25E72R Need some help.

[hardwater fisherman]

I have a 1972 25hp Johnson that I bought from a friend at work. For 100 dollars. He said it was rebuilt. The compression is at 150 psi on each. Im sure my gauge is reading high but the compression is good. I took a chance but the shift lever is broken off flush. I put the motor in neutral by pulling off the plate on the exhaust housing,and lifting the shift rod.It has electric start that does not look like it has ever been used but works. The electric choke also works. The first time I started it the motor was like loading up and it would swivel and die. Then after it ran a little it was ok and idled down very slow. Today it would run for a while and then swivel and die. It would start right back up and sometimes run for a while and then repeat the swivel and die. It passed the cylinder drop test. And it starts with only the top plug, or bottom plug attached. I removed the carb and it has a new float, needle and seat.And the carb is clean, including the high speed orifice and the idle circuit. He told me it had been rebuilt but not run for 2 years because of the broken shift lever. I did remove the flywheel also and it appears that it has a complete new ignition. I will clean and check the gap on the points in the morning. I have already ordered the parts I need to repair the shift lever. So if anyone can suggest what I should try next then thanks.EDIT When the motor seems like it is loading up , pumping the bulb makes it die.

 

[oldboat1]

sounds like it has a lot of promise. Put in a new impeller, and check operating temps. May need a t.stat (obviously don't want it to overheat, but cold running can give you some of the issues you describe.)

 

[hardwater fisherman]

It is pumping water well and I checked with the gun and it never went above 155 degrees. All though it is running in a barrel of very cold water. I will be replacing the impeller and thermostat for sure. The gear lube looked like new and the spark plugs are brand new also.

 

[oldboat1]

rich running, maybe? Could be it hasn't been dialed in -- close the idle mix needle, then open 1 1/2. Lean it out slowly until it stumbles, stalls or lean sneezes, then back out 1/4 turn. (Fuel ratio is 50:1.) Think you've done a number of them, so probably preaching to the choir....

155 is pretty warm. I usually see something between 120-130F idling in a barrel (thinking of my old 18) -- guessing hose water temp is probably somewhere around 40-45.

 

[hardwater fisherman]

It only reached 155 once and then fell down to around 135 on top and 125 on the bottom. I assume that is when the thermostat opened. I had to break the ice off the top of the barrel. So the water is very cold. It did run better last week when the water was warmer.

 

[hardwater fisherman]

This carb does have a needle valve bearing that I have not seen before. Part number 0314166. And when I look into the carb I cant see it. I saw on anther site that to replace this valve you need to fish it out. Could this be my problem?

 

[oldboat1]

If it's clear and only one of them in there, should be OK. You said the idle circuit was clear, so assume you removed the expansion fitting on top -- may need to do that again, and run a narrow wire in the orifice. With the core plug/domed plug off, you should be able to see the point of the needle poke through the orifice. If so, I would think you should be OK.

 

[hardwater fisherman]

No Title

No i did not remove the plug but air passes through and I poked through the holes underneath. I normally clean them with acetone but I was not sure with this one. Because of that needle valve I did not want to melt it.

 

[oldboat1]

If it were mine, I would want to confirm the needle is fitting properly in the orifice. I would take the domed fitting off, and soak the top of the carb (needle removed) whether or not the "bearing" is in place, then fit the needle while you can get a peek at it from the top. Would take the float and float valve out before soaking -- probably all can be reused. (JMO)

 

[F_R]

So, you said pumping the bulb makes it die. That suggests either a bad float valve, or more likely a pin hole in the fuel pump diaphragm. Gas leaks through the hole, into the crankcase, making that cylinder too rich.

 

[oldboat1]

^^Good point! Your motor has that blasted little square pump -- effective little rascals, but I usually replace them rather than try to rebuild. The last one I bought was under $40 (origin unclear), but still fine.

 

[hardwater fisherman]

No Title

To test the fuel pump can I pull it away from the motor and pump the bulb? To see if fuel is leaking. I was thinking about the very first time last week when filling the carb with fuel. there was some leakage from the top of the pump. I tightened the screws a little and it stop leaking. Also this morning I noticed the hose from the upper bypass cover bleeder valve is missing. And it looks like the nipple has been plugged. There is a hose running from the bottom right hand corner of the fuel pump bypass cover around to the intake below the carb. The parts breakdown does not show the hose going there.

 

[racerone]

Does the hose go to a bolt ?-----Is there a hole through the bolt ?-----Does the bolt hole go through into the crankcase ?

 

[hardwater fisherman]

I just looked and yes it is a bolt with a nipple and a hole that goes through it.

 

[racerone]

And does the threaded hole go right trough the block and into the crankcase , yes or no ??

 

[hardwater fisherman]

I think F_R may be right about the fuel pump. When I pulled it off the outside of the gasket was wet with fresh fuel. And it is leaking again at the seam of the 2 black parts when I pump the bulb. And after I stop pumping I can hear air escaping from the pump. I will try a different pump later today.

 

[F_R]

Yes, you can test the diaphragm by unbolting the pump and squeeze the bulb. Gas should not come out the backside.

I think I know where racer is going with this. Those motors were early attempts at reducing emissions into the water. They really didn't idle too well, and people made some mods to improve the idle.

 

[hardwater fisherman]

And does the threaded hole go right trough the block and into the crankcase , yes or no ??

I just pulled the hose off and there was a little oil dripping out of the nipple. So I assume it goes right through.

 

[racerone]

?---Can you blow thrpugh the bolt and into the crankcase, yes or no ?

 

[hardwater fisherman]

?---Can you blow thrpugh the bolt and into the crankcase, yes or no ?

Yes I can.