3.0L Mercruiser Automatic Choke

[mnowicki]

I have a 1983 Mercruiser 3.0L 140 HP engine with a Rochester 2GC carb. I think i need a new Automatic choke but not sure...

I was out on the lake cruising @ about 3400 rpms (25 mph) went to power down & the engine stalls out??? Took off the carb cover and the top butterfly is loose??? Moving the throttle wouldnt do anything...

Got towed back in to the ramp, drove home and when i checked it agian the butterfly is closed. Hooked it up to the hose and the engine fired right up!

This happened another time before that exact same thing but not on the water is was at home - drove to the mechanics house and it was fine???

Does these things over heat and then after it cools down its fine???

Any help with this would be excellent...

Thanks....

 

[Saqbcq]

Re: 3.0L Mercruiser Automatic Choke

Sounds like the choke is working closed/cold and open/warm. I'd rebuild the carb if fuel pressure and filters check out OK

 

[mnowicki]

Re: 3.0L Mercruiser Automatic Choke

I noticed that there are 2 wires on the auto choke??? One looks like its a ground and the other goes into the wire harness??? Im a bit confused about the wires, i do understand how the auto choke works... Its been more than a dozen fishing trips and this is only happened a couple times. Is this a red flag on needing a new auto choke???

Thanks....

 

[dubs283]

Re: 3.0L Mercruiser Automatic Choke

loosen the cover on the choke spring assy and see if you can rotate the spring to move the choke plate

if you get no movement at the plate take off the cover and look for a broken spring or if it has come loose

you should have 12 volts (+) on the purple wire with the key on and good continuity to ground on the black wire

 

[mnowicki]

Re: 3.0L Mercruiser Automatic Choke

Loosened the choke plate and the spring assy is not broken... With the key on i have 10.9 V on purple wire with a good ground...

I have had the boat in the sun for about 15-20 mins and the auto choke must be gettting hot because it is opening up the top butterfly on the carb...

Is this a sign that it is worn out??? i wouldnt think a lil bit of heat from the sun would open this up like that... I plan on getting a new auto choke thermostat... maybe this will fix my problem...

 

[dubs283]

Re: 3.0L Mercruiser Automatic Choke

if the choke isn't adjusted properly, it won't operate properly

with the engine running and warm, adjust the choke so the plate is fully open, then close it partially with your finger and it should go back to fully open on its own, if it stays partailly closed, adjust further to open but don't go too far

once adjusted to open, shut down and let the engine cool, overnight if you have to, then set the choke by pumping the throttle once and check to make sure it is fully closed, if not you can try re-adjusting it, or it may just be worn out