85' Merc 115 L6 Won't Idle

[Ware5150]

I have tried everything to get this motor to run right. So far I have rebuilt the carbs, fuel pump, water pump, new plugs, and linc & Sync.

I have set my primary timing to 4-7deg BTDC & ATDC. So far it will run great at home in the trash can but not at the lake. Normally it will not idle unless I advance the timing or advance the trottle lever about 1/4" off idle stop. I just did a complete link and sync set timing at 5deg ATDC and carbs at 1 1/2 turns out. The motor will crank and run fine above 1100 rpms but as soon as I put it to the idle position it will die.

Fuel delivery seems to be fine and strong. Tested all fuel lines for leaks found one small leak but fixing it didnt help.

So, I adjust the throttle lever up to maintain idle and take it to the lake. It cranks and idles fine. As soon as I put it in gear it dies. Tried slamming it into gear just to stumble a little longer before it dies. Seems like it may be flooding itself after it dies. When I try to restart I must choke before it will fire up.

Anyway I am at a loss. Please post ideas and help me get this thing to run.

Thanks

 

[Chris1956]

Re: 85' Merc 116 L6 Won't Idle

Re: 85' Merc 116 L6 Won't Idle

Idle pickup timing should be 4-6* BTDC. If that motor has an idle stabilizer, disconnect it before link and sync. After that it is a matter of getting the carbs adjusted correctly. Carbs must be synched with each other and then adjusted to allow smooth acceleration. In the water with a warm motor, adjust idle mixture screws a little ata time to max RPM. Now try to accelerate. If it dies, open top carb 1/8 turn and try again. If it dies, open mid carb 1/8 turn and try again. Next is to open bottom carb 1/8 turn and try again. Repeat sequence until you have reasonable idle and smooth acceleration.

 

[Ware5150]

Re: 85' Merc 116 L6 Won't Idle

Re: 85' Merc 116 L6 Won't Idle

Thanks for the reply. I am still confused about the timing. The manual says BTDC and the sticker says ATDC. I am no mechanic but there does not seem to be enough timing gap from idle to wot if I time it BTDC.

FYI - I dont think mine has the idle stablizer.

 

[Ware5150]

Re: 85' Merc 116 L6 Won't Idle

Re: 85' Merc 116 L6 Won't Idle

Bump, Bump.......Please lets talk about this

 

[Chris1956]

Re: 85' Merc 116 L6 Won't Idle

Re: 85' Merc 116 L6 Won't Idle

I am not sure what to add. if you have a OEM Manual, use the timing specs from it. make sure the link and sync is correct, and do not try to reengineer the spark advance.

Try to adjust the carbs to be rich enough to accelerate and lean enough to idle, as I had described.

 

[Ware5150]

Re: 85' Merc 116 L6 Won't Idle

Re: 85' Merc 116 L6 Won't Idle

Thanks for your suggestions Chris. I will try what you said.

 

[Ware5150]

Re: 85' Merc 116 L6 Won't Idle

Re: 85' Merc 116 L6 Won't Idle

I just have one question. After doing a link and sync and carbs set should a boat idle as is?

 

[Chris1956]

Re: 85' Merc 116 L6 Won't Idle

Re: 85' Merc 116 L6 Won't Idle

The initial carb mixture setting is 1-1/2 turns open from lightly seated. This will allow the motor to start, and run at fast idle. Adjustments from this point make the idle smooth and correct the mixture for smooth acceleration.

 

[daveswaves]

Re: 85' Merc 115 L6 Won't Idle

Chris has given you good advice, I think your motor may have the stabilizer circuit and it will have to be disconnected before you do the link and sink. You will reconnect it later The link set up ensures that the timing and carb set up all happens at the right time and the sync process ensures that all your carbs are acting together. Start over and double check all the settings starting with the timing pointer. Make sure it is pointing to TDC on the fly wheel before you do anything else. You are very close as your engine at least starts. You do have to go back and re do the procedure, you will never be able to tweak it into spec..

 

[Ware5150]

Re: 85' Merc 115 L6 Won't Idle

I think I found the problem. After doing a spark test I found the # 5 & 6 plugs were not firing. I traced it back to a bad reading on the Trigger Assembly. I had the same ohm readings for the other 2 that went to # 1 - 4 and a very high reading on the one that wend to # 5 - 6.

So I guess that it has been running on 4 cyl. and that is why it does not want to idle. I have a trigger assembly on the way so we will see.

So far I have search everywhere on that motor for the idle stabilizer and have not found one but I think I have found the problem

Thanks for all your suggestions and support.

 

[Ware5150]

Re: 85' Merc 115 L6 Won't Idle

Guys, I replaced the trigger assembly. Setup the timing like the sticker said and it would die on throttle and weak to no idle. I set it up like the link said on this form and it ran. I am still having one problem.

Boat will idle and forward idle great but when I hammer down it wants to die. I adjusted the timing and carbs while in the water. After a minute of trying it plained. I ran for a while went through another no wake and it wanted to bog again. Got it back on plain and opened her up at 43 mph.

It still wants to lag on the hole shot so what do I need to check?

http://forums.iboats.com/showthread.php?t=168855