Logo
FULL SITE MENU

1988 Mercury 115 HP stalls when put into gear

V

vgraff

New member
I purchased a Ranger fisherman with a 115 tower of power engine about 3 years ago. It has always had trouble idling, so about 2 years ago, I got a "tune-up," which replaced my spark plugs, fuel filter, water impeller, and also updated my gear shift box to a newer model. The boat still had problems idling.
During the current quarantine, my son and I decided to take the 3 carbs off rebuilt and clean them. We found that one of the floats was full of gas, the fuel pump was leaking, and the fuel line was leaking at the fuel attachment point to the engine.


After cleaning her up and putting the carbs back on, we tried to set the carbs with the muffs in the driveway. I have to say it was very satisfying to hear her purr in the driveway with my son.
We brought her out to the lake, and she started right up and "idled". However, as soon as we put her into gear, she would sputter and stall unless we gave her more gas and then backed off to a slower speed. If we return her to neutral, the RPMs rev up, and she stays running just fine.


I know the carbs are clean; I do not know if my idle screw settings are correct. I also have read that it could be a weak spark to 1 or more cylinders, or it could be out of timing?


Any help would be appreciated. She does run very well at top speed and starts very quickly once she is warmed up.


Thanks in advance!
 
racerone said:
Open low speed mixture screws 1/8th turn at a time.------Sometimes that makes the stalling go away.
Click to expand...
Thanks! would you have a suggestion on where to start the idle screws? 1 and 1/2? 2 turns out? before I start making the 1/8th increments. I also assume I have to do this out on the lake with the back pressure? Is there a way to monitor RPMs or something in the driveway with the muffs?
 
Muffs in the drive way are to see if the motor will bark and roar, nothing else.------Test and set the idle in the water and in gear.----Start at 1 turn out.
 
vgraff said:
Ok, thanks. I'll let the thread know how it turns out.
Click to expand...
I took the Mercury out on the lake last weekend. I turned the idle screws out 1/8th until it would switch into gear without stalling. However, after making the adjustments, it became tough to start. Also, when I was running wide open on the lake, it would periodically bog down... not sure if this is related or not.


On another note, I've checked my timing with a timing light and found that I had to screw the primary pickup screw all the way in to align the timing. I noticed when I open the throttle all the way down and then back to neutral; the throttle arm doesn't return all the way to allow the arrow on the crankcase to align with the mark on the throttle cam. I'm wondering if the original spring is worn out?


When I manually pull the throttle arm back after putting it into neutral, the primary pickup screw seems more reasonable and not all the way screwed in.




I did test the stator with an ohmmeter and put a spark tester on each cylinder..all looks fine. Any guidance from here would be appreciated.
 
Back
Top