Engine issue

ship happens said:
All fuel injected engines have a TPS. You cannot check the voltage without diagnostics.

Won't be a map sensor


Fyi those spark plugs are iridium and you cannot gap them or else you will scrape off the surface material ( iridium). Also this might sound a bit dumb, however those plugs are pieces of albsolute ****. Only plug in my 25 year career that I've seen just not work whatsoever or work intermittently. Like I'm talking not work at all. Most plugs get weak over time or get arched out but these plugs are absolutely bizarre.


Unplug the shift switch. Just rule it out

Also just assuming that your battery connections are proper and bolted down tight with a nut?
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Spark plugs are not irridium on the four strokes. Regular ngk. Going to get another set tomorrow. Lkar7c9 plugs

Looked thru the merc parts diagram
For a tps and can’t find one. Not sure if it is a fly by wire thing

Went thru all connections, battery to engine, clean and tight

Went thru fuel supply. Clean

Now my voltage is bouncing around too. 14.1-14.6 randomly all the time ever sec

This has a connection to rpm change not sure why

Coils! Has 3 and they are behind an exhaust tube! Changed one but never made a difference, painful to get at will try swapping the others with my new one

Trying new wires, plugs again, then take off alt belt to see what happens then pulling fsm
Module to test fuel pumps
 
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Ohh I see, I know what engine that is now. I have not worked on that engine. I'm assuming what they did was integrate what would be the TPS right into the control. Without an exploded view I have zero input. Sorry I assumed it was 200 verado
 
ship happens said:
Ohh I see, I know what engine that is now. I have not worked on that engine. I'm assuming what they did was integrate what would be the TPS right into the control. Without an exploded view I have zero input. Sorry I assumed it was 200 verado
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I wish at this point. Thanks though. Going to start with the basics and dig deeper. The voltage bouncing in tiny amounts but just started doing that in the last week where as the tach bouncing has been going on for a month. What’s the link?
 
salmonkiller01 said:
I wish at this point. Thanks though. Going to start with the basics and dig deeper. The voltage bouncing in tiny amounts but just started doing that in the last week where as the tach bouncing has been going on for a month. What’s the link?
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The answer to every boat issue is, bad ground. I swear, 90% of the time, it works every time.
 
Was the O2 code for lean condition? I would check for a manifold vacuum leak. With the engine idling, spritz some water around the throttle body (not into), vacuum lines and intake manifold. If you have a vacuum leak, the engine will stumble when the leak draws water mist in.

The ECM meters fuel quantity based on the volume (mass) of air passing through the throttle body (measured by Mass Air Flow Sensor). A vacuum leak after the MAF sensor will allow a quantity of unaccounted for air into the engine for which no fuel will be added. This will result in the O2 Sensor measuring more Oxygen than expected in the exhaust stream. The ECM will then add fuel to correct the lean condition which will increase RPM. The ECM will then reduce the fuel to achieve the RPM that the throttle control is requesting (idle). On and On.

The voltage fluctuation is probably a result of the rpm fluctuation. Alternator output is increased as its' rpm increases. Alternator output is lowest at idle. 14.1v is probably the voltage dropping to satisfy the demand for current, increasing to 14.7v when the engine rpm momentarily increases.

Good luck!
 
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Seriously though it's easy rule out the shift switch. The mercs really dont like faulty shift switches. I've replaced a dozen of those in the last couple years and I don't even let the merc outboards in the shop 90 percent of the time

I can't remember if it's normally closed or open for neutral. I should. But I don't. Either way unplug it. Let it idle with it unplugged. It's a 2 pin connector black and black yellow stripe I believe. It will either think it's in gear or neutral
 

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I'm not seeing a MAF sensor. I briefly looked. Grab a pen and paper and go through the intake assembly page, then go through the electrical page. Write down how many total sensors there are. Make sure they are not duplicated.
 
InterMechanico said:
Was the O2 code for lean condition? I would check for a manifold vacuum leak. With the engine idling, spritz some water around the throttle body (not into), vacuum lines and intake manifold. If you have a vacuum leak, the engine will stumble when the leak draws water mist in.

The ECM meters fuel quantity based on the volume (mass) of air passing through the throttle body (measured by Mass Air Flow Sensor). A vacuum leak after the MAF sensor will allow a quantity of unaccounted for air into the engine for which no fuel will be added. This will result in the O2 Sensor measuring more Oxygen than expected in the exhaust stream. The ECM will then add fuel to correct the lean condition which will increase RPM. The ECM will then reduce the fuel to achieve the RPM that the throttle control is requesting (idle). On and On.

The voltage fluctuation is probably a result of the rpm fluctuation. Alternator output is increased as its' rpm increases. Alternator output is lowest at idle. 14.1v is probably the voltage dropping to satisfy the demand for current, increasing to 14.7v when the engine rpm momentarily increases.

Good luck!
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Thanks for that awesome explanation. Will try and see
Anyone have a merc 4 stroke fluctuating. Maybe I have lost it and it is normal. Who knows
 
Rain City said:
The answer to every boat issue is, bad ground. I swear, 90% of the time, it works every time.
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Pretty sure I went thru them all twice. Engine, battery, night switch even removed fuses for boat part to rule that out. Have new plug wires and plugs to try and will look for intake leaks
 
Profisher years ago mentioned that he had a problem maybe corossion in the connector that pushes onto the end of the spark plug. Might be worth checking
 
salmonkiller01 said:
I wish at this point. Thanks though. Going to start with the basics and dig deeper. The voltage bouncing in tiny amounts but just started doing that in the last week where as the tach bouncing has been going on for a month. What’s the link?
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Sorry I jumped in a little late here but on my 200 mercury it would rev up when the alternator engaged as I believe it had a very large output. The voltage jumping around from 14.1 to 14.7 rapidly sounds like the alternator cycling on and off rapidly?
 
Those engines draw all their current to operate the ecu and ignition right from the battery. So unless there is a fundamental internal problem with a battery I would rule out the charging system.
 
ship happens said:
Those engines draw all their current to operate the ecu and ignition right from the battery. So unless there is a fundamental internal problem with a battery I would rule out the charging system.
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Does it need to be a fundamental internal problem? Would a weak battery cause issues?
I waited a bit longer than I should to replace my batteries, and all sorts of things were working smoother after replacement.
 
Gong Show said:
Does it need to be a fundamental internal problem? Would a weak battery cause issues?
I waited a bit longer than I should to replace my batteries, and all sorts of things were working smoother after replacement.
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2 brand new batteries for me just at start of March
 
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