Choke doesn't close on WOT

[TexasIvey]

I have a 1990 mercruiser alpha 1 3.0L. I have the mercarb 2 barrel carb (PN 13899562). I push the throttle only button in and push the throttle all the way open and then back to 1/4 throttle. I have removed the spark arrester and when i look at the choke it is open. it moves freely. I have 10.5 volts on the purple wire with the key on. This of course causes the engine to start hard when its cold. Thanks in advance for the help. I am certain this is a redundant post but I have used the search tool and can not find a post about this.

 

[Don S]

Re: Choke doesn't close on WOT

It could be nothing more than someone opened it so it wouldn't close. Are there 2 wires on the choke coil itself?
If so, then loosen the 3 screws around the edge of the choke coil and with the throttle at about 1/8 throttle, turn the choke coil until the choke plate just closes. Tighten the screws and turn the key to run. The choke should slowly open.

 

[TexasIvey]

Re: Choke doesn't close on WOT

I loosened the 3 screws, set throttle to 1/8, rotated choke coil until choke closed, turned on key and choke stayed closed. It did not open.

 

[Don S]

Re: Choke doesn't close on WOT

Either the choke coil is bad, one of the wires is not hooked up, or someone put a gasket where it shouldn't be.

Post a picture of your choke coil. http://forums.iboats.com/showthread.php?t=468676

 

[ktbarrentine]

Re: Choke doesn't close on WOT

I loosened the 3 screws, set throttle to 1/8, rotated choke coil until choke closed, turned on key and choke stayed closed. It did not open.

How long did you leave power to the choke? it does take a few minutes to heat up and expand the coil.

 

[TexasIvey]

Re: Choke doesn't close on WOT

1st 4 times out this year no problem starting and I haven't had any work done. I will check the coil tomorrow. I left the power on for about 5 minutes.

 

[makonnen]

Re: Choke doesn't close on WOT

Well these things happens. This is just a humble opinion, but I'm going to bet that many boat engine problems can be boiled down to electrical or cooling system (incl the raw water system).

When you open your throttle to 100%, the choke plate is supposed to crack open. This is done through the linkage system and is supposedto help you clear a flooded engine. On a some fuel injected engines, if you open the throttle to 100% with the engine NOT running, it cuts the fuel - again to clear a flooded engine.

When the engine is cold, remove the flame arrester, crack open the throttle slightly then return it to neutral. This should snap the choke back (assuming it was working previously). The turn the ignition ON but don't start the engine ... the choke should slowly open in a matter of minutes. If not, and you said you had power at the purple wire, you've got a choke coil problem.

 

[Struc]

Re: Choke doesn't close on WOT

My choke coil stopped working, and I just opened it up full and left it.

At the temperatures most of us boat, you don't need it. Just pump the throttle a extra time or two for the first start of the day.

 

[makonnen]

Re: Choke doesn't close on WOT

So what you are doing is compensating for the lack of a choke. Its cold up here in the Pac NW coast, I can get away without a choke too if I do that. No matter how warm the ambient air temp is, the engine is still cold when you cold start it. Fuel mixture needs to be extra rich for the first few minutes to compensate. Personally, I don't like revving the hell out of the engine when I cold start it. I want to start it, let it idle at low RPM while the oil circulates and warms up - which is why we have a choke.