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Stuart Adair

My first boat "Not starting" situation

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Hi folks, 

My first ever boat problem today. Chaparral Signature 27 1990 5.7 Mercruiser. Boat was starting and running lovely when I last turned it off 2 days ago. Came to start it today and the engine is turning over but not firing. The distributer is a bit hard to get to but I've pulled off the coil feed and there's a lovely strong spark. Plugs are hidden under the manifold so quite difficult to get to but thats something I'll have to check next. I never had any spanners to check the fuel line into the carb, so that's another job to check on Sunday when I can next get to the boat. 

Not sure if it is fuel because it still wouldn't fire with a squirt of Bradex. Fuel tap is on and there's fuel in the tank.

When I shut the boat down I get into the engine compartment to reach the battery shut off's. Is there a "Something" in there that I could have knocked that would allow the engine to spin over, spark but not fire ?

I'll keep you informed as things progress (And will doubtless be asking for more advice)

 

Stu

 

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yes, check the kill switch up by the dash as well as making sure your shifter is in neutral.  either will prevent it from starting....ask me how I know...

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The engine will not turn over if not in neutral. 

 

I think we have all been bit by the kill switch situation at one time.. I have. 

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As you have spark you can rule out the kill switch.  My bet is she is flooded.   Time to get a plug or two out.  I would push the neutral over ride botton and advance the throttle to approx 50% while cranking to clear the excess fuel and be ready to snatch the stick back if she fires.  I'm thinking your carb may have a stuck needle and seat or saturated float. If so, time for a carb kit.  If not then you may have a restricted exhaust passage from a failed exhaust flapper. Go real easy on starting fluid on gasoline engines as it really easy to break a compression ring.  You also mentioned a strong coil spark but that does not mean it's gettin to the the plugs. The cap and rotor used on those engines are problematic.  W

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30 year old engine should be due for some parts.

A cold engine can not start sometimes when cold in the morning.   If a carburated engine ?  Stuck open choke will not fire.  Do you have a carburetor or   Fuel Injection ?

Did you refill the gas tank before docking the last time. A bad batch of watery gasoline is extremely difficult to start.  Your running great and then no starting or any spitting at all is very odd .

Did you POSITIVELY get that wire back into the rotor cap ?   Was anyone working on the boat at all.  Between a great run & shut down and the surprised NO FIRING AT ALL ?

Very odd & sudden.

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10 hours ago, Stuart Adair said:

Hi folks, 

My first ever boat problem today. Chaparral Signature 27 1990 5.7 Mercruiser. Boat was starting and running lovely when I last turned it off 2 days ago. Came to start it today and the engine is turning over but not firing. The distributer is a bit hard to get to but I've pulled off the coil feed and there's a lovely strong spark. Plugs are hidden under the manifold so quite difficult to get to but thats something I'll have to check next. I never had any spanners to check the fuel line into the carb, so that's another job to check on Sunday when I can next get to the boat. 

Not sure if it is fuel because it still wouldn't fire with a squirt of Bradex. Fuel tap is on and there's fuel in the tank.

When I shut the boat down I get into the engine compartment to reach the battery shut off's. Is there a "Something" in there that I could have knocked that would allow the engine to spin over, spark but not fire ?

I'll keep you informed as things progress (And will doubtless be asking for more advice)

 

Stu

 

You'll have MerCruiser Thunderbolt IV ignition, and as was mentioned earlier, you can have spark at the coil but nothing further on where it matters. Highly recommend you perform the following Thunderbolt IV trouble shooting to help identify the real problem. NOTE: should the ignition sensor (located under the distributor prove to be the problem, HIGHLY recommend the following parts:

 

1 of 892150K02 or Q02 - Mercury or Quicksilver ignition sensor (newer style)

1 of 805759T3 or Q3 - Mercury or Quicksilver distributor cap and rotor kit V8 (rotor typically gets bent during removal - also apply some grease to the 4 brass screws holding the distributor cap down)

 

Link below to trouble shooting as I could not attach a picture...

https://bpi.ebasicpower.com/faq/MERCSB92-11.htm

 

Link below to look up of parts. NOTE: some models had the ignition amplifier (which controls engine timing) mounted typically to the exhaust manifold, while some other models mounted them on the back of the distributor.

https://www.marinepartsplus.com/catalog/mercruiser/serialize(value)/5.7L_2_BBL._GM_350_V-8_1988-1995/816596/1014-110

https://www.marinepartsplus.com/catalog/mercruiser/serialize(value)/5.7L_2_BBL._GM_350_V-8_1988-1995/816596/1014-100

https://www.marinepartsplus.com/catalog/mercruiser/serialize(value)/5.7L_2_BBL._GM_350_V-8_1988-1995/816596/1014-90

 

Hope this helps.

Chris

 

 

 

 

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Has the distributor cap ever been removed to see if the inside is ABSOLUTLY in perfect CLEAN, brand new condition ? Any corrosion 0n the metal pins ?  Center rotor arm is also SPOTLESS and fits snugly ?  

Shepherd

Does he have that LOW OIL PRESSURE SWITCH setup that cold have died suddenly & completely ?    Or is the engine that low on oil ?

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Hi all and thank you once again for the good advice.

I had a mechanic check the issue out today and he quickly diagnosed plugs. Sure enough, he took the plugs out of the right hand bank and found one wet with petrol, two only finger tight so letting gasses past, and one snapped in half with the top still in the plug lead. If the left hand bank is as bad then its no wonder she wont fire. Cap, roter and leads all looked ok but I'll change them anyway. New parts should be here on Tuesday.

Its annoying as the boat had been supposedly serviced last summer and allegedly hardly used since. I should have realised as I found a set of 8 brand new plugs on the boat but they are the wrong sort. I guess that the past owner bought new plugs, realised that they were the wrong ones  and never bothered to buy the correct ones.

Oh well, at least I know it'll be sorted soon.

Stu

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I find it hard to believe all that damage occurred in 2 days .  I have been spinning my wheels.

Pass

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1 hour ago, cyclops2 said:

I find it hard to believe all that damage occurred in 2 days .  I have been spinning my wheels.

Pass

I think you're right and this has been an old issue. The plug that was broken was clearly corroded and had been faulty for some time. Its got really cold here so perhaps the low temperature has just pushed things over the edge to the point that it wont start ?  Anyway, lets see how we get on when the new kit arrives.

 

One other question, does the rotor arm on the 5.7 Thunderbolt ignition just lift off the distributor spline or is there a grub screw somewhere. From the pic it looks like the rotor has a plate attached to the bottom to time the spark ?  Thanks once again. Stu

 

 

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3 hours ago, Stuart Adair said:

I think you're right and this has been an old issue. The plug that was broken was clearly corroded and had been faulty for some time. Its got really cold here so perhaps the low temperature has just pushed things over the edge to the point that it wont start ?  Anyway, lets see how we get on when the new kit arrives.

 

One other question, does the rotor arm on the 5.7 Thunderbolt ignition just lift off the distributor spline or is there a grub screw somewhere. From the pic it looks like the rotor has a plate attached to the bottom to time the spark ?  Thanks once again. Stu

 

 

They pull off hard and the reluctor plate come with. You then remove the tiny hex screws and switch the plate over to the new rotor.   W

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2 hours ago, Stuart Adair said:

Many thanks

You may likely even break the old one getting it off, but that's ok too. For some reason that type really gets fused on there.  W

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Good news update today. 8 new plugs fitted and the boat started straight away. In the end I found the 4 middle cylinders had plugs that were finger tight, and one of the others was broken. I suspect that the issue was whoever fitted the old plugs never used a 1/4 in drive very thin plug socket. Mine only just fitted and anything larger might give the impression of a tight plug. Then again, he could have just been an idiot!  

I should have known really as I was getting the occasional smell of petrol when the engine was running and that was the unburnt fuel getting past the loose plugs.

Everything back together now and looking forward to finally taking her out at the weekend for a play.

 

Stu

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