87 40 hp Evinrude won't idle

[bswygard]

Runs great at high speeds but can't go slow. Cleaned carbs and works great in tank, but at the lake same problem, When you start it you have to gun it and get speed or it will cut out. Idles fine with hose on it no rpm. Had it idle in tank for 20 minutes with rpm, Usually hard to start, especially after it dies.

 

[Bosunsmate]

did you make sure the small holes/jets in the carb were clear? if you dont blast carb cleaner down every hole and check it comes out another then carb gunk is generally still left in there

 

[gm280]

Cleaning a carb and rebuilding a carb are two different issues. Most of the time folks spray some carb cleaner on the outside of the carb and maybe even remove the fuel bowl and think they rebuilt their carb. You literally have to disassembly the carb in its entirety and then use carb cleaner via spray type or even soak it in carb cleaner for a few hours. Then follow that up with compressed air and make sure every little hole and slot is free from built up varnish and dirt. Then reassembly the carb using new needle and seat and gaskets and "O" rings where called for. Otherwise, you haven't really rebuilt the carb. JMHO!

 

[bswygard]

Ok, I have not soaked it yet. But are we saying this is the main cause of problems like mine?

 

[jakedaawg]

Basics first, fuel sample, compression test, open air gap spark check at 7/16". Anything else and you are just wasting time.

 

[scrapper042000]

87 model that doesn't have the adjustable mixture screws quite yet ? ...so yep therefore you have fixed idle mixture jets that may be plugged ......if you can run fast then your floats are set ok and your needles are not hanging up ,,so it can only be in your idle circuits and or check your roller on the the throttle plate to the carb there is an alignment mark ,if your linkage is incorrect and its starting hard you might be opening your throttles early before the timing has a chance to advance to keep up with the throttle position ...similar to a lean or late response condition ...and yep ..........check comp first ..........an outboard cannot be tuned or adjusted when the cylinders are not contributing evenly ,but you are reaching high speed and generally a weak cylinder will cough and spit and not let you make it to high speed ......

 

[racerone]

Everybody starts with carburetor work ????-------But a compression test is the first thing to do !!

 

[bswygard]

Thanks, everyone