1977 1150 IL - Idle problem

[pfoley]

When I put the boat in the water, I pump the bulb, start the engine (easily), warm it up a second, and drive away. No problem. Engine runs smoothly through the RPM range. Perfectly in fact. I was out for about an hour. Get back to the dock, pull the boat into neutral, engine dies. Won't start again unless I use full fast idle, then when I try to put it in gear, it dies. Finally, I pump the primer bulb a bunch of times and get it going enough to put it in gear, and again it's perfect though the rpm range until I pull it back into neutral, then it dies again. Won't start unless in full fast idle. Pump the bulb a bunch more times, get it started, etc.

I have:
Rebuilt the fuel pump (could I have done this wrong?)
Decarbed with the 1 gal of gas/seafoam trick (twice)
Bought new OEM primer bulb, connections, and fuel tank
Removed idle jets (which looked nice and pointy) and shot carb cleaner in the holes

Any ideas?

 

[Chris1956]

Re: 1977 1150 IL - Idle problem

Pfoley, I will guess that the motor starts, idles and runs great in the morning, and after a high speed run, it starts to act up. If so, the only thing I could think of is that you either have carbs set too rich, or you are getting vaporlock. The motor and carbs should be staying pretty cool, under all circumstances. If you just idle around for 5 minutes, does the motor still idle correctly?

 

[timmathis]

Re: 1977 1150 IL - Idle problem

Check tank vent and all hoses, clamps. Check timing. Readjust carbs and see what it does.

 

[pfoley]

Re: 1977 1150 IL - Idle problem

All tanks, vents, and hoses, connections, have been replaced because of this problem. No change.

I don't think it's a heat problem because last weekend I ran it hard for an hour, stopped at a good lunch spot for an hour before I tried to start it again. Wouldn't idle until I pumped the ball hard again.

In "idle forward" it's perfect. In idle neutral, in the water, it will eventually die I think.

Wouldn't vapor lock also happen when I was running at higher rpms?

If I had carbs set too rich or a vapor lock issue, would pumping the primer have an effect? Would a "too rich" setting allow the engine to run normally at first then idle poorly later?

Thanks again for all of your time.

 

[tashasdaddy]

Re: 1977 1150 IL - Idle problem

i agree with tim, carbs adjustments.

 

[timmathis]

Re: 1977 1150 IL - Idle problem

Try a good dose of seafoam in the fuel supply and adjust air screws. Tim

 

[pfoley]

Re: 1977 1150 IL - Idle problem

Thank you, but I'm confused. How does the wrong carb setting work one minute, and then later not work?

After I removed the idle jets and cleaned them (and the hole), I re installed them to 1.5 turns from lightly seated per the manual. What other adjustements can I make?

I have done the Seafoam shock twice by the way.

Thanks.

 

[pfoley]

Re: 1977 1150 IL - Idle problem

Anyone? Clams?

 

[sundog]

Re: 1977 1150 IL - Idle problem

I would think carb adjust too, altho I dont know why it wouldnt die in idle forward if the adustment was to low. I had to adjust my inline6 just a tad to the high side of the 1.5 turns or it died on my in neutral. The 1.5 turns in a place to start, not the final setting.

 

[roger3645]

Re: 1977 1150 IL - Idle problem

When you pumb the bulb does it get firm?

 

[pfoley]

Re: 1977 1150 IL - Idle problem

The bulb is soft to start, but it does get firm. I would agree with the carb adjustment if it didn't act fine in the beginning. In the beginning it idles great (neutral), over time it starts to die and the bulb gets softer. In idle forward it seems just fine.

Could I have a sticky float or something? If the float was stuck either up or down, would it run so well at faster speeds?

Thanks!

 

[akendall]

Re: 1977 1150 IL - Idle problem

When you pumb the bulb does it get firm?

Had the EXACT same problem with my 1986 115HP IL6 and it turned out to be both timing AND idle speed settings. Suggest you take it to a dealer or purchase a timing light and evaluate... Keep in mind that the settings in the Seloc manual for your motor may not be valid anymore because of wear and tear over the years... hence the need to perform retard/fwd timing with a timing light.

BTW - I know this is VERY frustrating and I did everything before getting to this step!!!!

 

[Chris1956]

Re: 1977 1150 IL - Idle problem

Pfoley, Cold motor need a richer mixture to run. As they warm up, they like a leaner mixture. A choke temporarily richens the mixture for cold start. My guess is that if your carbs idle mixture is set too rich, the motor will run well when cold, and after warm up, the motor will not like the rich mixture. It was the only premise I could come up with that fit your description.

As for vabor lock. Again a guess. When the motor runs at high speed, heat builds up in carbs, but is offset by lots of cold fuel entering bowl. When you stop, the residual heat will evaporate the fuel in the bowl, giving vaporlock.

 

[timmathis]

Re: 1977 1150 IL - Idle problem

Try adjusting air screws 1/4 turn at a time until you get the best holeshot. After you do the link and sync.
Set timing at 21 degrees max advance. If you set the timing at cranking speed double check it with it running.
Tim

 

[pfoley]

Re: 1977 1150 IL - Idle problem

I'm still a little hesitant about performing a lync and synch. This is my first attempt at outboard repair, so I want to exhaust the obvious before I start pulling things apart :^.

Let's say that the idle is set too rich to idle when it's hot, which way do I turn the idle screw to lean it out? I ask this because I'm not sure if air or fuel is passing by the idle jet .

Akendall - It is comforting to hear that there is at least one person who has experienced this. It is sooo frustrating. Unfortunately, there isn't really a dealer around (Washington, D.C.) who wants to look at an old merc.

Thanks everyone.

 

[roger3645]

Re: 1977 1150 IL - Idle problem

Clockwise.

 

[timmathis]

Re: 1977 1150 IL - Idle problem

Study this link by Clams. It should help you set the air screws. He is the inline man.
http://www.iboats.com/bbboard/bbBoard.cgi?a=viewthread;fid=29;gtid=891893
Good Luck, Tim

 

[Clams Canino]

Re: 1977 1150 IL - Idle problem

Yes.... the idle mix is touchy. In or out of the water, hotter or colder, tilted up or down a bit, all these can make it OK one minute and bad the next.

You gotta do all 3 carbs idle screws, prolly over and over, till you find a good compromise.

-W

 

[pfoley]

Re: 1977 1150 IL - Idle problem

Thanks people! Looks like I have my weekend cut out for me. I'll post results on Monday.