15 hp evenrude won't rev under load

[cdwill007]

Motor had sit for about 18 months, I put in my pond startred it ,ran sluggishly,so I removed carburator and cleaned it .Ran it in pond was
running great,but was difficult to start ,used starting fluid and wd40
would start right up. I took it to the local boat place and told them to tune
it up. They removed carb cleaned it($116).I took boat to the river for a little fishing, motor would not rev under load,would rev fine in neutral.Took boat back to dealer prepared to raise h---,dealer told me the mechanic had a heart attack shortly after I picked motor up,felt like a jerk. Dealer suggested that prop might have spun,bought new prop ($77) purchased new fuel pump
because I thought that might be the problem ($57).Put boat in pond, wouldn't rev under load,wouldn't start without starting fluid.Took boat out decarbed , ran compression check (90 on one cylinder,70 on other),put new spark plugs in gapped at .030,replaced tank hose and hose to motor .Put boat in pond ,wouldn't start with out starting fluid,wouldn't rev under load,ran for about 15 minutes around pond hoping it was trash from decarb procedure,no luck.Shut off motor removed air intake to check for anything obvious, didn't see anything,now motor very difficult to start,even with
starting fluid,dies when you put it in gear,revs ok in neutral after you finally get it started.
Any and all suggestions would be welcome.
I had planned on trading for a larger motor (40hp jet prop),but need to get
this one running or lose it in the river first.

Thanks

 

[Kajun37]

Re: 15 hp evenrude won't rev under load

have you checked the spark? should jump a 7/16 gap.....also looks like your compression is a bit low...also instead of using starting fluid use gas/oil mix in a squirt bottle.

i'd quit bringing it to that mechanic shop if i was you...sounds like they shooting in the dark and making you pay for it....a good service manual and compression checker and spark checker and you could do it all yourself...good luck and keep us updated.

 

[cdwill007]

Re: 15 hp evenrude won't rev under load

Thanks for the reply.
I will check the spark when I get home tonight.
I have been using wd40 and starting fluid ,but I wiluse an oil and gas mix
per your suggestion.
I knew the compression was on the low side, but I would think it should
rev better than it is. It was running fine until I took it to the dealer,
just a little hard to start.
I really appreciate the help.

Thanks

 

[reload]

Re: 15 hp evenrude won't rev under load

That low cylinder could be the trouble. I had a 6hp that would run in nuetral and not in gear once. Low comp. on bottom hole was the trouble. Honed and replace rings ran fine.

 

[cdwill007]

Re: 15 hp evenrude won't rev under load

Thanks for the reply reload.
I have never been into an outboard engine,lots of cars. Guess I will pull the
heads as a last resort.

Thanks

 

[Xcusme]

Re: 15 hp evenrude won't rev under load

Before you pull the head, place motor on floor with plug holes up, remove plugs. Rotate that 70lb piston to TDC and spray piston with PB Blaster and let her sit, perhaps you've got a stuck ring and might help free it up. Have you tried running on the water under load with the motor cover off?? Perhaps you've got a bad exhaust gasket feeding exhaust gases back into the intake.

 

[Kajun37]

Re: 15 hp evenrude won't rev under load

yea before you pull the head ..also do a decarb with seafoam or deepcreep

 

[cdwill007]

Re: 15 hp evenrude won't rev under load

xcusme and kjun37: Thanks for the suggestions.
I have ran the motor with the cover off, no change.
I did spray Seafom deep creep into cylinders last night, let it sit for
about 4 hours, compression on cylinders came up to 85+ on low one and
stayed at 90 on the other.
I removed the carb last night ,it appeared to me that the float might
have been sticking ,not sure,but assembled it and filled it with gas to check it
seems to be working ok now.
I also noticed that the throttle was sticking (roller was not touching cam) sprayed with wd40 it seems to be free now.
I will take it out on the pond tonight and let you know the results.
It appears to me that the engine was getting excess fuel, is it possible that
excess fuel and the low compression on one cylinder would create the symtoms I described ?
Appreciate all the help I have been given.This is a great site.
Hope to be able to return help to others as I learn.


Thanks

 

[tashasdaddy]

Re: 15 hp evenrude won't rev under load

all the things you found would make it run bad. stick float makes the engine flood, stuck roller throws off linc n sinc. etc.

 

[mikesea]

Re: 15 hp evenrude won't rev under load

some of the 9.9 15 engines have a plastic piece on the timer base under the flywheel that can break off,OR the roller might have a rubber protector type thing on some,the end result is you get fuel,no timing,the fact that the roller isnt touching could be an indication,check on the flywheel piece and see if it looks like a little piece broke off,the piece may be lying in the engine cowlings

 

[cdwill007]

Re: 15 hp evenrude won't rev under load

tashasdaddy ,mikesea: Thanks for the info.
I got good news and bad news when I put it the pond tonight.
Good news,started on first pull without any starting fluid .
Bad news,it would quit running as soon as I put it in gear. Finally got it to
run in gear,but same problem it would not rev up under load.After I shut down had probem starting again and would not stay running when I put it in gear.
I have too much time in it to quit now.
Mikesea I will check on the broken piece tomorrow, but I don't believe it
has a broken or missing piece on it.
Thanks your help is really appreciated.

 

[cdwill007]

Re: 15 hp evenrude won't rev under load

I read through 48 pages of threads yesterday and came across a thread that
said the low speed adjustment on the carb should adjust the idle rpm.
This adjustment has no effect on this motor. I assume that the orrfice is
plugged despite three cleanings. My question is "would this create the problems I described in my last post"?
Sorry to keep bugging everyone.
Appreciate all the suggestions that have been given.

 

[mikesea]

Re: 15 hp evenrude won't rev under load

there were a few different carbs and configureations over the yrs.if yours has a plastic top,be sure there arent any cracks where the adjustment goes,if its older all metal,it may have a plastic tube in the carb bowl that may have disintergrated,,if you have good spark and comp.i would believe its the carb,the carbs have very small passages inside and could be clogged,the best way to clean them is soaking in a solution designed for carb cleaning,sold at auto stores,be sure to get a can of spray carb and use that as a final cleaning,look to get a breakdown picture of your carb to be sure all parts are there,as I mentioned one carb i have in mind had a small plastic tube that would disappear with the new fuels,if you look at the inside of the carb you might see a metal tube that would be where the piece goes and connects to a plastic (white color)jet body,if this is your carb,it also needs a circular gasket on top of the jet body and at the foot.

 

[CATransplant]

Re: 15 hp evenrude won't rev under load

Did you ever check the spark on both cylinders? You have all the symptoms of running on one cylinder. If you checked and it's OK, then it's something else, but if you haven't checked....

 

[Kajun37]

Re: 15 hp evenrude won't rev under load

yea sounds like a dead cylinder to me too.... try a "cylinder drop" test....get motor running...take a pairs of pliers that has a rubber coated handles and pull one plug wire off ....does it runs different?..put wire back on...and pull the other one....run different?

if it doesnt run any different than with both plugs on..you got a cylinder that is not firing....recheck spark to 7/16th gap...lets us know the results of these tests.

 

[cdwill007]

Re: 15 hp evenrude won't rev under load

CATtransplant,Kajun,Mikesea:
Thanks for the replies.
I did the 7/16 spark test on both plugs,spark jumped gap with no problem.
I will try to get it running long enough to take the spark plugs off one at a time and let you know the results.
I had a dealer take the carb out and clean it and I took it apart twice myself and cleaned it. It does not have any plastic parts in it,but from another thread I think the idle adjustment must be plugged.It doesn't make any difference how many turns you make on it,there is no change in the rpm.
It is difficult to see the path of the gas controlled by this needle valve.
That part of the carb appears to be sealed with no visible access. I am going to try to blow it out with air from my compressor,unless someone tells me that might be a bad idea.
Thanks

 

[Xcusme]

Re: 15 hp evenrude won't rev under load

Low speed idle circuit in carb is blocked. Either dealer didn't clean-rebuild carb or you sucked up garbage that re-clogged idle circuit. A down and dirty way to clean the upper idle circuit is to completely unscrew the low speed idle screw. Insert long plastic tube from can of carb spray. Spray carb cleaner into needle seat area to flush the idle jets. Replace the needle valve. Lightly seat needle valve, open 1.5 turns , start motor and try adjusting per Joe Reeves carb adjusting instructions. If you still get no response in idle speed, carb should be removed and throughly cleaned.

(Carburetor Adjustments - Two Adjustable N/Vs)
(J. Reeves)

Initial settings are: Bottom high speed = seat gently, then open 1 turn out. Top slow speed = seat gently, then open 1-1/2 turns.

Setting the high and low needle valves properly:

NOTE: For engines that DO NOT have a shift selection, obviously there is no NEUTRAL position. Simply lower the rpms to the lowest setting to obtain the low speed needle valve adjustment.

(High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn, wating for the engine to respond between turns, start turning in the bottom high speed needle valve. You'll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out the needle valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest setting.

(Low Speed) Slow the engine down to where it just stays running. Shift into neutral. Again in segments of 1/8 turns, start to turn the top needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back. Again, at that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustments, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

 

[reload]

Re: 15 hp evenrude won't rev under load

Could be the throutle is open far enough that the idle circuit is not even coming into play.

 

[Xcusme]

Re: 15 hp evenrude won't rev under load

Cdwill007, what motor do we have here?? Post the model number...

 

[cdwill007]

Re: 15 hp evenrude won't rev under load

reload,Xcuseme:
Thanks for the help. I will follow your advice on cleaning the carb and I will
post the model no. this evening when I get home.

Thanks