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Tan
Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 10620
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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1985 15hp evinrude, will crank on choke, will run at full throttle,

Customer Question

1985 15hp evinrude, will crank on choke, will run at full throttle, but will not idle! I have replace all fuel lines, cleaned carb, flipped the reeds, replaced the pump! Where do I go from here?
Submitted: 1 year ago.
Category: Boat
Expert:  Jason replied 1 year ago.
Hello my name is ***** ***** am I speaking with?
The very first thing that needs to be done is the compression needs to be checked. Has that been done yet, and if yes, what are the numbers?
Customer: replied 1 year ago.
Both cylinders are almost identical, 1st pull 85, 2nd 88, 3rd 93
Expert:  Jason replied 1 year ago.
Got it. When you say will run at full throttle, is that with the engine in gear and the boat at full speed, or just reving in neutral?
Customer: replied 1 year ago.
In neutral
Customer: replied 1 year ago.
Haven't had it back in the water since this started last weekend
Expert:  Jason replied 1 year ago.
Got it. The next thing that needs to be checked is to see if it is sparking on all 3 cylinders with a timing light or adjustable gap spark tester. Let me know if it has spark on all 3, or not.
Customer: replied 1 year ago.
They are both firing
Customer: replied 1 year ago.
I have been thinking and scratching my head and throwing parts at it for days now, I noticed when I first got it the choke was not setup correctly, now I am thinking they had the choke partially closed off cause the rich lean was turned down to lean
Expert:  Tan replied 1 year ago.
Hello. My name is***** you adjusted the idle jet in the top of the carb? The choke should only be used for starting. If you have to use the choke to keep engine running at any rpms you have not enough fuel or to much air. Will the engine run at any rpms without the choke?
Customer: replied 1 year ago.
Wide open it will run fine, but when I allow it to start to drop back it falls flat on its face, and I have adjusted on the idle jet with lil to no change
Expert:  Tan replied 1 year ago.
So if you pull the choke out part of the way will the engine idle? Can you put the choke in any position to get the engine to idle? What are you starting at for adjustment on the idle jet? Have you pulled the idle jet all the way out and inspected the needle at the end. Is it broken?
Customer: replied 1 year ago.
I have not been able to get it to idle, I had the choke tied off with a zip tie around 1/4 I would say and adjusted with the lean/ rich and was able to lower the rpms slightly but when I tried to throttle up it died and it took several tries to get it back started
Expert:  Tan replied 1 year ago.
Just having to use the choke to keep the engine running is a carburetor issue or a leaking intake gasket. . Now the compression is questionable it is awful low. It is possible you have a blown head gasket. On an engine of this age the gaskets do deteriorate. It will be blown between the 2 cylinders other wise you would be getting water in the cylinders.What do the spark plugs look like?
Customer: replied 1 year ago.
I have them a couple times after flooding it from using the choke, but when I do they have a black cruddy mess in them along with fresh fuel
Expert:  Tan replied 1 year ago.
What does the idle jet look like? When you rebuilt the carb did you pull the core plug # ***** over the calibration pocket? This can get crudded up. http://www.boats.net/parts/search/BRP/EVINRUDE/1984/E15RCRM/CARBURETOR%20&%20MANIFOLD/parts.html Will your spark jump a 7/16" gap on a spark tester?
Customer: replied 1 year ago.
What is the torque specs on the head bolts, I think I will just build the motor, and go from there
Expert:  Tan replied 1 year ago.
Give me a minute to look that spec up.
Expert:  Tan replied 1 year ago.
Ok the specifications on the head bolts are 216-240 inch lbs. I suspect the engine is a little on the weak side due to the compression. It's hard to get an engine to idle with low compression you are below the specs.
Customer: replied 1 year ago.
What are the torque specs on the connector rods
Expert:  Tan replied 1 year ago.
60-70 inch pounds.
Customer: replied 1 year ago.
I put new rings, pistons, all new gaskets cleaned the carb and replaced all lines to the tank, still does the same
Expert:  Tan replied 1 year ago.
Did you replace both crank shaft seals? What is your compression now?
Customer: replied 1 year ago.
No crank seals but both cylinders are over 120
Expert:  Tan replied 1 year ago.
The crank seals will allow air into the crankcase causing a lean fuel condition. The bottom has 2 seals # ***** & 13 and the top one seal # ***** The engine needed to be rebuilt due to 88 psi isn't very good compression. Is there a reason you didn't replace these seals?http://www.boats.net/parts/search/BRP/EVINRUDE/1984/E15RCRM/CRANKSHAFT%20&%20PISTON/parts.html
Customer: replied 1 year ago.
Had no clue they did so, but as of now there is no worry with it cause I give up on this turd!
Expert:  Tan replied 1 year ago.
Let me know if you decide to continue.

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