1994 200h.p. Merc -terrible idle.

[1nebel0]

I have rebuilt the carbs, retimed it, put new reeds in as old were leaking and it still had a terrible idle. Due to gasket leaking under power head, I have taken it to a guy who took it apart only to find the exhaust diffuser missing. The original owner says he took it out for better high end performance. The heck with that, what about being able to keep it running around the docks. Is this contributing to the lousy idle due to lack of back pressure? This stock motor should work better that it is. <br /><br />Thank you,<br /><br />Steve..

 

[andy6374]

Re: 1994 200h.p. Merc -terrible idle.

I'm not if a missing exhaust diffuser would cause a poor idle. However, ff the power head adaptor gasket is damaged, like you mechanic said, this could cause a nasty idle. If this leaks, exhaust will leak in under the cowl and that merc will start breathing it's own exhaust.

 

[1nebel0]

Re: 1994 200h.p. Merc -terrible idle.

Thanks for the response. The crazy thing is I have never had the cover on it as it has not been in the water since purchase so it must be other things. Your explanation does makes sense which would have compounded my issues even more. I love Merc's but frankly getting tired of the problems. When looking at the other brands, seems that all models have their challenges in some aspect or another. I am curios if anyone has taken out the diffuser and noticed the problem at idle. Does it make that big of difference at top end?<br /><br />Thanks,<br /><br />Steve..

 

[Ross Rains]

Re: 1994 200h.p. Merc -terrible idle.

If you are running stock compression and no porting work you'll never turn a stock motor the kind of rpm it takes for the missing diffuser to make a difference. In the meantime, you'll have to find a hill to run down to get any credible acceleration (hard to do on water). If you are going to run a stock powerhead I suggest you put a stock exhaust diffuser back in and go play. You will have better all-around performance.

 

[1nebel0]

Re: 1994 200h.p. Merc -terrible idle.

Thanks Bentrod!<br /><br />I have ordered a stock one. I just want a nice idleing motor that has the 200h.p. that it came with. The 19ft Daytona should go 80's with that. I don't care if I break the 100 mark. When you get older you want reliability over a few more ponies.<br /><br />Regards,<br /><br />Steve..