140 hp mercruiser idling problems

[eringgold84]

I have a 1983 Chris craft scorpion 168. Had boat about 1 year. Previous owner told me he had carb rebuilt. Once I have it running the boat runs awesome. When I go from cruising speed to an idle it dies. Then takes a few times to restart. Any ideas?

 

[achris]

Re: 140 hp mercruiser idling problems

I would first do ALL the basics, assume nothing. The PO said he re-built the carb. You didn't see that, you don't know if it's true... As I said, assume NOTHING!

Engines require certain things to operate properly... Basically they need the correct fuel/air mixture to be compressed and then fired at the right time.

So, in this order.

1. Compression tests.
2. Check spark plugs, replace if needed.
3. If points, replace, along with condenser and rotor. Check and adjust, if needed, points cam dwell angle.
4. Inspect distributor cap, rotor and leads, replace if necessary.
5. Check spark quality (needs to be a nice BLUE spark drawn over 1/2").
6. Set timing. Check timing advance is working correctly.
7. Check/change fuel filters and check that the fuel system is not sucking air.
8. Check fuel pump pressure.
9. Check for full opening of the carb. Also ensure choke is opening fully when the engine is warm.

When all of these items have been done, THEN move to the fuel system....

You can have the best, cleanest carburettor in the world, but if the compression's low and/or the ignition system's not doing its job, the engine will still run like crap.....

Chris.........

 

[fishrdan]

Re: 140 hp mercruiser idling problems

Once I have it running the boat runs awesome. When I go from cruising speed to an idle it dies. Then takes a few times to restart. Any ideas?

Explain further...

- Does the engine start easily, if it starts hard, what's your cold and warm starting procedure.
- Going from cruise to idle and the engine dies, is this staying in gear or coming out of gear into neutral?
- Once the engine dies, what do you do to get it to restart? (just crank the engine over, prime carb by pushing throttle, other)
- Does it have any problems coming off idle, accelerating?
- Does the engine every idle smoothly, does it idle smoothly in gear?

 

[eringgold84]

Re: 140 hp mercruiser idling problems

Dies going from gear into neutral. To restart I pump carb once or twice then crank. Runs until I put in gear and back into idle. Engine runs just a lil bit rough in idle.

 

[achris]

Re: 140 hp mercruiser idling problems

Dies going from gear into neutral. To restart I pump carb once or twice then crank. Runs until I put in gear and back into idle. Engine runs just a lil bit rough in idle.

Check the lower shift cable. Watch the shift interrupt switch as FORWARD gear is selected. It should NOT move. If it does, replace the lower shift cable...

Read all about the shift interrupt system HERE.

Chris...

 

[eringgold84]

Re: 140 hp mercruiser idling problems

OK. Sounds like that might be my problem. Is it hard to do? I will be doing all the work myself. Expensive?

 

[fishrdan]

Re: 140 hp mercruiser idling problems

Kind of a pain, but not terribly bad. DO NOT kink the cable (core) while installing it back into the sheath.

Buy a genuine Mercruiser/Quicksilver cable kit ($75-100) as it's a much better cable than the aftermarket cables, made differently.

Do you have the downloadable manual?

 

[achris]

Re: 140 hp mercruiser idling problems

OK. Sounds like that might be my problem. Is it hard to do? I will be doing all the work myself. Expensive?

Plenty of 'back-yarders' replace their own cables... And this forum is about the best help you'll find (short of someone looking over your shoulder ) Ask question before you do ANYTHING. There are tips and tricks that are not in the manuals... Like attaching a pull cord, and putting a little liquid soap on the bellows, or replacing the bellows at the same time as doing the cable, or buying the right kit.... Ask, ask, ask....

The best advise is to replace the bellows at the same time, and the kit for that is -865436A03 (about $92). It has everything you need to do the job... You need to get it from a Merc dealer though. iboats also sells a kit, if you want to go the aftermarket route... http://www.iboats.com/Mercruiser-Lo...7041229--session_id.308099510--view_id.268911

Chris......

 

[eringgold84]

Re: 140 hp mercruiser idling problems

Thank you. Soooooo.....first question....what is a bellow?

 

[achris]

Re: 140 hp mercruiser idling problems

Thank you. Soooooo.....first question....what is a bellow?

That's the rubber part that stops water getting in.

 

[eringgold84]

Re: 140 hp mercruiser idling problems

OK. I looked at the kits. Are they universal fits or are they size specific? This is my very first boat and I have limited knowledge on them.

 

[Bondo]

Re: 140 hp mercruiser idling problems

OK. I looked at the kits. Are they universal fits or are they size specific? This is my very first boat and I have limited knowledge on them.

Ayuh,.... Welcome Aboard,.... They're drive/ vintage specific,...

Chris gave ya the part number ya need,...

 

[eringgold84]

Re: 140 hp mercruiser idling problems

Do I have to get inside the out drive at all? Could a novice like me change it or should I take it to a shop?

 

[achris]

Re: 140 hp mercruiser idling problems

Do I have to get inside the out drive at all?

No.

Could a novice like me change it or should I take it to a shop?

Depends on just how 'novice' you are.. Have you done work on cars/car engines, etc? If so, and you follow the manual, then you should be able to do it...

 

[eringgold84]

Re: 140 hp mercruiser idling problems

My apologies. I must have skipped the line asking me about if I have a downloadable manual in the previous posts. No. I do not have one. Where can I get one?

 

[achris]

Re: 140 hp mercruiser idling problems

My apologies. I must have skipped the line asking me about if I have a downloadable manual in the previous posts. No. I do not have one. Where can I get one?

First we need to identify EXACTLY which drive you have.... Can you post either a photograph or a serial number of the drive? If you don't know where the serial number is.... -> http://forums.iboats.com/non-repair...engine-serial-numbers-630103.html#post4398812

Chris.....

 

[eringgold84]

Re: 140 hp mercruiser idling problems

Only number I could find is 6252220 on the drive.

 

[achris]

Re: 140 hp mercruiser idling problems

Only number I could find is 6252220 on the drive.

That's the number I needed. It is an 'R' drive, and HERE is your manual.... Enjoy. (don't forget to save it once you've downloaded it)

 

[eringgold84]

Re: 140 hp mercruiser idling problems

Thank you. It is much appreciated!!!

 

[eringgold84]

Re: 140 hp mercruiser idling problems

I was skimming the manual and came across the section for adjustments and replacements for the shift cables. Didn't really say anything about replacement but more about adjusting it. Should I try to adjust the cable first and see if that fixes the problem??