1981 70HP OB 3 Cyl. wont deccelarate

[KathyNMich]

I am a novice boater. I recently replaced new cables. I can get the motor started with fast idle, let it run 2 mins., take it off of fast idle and it runs. When I go to accelerate the engine and then want to slow it down, it is running to fast. The engine will slow down slightly but is still racing very fast. I have adjusted the throttle cable to the start position (there is a line mark to show where to position the lever) and like I said it will start, but it will race to fast after its accelerated. I need direction in novice terms. I dont have any other equiptment such as timers etc. I have tinkered in the past with cars but never a boat engine. I need someone to have patience and quide me through the steps I will need to do in order to fix this problem. Thanks for any and all help.

 

[Tom Scully]

Re: 1981 70HP OB 3 Cyl. wont deccelarate

Check and see if the spark advance lever is sticking. It is located next to and uder the flywheel. It is attached to the throttle via the linkage on the starboard side of the engine. there is a spring which should return the lever to the normal position.

 

[KathyNMich]

Re: 1981 70HP OB 3 Cyl. wont deccelarate

Thanks for responding... If I manually take and push the lever back the engine will slow down. I have tried to adjust the screw on that lever to try and push it back but it wont work. I also tried to put a spring there to pull it back, but it just stalled the engine out when I accelerated, so I just took it off. I think you are right it has to with that lever not going back far enough. It is in a straight up postion but should go back further? How do I adjust this?

 

[Tom Scully]

Re: 1981 70HP OB 3 Cyl. wont deccelarate

Before you go too far do a search on this site for "link and sync". It is critical for proper operation and should be checked anytime the cables have been replaced. Basically link & sync ensures that the starting point for spark advance and the opening of the throttle plates in the carb happen at the proper time.<br />There should be a spring at the base of the two levers,(arms), which the throttle cable attaches to. One is for the throttle plates in the carb and one is for the spark advance. It is a large coil spring which sits behind the lower portion of those two levers. The bolt, rollers and spacers which attach the levers to the motor go thru the center of this spring. Make sure it is in place so that it returns the lever to its normal position. Also make sure the nut is not too tight, and spray some wd-40 around the spacers and rollers for the arms. The screw you were adjusting is the stop for idle timing and is usually somewhere around mid way as a starting point. If you don't have a manual you can check the BRP website for some illustrations to help out.

 

[KathyNMich]

Re: 1981 70HP OB 3 Cyl. wont deccelarate

I was afraid to loosen the bolt your referring to. I does seem to stick I thought maybe an new spring perhaps if this doesnt work? I will try to loosen and wd-40. Will this also make my engine idle and then race and the only way to stop it is to cut the engine off and wait for the gas to run out of the engine? (I was told I could do this job myself by changing out the cables. I am extremly frustrated at this point and I am ready to scream!) I appreciate your patience with me and you quick response to my situation. Thanks again!

 

[Tom Scully]

Re: 1981 70HP OB 3 Cyl. wont deccelarate

If the lever does not go back to the idle stop position the engine will race.

 

[rickdb1boat]

Re: 1981 70HP OB 3 Cyl. wont deccelarate

I would change out the throttle cable and shift cable. Sounds like it hanging up inside the casing...Sticking throttle is nothing to fool with...

 

[KathyNMich]

Re: 1981 70HP OB 3 Cyl. wont deccelarate

They are new cables that have been installed. I am trying to get the engine from racing. I have loosened and lubed that bolt as Tom has suggested. Which helped out a lot, but now getting the right combo in the carb is my next challange. I can get it to start on fast idle but when I take it from the fast idle the engine then slows down then chugs until it stalls out. ( have used that screw to make adjustments but to no avail) Then its hard to restart again. I am thinking I better stop while I am ahead the engine is racing so hard at times I dont want to do anymore damage. I was hoping I could beat this thing and fix it myself. I will keep trying...