2004 70 hp hard starting will not idle

[boca-mailman]

Replaced fuel pump which was bad also replaced fuel lines and ball from tank to engine new spark plugs cleaned fuel filter. ran denatured alcohol through carbs and used a carb cleaner. last outing engine started but idled rough ran out to fishing spot ran well. stopped engine and fished after 45 min. went to start engine it would crank but did not start. moved red primer switch on middle carb. engine started and ran back to ramp no problems. Got home would not start without moving red primer to open . today took boat to ramp same story needed to use primer on open position to start engine ...let run at high idle . got to where engine will start with red switch in normal position but will not idle coughs and dies out restarts and will run if throttle advanced but dies when put back to neutural position. . I was told I should rebuild carbs. does that sound right engine has 300 hrs. use. any suggestions ? thanks Vic

[boats.net]

Need to remove and clean carbs.

[boca-mailman]

Thanks for the help is there a procedure to follow for this perhaps online or something and what should I use to clean the carbs . It is something i have never done before but am willing to learn..... Vic

[TownsendsFJR1300]

Thanks for the help is there a procedure to follow for this perhaps online or something and what should I use to clean the carbs . It is something i have never done before but am willing to learn..... Vic

Your best bet is investing in a manual for your engine.

If your mechanically inclined, you can clean the part of the carb(s) that's causing your problem. Pull the carb and remove the float bowl. There should be two brass jets, one larger than the other. The larger is the main jet, the smaller, the idle jet (which is likely your problem). Remove both from the carb body, DON'T just look thru them in the body and leave them.

Once removed, the idle jet sometimes has very, very small holes in THE SIDE OF THE JET that gums up. That MUST BE SPOTLESS when done. The holes are small enough that I've had to use a wire from a wire brush (a needle was too big). Make sure its spotless and you can actually see thru the jet, especially the sides.

Carb cleaner and an air compressor is your friend with these jets. I would NOT use the carb cleaner near any rubber/plastic parts as some products are extremly aggresive. Make sure the float bowl itself is clean of any varnish before re-assembling.

Seafoam or Chevron Tectron make a good product that will help clean the fuel system and keep the fuel from fowling quickly. Untreated fuel will go bad in as quickly as a month...

If you go to a parts website for your engine, it should show a breakdown of your carb and how its assembled (where the jets are, etc) and be a big help.

Re-assembly, sync if necessary, you should be good to go...

Good luck..

[99yam40]

Always do the link and sync after reinstalling the carbs like the manual states, as they do not end up exactly where they were before. Just a little bit off and they are not opening and closing exactly the same.
Make sure you do not swap parts from one carb to the other as some have different size jets on the same motor. And make sure you put the carbs back in the same spot they came from

[boca-mailman]

Thank you guys I appreciate all the help before taking anything apart I will definitley by a service manual, I have been meaning to do that anyway but while it was trouble free it wasn't a priority if you know what I mean. I do regularly use startron in fuel tank. It does claim to treat ethanol enriched gas , but will also put some tectron from here on in. Hope to get to this project soon, But this working for a living get's in the way. hey but at least I still have a job. Merry Christmas to you and a blessed holiday season. Vic
Just FYI I have a 2004 Triumph 170 cc It's a nice ride......

[boca-mailman]

cleaned carbs but have a idle problem 2004 79 hp

Well got a manual removed carbs disassembled and cleaned them. I did not find much in the way of varnish but found corrosion and a powdery substance in float bowls I think it was caused by water in fuel ? any way thoroughly cleaned them. And added a fuel water separator to fuel line, Took boat for a trial today runs great at all speeds but coughs ,sneezes and will stall at idle. Manual refered to pilot screw which on my carbs is covered by what looks like a brass plug which is flush with top of carb body . so I left that alone during cleaning and disassembly, When I reinstalled carbs and ran engine it idled very nicely but had a cough at higher rpms . checked manual and found i missed the sentence that said assembling high speed nozzle small lines of holes were to face port and starboard, I had not done that so I took carbs off and did that ,put things back together and that is when poor idle occurred. I then did the sync of throttle linkage and adjusted idle speed to where it was suppose to be . Thought by running the boat today things would clear up however idle situation has not really changed will sometimes run well at idle for a long period and then will cough shudder and sometimes stall, at all other times engine runs great low speed midrange and wot .I am at a loss as to what to do now. how do you access pilot screw adjustment behind brass plug ? is that what I need to do ? There has to be something I am not seeing . Can anyone solve this dilema ? Put the boat back in the garage for another day..............Thanks for the help... VIC

[99yam40]

pilot screws need to be removed for cleaning passages properly while cleaning the carbs.

I believe I have read about drilling small hole in brass plug and then running a small screw into it and pulling the plug out. being carefull not to damage the pilot screw. May need to do some searching and reading to make sure