'99 Mariner 4 stoke won't rev out.

R

Rudd

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Joined
Aug 31, 2010
Messages
2
I have a '99 4 stroke 4hp engine fitted to an 8 foot dinghy. I'm told these rev out to around 5000 rpm? Be lucky if I'm getting 3000. I've just bought the engine second hand. Apparently has a high thrust prop fitted. Is there any adjustment, carburator or otherwise I should be looking at? Anyone know where I can download a manual? Thanks
First posting ever, hope I've done this right?
Cheers
 
jerryjerry05

jerryjerry05

Supreme Mariner
Joined
May 7, 2008
Messages
18,196
Re: '99 Mariner 4 stoke won't rev out.

The only thing missing is the ser# But it's probably not needed in this case,
Basics. Compression test,spark test,fuel system check.Vent on the tank open?
Ethanol is messing with lots of stuff on these outboards.Check the carb,remove the bowl.Then rebuild the fuel pump.Any soft hoses and the squeezie replace.Any inline quick disconnects remove/replace.
Then the prop.If someone has replaced the prop with a bigger pitch could cause the drop in rpm.I think,7 or 8p is standard they come 6-7-8-9 pitches. What do you have?J
 
R

Rudd

Recruit
Joined
Aug 31, 2010
Messages
2
Re: '99 Mariner 4 stoke won't rev out.

Thankyou for the excellent reply...very comprehensive. Once I've found the problem I will be sure to post a repsponse. Do you have any idea of correct compression PSI ?
I've been told the later model engines have automatic decompression to aid starting, is that the case with these earlier engines too?
Serial # is OR002097
Have found a "7" on rear of the prop.
The fuel line,bulb,and pump have already been changed by previous owner. Best I check the rest.....thanks again.
 
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