1987 johnson 70 hp fuel/carb problem

[natecollins]

I am trying to fix a 1987 johnson 70 hp. When I first started on this motor, I noticed that I had way to much gas at the carbs. I could put my hand over each of the carb opening and come off with gas on my hand. I had to open the butterfly valves on the carbs to get it running. I rebuilt the carbs (gaskets, needle, seat, float) per the manual. I put the carbs back on, but still have the same problem. I took off the air line of the fuel pump and was able to get the motor to run better until it the carbs started to run out of fuel. I also left the air line of the fuel pump disconnected and was able to keep the engine running by pushing on the fuel tank primer bulb. This engine has a primer solenoid not a choke. I think the problem is that the carbs are still getting too much gas. Can anyone help me?<br /><br />Thanks,<br />Nate

 

[Goodoleboy]

Re: 1987 johnson 70 hp fuel/carb problem

Hi Nate!<br /><br />All air that your motor gets is through the carb throats. Theirs no such thing as an air line going to a fuel pump or any other place for that matter.<br /><br />I doubt that your geting to much gas to the carbs. With your motor setting dead, Try squezing the primer bulb and see if it gets quite hard. If so then your needle and seats are working the way they should and so is your primer bulb.<br /><br />If it stays squishey then one of two things is going wrong. Either you have a needle and seat bad in one or more carbs.<br /><br />If you see gass running out the carb throat then thats the bad one.<br /><br />If no gas is seen, then the check valve has gone bad in the primer bulb.<br /><br />You say you have a manual. Try doing a link and sink on this motor. <br /><br /><br />Good luck

 

[the rebel]

Re: 1987 johnson 70 hp fuel/carb problem

I think the "airline" to the fuel pump that Nate is refering to is the pulser(vacuum) tube from the crankcase to the fuel pump. BWJ

 

[Goodoleboy]

Re: 1987 johnson 70 hp fuel/carb problem

Yep.... Ill bet your rite. BWJ<br /><br />I had it in my dumb head that he was thinking air was being mixed with gas at the fuel pump.<br /><br />Sorry bout that Nate!

 

[natecollins]

Re: 1987 johnson 70 hp fuel/carb problem

I have checked the fuel line and it is getting firm. I do not see any fuel leaking out of the carbs. The air line I am talking about is the pulse line off of the engine. Is it possible that the primer solenoid valve is sticking open? Thanks,<br />Nate

 

[Goodoleboy]

Re: 1987 johnson 70 hp fuel/carb problem

Nate!..The primer solenoid is an injection pump directly into the cylinders it bypasses the carbs. It only gives one shot of fuel each time you push the key in.<br /><br />If it is set on run its activated by the push of the key. If its set on manual it will inject fuel by squeizing the primer bulb. The more you pump the bulb the more fuel it injects.<br /><br />If the tank is seting in the sun and it builds up pressure, and the solenoid is set on manual it can litterly fill the cylinders full of fuel.<br /><br />A test you can run with your ohm meter is to check reading betwen the blue and white stripe wire and the black ground wire.<br /><br />should check 5.5 ohms +or- 1.5 ohms. If it dosent then replace solenoid.

 

[natecollins]

Re: 1987 johnson 70 hp fuel/carb problem

I looked at the system again. I pressed the fuel tank primer bulb. Even though it firmed up considerably, I could still hear some gas leaking out in the carbs. I opened the butterfly valves on the carbs and noticed that it was coming from the primer ports behind the butterfly valves. I checked the ohm reading on the solenoid and it checked out at about 6 ohms. I still did not feel it was working right, so I opened it up. I found that the tip of the needle inside the primer was melted. I can guarantee that this in not letting it seat against the valve seat properly. I was able to get the motor running in idle good with the primer taken off. I will replace the solenoid or solenoid parts when I can. I hope this helps someone else in the future. Thanks for your help.<br /><br />Sincerely,<br />Nate