electric choke question

[rebars1]

Project boat ChrisCraft Scorpion 230 circa 1990 merc260, GM5.7L V8, Rochester quadrajet carb. Fired up the engine for the first time last week on muffs, ran great for 30 minutes, turned off. Worked on sorting out the wiring for some of the guages. Started it up yesterday and it was running heavy, blowing blue smoke, like it was over choked, so I shut it off. I turned the key on and noticed that the wire to the electric choke was getting hot, as well as the electric choke body. This morning I removed the flame arrestor, turned the key on to first position. The wire and choke body warmed up again and the choke valve (flap?) opened full. Is the electric choke supposed to get warm? How is it regulated? What voltage should the lead wire have when the key is just turned on? Am I getting a short circuit in this wire now? Finally, could this be why the engine was blowing smoke?

 

[Fishermark]

Re: electric choke question

I don't know that the wire itself should be getting hot, but the electric choke part on the side of the carb does. It is basically just a heater element that heats up and in turn, the dielectric spring expands or contracts and opens / closes the choke butterfly.

 

[bjcsc]

Re: electric choke question

rebars: blue smoke is almost always oil. If you were over rich you woud have seen black smoke and there would be carbon all over your transom (after awhile). How long has it been since this engine was run prior to this?

edit: forgot about the choke questions...I have never noticed the wire to the choke body getting hot...I don't think that's normal. You should read system voltage on the wire...are you saying it opened up with the key simply in the run position?

 

[rebars1]

Re: electric choke question

The valve opens up with the key in the run position, but without the engine running.

The engine had not been run for about a year and a half until about two weeks ago. I had turned it over a few times since getting it and did one shorter run a couple of weeks ago. The carb is new rebuilt. The gas is probably two years old, with some stabilizer added about 6 months ago. The only thing different from last week and this is that I was cleaning up the spagetti bowl of wires the guy before me left. That is why I thought I might be getting a short.

How does the choke know when to open or close?

 

[Gary H NC]

Re: electric choke question

Not sure about the choke but putting stabilizer in gas that is already a year and a half old will not make the gas good again.If the engine set that long it could be valve seals leaking oil into the cyliders causing blue smoke. Or bad rings,First thing i would do is get some fresh gas in it then diagnose the choke problem.You could unhook the choke wire and get it running with fresh gas and go from there.

 

[rebars1]

Re: electric choke question

Now that I think about it, the gas has that kind of sweet shellac smell.

 

[Don S]

Re: electric choke question

If the choke is opening with the key on, it's doing exactly what it's supposed to do. And they get hot doing it. The wireing shouldn't get hot though.
Some electric chokes ground thru the choke mechanism. Using a gasket of any kind can cause problems. So make sure there is no gaskets between the choke coil and where it mounts to the carb.
If you suppect bad fuel, run the engine on a remote tank (a 3 to 6 outboard tank works great) with new gas in it. See if that cures the problem. Then drain the old gas and put in new.

 

[Bondo]

Re: electric choke question

How does the choke know when to open or close?

As soon as you turn the key On,.... It starts Openning.....

To Close it for a Cold Start,......
That's 1 of the reasons to actuate the Throttle to WOT once,...
Before you turn the key to Start........That's what Sets the Choke......

 

[rebars1]

Re: electric choke question

Thank you for the information and tips. I connected a different gas tank with new gasoline and squirted a little GumOut on the valve hinges. Worked like a charm! Thanks again.

Now, what do I do with about 35 gallons of bad gas (looks like apple cider)?

Also, how does one check a gas tank for leaks? I think I might need to replace it (70 gal aluminum)

 

[Gary H NC]

Re: electric choke question

About the only thing that would burn that gas is a lawnmower..maybe.

Are you finding gas in the bilge? about the only way to test for a leak is seal everything off and put a little pressure to the tank.
maybe some of the other guys will chime in with some ideas..

 

[capecodder116]

Re: electric choke question

I have burned 3 year old fuel from my boat in my pick up truck. Just blend a few gallons at a time with a full tank of fresh gas. Just put the old fuel in first then fill your tank at the gas station to mix. About checking your tank for leaks, I have plugged off vent and fill hoses, then removed the threaded anti-sihon valve and replaced with an assortment of threaded fittings which would allow me to attach a schrader air fill fitting, ball valve, and a simple air pressure gauge. Put about 10 to 15 pounds of air into the tank shut the ball valve and check the gauge in a few hours....also while under pressure you could spray the tank seams and around the hose fittings with a soapy water solution and see if you get bubbles.

 

[Don S]

Re: electric choke question

Also, how does one check a gas tank for leaks? I think I might need to replace it (70 gal aluminum)

About 90% of the time, a leak develops from corrosion holes in the bottom of the tank. The other 10% will be cracks in welds or bends.
Only way to check them is to empty the tank, remove the tank from the boat, pressureize the tank to 3 psi max. (more and you could damage the tank) then spray with a soapy water solution and watch for bubbles.

 

[Bondo]

Re: electric choke question

Ayuh,......

And there's another 20% that Rot under the Straps,+ at the Saddles..............

 

[capecodder116]

Re: electric choke question

Absolutely right....my aluminum tank had pin holes, on the bottom, under the straps. Welded some strips over them.

 

[Speakrdude]

Re: electric choke question

By-the-way, I just installed the coolest (pun intended) electric choke on my quadrajet. It looks like a normal electric choke conversion kit, BUT, it has a thermostat module that bolts onto the front intake manifold bolt. That way, it doesn't heat up just because the key is on. It actually heats up according the block temp.

Cool huh?

Jim

 

[Don S]

Re: electric choke question

Speakerdude:
An even easier way to do an electic automatic choke is just hook it to the AC tap terminal on the alternator. Then it only supplies power to the choke when the engine is running.
Personally, I like the choke coming off a lot quicker than when the intake manifold starts getting hot.

Uhhhh Bondo, wouldn't you consider that 20% as part of the 90% corrosion holes in the "BOTTOM" of the tank I mentioned.?

 

[rebars1]

Re: electric choke question

Wow! So I have about 120% chance of leaks!

Capecodder, where did you get a replacement tank? Has anyone tried SpeedyTanks.com?

 

[Bondo]

Re: electric choke question

Uhhhh Bondo, wouldn't you consider that 20% as part of the 90% corrosion holes in the "BOTTOM" of the tank I mentioned.?

Ayuh,.... Ok,......

I misread it as from the Water laying In the bottom of the Tank........
Rather than laying Around the bottom of the Tank.....

Throwing in the Rot from the Straps,........
I guess you've only got 110% chance of a Leaky Tank Rebars.............