Wont idle - Carb or Electrical?

[81 Checkmate]

Vacation last week...... Having issues with the Pontoon.

2001 - 3.0 Merc I/O
Serial Number - #OL647903

1. It will start no problem...crank and it fires.....but it wont idle. You can rev it to 3 grand and hold it there and it has a very slight miss...but when you back it down to idle it quits.

2. Its getting fuel...change the fuel filter at carb. Had good pressure on the fuel line.. No fuel/water seperator installed!

3. New spark plugs and cap - rotor/button...Its getting good blue spark...becouse it runs

4. 1 can of sea-foam and 1 bottle fuel additive....about 15 gallons total, 5 gallons of 6 month old gas and 10 gallon of 89 fresh.

I did not check to see if there is water in the fuel... My bad will do this weekend. Its prob what the issue is!
But.... when it's running the volt gauge is reading almost 18 volts...not sure if this might be the issue?

Any thoughts?

 

[Bondo]

Re: Wont idle - Carb or Electrical?

Ayuh,.... The Idle circuit in yer carb is Plugged up,... rebuild the carb,...

18v is Way to high, check it with a meter to see if it Is that high, or the gauge is bad,...

 

[Don S]

Re: Wont idle - Carb or Electrical?

Disconnect the two small wires on the alternator and start the engine and see if the engine will idle then with the lower voltage. If it does, it's probably electrical, if it still doesn't, it most like the idle circuits in the carb.

 

[81 Checkmate]

Re: Wont idle - Carb or Electrical?

Got to the boat this past weekend.........

1. Checked the fuel for water......No water
2. Pulled the two wire clip on the Alt......No change......Checked the Volts at gauge with meter...just above 14 volts at 2000 RPM. Gauge is slightly off.
3. Took out the single idle jet screw...sprayed carb cleaner and i can see it coming thru inside carb...No change
4. Took throtle cable off...When you thottle good jets of fuel squirting into carb.

Got to looking....Im working on it by myself...But it seams the choke plate is not closing at start up. Unpluged the purple wire while running and have 12 volts at the wire...so its getting power. Check/ cleaned ground wire

Zip tied the coke plate about 3/4 closed and it starts good and idles....but no top end power of course.

So its in the electric choke.

I know nothing about carbs.....Does the carb need rebuilt or can the round black choke thing be rebuilt on the boat or ?????

 

[81 Checkmate]

Re: Wont idle - Carb or Electrical?

Anyone?

 

[Bondo]

Re: Wont idle - Carb or Electrical?

Anyone?

Ayuh,... The Choke should only work for Cold starts,...

I'm still thinkin' the Carb needs Rebuildin',....

 

[81 Checkmate]

Re: Wont idle - Carb or Electrical?

OK........Ill give it a try.

Will post results after rebuild.

 

[stonyloam]

Re: Wont idle - Carb or Electrical?

The miss at high RPM has me wondering, if you have a weak cylinder. Try setting the throttle advanced enough to keep it running then pull and replace each of the plug wires, see if one or two have little or no effect on the engine when pulled.

 

[spdracr39]

Re: Wont idle - Carb or Electrical?

Or its sucking air through one of the carb gaskets and closing the choke gets it close to proper mixture. I agree with the rebuild suggestion. Or at least make sure its bolted tight to the intake.

 

[81 Checkmate]

Re: Wont idle - Carb or Electrical?

Don or Bondo or ?.....

I did not get the serial # number off the carb last week when at the lake. Kind of in a pickle...boat is 1.5 hrs away

Wanting to order the carb rebuild kit......will this kit fit my aplication that im getting of iboats.
Sierra carb kit - Part # 18-7097, Merc Marine # 3302-80485.
What ive been reading it should be the newer style with the bent acelerator pump rod.

 

[81 Checkmate]

Re: Wont idle - Carb or Electrical?

I figured it out.......

Will let you know how it turns out after this weekend.

Thanks!

 

[81 Checkmate]

Re: Wont idle - Carb or Electrical?

Carb rebuild a success??..fired right up and purr?s like a kitten. Idles great and no high speed missing either. That was the culprit??Thanks Bondo

First time rebuilding a carb??.Used Mercarb manual, 2 barrel carb ? Fuel system 5-B. The manual takes you step by step and is very easy to do. Must follow each step and you can?t go wrong.

I did not have the carb serial number?but I had the engine serial number.

I did not get the carb kit from iboats?..because it did not give a good description of what each kit fits?.. You have to have the carb # to order the correct one.
The one I ordered was from Carb-Junkys on e-bay and it gave a good description and also listed the engine serial # + the carb #.....10 bucks cheaper too.

In my opinion - iboats need to change how their kits are listed on the site??Just me !

Happy Boating!