Hey guys, the forum is great, I've learned alot already. I've read alot of other posts, but none seems to fit my situation exactly.I'm having a problem with a 1989 Searay (Mercury/Mariner?) 135 HP V6, serial # C213481.Original equipment on an 89 sea ray 180 open bow. Just bought it, ran great. After a couple of trips, all of the sudden, it just didn't have any holeshot, (wouldn't pull me up on a slalom ski, with only 2 men in the boat) and would only pull about 4500 rpm WOT.Took it to reputable outboard guy, who said it was probably bad gas. He checked compression & is approx. 135 on all holes. So, I filled it full of 92 octane and it ran like a champ on the next outing. With 1000 lbs of people and a full gas tank, it yanked me right out of the water on a slalom ski, (I'm about 225 lbs).So, I carefully filled the tank full on the way home from the lake, thinking I must've taken on water condensation from not having the tank full before, and that perhaps that had caused the previous "bogging". Next trip out, the same problem showed up, it would barely pull me up on two skis. I have to admit, there is a noticable smell of gas, so it could be loading up or something. But I guess I just figured that would "clean up" after running at the "crippled" WOT rpm of 4500 rpm for a few minutes. But it never does "clean up" after it begins the bogging. I'm not calibrated, but the plugs all seemed reasonable to me.Battery is at about 12.58V when engine is off, and 13.5 V when the engine is at 2000 rpm.So I assumed that the regultor/rectifier is ok.Though only a "simple test", an inductive timing light indicates "fire" to each plug wire, (assuming that I'm not getting erroneous "crossover" from a nearby plug wire that would falsely trigger the timing light's pickup).I've read alot of posts from this forum that indicate many possible sources of this problemin Mercury/Mariner 135 v6's: bad gas, water in gas, stuck float, bad fuel pump diaphram, bad coil, bad power pack(s), bias of power packs not equal, stator, voltage regulator, and rectifier. I guess I'm overwhelmed and wondered if there was a most likely candidate considering the year/make/model of this motor?Any help is greatly appreciated,Thanks,
I would stongly suspect a sticky float causing at least one of the carbs to throw neat fuel into the old girl. However you will have to use a systematic approach to eliminate one thing at a time until you find the root cause. I only draw the float thing to mind as that was the same symptoms that afflicted mine. Turned out was a bad seat. You could physically see fuel pour into the motor and, whilst it kept running, it had no power at all.
The idle is usually perfect, but when this happens it roughens up a bit, (occassional jerk),but is still ok, not silky smooth, but just ok.Is it an acceptable idea to "pinch off" a certain hose (like for the bottom carb) for about a minute or two to see if the engine regains power, confirming a stuck float? Or is there a better test other than disassembling the carbs?thank you for your responses.
You could remove the little inspection plugs from the airbox and from there you should be able to look down the throats of the carbs. Be aware though that this will cause the engine to run lean and could cause thermal damage if you run too long. When the fault condition exists you should be able to see which if any carb is leaking excessive fuel into the motor. If you cannot see clearly then you may have to remove the plastic airbox but take care and don't run it for very long like that for the above reason.If it is not the carbs then have a look at the fuel pump. I assume you have checked the fuel bulb to see if manual priming whilst in the fault condition changes matters. Obviously if it does the chances are that the fault is with the fuel pump which is esaily replaceable.Andy
Took it out again this weekend.Tried the primer bulb idea above, but didn't affect it, (bulb was "full").Had lots of family & guests so I couldn't pull the intake airbox to look for lots of gas,but fuel usage was typical (7 gallons for anafternoon of tubing, ((my friend has the exact same boat and agrees 7-8 gallons per outing).Symtoms remain the same.Runs like a champ for 1/2 hour to 1 hour.Then, just doesn't have any power coming outof the hole, and max's out at 4500 rpm.I did note that the temp guage was at a steady 100 while this was happening.Earlier in the day, it was up in the 145 Frange. I'm assuming this means the t-statsopened. Could this have anything to do withthis "timing" issue (always happens after aboutan hour or so)?)Thanks for your help!
Sounds like switchboxes - heat related electronic failure. An easy test is to get some freeze-mist spray for checking thermal electronic component problems and spray your 2 switchboxes down when the performance drops off. This spray is available at radio shack or you can use "canned air" from office supply stores, just hold can upside down to get the liquid out. Or you can get the stuff they use to freeze gum out of carpet. If the switchboxes I recommend aftermarket ones from CDI/Rapair, cheaper & better.
I agree with Das Boot on this. One thing you may try is to change the Spark plugs for new. My 135 had a weak stator and even though the plugs looked good as new they were prone to early failure causing loss of power.Maybe if you could borrow a set just to prove its not that simple if the switchbox freezing has no effect.
Yep, I'd almost bet my boat that you are not getting fire to one of the cylinders (possible switchbox problem)....100F is way too low of a temperature for a black max. Since your temperature sender should be measuring metal near the top spark plug of the port bank! It should run up to around 180F at WOT...I bet you are not getting fire to at least that top cylinder where the temp. sender is located.. If no combustion occurs your temps will be drastically lowered...I would purchase a spark gap tester (which you can buy at any auto parts store for 10-15 bucks). Run the engine at idle and check the spark on each cylinder one at a time... Follow the directions and start with a 1/4" gap...Let us know...
Took it out yesterday. The "freeze mist" on the switchboxes is a cool diagnostic tool, but didn't make any difference. I put fresh plugs in, and it ran great all day long, (longer than I've everrun the boat at one time). I am very happy that the plugs seemed to fix my problem, but I just didn't think the old one's looked that bad.If I'd have known that's what she wanted, I'd havefed her fresh plugs every other weekend! Thanks for the help, and sorry for the "false alarm"
hawktuner, Thanks for posting the update and I am pleased the fix wasn't as expensive as it could have been. Not to cast to dark a cloud on the horizon but on my 135 the short life of the plugs was attributed to a weak stator. If after a relatively short amount of running hours the problem re-occurs it may be worth having the stators checked out. I have dozens of plugs that look as good as new as it was the cheapest fix to get my motor back up to power when it suffered similar problems, strange thing was it didn't sound like it was missing it just had no power.Happy boatingAndy
Roger that one AndyL, it does seem a little too simple of a fix. Like you suggested, I'll justsee how long until it runs with what feels like1/2 power, and then I'll look into the stator.I know exactly what you mean on the not-skippingbut- no-power thing!Thanks for all of the tips and help everyone!
Sometimes, plugs will fail internally, meaning that even though they look 100% fine, there may be a crack in the insulator or conductor which is either prematurely grounding out the spark or cutting it out altogether.
Mercury/Mariner 135 V6 intermittent "bogging"
Linear Mode
