RPM's drop off at WOT

V

VTSeaRay

Active Member
Feb 19, 2008
1,905
Northern Vermont / SW FL
Boat Info
2007 210 Select w/5.0L 260HP MPI Mercruiser Alpha 1
Engines
8 cyl 5.0 Merc mpi, w/alpha 1 with 19" prop, with the speedo hole on the leading edge just above it
I haven't been here in a while, did some searching to no avail.

I think i have a fuel starving situation - a yr or 2 ago I posted how I was seeing what felt like slippage at WOT - well, now I don't think it was, it's more prevalent now and it feels more now like fuel starving while at WOT - I only go there once in a while, but don't like this feeling - I found if I feathered the throttle up/down a bit, I'd get my RPM's and speed back. (almost like I'm pumping the EFI ?) This is on a 210 SLX '07 with 5.0L EFI Engine and standard Mercruiser outdrive.

I'm wondering what I should look at here?

Thanks,
-VTSeaRay
 
That's what I'm thinking, it's some sort of bad filter, or screen. Where was this screen located again(any pics? of it's location? - or online pointers?)?
 
They are original. so they're only 7 yrs old. (and in fact, the boat only has maybe 65 hrs on it so far. I live in northern vt, so it sits covered in my garage 6 months of each year.)
 
VTSeaRay said:
That's what I'm thinking, it's some sort of bad filter, or screen. Where was this screen located again(any pics? of it's location? - or online pointers?)?
Click to expand...


I added pics to my original post....go look at it again. I also changed all my plugs as they were fouled.

I put in the latest recommended plugs by Merc = AC 41-993
 
Ah, thank you - Great Info - I'll have to check on mine! I'm going to pull my plugs too and check them, but it seemed more like fuel starvation than plug misfires.
 
With it sitting so long could it be moisture in the fuel? My outboard use to act funny only when I floored it and it would sputter and then gain speed then sputter again.
 
It might be - that's similar to the symptom I'm seeing. I had put in fresh fuel, but have since added in ethanol fuel treatment
 
VTSeaRay said:
I haven't been here in a while, did some searching to no avail.

I think i have a fuel starving situation - a yr or 2 ago I posted how I was seeing what felt like slippage at WOT - well, now I don't think it was, it's more prevalent now and it feels more now like fuel starving while at WOT - I only go there once in a while, but don't like this feeling - I found if I feathered the throttle up/down a bit, I'd get my RPM's and speed back. (almost like I'm pumping the EFI ?) This is on a 210 SLX '07 with 5.0L EFI Engine and standard Mercruiser outdrive.

I'm wondering what I should look at here?

Thanks,
-VTSeaRay
Click to expand...

I am having same problem started like yours and it is getting worse over last year.
Put in new plugs rotor cap and both fuel filters.
Had engine codes read by dealer and no codes showed up????
Had fuel pressure checked and of course could not duplicate problem but pressure checked out OK across all RPM range.
Dealer wants to start to throw parts at it...................

After research - Nnow looking at
1. throttle position sensor - sends voltage to ECM
2. Ignition coil - $250 replacement part
3. Electronic Control Module (ECM) - $1400 to replacement part
4. Manifold absolute Pressure (MAP) - $225

I believe the ECM is getting a voltage "burp" which impacts it's function for a momentary pause and then re-sets and engine takes back off and runs fine.
I have also experinceced a very rough running engine after getting shut down by same issue......... I switch off engine and it starts up fine and runs fine - that leads me to vltage - coil or ECM.

The other night I ran for a hour across Bay without a RPM change or drop and 1/2 hour back across Bay after dinner and then had RPM drop.
When problem started it was worse at full RPM and now is starting to occur at RPM above 3000.

I am going to play with running on battery 1 and then battery 2 and then both to see if voltage is occuring from AGM battery. Mine seems to be worse when I play with motor tilt that drives me to electriacl problem not fuel.

Any suggestions out there?
 
tcason said:
I am having same problem started like yours and it is getting worse over last year.
Put in new plugs rotor cap and both fuel filters.
Had engine codes read by dealer and no codes showed up????
Had fuel pressure checked and of course could not duplicate problem but pressure checked out OK across all RPM range.
Dealer wants to start to throw parts at it...................

After research - Nnow looking at
1. throttle position sensor - sends voltage to ECM
2. Ignition coil - $250 replacement part
3. Electronic Control Module (ECM) - $1400 to replacement part
4. Manifold absolute Pressure (MAP) - $225

I believe the ECM is getting a voltage "burp" which impacts it's function for a momentary pause and then re-sets and engine takes back off and runs fine.
I have also experinceced a very rough running engine after getting shut down by same issue......... I switch off engine and it starts up fine and runs fine - that leads me to vltage - coil or ECM.

The other night I ran for a hour across Bay without a RPM change or drop and 1/2 hour back across Bay after dinner and then had RPM drop.
When problem started it was worse at full RPM and now is starting to occur at RPM above 3000.

I am going to play with running on battery 1 and then battery 2 and then both to see if voltage is occuring from AGM battery. Mine seems to be worse when I play with motor tilt that drives me to electriacl problem not fuel.

Any suggestions out there?
Click to expand...

I haven't seen the rough running piece, but this is interesting information. Keep us posted on any other findings - I will also update this if I find anything else.

-VTSeaRay
 
Unfortunately, I haven't been out in my boat again since I last reported this. (I'm replacing carpeting with hardwood flooring in my entire main floor of the house and between that and the rain, it's consuming all of my free time). I guess in a way it's good it's raining, so I don't feel so bad about being inside on nice days doing this (and yes, I know, I should have done it during the winter, but then, when would I ski/snowshoe? :)
 
VTSeaRay said:
Unfortunately, I haven't been out in my boat again since I last reported this. (I'm replacing carpeting with hardwood flooring in my entire main floor of the house and between that and the rain, it's consuming all of my free time). I guess in a way it's good it's raining, so I don't feel so bad about being inside on nice days doing this (and yes, I know, I should have done it during the winter, but then, when would I ski/snowshoe? :)
Click to expand...
I've lived in Burlington once. The nice summer days as I remember where middle of July to end of August. So you still have some time for those floors.
 
Exactly. Though, I did take Sunday off to enjoy the day! ;) It was gorgeous - mid-70's. sunny, just great, but didn't get out in the boat. :( I had to other obligations.
 
Mercruiser had a problem with their Fuel Cool Module in your engine. Apparently, they painted the inside of the unit and over time the paint breaks down and causes problems. The Generation III Fuel Cool Module were only installed on the 5.0 and larger engines. You might want to have your dealer look and see which one you have on your boat.
 
I'll ask them, thanks.
 
I did ask them, they said that if it was the cool module, I'd notice issues at idle too, and I don't. They're thinking I might have dirty fuel filters, and want me to bring it in, so they can check it out. I might do that tomorrow, if I get a chance.
 
You aren't going to believe this... or maybe you will

So went out on the lake today... I had 7/8's a tank of gas, motor was sputtering for 4 miles from 4-5k... I'd drop to 3500, then back up and again it'd stall/sputter in the 4k-5k range. Dropped anchor. Put 1/2 bottle of startron in(the walmart 8 oz for 128 gal - careful, there are different strength mixes!!!! in same bottle!!! - I've seen 8 oz for 24, 40 and the 128 gals), sat around on the lake, with wave action working sloshing the gas around. for 4 hrs... took off... Not a single sputter for the next 4 miles back in!!!! It seems it was that Damn ethanol!!!!

My boat is back to it's original self, no sputtering, no stalling @4k and above! I was doing 50mph @5k (GPS measured!) I stopped/restarted 4 times over the 4 miles back in to the docks, no difference!!!!
​
 
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