Mercruiser 4.3

[Kane]

Hey guys, I bought a brand new 2008 Chapparral with a Merc 4.3 in it last year. We had a great 1st season with it and as a new boater I am very happy with the purchase.

One problem, when going out for the start of the days boating, the first time I take off the motor kinda bogs down for a moment. I always idle out after launching and let things warm up to op temp but it doesnt seem to matter. It always bogs down the first time I accelerate than its fine the rest of the day. weird. My Uncle has a brand new boat with the same motor and his does the same thing. any thoughts?

 

[Don S]

Re: Mercruiser 4.3

Kind of lacking on informtion. Is this a carbed or MPI engine? Was any winterization done, things like fuel filters changed etc. Any getting it ready for this season, like tuneups etc?

 

[Kane]

Re: Mercruiser 4.3

sorry, its carbed with 55 hours on it and Im in Wisconsin so its outta service right now. It was winterized by the dealer. This has been a issue with the boat since the very first time it hit the water with zero engine hours. When I brought it in for its 50 hour service I told them about this issue and the tech who did the work said he didnt find anything wrong. Ive basically followed the Merc service schedule exactly. I was surprised when I described this issue to my uncle and he said his motor does the same thing. Like I said, it only does this bog/hesitation the very first time I accelerate for the day than it never happens the rest of the day

 

[Don S]

Re: Mercruiser 4.3

You have a warranty issue if it did it from day 1. It could be as simple as a carb adjustment, but the dealer should make it right at no cost to you.
Nothing you can do with it without being able to run it.
One other note after re-reading. It may be that after prolonged idleing for warm up and idle out of the harbor that it may just have the plugs fouled a bit. Have you ever just given it some throttle in neutral (gas it a couple of times like you would a car with a carb) to clean out the excess fuel?
Might try that.
Carbed engines DO NOT act like fuel injected ones.

 

[JustJason]

Re: Mercruiser 4.3

Carbed motors are not fans of idleing/trolling for extended periods. They get loaded up with fuel and need to be blown out (racking the throttle to wide open) to get the extra unburnt fuel out of the motor.

So it could be normal. Or it may be a mis-adjusted carb. Did your transom get black this summer?

 

[Fun Times]

Re: Mercruiser 4.3

You have a warranty issue if it did it from day 1. It could be as simple as a carb adjustment, but the dealer should make it right at no cost to you.
Nothing you can do with it without being able to run it.
One other note after re-reading. It may be that after prolonged idleing for warm up and idle out of the harbor that it may just have the plugs fouled a bit. Have you ever just given it some throttle in neutral (gas it a couple of times like you would a car with a carb) to clean out the excess fuel?
Might try that.
Carbed engines DO NOT act like fuel injected ones.

I agree, Plus it's a (TKS) Turn key start and those Carbs can be sensitive sometimes.

 

[Kane]

Re: Mercruiser 4.3

where I boat there are some pretty long no wake areas after launching so I am at idle for awhile before open water. I did try reving up a little in neutral but it didnt seem to make any difference. The transom has always been clean.

 

[cr2k]

Re: Mercruiser 4.3

I think part of the problem may lie in the accelerator pump. My 3.8 is that way too. Once they get "loosened up" they seem to run ok. Other thing I can think of is maybe the advance weights are a little rusty and stick until they get "worked" a little.

 

[Don S]

Re: Mercruiser 4.3

Other thing I can think of is maybe the advance weights are a little rusty and stick until they get "worked" a little.

Merc hasn't used mechanical advance on the V6 for 25 years.

 

[jkust]

Re: Mercruiser 4.3

Which Chap do you have? Seems they are not well represented here.

 

[havasuboatman]

Re: Mercruiser 4.3

For what it's worth...
I had a customer with the same issue last year. I was thinking too much idling also. Until I couldn't get the problem to repeat. Only happened when the boat came off the trailer. (sat over night)
Finally, I just replaced the accellerator pump, mostly because I was stumped and the customer wanted his boat for the weekend.
He's a loyal customer now because I fixed the little glitch 3 other shops couldn't. I have no idea what could make that pump act like that. Just on the first accelleration of the day, and just under load, at that, but it worked.