Mariner 4hp HELP ME BEFORE I GO MAD!

[mercuk]

Hi all, I have this Mariner 4hp (Yamaha engine) from 1986 model number 6EO and its driving me MAD!!!!.......
Ever since I got it, it wouldn't run without the choke half way out. Easy, I thought, clean and rebuild car.

Well after the 3RD carb clean and rebuild, its still playing stupid with me. I put a new fuel pum diaghragm at great expence, no change.

I'm at my wits end with this one as it owes me quite a lot of money. The idle settings seems to like anything from 1.5 turns out. Anything below, it won't run. Pretty much anything after 1.5 turns out is fine....
It will run with out choke but it boggs down on acceleration nearly every time, Stick choke out about half way out and it accelarates fine.

Why is it still doing this?! Ive seriously had it with this engine......
Please help.....

 

[Bosunsmate]

Re: Mariner 4hp HELP ME BEFORE I GO MAD!

i thought these had an internal gravity fed tank so no fuelpump needed.
If you have another setup try priming the fuelbulb to see if that helps.
Pull the sparkplug, clean it then reinstall and put the spark wire to ground and then pull start a couple of times, no choke, is the plug wet?

Might be top or bottom crankseals, pretty easy job if it is

 

[Bosunsmate]

Re: Mariner 4hp HELP ME BEFORE I GO MAD!

i thought these had an internal gravity fed tank so no fuelpump needed.
If you have another setup try priming the fuelbulb to see if that helps.
Pull the sparkplug, clean it then reinstall and put the spark wire to ground and then pull start a couple of times, no choke, is the plug wet?

Might be top or bottom crankseals, pretty easy job if it is

 

[Bosunsmate]

Re: Mariner 4hp HELP ME BEFORE I GO MAD!

i thought these had an internal gravity fed tank so no fuelpump needed.
If you have another setup try priming the fuelbulb to see if that helps.
Pull the sparkplug, clean it then reinstall and put the spark wire to ground and then pull start a couple of times, no choke, is the plug wet?

Might be top or bottom crankseals, pretty easy job if it is

 

[mercuk]

Re: Mariner 4hp HELP ME BEFORE I GO MAD!

i thought these had an internal gravity fed tank so no fuelpump needed.
If you have another setup try priming the fuelbulb to see if that helps.
Pull the sparkplug, clean it then reinstall and put the spark wire to ground and then pull start a couple of times, no choke, is the plug wet?

Might be top or bottom crankseals, pretty easy job if it is

Yes thats right, it has an internal tank. However this thing has a fuel fump built into the side or the carb that I presumed feed fuel to the carb bowl......

Might be crank seals, but would of thought it would idle rubbish being a single cyl and show other sytoms as well....

I'm still pretty sure is a fuel/ carb issue but I don't see what else can be done to them. As far as I'm aware the carb is spotless but yet still won't consistenly pull away without a bit of choke.... Anything over 1.5 turns over the air/fuel made little difference in performance...

I don't mind doing the C/S seals. I'm pretty confident in doing that level of work but not keen on tearing into the powerhead if thats not going to cure anything.....

Help me people this thing is driving me nuts!! Just want to get it sorted. Any more votes for C/S seals being route cause of my problems?!
Anything I might of over looked?!

 

[Bosunsmate]

Re: Mariner 4hp HELP ME BEFORE I GO MAD!

Fuel pump built into the side of the carb? Does pulling the powercord squirt fuel out the outlet sufficiently?
Are you sure?
Get someone to pull the powercord and put a piece of paper over the end of the carb to check it has sufficient suction