johnson/ evinrude question

[flaxterra]

first off, i have a 1970 johnson 18 hp outboard. i just bought this thing for dirt cheep. the guy i bought it from said he did a lot of work to it. like new water pump, cleaned carb, new plugs.... this things looks really clean and i was thrilled to get it. anyways, he told me that it had an idle problem. he said that it problay was the fuel pump cause he could pump the fuel bulb and it was stay running. anyways, i got it home and ran it, like he said it didnt want to idle but higher rpm seemed good. top end seemed a little sluggish, like it was bogging down. it also seemed to smoke a lot even know it was in a large buckey - half a 55 gallon plastic drum. well, i put it on my 14 ft aluminum jon boat today, i was a little worried about it being over powering and too heavy. this boat is only 48" wide and light as a feather. well i took off and it seem to plan off. it didnt exactly blister across the water, it pretty much just ran above plan. i guess my question is, where should i start? i know it doesnt idle well, and i also know it boggs down up top. could this be cause by the carb?? it seems to run really well, fires right up other then idle and top end. just seemed like it didnt have any guts once opened up. sorry for the long post. any suggestions would be great. bye the way, the serial number is 18002c-e09822 i dont know the model number cause the hood is missing, which if anyone knows of one or where to find one it would be great.

 

[jtexas]

Re: johnson/ evinrude question

one thing is certain, bogging down at high speed is a possible symptom of gummed up carb - if that turns out to be the case, you don't want to run like it is because lean running means insufficient lubrication. Not good.

model number is usually on the port side of the engine mounting bracket.

Start with a compression test, then a spark test.

If pumping the primer bulb makes it run good, that does indicate a faulty fuel pump.

Did you use fresh 87-octane gasoline? Did the fuel line hold pressure?

Spark plugs should be champion [edit -- J4C...thanks c/w]

 

[Xcusme]

Re: johnson/ evinrude question

Call me a skeptic, but I take stories of work done with a grain of salt until I verify for myself. Start but checking the usual suspects. Check for spark on both cylinders you could be running on one lung. Do a compression test, this gives you a good base line figure for future reference. If you have to pump the primer bulb to keep it running, it points to a fuel faulty fuel pump. Check the link and sync and mixture settings. All this is pretty normal stuff and more easily done with a service manual.

 

[flaxterra]

Re: johnson/ evinrude question

thanks for the help!!! yeah i pretty much feel the same way about what he said he did. the gas is good, i just got it today and just mixed it. the fuel lines are new. the other day when running in the tank i did pull the spark plugs and they both seemed to be same, neither one was really wet or really dry. can anyone suggest a good online store to find a carb kit and fuel pump kit for these things??? possibly a repair manual?? thanks again for the help.

 

[ColdPat]

Re: johnson/ evinrude question

I have a 25hp 1975 johnson that I clean the carb every year now. I would take the carb apart which is really easy if you go to crowleymarine you can get a diagram. Anyway, on the bowl there is a hole on the side wall that needs to be cleaned out. I would take weed eater line and cut at angle so that it is sharp and start screwing it into the gunk that is down there. it should be able to pass all the way through till you see it in the high speed tub at bottom of bowl. I did spray alot of card cleaner and let it sit. That should definitely fix your idle problem.. Just remember don't anything metal in these little holes.

 

[JB]

Re: johnson/ evinrude question

Needing to pump the primer bulb is NOT and indication of a bad fuel pump. It merely indicates that the engine is not getting enough fuel in normal operation.

Possible causes include restricted fuel tank vent, restricted fuel pickup in tank, restricted (pinched) fuel line and air leaks in the fuel line as well as a weak fuel pump.

 

[jtexas]

Re: johnson/ evinrude question

thanks for the help!!! yeah i pretty much feel the same way about what he said he did. the gas is good, i just got it today and just mixed it. the fuel lines are new. the other day when running in the tank i did pull the spark plugs and they both seemed to be same, neither one was really wet or really dry. can anyone suggest a good online store to find a carb kit and fuel pump kit for these things??? possibly a repair manual?? thanks again for the help.

I get mine at iboats

 

[F_R]

Re: johnson/ evinrude question

You may have more than one problem. 99% of lack of top end power is because it is running on one cylinder. Pull and ground one spark plug wire and see how it runs. Then do the same on the other one. Chances are it won't make any difference with one, but with the other on it won't even run.

Also, check the compression. It may be unacceptably low on one cylinder.

 

[wbeaton]

Re: johnson/ evinrude question

Nothing more I can add except that the 18002c part of your serial number IS the model number, which confirms that you have a 1970 18hp.

 

[Chinewalker]

Re: johnson/ evinrude question

And the plugs should be Champion J4Cs (or J6Cs if you idle a lot) not L77JC4...
- Scott

 

[flaxterra]

Re: johnson/ evinrude question

thanks guys again for the great info!!! i have a carb kit, fuel pump and repair manual on the way. i think im going to just do a complete tune up - carb, fuel pump, spark plugs, ignition and foot oil. which is probaly what i should of done in the first place. it was just too great to hear her run and not take it on a test drive. thanks again and i will keep you posted.