johnson/ evinrude 18 hp

[flaxterra]

i posted on here about my 1970 johnson 18 hp motor and for just a quick recap, when i got this motor i ran it and found that it didnt want to idle and seemed to bogg on top end. other then that it ran good. the person i bought it from told me it was the fuel pump. after reading everyones advice i purchased a fuel pump and carb kit. well it came today and i installed the fuel pump first just to see if it made any differance. it fired right up and seemd to idle better. i let it warm up and goosed the throttle and it also seemed to wind out better. after about a minute, it began to kick back, i guess misfire. not all together, just like every once and while, and then died. so i pulled the spark plug wires loose to check the spark. something wierd kinda happened. i got it started and pulled one wire off, as soon as i did it quite like it was only firing on one cylender. after i started it again, both wire seemed to have good spark and both ran with the other unplugged. i ran it a little longer and it began to kick back again. now it runs better as far as idle and top end but this misfire thing has thrown me. not sure where to go from here. i do still have the carb kit and plan on installing it. any info would be great.

 

[samo_ott]

Re: johnson/ evinrude 18 hp

I'd still put the carb kit in it.

Also check the compression for a baseline.

Also, Johnson did not make an 18hp in 1970. What model # do you have?

 

[tmcalavy]

Re: johnson/ evinrude 18 hp

If you have good spark and the coils look sound, you have pulled the flywheel to have a look right?, then pull and clean the carb. Then re-install and reset the high/low speed needles. Sounds like you are too rich or too lean at idle.

 

[flaxterra]

Re: johnson/ evinrude 18 hp

thanks again guys. great info. the only number i have found on this was 18002c - eo9822. anyways, do you have to have a puller to pull the flywheel??

 

[Basher]

Re: johnson/ evinrude 18 hp

Flax

I just pulled my flywheel to change the ignition components a while back and yes a puller will definitely help. Also you may want a second person with good strong hands to hold the flywheel when you loosen the nut, otherwise the flywheel will turn instead of the nut.

Basher

 

[flaxterra]

Re: johnson/ evinrude 18 hp

ok guys this problem is beginning to get really strange. so, i pulled the carb and began to rebuild. the inside looked great, passages clear. i went ahead did all the cleaning, check the float and replaced all the gaskets. put it back on and set the mixture. here is where it gets wierd. the motor runs great at idle and in gear. after setting mixture the motor runs good, then out of the blue it idles up and starts spitting back, while it does i tried to change the mixture, nothing. now, in gear it never seems to do this. at idle though after running for a minute or so it idles up and starts spitting. i can pump the bulb and it seems to clear up. seems like a lean miss only it doesnt do it all the time. im going to get a new set of plugs right now cause one of the plugs seemed to keep fouling out, so i switch them and the same plug fouled in a differant cylender. any suggestions???

 

[F_R]

Re: johnson/ evinrude 18 hp

Speeding up and lean sneezing sounds like it is running out of gas. Confirmed by squeezing the bulb. Check for air leaks in the tank hose, leaks where it plugs onto the motor and tank. If no air leaks, it probably has a bad fuel pump.

 

[samo_ott]

Re: johnson/ evinrude 18 hp

I concur, sounds like a lack of fuel situation...

But you never mentioned high speed. Does it get to WOT? did you try? As if it does then it's not a lack of fuel.

 

[flaxterra]

Re: johnson/ evinrude 18 hp

first off thanks for all the advice guys. so the new plugs didnt really change anything but at least i can mark that off the list. in the mean time i pulled the fly wheel. every thing under there looks good, i think the last owner said he replaced all that. so i decieded to put on the old fuel pump, which by the way i was told by the owner was the running problem, boggs out on top end and wont idle. no more miss but loads up like before. a quick question. my new fuel pump looked a little differant then my old one. the back plate, the aluminum piece, was longer. i had to get longer screws. also the fuel line inlets were in a differant spot so i had to take the back aluminum plate off and turn it to make it fit. has anyone else had this problem?? wondering if this is even the right pump? now im thinking i should just take the new parts out off the new pump and put it in my old one. any thoughts?? by the way the part number for the new pump is 18-7350 in case anyone is wondering

 

[samo_ott]

Re: johnson/ evinrude 18 hp

18002c is an Evinrude 18hp 1970. Does it have a Johnson hood on it?

 

[flaxterra]

Re: johnson/ evinrude 18 hp

no hood on motor when i got it. i guess it is a evinrude. any suggestions on the running problem??