'88 115 power loss

tailgunner · Aug 31, 2003

I searched all the previous msgs before posting this question. Running along fine for days. This morning about 20 minutes out running at 3/4 throttle I lost power. Full throttle gives me about 1/4 normal power. Idles fine, in neutral it has full blast. I think it's fuel related. But I know very little. Several people stopped by and looked and seem to agree. Here's what I have done: Replaced fuel water seperator. Replaced all 3 small fuel lines to carb. Checked plugs. Checked clevis pins on throttle cables. Replaced inline gunk filter. What next? Marvel Mytery oil? Should get an external tank and try it? Nick

mellowyellow · Aug 31, 2003

Re: '88 115 power loss

I would check the compression first. did she overheat? external tank is good idea. is primer bulb firm? good luck, M.Y.

FishermanRich · Sep 2, 2003

Re: '88 115 power loss

I have vertually the exact same problem at this moment. 115 HP 1984. Runs ok, somewhat rough at idle. When gunned it usually goes to about 1/3 speed and pops another cylinder (or two) for about 1 second in an attempt to go faster. On very rare occasion, when gunned it will make it to full speed, only to run there for about 30 or so seconds before dropping to about half and then another while (5-10 seconds) down again to 1/3 speed. Put inline filter on and using High octain gas with Sea Foam - 16oz to 5 gallons. I did clean gunk out of incoming fuel needle valves on top and bottom carb (center was ok) which had gas spitting out vent hole located on cover of the bowl. Bulb now pumps hard with no gas leaking/squirting out any carb. I also shot gum out through any holes I found. I poured some Sea Foam in each of the bowls. I didn't remove carbs to do a thorough cleaning.

FishermanRich · Sep 2, 2003

Re: '88 115 power loss

My 115HP Merc is a '84 in-line 6 cylinder Serial #6478920 I just finished a detailed search for this topic and what A List! Here is the summery of what I found on both that could be the problem(s): Water in Gas, Junk in tank collecting on fuel pickup screen in the tank, Cracked fuel hoses or connections allowing air into fuel line, Backwards facing primer bulb (not likely), Fuel Tank Vent clogged, Fuel Pump clogged or diaphragm broken - not pumping enough gas - need to pressure test, bad spark plugs, bad wiring, bad distributer, bad stator - frayed wiring under the flywheel, bad CDI or switch box, bad stabilizer module, bad coil, Sticking float(s), clogged carbs - requiring rebuild/cleaning - Check main jets & imulsion tube - reset/check float levels, out of sync carbs, out of timing - also should grease zerc fittings under distributer, crank case vent hose clogged, compression may be bad due to hole in cylinder(s).

tailgunner · Sep 3, 2003

Re: '88 115 power loss

FisherMan Rich, My engine purrs like a kitten when it's down to trolling speed at full throttle. Happens after the motor gets hot. Compression was in the 120's. For me, it's either power packs or high speed stator. I bought 2 power packs yesterday and hope to have them installed today. Boat is on it's mooring and the wind is a factor when it comes to working on it. Then there's Fabian. I will pick up some SeaFoam when I can find it and try it for giggles.

The Marine Doctor · Sep 3, 2003

Re: '88 115 power loss

If its the stator you will lose 3 or 6 cyls. If its the trigger you will lose 2 4 6 cyls If its the power packs you can lose 1 2 3 4 5 6 cyls. TMD

tailgunner · Sep 3, 2003

Re: '88 115 power loss

2 new Power Packs installed this morning. Nope. Noticed the post going to the starter from the ignition switch was loose. Despite wiggling it while motor was running having no affect, I will replace it. When we bought this boat I tried to explain to the wife the cost has only begun..............now she knows.

FishermanRich · Sep 3, 2003

Re: '88 115 power loss

I'll be getting a manual some time this week. I'll let you know what I find with mine as the saga continues.

tailgunner · Sep 3, 2003

Re: '88 115 power loss

I have the Clymer service manual which sux in my opinion. The troubleshooting section is pretty much useless as is the index. I am still waiting on the "official" service manual. The old power packs are apparently fine and I'd be willing to let them go for beer money. After taking a buddy on board today to move my mooring, I'm leaning towards a fuel starvation problem. I will continue to post until it is fixed.

The Marine Doctor · Sep 3, 2003

Re: '88 115 power loss

If it is the fuel pump that is giving you grief...have your buddy squeeze it while you are trying to accelerate. If the engine picks up and runs normal...it will be starving for gas. But losing all the power down to 1/4 throttle sounds like 1 or 2 cyl's dropping out. TMD

FishermanRich · Sep 3, 2003

Re: '88 115 power loss

As for my motor - Yes on the cylinders dropping out - I tried pumping the bulb with no change noticed and it was hard & full. Once when it dropped to 3/4 power I felt like it was a one cylinder drop out and it would give 1/2 second spurts at trying to come back running. After a short while (1/2 minute or so) it dropped another then quickly (5 -10 seconds) lost another to put me back down to 1/4 speed. What would cause this - carb clogged or electrical? - I'd really like a detailed clue as to how to check the stator and packs (ignition stuff) to see if they (each component) are operating correctly. I will be checking compression within next few days - (other things have to get done). I have a supposed comprehensive repair manual on order - if it turns out to be worth the $15 I'll let you know. Ordered it from walmart.com UPDATE: - Good for BASIC HOW TO's but not for detailed information on specific motors - still need a 'real' service manual.

tailgunner · Sep 5, 2003

Re: '88 115 power loss

Quick recap: No power beyond trollng speed at WOT. In fact if kept at WOT, it eventually dies. Was happening after 20 minutes, since replacing power packs it happens right away. Neutral has plenty of juice. What has been done: New spark plugs. New Power packs. New inline gunk filter. New fuel/water seperator. Replaced 1/4 lines on all 3 carbs. Rebuilt fuel pump. New fuel lines and primer bulb. Drained carb float bowls. New starter solenoid. While it was bogging down, I squeezed the primer bulb. No difference. Compression around 120 on all cylinders. Spark to all cylinders. Frustrated on Cape Cod.

The Marine Doctor · Sep 5, 2003

Re: '88 115 power loss

Plugged exhaust? Do you park on shore? TMD

tailgunner · Sep 5, 2003

Re: '88 115 power loss

Exhaust seems fine. The boat stays in the water on a mooring. I just bought some Pir-G(I think that's the name) to run through the system. I don't expect much but it's worth a try. Can't find SeaFoam anywhere.

jim dozier · Sep 5, 2003

Re: '88 115 power loss

Start pulling plugs 1 at a time (best to ground the loose plug) and see if you can narrow down which cylinder isn't pulling its weight. If its the cylinder attached to the fuel pump, pull the fuel pump and check for leaking diaphragms. A leaking inner diaphragm can inject fuel into the attached cylinder intake port and cause it too drop that cylinder at lower speeds (too rich). Otherwise you may be able to narrow the problem down to 1 cylinder and concentrate on the carb and ignition for that cylinder.

tailgunner · Sep 5, 2003

Re: '88 115 power loss

All cylinders are firing and fuel pump was rebuilt this morning.

FishermanRich · Sep 5, 2003

Re: '88 115 power loss

I checked for H2O in Gas - none. I checked for air in Gas line from tank - none. I checked for clogged Gas Tank Vent - not plugged. I pulled and changed plugs, checked for spark, checked Pressure: Plug SPARK POUNDS 1.....YES....140 2.....NO.....140 3.....NO.....140 4.....YES.....140 5.....NO.....140 6.....NO.....couldn't check this one, couldn't get to it. From what The Marine Doctor said earlier, my engines problem is probably the trigger or the packs. Did you look for sure for spark AT each plug? What I did is pulled a plug and re-inserted it into the rubber plug boot and held the edge of the ring against one of the bolts on the engine. I used insulated plyers to hold the boot so I wouldn't get zapped. Then cranked the engine & watched for spark. The two that worked were a virtual ring of fire! The others didn't even spark once. It is dark here now and that made it very easy to see the light (spark). Since you changed out the packs - maybe its your trigger or the notorious stator unless you verified spark at the plug... My engine was idling just slightly rough and has an ok hole shot (not really too good) until it bogs done. I found SEA FOAM at the NAPA Auto Parts Store. From what I have read on the WEB, that's about the only place that seems to carry it. It was 5.99 per 16 oz can up here. Where is Woods Hole?

tailgunner · Sep 6, 2003

Re: '88 115 power loss

Woods Hole is on Cape Cod. Had a mechanic on board yesterday. "Carbs are stuck. Pull 'em apart and clean them." I borrowed a Fluke meter and will check the stator BEFORE I pull the carbs. It's slack tide and I'm on my way to move the boat off the mooring and to my work's dock. Where I work we have large ships. We are the one's who found Titanic, among many other way more important scietific discoveries. Anyway, your problem sounds electrical. The trigger is what the stator sits in. I saw the stator and trigger sell for around $130 each. I checked for spark the same way you did. Napa in my town had never heard of Sea Foam. I emailed Sea Foam last week but no response. I bought Pri-G at West Marine which did nothing. I'm rushing off now to move the boat. I have to go through a major channel to get to the dock and want to do so before the tide satrts. I'll be back this afternoon. tailgunner@nbrigham.com

tailgunner · Sep 6, 2003

Re: '88 115 power loss

Pulled all 3 carbs and cleaned them. Nothing obviously wrong. Started the motor and voila, same problem. Stator tests out fine. Red is around 180 and blue 40. I'm pulling the boat. Which is truly frustrating as the big stripers are in town now. Saw 3 buddies pull >30lbs stripers out as I was headed for the dock. Oh well.

mellowyellow · Sep 6, 2003

Re: '88 115 power loss

gonna guess an air leak in the fuel delivery somewhere... only leaks when pressure is high. I vote fuel starvation also. good luck, M.Y.

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