Mercruiser problems

[edb]

I have been having a hell of a time with my 1985 Mercruiser 140 HP, serial #6922453. I have owned for 3 years now and this is the first troubling year. <br /><br />Problem 1-<br />Rough starting or not starting after being run a while, and warmed up. It starts great cold, but when warmed up and after floating a while it would start hard or not start at all. <br /><br />After being towed back to shore, I noticed the rubber positive battery cover was melted and the battery wire to the starter was hot. Trailered it home and went out next morning and it started fine with muffs.<br /><br />I had the battery load tested - ok. I pulled the alternator and had it tested, it was bad -- replaced it -- $180. While I was at it I changed the plugs, put in a new coil, points, condensor, rotor and distributor cap.<br /><br />Engine started right up on muffs as before. Seemed to fire quicker.<br /><br />Took it out Saturday 8/4 and it ran great, pulled the kid around on the tube, started fine after running. Checked battery terminal while running, not noticably warm. Volt meter while running about 14.<br /><br />Pitted for an hour went back out, started and ran her at 3500 - 4000 RPMs 10-15 mins. Ran great in the 3500 RPM range. However, when I went WOT at 4500 RPM's it was sputtering and cutting out. Also noticed when I trimmed up at 3500 RPM's or more it cut out the engine enough to notice. <br /><br />Back her down to 3500 and is fine. Stopped and floated 15 minutes, and it started up. Accelerated (see problem 2) and she died. Would not restart. Would turnover and hit but would not go. Had to open throttle to get her to hit though. Checked battery + terminal and wire - hot, coil hot, alternator hot. Pulled off + wire sat for 30 minutes and floated. Finally started. Had to choke it good though.<br /><br />Problem 2-<br />I had always had a slight hesitation on a fast acceleration, I learned to live with it and just accelerated slowly. However this year it has become worse, to the point where I have to back down the throttle accelerate again or it will die. This problem occured before the alternator problem. I have never done any fuel system work, ie. fuel pump, filter, carb. Not sure how to test, replace etc. <br /><br />Problem 3-<br />When in reverse and accelerating out of idle speed engine stalls. Shifts into gear fine and will reverse at idle speed but beyond that it kills. No similar problems in forward.<br /><br />Sorry to be so long. Looking for some help! Should I CTG (call the guy) as my wife says and get a pro involved now? Season is almost over here, so I don't want to dump a bunch of money into swapping parts. About to put an ad in the paper!<br /><br />ed

 

[fone_man]

Re: Mercruiser problems

How can you answer this????<br /><br />For starters you have one of the most economical, easy to work on & repair IO's on the market... so keep it out of the papers for awhile as it will go quick!!!<br /><br />Prob 1: Hard starting would be ign & fuel areas! This would be causing warm/hot cables, wire, etc... Starter is just to start you engine... not constant running; over spinning of starter & low torque of such will generate heat!!!<br /><br />What is gap on points??? What is timing???<br /><br />Start here... go back & reset & get back to board......<br /><br />Prob 2: See above plus are you seeing any dripping in carb from venturi's??? This will cause hard re-starts plus poor idling...<br /><br />Prob 3: Sounds like call out of adjustment & causing kill switch to shut doen engine...<br /><br />Heck... it is easy from this side of the computer/boat but this is where I would start because this could be a combination of all three causing the "hair pulling" routine that your fixin to do!!!<br /><br />Let us know & keep us posted & awaiting your reply... Also, it was good that you where so lengthy as it provide useful information, keep it up & I hope we can help.<br /><br /><br />

<br /><br /><br /><br />------------------<br />"Keep It Between The Bouys" & "Good Luck"!!!<br /><br />fone_man

 

[fone_man]

Re: Mercruiser problems

Revised:<br /><br />Prob 3: Sounds like cable out of adjustment & causing kill switch to shut down engine...<br /><br />Hey... ADMIN5... when are we going to get a spell check????<br /><br />

<br /><br /><br /><br />------------------<br />"Keep It Between The Bouys" & "Good Luck"!!!<br /><br />fone_man

 

[edb]

Re: Mercruiser problems

Fone_Man,<br /><br />Thanks for the information and encouragement. I won't sell it, since it is paid for.....except for the repairs!<br /><br />I understand the concept of timing and somewhat the gap on the points and the dwell. I have check timing on a car with a borrowed light. How do I check the gap on the points? I will have get a light for the timing.<br /><br />I have a manual reserved from the library, but I have not received it yet. The manual probably addressing the cable adjustment?<br /><br />I might be getting in over my head here and need to CTG. What do you think? -- remember I am a rookie when it comes to this.<br /><br />ed

 

[fone_man]

Re: Mercruiser problems

What you will need for checking Timing & Dwell are three things....<br /><br />Timing Light... always good to have around, mine is from Sears & have had it for over twenty years!!!<br /><br />Dwell Meter... this checks dwell of points... another good investment... can get at Sears also or any reputable Auto parts store.<br /><br />Feeler gauges... .016 is the requirement on SVC bulletin on engine.<br /><br />Also, post email address & I will forward these Merc SVC bulletins to you for storage on your computer.<br /><br />As for Manual... always good to have around, I use Clymers & they has a special on iboats the other day... so you can order from them... Library is good source but you like to have one sitting on the boat & not at library.<br /><br />Basic tools & a little mechanical ability & you are on your way.... One other thing, remember patience!!!! Number one key!!!<br /><br />c-ya<br /><br />

<br /><br /><br /><br />------------------<br />"Keep It Between The Bouys" & "Good Luck"!!!<br /><br />fone_man

 

[edb]

Re: Mercruiser problems

Fone_Man, <br /><br />Email address is baumane@chorus.net. Funny you should mention the dwell meter, I was just at the store, timing light $30, multimeter/dwell meter - $30, gap gauge - $6. I do plan to buy a book.<br /><br />I will see what I find tonight. Any other directions for the use of these new tools?!? Wife will get a kick out of this.<br /><br />ed

 

[fone_man]

Re: Mercruiser problems

EDB,<br /><br />When I work on something & my Dad is around, he wants to look at what I am looking at but usually there is no room... same thing goes for a boat, not enough room. So have wifey on standby should need something or get you cold beer while watching the boat purr like a kitten & you are smiling because you got it fixed!!! Tools wil take care of everything else.<br /><br />I am emailing all the service bulletins right now...<br /><br />

<br /><br /><br /><br />------------------<br />"Keep It Between The Bouys" & "Good Luck"!!!<br /><br />fone_man

 

[ODDD1]

Re: Mercruiser problems

EDB, Prob 1 , dont go after ignition....chances are you carb is dripping fuel after you turn it of and flooding the moter...hence th hard/no restart...Veiw other posts in last few days on this..[3.7]<br /> 1a..only high resistance connections get hot..CLEAN AND TIGHTEN THOSE WING NUTS WITH A PLIERS!!!<br /> Prob 2 same as 1..fix the carb<br /> Prob 3 a cable adjustment MIGHT help, but murphys law says you gonna have to pull the gearcase apart an change a worn out shift spool...<br /> CTRG...call the right guy...technitians who pride themselves on their work find the term 'parts changer' a personal insult...you get what you pay for...an pay for what you get...

 

[edb]

Re: Mercruiser problems

Fone_Man<br /><br />Thanks for the service manuals. I believe I do have a carb problems. I checked the gap on the plugs and the points, plugs ok, adjusted gap to the .016 per the bulletin, dwell was within the range, then checked timing, was ok. Checked all the ignition voltages per the manual, and they were good. <br /><br />The more I think about it and after reading the service bulletin, and some other posts, my problems seems to occur more so when I run at high RPM’s and then pulled back off plane to idle and shut her down right away. If I idle into shore and the restart it tends to start fine, as was the case last Saturday. I am beginning to think ODD1 was on the right track with the flooding, gas continuing to pour into carb after shut down. No clue where to begin now. I have never tinkered with the carb or any carb for that matter. What kind of fix are we talking here and how much? Something I should attempt or not?<br /><br />Looked at carb and it has a “Carb Shop” sticker on the top, and then a Mercruiser stamped aluminum tag screwed on with the following “MCM 120/140 1389-8490.” The number stamped on carb is 13898490 with 4603 under it. No idea if this is the original.<br /><br />ODD1, I did not mean to offend the technicians, I was referring to myself as the “part swapper,” I wondered if it was better to just take it in and have it diagnosed and done right first shot!<br /><br />ed

 

[fone_man]

Re: Mercruiser problems

Help me identify whether a Merc or Rochester carb... ONE or TWO air/idle mixture screw???<br /><br />Let me know......<br /><br /><br />------------------<br />"Keep It Between The Bouys" & "Good Luck"!!!<br /><br />fone_man

 

[fone_man]

Re: Mercruiser problems

I agree w ODD1 also but you need to remove all other possiblities before you procede.<br /><br />My answer to Prob1 was fuel & ign... since everything is set to specs with ign then you proceed to fuel area... Easy to diagnose after you post that "everything in SPEC"!!!<br /><br />We will get you through this & you will be out on the water this weekend... tell wife to pack the gear!!!<br /><br />waiting on your reply.......<br /><br /><br /><br />------------------<br />"Keep It Between The Bouys" & "Good Luck"!!!<br /><br />fone_man

 

[edb]

Re: Mercruiser problems

Sorry, should have told you that it only has one air idle screw w/ spring on the right side. I saw that question b4. <br /><br />I agree that I needed to rule out the other ignition items ---- I was actually hoping it was on the ignition side. <br /><br />I am glad I checked out the ignition side, it makes me feel better knowing that it all checked out.<br /><br />When you said fuel side on your first post, I shuttered. I was always told messing with it--- if I don't know what I am doing can create even more trouble! I will give it shot.<br /><br />ed

 

[fone_man]

Re: Mercruiser problems

Ok... you have the Merc Carb... easy way to identify w/one screw MFg by Nippon, I believe...<br /><br />You are worrying to much... relax & take a breath... order a carb kit (marine), get new float (brass)... I am going to catch flak on that remark from the BB (because I do not like the synthetic/plastic floats)...<br /><br />I believe your carb has been rebuilt before as it has sticker from a "rebuild" shop... so i would assume you are OK... Check svc bulletins that I sent you to ID carb... with Merc tag number you can order carb kit...<br /><br />1389-8490A2<br />Model MCM140/3.0L<br />SN 6229718-C85856558<br /><br />Sierra # 18-7907 / Carb Kit<br />Sierra # 18-7202 / Float (get brass)<br /><br />Also, you can check NAPA or local parts store for availablity<br /><br />Loc-Tite (blue) for base to airhorn screws<br /><br />Follow specs on kit rebuild & go from there...<br /><br />Any problems... we are here to help<br /><br />

<br /><br /><br /><br /><br />------------------<br />"Keep It Between The Bouys" & "Good Luck"!!!<br /><br />fone_man

 

[edb]

Re: Mercruiser problems

Decided not to do carb kit. Bought a rebuilt carb, the extra $120 was worth my time and avoided hairpulling! Bolting on new one seemed much easier! New one will go on tomorrow. Local boat doctor says the new carb will need some tweaking. What is involved, I assume setting idle, etc?<br /> <br />ed

 

[fone_man]

Re: Mercruiser problems

Read Svc bulletin on "Quad"... should give prelimeinary settings & adjustments... <br /><br />***Note: I understand your hesistancy to rebuild "Quad" but I always hate to give up original carb if a rebuildable core. But you know your abilities, not me. Things that seem easy to one person are difficult to another. I hope this takes care of your problems.<br /><br /><br /><br />------------------<br />"Keep It Between The Bouys" & "Good Luck"!!!<br /><br />fone_man

 

[fone_man]

Re: Mercruiser problems

Sorrrrrrrryyyyyyyyyyyyyy!!!! I thought this was "Quad" carb problem!!!!!!!<br /><br />It stil should have preliminary settings on "Carb" svc bulletin I sent you.<br /><br />Again, I am sorry for wrong carb post, as I recalled after post... this had been replaced before... right???<br /><br />Keep us posted<br /><br /><br /><br />------------------<br />"Keep It Between The Bouys" & "Good Luck"!!!<br /><br />fone_man

 

[edb]

Re: Mercruiser problems

Fone_man,<br />Can you verify the timing spec for the 1985 Mercruiser MCM140. Engine plate says 6 degrees BTDC. What are the tolerances and the RPM? <br /><br />I should also verify the dwell. I registered at 30 degrees, plate says 28-34.<br /><br />I was just curious if any of the service bulletins address these setting as was the case with gap at .016 while the plate says .018-.024.<br /><br />I am double checking all the ignition items before I put the carb on.<br /><br />When I put the new carb on should I use some gasket sealant? I have some Permatex gasket dressing, it is gas resistant. Should I use that? Or just use the gasket after I clean up both surfaces?

 

[fone_man]

Re: Mercruiser problems

EDB:<br /><br />This is all addressed in Service Bulletin Merc_sb_95_11-Ignition that I sent you...<br /><br />8 BTDC<br /><br />16 gap<br /><br />39-45 dwell<br /><br />idle 650-700 in gear<br /><br />Disclaimer: Review Merc_sb_95_11-Ignition to confirm dist model before applying above specs.<br /><br /><br />DO NOT USE GASKET SEALER ON CARB... use only gasket provided with carb or carb kit.<br /><br /><br /><br />------------------<br />"Keep It Between The Bouys" & "Good Luck"!!!<br /><br />fone_man

 

[edb]

Re: Mercruiser problems

Ok, got the new carb on, set idle, runs smoothly on the muffs. Idle holds steady going into forward and reverse, does not accelerate until fully engaged. Checked timing again, right on. Going to put on water on Saturday morning.<br /><br />With the new carb what can I expect when opening it up? I am trying to anticipate any problems and how to make any adjustments if needed. Will take tools with me, what if any, adjustments can be made to the carb if it does not run smooth at the high end?<br /><br />ed

 

[fone_man]

Re: Mercruiser problems

ZZZOOOOOOMMMMM! ZZZZZOOOOOMMMMMMM!<br /><br />I wouldn't anticipate any high speed/RPM problems... cannot adjust anything of that nature without carb teardown or in your case, pull off & carry back to parts store.<br /><br />All other adjustments will require screwdriver!!!<br /><br />ZZZOOOOOOMMMMM! ZZZZZOOOOOMMMMMMM!<br /><br />(what a great commercial... kid going zoom, zoom... wished I thought of it as I would be quite wealthy)<br /><br /><br />

<br /><br />Good Luck & keep us posted.<br /><br />------------------<br />"Keep It Between The Bouys" & "Good Luck"!!!<br /><br />fone_man