TOPIC: 1989 Mercury 25HP tiller model troubles.

Picked up this motor about a year ago. Previous owner used it for 2
years in salt water. I believe it was a fresh water only before that but it may have sat a little. You could eat off this power head.

His symptoms were it was dying at idle and generally not running right.

I have since checked compression, (89 on each cylinder), checked spark, (nice and healthy blue 1/2" on both)drained lower (looked good) and put water pump kit in.

Trying to fix this issue, I put a complete carb kit in. When I tore it apart, it looked good. I am not getting many helpful responses at the usual help forum (marineengine.com) mostly I think because no one knows what to do next.

It simply dies at idle after about 45 seconds. I have played with the timing a little (to no avail). If I pump the bulb I can keep it running a long time at idle. It is a little rough.

Should I go through the carb again paying special attention to the pump?

I am using the Seloc manual but it isn't very accurate for this engine.

Thanks

I know it is a newer engine, but it is the newest I own.

try to pump the primer bulb when it is running if it helps then it is most likely the fuel pump.

The fuel pump is integrated with the carb on this model.
I went through the whole carb including the fuel pump.
I replaced everything that was in the kit that was for this unit even though everything looked OK.
I soaked it overnight in a gallon of carb cleaner anyway even though it looked clean then sprayed every thing down with regular carb cleaner, then my compressor.
I am at a loss on this one other than to remove the carb again.

Thanks

are you getting pulse from the powerhead?try the pumping of thembulb first to see if it is the pump.

If I pump the bulb I can keep it running a long time at idle.

I'd try a new primer bulb first....cheap, and go from there..

Previous owner had the same issue.
Tank, fuel, fuel fitting, and hose/bulb are brand new.
I didn't get them from the other owner.

I even replaced the fuel lines on the engine.
I checked the fuel filter but it looks OK.
I may bypass it with an elbow to be sure.

Are you sure when you blew out the carb passages they were clear with air coming out the other side freely? It might be possibe for enough varnish to form from sitting for a long period to cause that maybe? Just something that happened to me after purchasing a 650 that sat a couple years in the main jets of both carbs...varnish was rock hard and carb cleaner did nothing so chipped it out with a probe.

I guess my only option is to remove the carb and check that passage.
Thanks guys.

I think I found the issue?

I actually was thinking reeds should be checked but thought they were on the bearings and not something to get into yet, guess they got cheap with the newer Merc's Is that plastic? Glad ya found the problem:)

Dave kinda nailed it when he said; "are you getting pulse from the powerhead?"

The reed block is aluminum, and the reed stop (not in pic) is steel.
The reed itself is of course, some kind of steel, but I think you were joking.
I was told they are NLA, but marineengine.com claims 10+ in stock.
We'll see if they actually arrive. (there are 2 on ebay)
Other option is to install the entire assy. which is available, and of a different design, maybe because of this?

COOL! Make sure the surface the reeds seal to are very flat.

I have an ESKA 5hp that the reed contact surface was questionable testing with a straight edge, so I used a flat piece of scrap steel bar to back a piece of fine Wet & Dry sandpaper and saw in fact there were spots that left gaps the W&D wasn't touching. when all smooth used a very fine piece of wet and dry sandpaper to bring it to almost a polish and maybe fine crocus cloth. That motor idles so slow without missing a beat you woundn't think possible of a 2-stroke, actually too slow to cool properly I think? Don't try this unless your sure of your skills.

They told you the reeds were NLA for an engine that new? Shameful.

Update. I thought I would share what else I found.
I got the reeds and was installing the reed block. No problem. Then I put the carb gasket back on the reed block instead of the carb. Good thing I did because I would not have noticed it was the WRONG gasket.


Left is the right one. Middle was the one I put on last week. Right one was as I received it.
Without that oblong hole, the port to the fuel pump was completely blocked.
I almost repeated the problem.
Tank test tomorrow, boat test Sat. hopefully.