Evinrude 50 HP Bogs at WOT

" OK, here's the situation

" OK, here's the situation . . .

83 50 HP Evinrude - sat out in weather for 4 yrs. Been cleaning - plugs, gas lines, carbs (pulled apart and sprayed lots of carb cleaner, but no rebuild), Seafoam in the gas tank (1 oz. to 1 gallon - 3 gallons), compression 155 & 160, what appears to be new power pack and new (?) things at the opposite end of the spark plugs (not the plugs, the other end), new gas bulb and line . . . that's pretty much it . . . NOW . . .

At WOT, she bogs down. Up to 3950 RPM's, runs great. Then, bogs down and the RPM's drop. No overheating (oh, yeah, new thermostat), good pee. Semi-firm bulb at WOT.
Tonight - went to WOT with the lever, and she bogged down, then pushed the key in and then she acted flooded till I released it, then up to 4700 RPM's and she ran like a CHAMP! For a few minutes, that is. Then back to the same old 3900 RPM's.
Any suggestions?

Thanks, in advance.

Jason "

"Jason... Remove, clean, and r

"Jason... Remove, clean, and rebuild the carburetors. They're fouled.

Joe "

" I already pulled them off an

" I already pulled them off and cleaned the crap out of them. I used four cans of carb cleaner on them! But I think you are right.


I already bought one of the rebuild kits for the carbs

I guess I was just hoping to not have to do that. I was hoping that the SeaFoam would have some "magic" in it that would clean them.

Oh, well, Enough whining . . . I'll clean 'em tomorrow when I get home.

Thanks

Jason "

" Jason; Is this motor is new

" Jason; Is this motor is new to you? This also sounds like the vent cap is closed on the tank. What's fuel pressure, your compression is outstanding, if the vent cap is ok, I would check fuel pump and clean, change fuel lines, and filter on engine. Let us know. "

" Yes, this boat/motor is new

" Yes, this boat/motor is new to me. Actually, it is my first one.

I looked for a vent area on the tank, but could find none. I read some other postings that mentioned that, but also heard that the gas tank is based on negative pressure(?) so there shouldn't be a vent for it? I have no idea about a vent, so I am pretty much clueless on what to check. Any tips would be appreciated.

Thanks,
Jason "

" Hi Jason; the vent is in the

" Hi Jason; the vent is in the gas cap itself 1/2" diameter if there isn't one loosen the cap on the tank, if it's a factory tank losen the cap 1 position. Let us know if that works. "

" Here is some more info on th

" Here is some more info on this . . .

I think I found the vent cap AND I think it is totally rusted closed. I'll clean that up, too.

I rebuilt the carb tonight. Very clean from the last time I pulled them apart. The only thing I am worried about is that the nozzel gasket (the tube that goes into the float bowl slides through the middle of this gasket) would not stay on the nozzel when I turned it right-side up. I pulled the other carb and looked in it and there wasn't one on that nozzel, so I just left this one off. Can anyone tell me what this gasket is for and is leaving it off going to cause big problems?

Anyway, the linkage and cam were all screwed up (probably from the last time I took the carbs off) and the throttle plates in the carb throats weren't even opening a quarter of the way. Fixed that now, the roll pins are exactly verticle and the plates open to horizontal at WOT now. I had to turn the WOT stop screw about 1/4 in. down! That seemed like a lot, but I figure I can keep an eye on the RPM level when I test it.

Sorry for the long post, just trying to be as descriptive as I can.

Two questions -
1.) Nozzel gasket - what is it for and is leaving it off OK? and
2.) Are the plates only being open a quarter of the way a probable reason for the bogging down after 3900 RPM's?

I guess that is actually three questions, sorry.

Thanks,
Jason "

"Jason... You said "The on

"Jason... You said "The only thing I am worried about is that the nozzel gasket (the tube that goes into the float bowl slides through the middle of this gasket) would not stay on the nozzel when I turned it right-side up. I pulled the other carb and looked in it and there wasn't one on that nozzel, so I just left this one off."

Remove the carburetors and dsimantle them again. Those gaskets absolutley need to be there! That gasket creates a seal that allows fuel to be drawn up the large brass high speed venturi, and also up the smaller inner brass slow speed tube. With that gasket missing, there is no seal and the vacuum of the engine will draw fuel straight up out of the float chamber rather than going through the high speed jet, then up the venturi.

It would be a good idea to obtain a service manual for that engine.

Joe"

" Crap again! I knew you were

" Crap again! I knew you were going to say that! OK, I have the manual. It showed that gasket in a exploded diagram, but mentioned it nowhere in the directions/instructions for removal and disassembly. It is a three pronged gasket, but it won't stay on. What do I do to get it to stay up on the nozzel?


I JUST GOT IT ! ! !

The float bowl has an area that that nozzel goes into, and that mating with the upper carb body will hold the gasket in place!

Thanks, now I understand.
I'll fix it tomorrow. It's to late to pull them apart tonight.

Thanks, Joe. Sorry my ignorance is sooooo profound.

Jason "

" Replaced those nozzel gasket

" Replaced those nozzel gaskets tonight. BOTH of them. Then tested it on the water. Was much harder to start, but ran quieter and a bit smoother this time. Starting off, it seemed like it was starved for gas, but then (suddenly, I might add) it took off. Straight to WOT - 5000 RPM's - 32 MPH. LOVIN' THAT! Any suggestions on making it easier to start up? Here's what I did this time -
Pump the bulb till fairly hard
turn key to on then push in
hold 8-10 seconds
crank
no start, raised the high idle lever
crank, crank, crank
pump bulb
press key in - 4-6 seconds
crank
START

Any other suggestions?

Thanks for your help, Joe and Mercury. I really do appreciate your assistance and your forgiveness for my being such a rookie.

Sincerely,
Jason "

"Jason.... Simply pressing the

"Jason.... Simply pressing the key in engages the primer (choke) solenoid, but that in itself does not prime the engine.

You must hold the key in and crank the engine at the same time. This forces the pressure/vacuum in the crankcase to draw fuel through the solenoid, into the intake plate area, and then to the pistons. Think of it as a choke... if the engine isn't turning over, the choke is doing nothing.

Do this... Prime the fuel bulb up hard, raise the idle lever (warm up lever) so that the engine isn't trying to start at a dead idle, push in the key to engage the primer solenoid (choke) and crank the engine at the same time. The engine should start within 4 or 5 revolutions.

Let us know how you make out.

Joe"

" Joe,

That worked GREAT.

" Joe,

That worked GREAT. I just tested her again tonight (shhhhh . . . don't tell my wife I need less than 4 hours to test it every time). Cranked right up. RPM's kind of bounced up and down at idle, like revving up then dying and catching itself and revving again. Went away after a while. Other than that she ran beautifully. I LOVE having a boat. Found a quiet little cove and tributary beyond that, full of grass and small islands. The grass actually walled off the entrance from view. Caught my first fish out of this boat in there tonight.

Thanks for getting me out there . . . and back.

Jason "

"Jason.... Glad to hear you&#3

"Jason.... Glad to hear you're on the water at last. That reving up and down at idle could be a slightly lean carb... but usually it's caused by the linkage between the carburetors (the one running from the top throttle butterfly to the bottom butterfly) being slightly too tight. That causes one butterfly to be closed and one slightly open... At idle, you want them both closed.

Joe"

" Thanks, I'll check it to

" Thanks, I'll check it tomorrow. Just before I go fishin'. I'm takin her out on Saturday - all day. Should be a good test for her.
The manual says I can adjust the timing. But I have heard otherwise(a couple of times, actually). What do you think? It has degree markings on the flywheel, so I don't know what to think.

Thanks for the help!

Jason "

"Jason.... The manual mentions

"Jason.... The manual mentions timing only because if you have replaced the crankcase, or changed the timing for some reason, this allows you to return it to normal. It absolutely has to be set to one setting only. Bottom line is: If you didn't move that spark advance screw (the one with a lock nut and a rubber bumper on it), don't play with it as you could very easily cause major internal damage! If you need to re-set the timing, look at the left side of this page, go to "Keyword Search" and search for the phrase "4°" without the quotes.

Note... If you don't know how to make the ° mark, hold down the ALT key and punch in 0176 on your numerical key pad.

Joe (30+ Years With OMC)"

" Neat tip on the ° mark.

" Neat tip on the ° mark. Never heard of it being so complicated.

I think I'll leave the timing alone for now. Anything that may cause major internal damage is something I want to avoid. Also, I haven't changed the crankcase or changed the timing.

Got to change the bunks on the trailer this weekend. One of them flat-out broke in half.

Thanks, and hope you get some fishing in this weekend.

Jason "

" Just purchased a 1987 14 foo

" Just purchased a 1987 14 foot Custom Craft with '87 40hp Evinrude. Took boat out on water and could not get boat on plane. At full throttle, motor felt like it was not getting up to proper rpm. Motor out of water runs fine, will get to high rpms. Starts right up and idles fine. But under load, she appears to bog down WOT. Suggstions appreciated. Thanx. "