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Cold Starting - Should I be Concerned

Posted: Sun Mar 11, 2018 5:47 pm
by BayouBengal
The last few times out with my boat, the engine (Mercruiser 4.3L V-6) did not want to start cold without some throttle. Once it's warm, no problem, she starts right up with no throttle.

Because it used to start cold with no problem, I became concerned that maybe I had a fuel leak, but I've not been able to find any signs of one.

Should I be concerned, or is this just the joys of having a carbureted engine?

Re: Cold Starting - Should I be Concerned

Posted: Sun Mar 11, 2018 6:46 pm
by Hercdrvr
Hey buddy,
You know a carburated engine is like a good dog, it only has one owner. Like my chain saw, 6 pumps on the bulb...pull at full choke till she burps then 1/2 choke and it fires up every time. Let the neighbor borrow it and he’ll never get it started.

How long did she sit between starts? If the bowl is dry she’s gonna need some cranking. If it’s hard to start after running it the day before Id make sure the choke is closing off air. I’d guess it’s an electric choke and not an old thermostatic spring type, maybe the power connector popped off. I doubt it though, your boat rides way too smooth for that.
If the choke isn’t closing and power is hooked up Squirt the choke linkage with something slippery.
If all that fails keep a can of ether handy.

Heather says “hello”
Matt B

Re: Cold Starting - Should I be Concerned

Posted: Mon Mar 12, 2018 8:41 pm
by BayouBengal
Matt, As soon as I read your post I instantly thought this may be the issue. I don't have my boat at my house; it's stored about 10 miles away, but I made a trip over tonight to look at the choke. There's no problem there, it's closed off just as it should be when starting.

It's been so long since I've had an automobile with a carburetor. But it seems that I was told way back when to push the accelerator to the floor once or twice before turning the key, then start it without giving it any throttle. Tonight I did that and the motor started with no throttle, but I'd just ran it last night, so maybe it hadn't sat long enough. And I really don't comprehend how exercising the throttle on a non-running engine does anything.

In any event, the motor starts and the boat floats. Maybe, I'll just have to be happy with having to give it some throttle to get it started when cold.

Re: Cold Starting - Should I be Concerned

Posted: Tue Mar 13, 2018 9:14 am
by Hercdrvr
You cracked your carbs code, now you and your engine are one. When you advance the throttle before attempting the start you’re mechanically moving the accelerator pump and giving the engine a shot of gas. However, if the bowl is dry because it sat for months you get nothing until you crank long enough for the mechanical fuel pump to fill the bowl. Life before the gentle hummm of the electric fuel pump in the tank, I love it.

Matt B

Re: Cold Starting - Should I be Concerned

Posted: Tue Mar 13, 2018 9:29 am
by Roberta
Matt is exactly right. In addition, stepping on the gas pedal or advancing the throttle releases the linkage on an automatic choke and allows it to close and sets a fast idle cam. As Matt mentioned, setting a spell will evaporate fuel in the float bowl. Some cranking will be required to operate a mechanical fuel pump to fill the bowl and allow the accelerator pump to provide that shot of fuel necessary to enrich intake air for cold starts.

Roberta

Re: Cold Starting - Should I be Concerned

Posted: Tue Mar 13, 2018 11:55 am
by BayouBengal
Thanks Matt and Roberta. My limited knowledge when it come to combustible engine operation can be easily exceeded; but, I think I'm beginning to understand.

Re: Cold Starting - Should I be Concerned

Posted: Wed Apr 11, 2018 8:12 am
by TAB
2 things I would check
1 st choke linkage
2nd is to make sure your CARB is not dumping fuel I to the intakes while trailering. The carbs on the older 4.3 were known to leak fuel I to the intakes while trailering. If you can pull the back spark plugs easily, I would do that at the ramp and see if they are wet

Re: Cold Starting - Should I be Concerned

Posted: Wed Apr 11, 2018 11:04 am
by BayouBengal
Thanks, I'll look into this.

Re: Cold Starting - Should I be Concerned

Posted: Wed Apr 11, 2018 11:20 am
by Bill Edmundson
Jeff

Now, someone can call BS on this. If you have a fuel shut of valve, close it before you put the boat up. I have a generator that is a pain to start after it sits up for a while. It is much easier to start if I close the valve. Oh! you have to remember to open it again. :lol: I've done that, too. :lol:

Bill