235 missing at low rpm

[bmstang]

I have a 78 235hp evinrude that is spitting and missing slightly at low rpm.If i manually hold the throttle open at about 2000rpm it is very noticeable.It runs perfect at high rpm's no missing at all. Everything has been redone on the motor rebuilt carbs, rebuilt fuel pump, checked spark, checked compression, changed timer base, checked stator,new head gasket i am thinking air fuel adjustments on carbs but i don't see the adjustment screws on these carbs. Any help would be great thanks.

 

[bmstang]

Re: 235 missing at low rpm

I would also like to know if anybody knows how to test a temperature sender. I already went through 2 gauges thinking one of the gauges were bad. I have 12v at the gauge good ground but get know readings and this is a new sending unit i put on. thanks

 

[keefallan]

Re: 235 missing at low rpm

I don't think you have adjustments for the carbs. You should have fixed jets. I am almost sure of this. If this is not the case disregard everything I'm going to post because then I don't know what carbs you have. You need to take your jets out and make sure they are completely clean and takea piece of soft wire thru the idle tubes. If they are clogged you won't idle for jack!! I know, I just went thru this with my 1985 150johnson(same block as yours). Also check jet sizes and make sure they are the proper size. Evinrudes website has all those numbers. The numbers are on the jets. Good luck.

 

[bmstang]

Re: 235 missing at low rpm

I do have fixed jets but there is usually an air fuel screw that you can adjust the air fuel ratio at least there is one on my 28 spl. It idles fine also no missing at all just when you start to get around 1500 to 2000 rpm's. The jet came with the rebuild kit for that motor so i assume there wright Thanks for your help.

 

[keefallan]

Re: 235 missing at low rpm

You should have three jets on each barrel. Two per carb. If your carbs are similar to mine you 2 idle jets in the butterfly area, 2 main jets behind the 2 large screws on the float bowls(sides) and 2 intermediate jets inside the float bowl. And no there are no air idle adjustments for the carbs if its a crossflow motor. That's about all I can tell you. Are you sure that jet you got in the rebuild kit wasn't the needle valve and seat? I got one of those in the three kits I ordered for my 3 carbs. I hope this helps.