad with boats, he has taken apart carbs on the outboards to find lots of gunk in them after sitting for as little as a week or two with ethanol blended fuels. He said they are having so much problems at the local Marina that they are spec'ing bids for fuel must not contain ethanol and they have no one who can supply the because its Michigan law, all fuel has to the at least 10% ethanol. Ethanol in fuel has a tendency to absorb water and separate from the gasoline, sinking to the bottom of the gas tank, where it quickly degrades and creates gum, varnish and other insoluble debris that can plug fuel flow passages and negatively affect engine performance.

Here is a link to the product ---->Quickshot SE.




See if some atv's etc are not operated in a similar fashion the boats..

Reasons Boat Engines Have More Problems with Ethanol Gas:

Boaters, often store gas in tanks longer than recommended for E10 (90 days).
Cars, unlike boats, usually replace fuel every week or two, which will successfully prevent the possibility of water-contamination/phase separation.

Boat engines live in a water environment - Alcohol gas loves to absorb water.
Ethanol E10 gas can absorb large amounts of water into the fuel tank, MTBE in conventional gasoline did not.