throttle problems

[kiw0n2]

i have a 1973 70hp johnson it just got new carbs put on it but i dont think the guy who did it synchronized the carbs because the engine idles fine but when i put it in gear it cuts out on me i have to have somebody actually sit back by the engine and choke it while i throttle up to get me going once i get going it runs fine so im thinking its something to do with the carbs synchronization or mybe something else?

 

[ob]

Re: throttle problems

To check carb sinc ,not sinc and link,remove intake cover.With motor off move throttle to wide open position .May need assistance with someone to turn prop while shifting throttle.Assure that carb flaps are horizontal and equal at WOT.Return to nuetral position.Not sure on your model but look at carb linkage and see if roller attached in nuetral is aligned with a scribe mark on linkage cam.This is factory link setting of carb position in relation to ignition timing.It should be dead center.With throttle in nuetral position carb flaps should be just closed.I usually open them at several throttle settings to insure they all open equally.I use hole guage or similar precission instrument for this measurement.Also,if sync looks good, try opening mix screws 1/2 turn each to see what effect it has on flat spot . Make and check this adj. on water.If you say someone has to assist by choking remote at motor your situation is lean.Continue 1/2 turn open procedure until effct is attained.Don't exceed 3 1/2 turns out from closed position.If all fails i would look for fuel restriction in carb fixed orifices.

 

[kiw0n2]

Re: throttle problems

thanks for the info ob yesterday when i checked the carbs when the throttle was in neutral the carb flaps where still wide open for some reason so i guest thats part of my problem right there how can i fix this? and where are the mix screws sorry im new to the boat game

 

[ob]

Re: throttle problems

If carb flaps are wide open in nuetral I don't quite understand your opening description that motor runs fine after initial starting problem.This is assuming by fine you don't mean wide open.You need to actuate the throttle control and verify movement of flaps without lifting fast idle lever.

 

[kiw0n2]

Re: throttle problems

the engine runs fine wide open in fact it only runs wide open if i shift the throttle to the first and second position pass neutral the engine stalls. but as far as the carb flaps being closed in the neutral position thats not happening with my engine.

 

[ob]

Re: throttle problems

You'll need to locate trunion nut on cotrol cable and adjust until you can achieve proper set -up.Could be that throttle cable will need to be replaced as any linkage that far off is likely to have severed throttle cable.Hopefully these are original set-up carbs and linkage we speak of.Would highly recommend obtaining service manual for motor to verify all carb components are original set-up.

 

[rickdb1boat]

Re: throttle problems

kiw0n2,<br /><br />Are you talking "Choke" Flaps or "Throttle Flaps"?Does your Motor have a choke system or primer system?

 

[kiw0n2]

Re: throttle problems

choke flaps...

 

[ob]

Re: throttle problems

The throttle flaps I speak of will be behind choke flaps.

 

[rickdb1boat]

Re: throttle problems

That puts a whole new twist on things! So I guess what you're saying is that your choke is not working when the Motor is cold, but the Motor runs fine after it warms up. Or do you still have to choke it after it warms up? Does that Motor have a Manual Choke or is it electric? More info again, please!

 

[ob]

Re: throttle problems

I figured he had trouble with both since motor only runs wide open.

 

[rickdb1boat]

Re: throttle problems

I don't know OB. I think he has the choke confused with the throttle plates. Sounds like the choke is not closing when he tries to start it. But that may be due to not knowing how to do it! Obviously, they should be open after warm-up! Wait and see what the next post brings. I know I'm confused at this point!

 

[kiw0n2]

Re: throttle problems

sorry for the confussion let me try to explain my problem again first off i did have the two flaps confused sorry but im new to boating but my problem is the engine starts fine and idles fine but when i go to put it in gear it stalls on me the only way it will get me across the water is if someone manualy chokes the engine as i give it full throttle and thats the only way it will run if i bring it back from full throttle it stalls i know this has to be something simple but thank you guys for all the help im learning alot about my engine from you guys.

 

[rickdb1boat]

Re: throttle problems

OK, then I would try what OB said in his previous post about sync. the Carbs. If that does'nt do it, I would remove the Carbs and recheck everything. You are running either out of sync. or very lean fuel mixture! Were these Carbs brand new or rebuilt. Please explain how the Carbs came about!

 

[ob]

Re: throttle problems

You'll need to block open choke flap and inspect carb flap sinc as per above instruction.If it is necessary to choke underway to achieve higher rpm opertation there is a problem between the air and fuel mix ratios due to either carbs out of sinc or fuel restriction in carb float valves or fixed ports.Generally these are in the form of gummy deposits or particulates from old fuel contamination. I would also recommend obtaining compression readings on each cylinder . Also, there is still possibility that fuel pump is weak causing fuel starved condition.Anything in system that has to do with fuel delivery needs to be ruled out. Pick-up in tank ,fuel connectors,primer bulb,inline filters,fuel tank vent.

 

[rickdb1boat]

Re: throttle problems

Also, instead of choking the Carbs while running, try having someone squeeze the primer bulb on the fuel line. If it speeds up, probably fuel pump! Does the Bulb stay firm when running? Is Tank Vent open?

 

[kiw0n2]

Re: throttle problems

Ok guys did what you said and believe it or not the boat is running alittle better just need to fine tune i think now with the throttle in the first position it runs for a min or two before it shuts down but i dont need anyone to choke it anymore to get going but i do have to punch it to get going but it still acts like it wants to bog down any suggestions?

 

[almost retired again]

Re: throttle problems

Hi Kiwon2, <br />I kinda hate to jump in here as rickdb1boat, and Ob are giving you very good info, but you still havn't answered Rickbd1boats question. Were the carbs new or used or a rebuilt by someone. If they were used, or just rebuilt by someone they may stil need a good cleaning or a rebuild. Being a 73 I believe that you do indeed have adjustable low speed jets, and OB gives good advice here. On your carbs as with most 2 stroke carbs there is usuallt 2-3 small openings at the top of the throat, and in front of the throttle plates that is supposed to add extra fuel between idle and full throttle. This is supposed to eliminate that flat spot going from idle to full throttle. I think that is why Rickdb1boat asked you were they used. They may still need cleaning.<br />Let us know

 

[kiw0n2]

Re: throttle problems

sorry yes they are new carbs but now that i think of it they where changed but the fuel wasnt so i think the bad fuel might of clog the jets. how do i find out if this is my problem can i take the little screws you talked about completly out? and how do i clean them.

 

[Bear]

Re: throttle problems

Carb cleaning:<br /> http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=17;t=013170 <br /><br />Have fun!<br />