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evinrude 70hp engine cut out on throttle.

H

hollygolly

New member
Good day people.
I have recently bought a second hand evinrude 70hp outboard, 1982 about 6 weeks ago. When out of the water on the trailer it starts fine, goes into gear and revs well. but when i put it in the water (sea) and start it it ticks over OK, but as soon as i try to put any throttle on it, it dies, just cuts out. I have tried to get some revs on it, and it will drop into gear and tick over and run at about 3knots, but try any more revs and it cuts out? I stripped the fuel pump and noticed the plastic plug and spring was siezed, so released that and cleaned it all out thinking problem solved, but no still the same. I have took the front cover off the carbs and put in some carb cleaner and left it for an hour or so, started it up and noticed it now races ever so slightly, more than it did before.
This was a month ago, started new thread now as i have not been able to get down to the boat due to bad weather, i have been able to get to the boat now.
Have now done a compression test and have 130 (top) 135 (middle) and 150 (bottom)
i replaced the spark plugs, which had a .70 gap, and put a .30 gap on the new ones.
I have replaced the prop to a 15 pitch as i was told that may be the problem.
I had it in the water yesterday and can now get a few more revs than i could before, but it still cuts out, so i have removed the carbs. They look pretty claen to me when the bottom bowl was removed. Can some one explain what i need to do to them to get them ship shape.
Thanks
Peter
PS if anyone has any other ideas as to what the problem may be please feel free to comment.​
 
Have you removed the jet that screws into the bottom of the carburetor bowl?? ---It must be clean.-------Have you check carburetor / timing synchronization?-----------If carburetors open too early then the motor will stall.
 
Good evening.
I have removed the screw (3) at bottom of bowl, and flushed through with carb cleaner, i have also flushed through the jet intake and it freely pushes a jet of cleaner through small hole which feeds the valves.. I did check the sync on the butterflys before i removed them, and as you open and close them they appear to open and close all at the same time. I did wonder what the screw (26) was for? Should i be removing this and cleaning inside, what is inside?
Thanks
Peter

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Number 33 is the brass high speed jet(s)... one to a carburetor. If clogged, the result is what you have explained. Those jets are are the way back in the middle of the float chamber... clean them out with a piece of single strand steel wire as cleaner simply won't do the job.

NOTE also that simply spraying cleaner into the throats of the carburetor(s) does nothing more than clean the leaf valves of the reed plates... it does nothing to the carburetors. To clean the carburetors, remove and dismantle to clean properly.
 
Hi.
Yes, i have the carbs off the boat, and have removed the bottom bowl and also the screw (3) and sprayed carb cleaner in there and it flows freely, and as mentioned, have sprayed cleaner through jets whilst dismantled, and again this flows through freely.
Does anyone know what the screw (26) is for and do i need to remove it and clean inside?
Thanks
 
Number 26 is simply a air plug to pevent air from interfering with the fuel flow of the slow speed jet which is number 27.

Yes.... fuel will flow freely thru even a partially fouled high speed jet but that won't allow the engine to run properly, hence the suggestion of what I always do with the piece of single strand wire.
 
33 has a 1/4"-20 NC thread.---There is a " special " factory tool to remove it.------Most of them can be taken out with a 3/16" diameter shank screwdriver.
 
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