1973 4hp johnson need help

[hobojoe]

My brother bought a 1973 4hp johnson sea-horse mod#4r73c,he is leagaly blind and a amputee,but loves to fish. the motor runs good but when we got on the lake it went about a half mile and died.when got started again did same thing.finally got running again and did not run in fast and it didnt die.could it be a carb prob?it is pushing a 1956 14ft aluminum elgin could it be to little for the boat? he has no manuals and as i said he is handicaped and cant afford to order one. I am unemployed and cant afford to help except as eyes, laber and researcher.any help would be greatly apreciated. thank you joe

 

[oldcatamount]

Re: 1973 4hp johnson need help

When the motor is running, is there a slight spray of water coming out of the little holes on the back side of the exhaust housing? I'm thinking it may need an impeller and it's running a bit hot. I've got the exact same motor and I found that the water pick up screen was plugged up with lake debris and causing the motor to run hot and shutting down like yours is. I cleaned the screen and replaced the impelller and ended the problem.

 

[Rick.]

Re: 1973 4hp johnson need help

Try running at fast rpm and just keep pumping the bulb. If it runs good stop pumping and if it dies that would indicate you have a fuel delivery problem. Plugged pick-up screen, weak fuel pump or even a dirty carb. He picked a good motor as these little guys run well and are economical to run. Size of boat won't matter as your only going to get to trolling speed and a wee bit faster. It's never going to plane the boat. Best of luck. Keep asking questions. Rick.

 

[hobojoe]

Re: 1973 4hp johnson need help

the guy my brother got the motor from said had been in his uncles barn for years.we replaced lower unit oil.the holes in back you can feel exhast come out but just a tiny bit of water,could not tell if was just spray or coming from holes.i had a 35 merc back in 80s and could tell see the water spray out on that but dont know about this motor. the guy he bought it from had a new impeller for it but am not sure of how to get to it. motor souds like a champ when running ussualy starts on 2nd or 3rd pull.my brothers going to replace plugs pulled 1 out earlier was black and oily and dry and brown on the tip.if that will help thanks

 

[hobojoe]

Re: 1973 4hp johnson need help

thanks rick.i know when went out i have to drive with him being leagally blind. when squeezing the bulb it it stayed flat figured had to work fuel through the line.thought maybe was getting air pokets in line or something.i dont think the fuel connectors are orig have a double prong on tank and line. this is the second motor he bought he got took on the first a 9.9 gamefisher the guy said it ran when he put it up 2 years ago but now it gets no spark he paid 250 for that one .the guy did give back 60 dollars.and didnt want motor back.it is at a boat shop now he told my brother that would be a science project for him and wouldnt charge him unless can find something in place of the electronic ignition then only charge for the part.joe

 

[jspansel]

Re: 1973 4hp johnson need help

The bulb should stay firm... Fuel pump or bad bulb?

 

[Rick.]

Re: 1973 4hp johnson need help

thanks rick.i know when went out i have to drive with him being leagally blind. when squeezing the bulb it it stayed flat figured had to work fuel through the line.thought maybe was getting air pokets in line or something.i dont think the fuel connectors are orig have a double prong on tank and line. this is the second motor he bought he got took on the first a 9.9 gamefisher the guy said it ran when he put it up 2 years ago but now it gets no spark he paid 250 for that one .the guy did give back 60 dollars.and didnt want motor back.it is at a boat shop now he told my brother that would be a science project for him and wouldnt charge him unless can find something in place of the electronic ignition then only charge for the part.joe

Well the bulb should not stay flat. I would check the pick up screen right in the tank and see if it is plugged up and if it isn't, it could be a bad bulb. When pumping the bulb it should get hard when the carb. is full of fuel. From the point the motor starts the bulb is nothing more than a fuel suction hose so it will get soft, not collapsed, just soft. Rick.

 

[nwcove]

Re: 1973 4hp johnson need help

is the vent open on the tank?....or not working? (sometimes its the little things that get overlooked!)

 

[1Crazymechanic]

Re: 1973 4hp johnson need help

Also check fuel connector at tank to make sure it is connected properly, and has good seal. Could just be a bad primer bulb. Sounds like that
motor definitely needs carb cleaned and water pump impeller also.

 

[hobojoe]

Re: 1973 4hp johnson need help

the tank is a yamaha and has no vent that i know of.but while on subject.looks like a digital fuel gage but shows nothing .is there a battery in it somplace? he found the spark plugs doesanyone know what the gap should be? thanks for all the help. joe

 

[the machinist]

Re: 1973 4hp johnson need help

If you are also using a Yamaha fuel line, that may be your problem as the Yamaha couplers look line the Johnsons, but the barb/female coupler is slightly larger & if you have not changed the motor end to a OMC coupler the Yamaha one will be loose on the motor & not give proper fuel delivery.

 

[Bill3434]

Re: 1973 4hp johnson need help

Loosen or take the cap off the fuel tank and see if the bulb stays flat. If the bulb is good and it stays flat is is trying to suck fuel back into it, therefore it's competing with the engine for fuel. I agree with "the machinist" you should be using Johnsons equipment on a Johnson motor. If the bulb does not inflate back to normal I would check the pick-up in the tank and see if it is clogged.

 

[hobojoe]

Re: 1973 4hp johnson need help

changed impeller today.the old one had a strange little thing hanging from it.dont know how to explaine, it hung down in the seal under impeller,kind of looked like the end of a liquid super glue spout that aet for awhile.at first thought was part of the seal but then noteced that was there,but put new one on and think im getting lower unit oil come up with the water but not sure.and its just a splatter of water coming out holes.cant really see but hold hand behind and comes away wet.didnt find a screen.replaced spark plugs didnt know the gap(think its .030 now)have to check on monday if thats what they are set at.and checked gas tank screen seemed clean.seems to run good but did that befor taking it to the lake it ran for about 30 min without dying.prob wont be working on it again till next week.but everybodys imput is agreat help to me thank you very much everyone..joe

 

[Rick.]

Re: 1973 4hp johnson need help

You have the plug gap set correctly. Can you borrow an OMC tank and hose from someone and give it a try? Rick.

 

[hobojoe]

Re: 1973 4hp johnson need help

You have the plug gap set correctly. Can you borrow an OMC tank and hose from someone and give it a try? Rick.

thank you everyone took out sat night ran good it stll wants to die at full power but runs great any other speed.we replaced the impellar,sparkplugs and checked fuel tank/fittings/screen.this is a good site all the posts were helpfull in working on the motor. happy up comming holidays to all and thank you. JOE