1973 50 hp evinrude (50373r) bogs down past half throttle

[AlTn]

a friend of mine used a hole saw to drill holes large enough to get a thin walled socket on 2 exhaust cover screw on a 18 hp. some years back, but he didn't have to drill through the curved portion of the pan and you're going to have to get these screws back in at some point...'bout all I can offer

 

[jake83]

Hole saw came to mind as soon as the bolts run into it. Just not sure if I want to do that. I'm assuming the right way is to go ahead and pull the powerhead. The manual isn't a whole lot of help. But if I am going to have to pull the powerhead anyway then I might as well just pull the head and get a full view of the pistons, right? I was just hoping I could loosen something to raise the powerhead just a little bit, the middle bolt feels free but the one on the rear has still got threads biting, but not many. If I have to pull the powerhead is that a terribly difficult task? I'm beginning to wonder if I have bitten off more than I can chew here

 

[AlTn]

remove 1 of the other screws to get an idea of how much more clearance you need...removing the head will give you a view of the piston heads, cylinder walls, block,cooling channels, combustion side of the head, etc. all do relate to engine condition and inspection.

 

[racerone]

If the fuel pump diaphragm has a hole in it you will flood the top cylinder with fuel.-------Motor will not run properly with too much fuel !!!!

 

[jake83]

Well that makes sense. I will pull the fuel pump apart before I dig into anything else, as that seems much easier. I will let you know what I find in there

 

[jake83]

So the fuel pump doesn't seem to be serviceable or rebuildable. I was just going to pull it apart to inspect the diaphragm but it doesn't seem that easy. Should I just break down and buy a new fuel pump or is there a way to test your theory without spending 100 bucks

 

[jake83]

No Title

I know it doesn't mean much but the pump looks relatively new. Seems like they would make it so you can rebuild it or at least take it apart. Screwdriver and bfh should get her apart. Lol.

 

[racerone]

????-----Not sure how or where you get your information.------They are rebuildable and it is easy !

 

[jake83]

I was just looking at the parts diagram. No diaphragm listed so I assumed that I cannot buy a new one. Guess I'm stupid for assuming. My daughter isn't feeling well so I haven't gotten a chance to pull it. I'll go pull it now.

 

[jake83]

No Title

Well that was easy. Unfortunately it looks fine. Even took the diaphragm into a dark room and held a flashlight behind it. I did not separate it from the gasket though because I was afraid of tearing it. Let me know if it is necessary.

 

[jake83]

So the motor ran fine never had a problem keeping fuel to it till I took the intake off and replaced with my custom gasket. Could that be my problem with gas? Or maybe not a gas issue, but it Sure seems I can run it longer pumping the bulb.

On another note I got the motor running about ten mins the rechecked compression just to see. 165 top and 170 on the bottom. Hmmm. I also took a can of brake cleaner and sprayed all over the motor while running, especially aimed under the flywheel and around gaskets and hoses. It did stall out when I sprayed the fitting under fuel pump leading to the intake, but it was the only original clamp so I removed it and cut back a little since it was kinda jacked up. Put a new zip tie on and that went away.Or maybe it just happened to stall when I sprayed there. It stalled one time when I sprayed under the flywheel too, but couldn't get it to repeat itself.

So I also talked to a two stroke mechanic (friend of a friend deal) and he suggested that it sounded like it could be a blown head gasket letting water into the top cylinder. Now I saw no signs of rust or anything but heck, I'm kinda learning as I go here so I welcome any and all opinions. He suggested to pull the boot off and run it without water for a min. (NO LONGER). Then see if the top cylinder gets stronger, which I figure a screwdriver shorting the bottom plug should tell me. I have a small water leak coming out the top of the foot anyway, so I kinda wanna see how everything works on the bottom end anyway and fix the leak while I am at it. I pulled the bolts attaching the foot and it dropped but not completely. After further research apparently there is a bolt holding the shift linkage under bottom carb. So when I get off this grill I'm gonna figure all that out.

If this doesn't show me something then I guess I'm gonna figure out how to pull the powerhead and pull this thing apart. I can't keep throwing money at this thing, but on the other hand if it's broke I gotta fix it. The stator and coils were both cracked and leaking so altough I still had spark it was just a matter of time before they failed. The rectifier was bad so that was worth it. The starter solenoid was bad so it was necessary. The carb rebuild was definately needed. All this to say I keep fixing things but am I just wasting my money? I hate to let this thing whoop me.

Just wanted to let y'all know where I'm at. I appreciate the help I get on here because lord knows I'm lost on my own. Thanks for your patience. I'm gonna go drink a beer now.

 

[oldboat1]

a note on condition of fuel pump diaphragms -- should look for flexible, with no set. If it has the feel of cardboard, it needs to be replaced.

and a note on using plastic ties. I've been using them regularly for a while, and a lot more convenient to use. I use a needle nose and bladed screwdriver to tighten them up -- can usually get an extra click or two by hold the end down with the screwdriver, and pulling on the other end with the needle nosed pliers, using a twisting motion. Don't seem to get leakage.

 

[jake83]

The fuel pump diaphragm was pliable and pushed back and forth easily. Everything seemed rather new. Heck I'll take it apart and check again, it only takes a sec.

Thanks for the tip with the zip ties. I actually have been using ss hose clamps but didn't have any left

 

[AlTn]

with the spark plugs removed, roll each piston up to tdc and look in with a flashlight...does that upper cylinder appear to be steam cleaned?..if so..you may have water intrusion...running without water going to the impeller isn't doing it any favors....pull the head and inspect before pulling the p/h...check the head for flatness while it's off, most of the time you'll find some warpage or low spots particularly between the 2 cylinders

 

[jake83]

I have looked in both cyliner and both seem to be dark brown. Definately not clean.

So I don't have to pull the powerhead to pull the head off? Seems like there is a bracket tied up in there. Don't mean to sound ignorant. Heck I got a buddy telling me "just pull the head, pop the pistons out the top and change the rings". Can it really be that simple?

 

[jake83]

Also I noticed that in the exhaust plate there is a plug in the top section that has two wires that have been cut flush. I'm assuming this was the thermostat? I have run trucks without one to keep it cool but what symptoms would that have on my little evinrude here? And I will look closer at the top of the pistons tomorrow as well as double check my fuel pump. And if u say running it with no foot can't help then I will just see if I can repair the seal.

 

[racerone]

Your " buddies " are not giving you top notch advice !

 

[jake83]

And that's why I'm turning to you for help. Lol

 

[racerone]

Organized trouble shooting MUST be done !---Throwing parts at it gets expensive.-------Visually examine the crankcase for cracks / holes.---Do you see any , yes or no ?

 

[jake83]

I have to work today (gotta pay for all these parts somehow), but when I get home I will take a closer look. I do believe the crankcase seems to be in good shape tho and I hosed it down pretty good with brake cleaner while it was running. I will let you know when I get the chance.