1974 johnson 115 running problems

[norman2013]

Hey guys! Finally a nice day out to get the boat out to test! Unfortunately mine is not running that great yet. I have a 15 foot four winns Fish/ski boat with a 1974 115 johnson on it. I took the boat out on the water today and it starts up good and idles good but when i go to open it up it gets up to about 15mph and that is it. It should reach up to about 50mph. I checked to see if my throttle cable was going all the way forward and it is. Now this motor does not have electro trim so I pulled the tilt pin out so it is all the way down, Im not sure if I should put a little more tilt to it. Also my prop is extremely beat up but have another I can put on if that will help tremendously. The air cap on the back of the motor wasn't there when I purchased the motor and all the part stores say it is obsolete? Do I need one? I did a compression test and all three cylinders are between 115 and 120. I also cleaned the carburetors before heading out to the water? Any suggestions on what I can do to get my boat going faster?

 

[kenmyfam]

Re: 1974 johnson 115 running problems

Was it OK last time you ran it ?? or is this outfit new to you ??
Compression you have done and appears OK, how about a spark test and fuel delivery test.
Oh Yes, fix or replace the prop !!!!
Air box cover should be in place but that is just my opinion to help keep any dirt and debris out of the fuel system.

 

[norman2013]

Re: 1974 johnson 115 running problems

yes the boat is new to me. I just put on the new stainless steal prop, Also should I put the tilt pin in at all to tilt the motor up some? How do I go by doing a fuel delivery test?

 

[norman2013]

Re: 1974 johnson 115 running problems

Some times when i go faster then idle speed the fuel funs out and the fuel ball gets soft and will stale if i do not pump the ball?

 

[boobie]

Re: 1974 johnson 115 running problems

Do a cylinder drop test on it to see if you have any cylinders that aren't firing.

 

[norman2013]

Re: 1974 johnson 115 running problems

I just did the drop test and it appears when I have them all hooked up and drop one then put it back on then same process to the others that they all appear to be working. But the two left cylinders when the right ones are un done and one of the lefts it stalls out after a second of running on there own that is for the top and bottom of the left side? I figured the top carb would go to the top two cylinders and the bottom carb would go to the bottom two cylinders but am I wrong does one control the left and the other control the right? the right two seemed to be able to keep the motor running when I just dropped one of them but very low rpm.

 

[norman2013]

Re: 1974 johnson 115 running problems

The gas pump ball does not stay hard and it runs out of gas pretty often? I just took the boat out for a spin with the new prop and the motor tilted up a few notches but nothing has changed.

 

[racerone]

Re: 1974 johnson 115 running problems

Inspect the fuel pump.

 

[norman2013]

Re: 1974 johnson 115 running problems

I just inspected the fuel pump and it does not seem to be working properly. I blew air through the intake spout and went to blow air through the other and air was going through that one as well? its my understanding that the sec on one should not let air pass? is there a way to fix it?

 

[175se]

Re: 1974 johnson 115 running problems

agree with racerone, fyi top carb feeds top two-bottom carb bottom two.

 

[emdsapmgr]

Re: 1974 johnson 115 running problems

The results of your cyl drop test is a little hard to understand. Your expectations of the cyl drop test is that if you pull one spark plug wire off a plug, the rpm's of the engine will go down-noticeably-but the engine should keep running on the other 3. Test all 4 cyls that way. If you pull one plugwire off and the engine quits-that could be a sign of an ignition problem. One of the other plugs is not firing and when you pull another plug off, now two cyls are not firing and it may stall. The primer bulb only gets rock hard when you pump it up. Once the engine runs and starts to draw fuel through the hose bulb, it will soften somewhat-but should not collapse on itself. That's normal.

 

[norman2013]

Re: 1974 johnson 115 running problems

Wile running the motor runs out of gas and I need to pump the bulb to get gas back into the motor. It doesn't appear to be dragging the fuel into it. The fuel pump seems to not be working properly when I pulled it off. Also I believe The drop test showed that all cylinders were firing. I need to do a spark test tomorrow. What is the best way to do one?

 

[emdsapmgr]

Re: 1974 johnson 115 running problems

Another spark test is to use an inductive timing light. Put the clip-on lead on each plugwire. You should see, sharp, rhythmic flashes from the gun. You will be able to see misfires, weak firing, etc. If an engine requires constant priming of the fuel hose bulb, you have a fuel delivery problem. Could be bad ball valves in the hose bulb, a bad anti-siphon valve at the fuel tank (if it's a built-in tank) or even a weak fuel pump.

 

[kenmyfam]

Re: 1974 johnson 115 running problems

Put temporary line on output side of pump into a container. Crank the motor and see what happens.
Regular strong spurts of fuel = pump working
Strong spurts tapering off in quantity as you crank the motor = failing fuel pump
Dribble or nothing = failed fuel pump.

This does not discount bad bulb or anti siphon valve.

 

[norman2013]

Re: 1974 johnson 115 running problems

I just purchased a new bulb for the gas tank, new connectors for the tank and line, and used another one of my fuel pumps that is identical that appears to be working properly. Also I soaked the carbs in parts cleaner for some time and we will see what happens today!

 

[kenmyfam]

Re: 1974 johnson 115 running problems

I just purchased a new bulb for the gas tank, new connectors for the tank and line, and used another one of my fuel pumps that is identical that appears to be working properly. Also I soaked the carbs in parts cleaner for some time and we will see what happens today!

Good Luck. Make sure the bulb is the correct way around.

 

[norman2013]

Re: 1974 johnson 115 running problems

ok guys, an update on my 1974 johnson 115. I took it out today and it started up and idled great but when I went to go any faster it putted like its not getting enough gas or air? It would not go any faster than 5-8 mph. I did a compresstion test on it wile it was cold and Results we're #1 130, #2 131, #3 130, #4 128 which seems really good. Did a cylinder drop test and it appears that all cylinders are firing. I took the carbs off and cleaned them with carburetor spray. then took them off again and cleaned them in a parts cleaner over night. I took the fuel pump and tried to test it by blowing air into one hole and it passed right through, then i blew through the next one and it had a small leak of air. So after I heard that I took a fuel pump off of a similar motor and used the front parts of it to see If that would help and at first It seemed to not let air through the sec on hole but i checked it again and now it seems to be letting a little? The only thing I have not done yet is do a proper spark test. And I was thinking about putting the original duel pun back together and using gasket sealer on all gaskets? What do you guys think? After this I will be hitting a wall of stuff that Iv done to motors? Open to anything! thanks!

 

[norman2013]

Re: 1974 johnson 115 running problems

Another note, In the driveway on muffs it seems to run great! It gets up to full throttle and sounds great?

 

[kenmyfam]

Re: 1974 johnson 115 running problems

Do not wind the RPM up while on muffs. Motor can run away and destroy itself.
There is no actual load on the motor when on the driveway.
Did you do the pump output test ??

 

[norman2013]

Re: 1974 johnson 115 running problems

I wasn't clear on what I should be looking for when I do that test?