2005 yamaha f40 problems

alex88 · May-01-2007, 09:47 PM

it all started with a bottle of fuel system cleaner. now it runs like straight crap. idles real rough. dies so i had to increase the rpm's to prevent that. bogs and hesitates(sp)? when i give it gas. read that i could have clogged jets so i took the carbs aprt and cleaned them completely. changed plugs. same problem. anyone have any ideas. i really cant afford to take it in right now.

Honda Dude · May-01-2007, 10:07 PM

It really sounds like you have clogged jets. You say you cleaned the carbs, but, and no offense intended, do you really know what you are doing? If you missed a jet or two, and there are a lot of them, then you didn't really clean out the carbs.

Check your gauge, does it show an overheat signal or low oil pressure? If you get overheat/low oil pressure (even if it is a false signal) the computer will retard the timing and cuase the engine to run rough/shutdown. If you post more info, I'll try to help.

Also, you may want to go back to basics: check compression, if OK, check spark: if spark on all cylinders, then..... carbs.

alex88 · May-01-2007, 10:21 PM

well ive never messed with a boat carb before, but i work on my quad's ll the time. there are 3 carbs on it and i took the bowl off and cleaned there, and then took the top plate off and there were all kinds of channels and shit in there and cleaned there, didnt look like there was any other spot for a jet to hide. and i dont have ny gages just the control box. and it never buzzes.

KruzCan · May-01-2007, 11:33 PM

How do your filters look? I had an issue with shitty gas and it fucked my whole fuel system. Carb., fuel separator etc.

bigbrownbuku · May-01-2007, 11:43 PM

those carbs have to be re-balanced. you cant pull 4s carbs and just put them back on. in all likeliehood you did a great job cleaning them and now they arent balanced. unless you have a set of 4 balance guages or know someone that will lend them out, you have to take it in. the good news is any tech worth his salt will have them balanced in about 30 minutes. unless you didnt do such a flash job cleaning them.

Jan from Humbol · May-02-2007, 01:49 AM

E 10 fuel strikes again.

Did you find a bunch of white stuff in the bowls? My 40 hates E10 fuel.

Install a ten micron water fuel seperating filter (I use a Raycor) and start using Star Tron and ring free at 1 oz per ten gallons.

E10 fuel cleans all the crap out of your fuel system and sends it towards the engine so if you have an older boat it could get ugly the other issue is the alcohol attracts moisture which in turn attacks the insides of the carbs hence the white shit which is an oxide. You also need different jets to handle the E10 fuel.

alex88 · May-02-2007, 09:45 AM

no white shit just a lot of brown looking fuel inside the top covers. and i changed the fuel filter out yesterday too. but when this shit first started i dumped the whole tank and there was all kinds of floaters and crap in the tank where it used to be stuck to the sides.

alex88 · May-02-2007, 09:51 AM

got it, took the carbs apart again this morning. found the jet i missed yesterday under a rubber plug. thanks for all the help.