Have To Accelerate Slowly, In Increments. Help Needed. Mercruiser 228 MIE

[Redstarbjj]

Hi I have 1979 Penn Yan Explorer 20.5 feet with inboard 8 cyl Mercruiser 228 MIE, 305 size.

I don't post much as you can see, so apologies if this topic exist. I haven't found anything like this though.

Last season it started misbehaving under acceleration throttle. So, when in neutral, the engine runs great. Put in gear and start to accelerate:
If I try to accelerate fast, let's say putting the throttle even half way, the revs go up for a second, and then starts to die down and starts to really struggle. Engine doesn't die, but revs go down and lots of struggling happens. So I have to lower the accelerator down, and slowly in short increments accelerate all the way up to max speed. Takes around a minute, maybe longer to get to the max revs, all the way to 3800. Then it runs fine. If I have to slow down, drop the speed, and then have to go faster again - I have to do it in increments again.

Idling is perfect - revving up is not an issue in neutral
New oil new oil filter
Transmission fluid is at good level
Fuel filter is new, replaced last year
Prop is in good shape
Doesn't have many hours since carbs been cleaned - maybe 50 hrs.

Before I go to local marina and ask them to bill me hundreds of dollars, I'd like to know if I can do something myself.

Any help is appreciated. Thanks.

 

[Bt Doctur]

have you tried running it on a remote tank to eliminate the fuel system, sounds like fuel starvation.

 

[Redstarbjj]

have you tried running it on a remote tank to eliminate the fuel system, sounds like fuel starvation.

Honestly, I wouldn't know where to begin with something like that. Haven't tried, no.

Can it be a fuel pump? I thought it felt like it's just not getting the fuel fast enough.

 

[Bt Doctur]

remove the hose going to the fuel sep or fuel pump and plug it .hook a outboard tank hose to the fuel sep or fuel pump fitting

 

[thumpar]

Look down the carb while someone pushes on the throttle (not running). You should see a stream of fuel shoot out. If you don't it is the accelerator pump and would need a carb rebuild.

 

[Bondo]

have you tried running it on a remote tank to eliminate the fuel system, sounds like fuel starvation.

Ayuh,..... Agreed,..... Tank, fuel pump, or carb, any one, or all three,....

 

[Redstarbjj]

OK, here is the update:

Tank - checked rechecked, even replaced the fuel lines. Vent line is free of crap, blew through it.

Carbs - fuel is flowing without engine on when I press on accelerator. But only about quarter of the way, not all the way up. Normal? Not?
Don't know what else to do there YET (studying the manual for now), but after removing the air round filter thingy that sit on top, the carbs didn't look spanky clean, maybe they supposed to look like that - not silver clear clean, slightly darker wet kind of colour. I remember from my young dirt bike days, carbs looked like they were just polished on the bikes, but not on my Merc.

Fuel pump - nothing really tested. The clear glass "cup" looks empty, no fuel in there. Fuel pump looks like it was replaced very recently. I am assuming when the engine was rebuilt few years ago for the previous owner.

Electrical - ok, so tell me this...... I started going through spark plug cables, just visually checking them, detach, attach...nothing special for now and got to the ignition coil - took the cable off and there was liquid inside where the cable attaches...like an oily liquid. Then I noticed the whole ignition coil is wet, on the top. I checked all around, thinking maybe oil is leaking, or spraying somewhere - no - all other parts are dry and clean. So...is it supposed to be wet? Or is it gone? I am assuming anything related to electrical not supposed to be wet even with an oily substance. Please let me know, gents.

Also, someone suggested to check advance weights in the distributor can get sticky. I will check.

BTW...all of you been a tremendous help so far. I am very new to this, but I'll get there.

 

[pureinsanity]

Coil wise..No it should not be wet. It sounds like the coil is leaking, you should replace it. The fuel filter was replace last year. Was that before or after you started having the problem? You say it revs fine in neutral, I would wonder about something in the outdrive slipping or binding.
Sorry for the questions but just trying to get a better grip on this. You said it revs for a second then dies down. The engine revs up and the boat tries to launch then it drops off and the engine is struggling or just the movement of the boat is, and the engine is running fine?

 

[Redstarbjj]

Coil wise..No it should not be wet. It sounds like the coil is leaking, you should replace it. The fuel filter was replace last year. Was that before or after you started having the problem? You say it revs fine in neutral, I would wonder about something in the outdrive slipping or binding.
Sorry for the questions but just trying to get a better grip on this. You said it revs for a second then dies down. The engine revs up and the boat tries to launch then it drops off and the engine is struggling or just the movement of the boat is, and the engine is running fine?

It's getting worse and worse.... I noticed that the voltage on the meter dropped all the way to 11 volts, and when it used to run it was always 14. And at this voltage I could not bring it higher, than 2000 revs. Last night was around 2700 max, night before that was around 3200.

"The engine revs up and the boat tries to launch then it drops off and the engine is struggling" - yes, exactly that. It tries to rev up, so literally for a half a second, and then down down down....below previous revs. And yes in neutral it revs fine, all the way up, ran it today at 4200 rpm for a good minute.

Fuel filter replaced when I started having these issues, they were minor comparing to now, seems like every time I go out (hey, man's'gotta fish) it gets worse and worse.

No apologies for the questions needed, you're trying to help and I welcome it.

 

[Redstarbjj]

OK, so it was the ignition coil, who knew. I got an after market Flame Thrower 40000 volts version, installed it, and the boat is flying like never before. I also noticed the engine is working much smoothing with less vibration. It run all the way up at 4000 rpm and acceleration takes about 20 seconds to go full plane full speed.

I am still going to rebuild the carbs, ordered the kit, but that's later after the season most likely.

ONE NEW THING: the voltage shows only 12 volts, and I understand it should be showing around 14, closer to 13.8, and that's how much it used to show. Should I be concerned? Should I prepare myself to replace/repair the alternator? I need to mention, that when I was replacing the ignition coil, it felt really warm, almost too hot to the touch, and the boat was not running since previous evening. Seems to me like something shorting.

 

[Redstarbjj]

Common guys, nothing?

Boat died in the middle of large lake. Two fuses blew next to solenoid > replaced > motor turns but not firing. Voltage at the coil is only 6 Volts. Turn the key on without turning the motor and one of the wires at the ignition coil gets warm.

Any ideas?