Mercrusier 5.0 MPI (2008) RPM stops @ 3200.

[AH1Cobraguy]

My mercury 5.0 MPI engine just started acting up. It WILL NOT accelerate beyond 3200 RPM. There is no damage or known issues with my lower unit or prop. I have a “high five” mercury prop that I had on it for 3 years with no issue. I am starting by replacing the fuel filter (which I do annually anyway), replacing the rotor distributor, spark plugs and ignition wires. Any ideas? The oil pressure and water temps are both running perfectly normal.

 

[alldodge]

Have a motor serial number?
Does the alarm work on the boat?
Meaning do you get any beeps when the key is turned ON?

If you do, check your fuel pressure at the rail

 

[tpenfield]

My idea is that replacing all of that stuff won't make a difference. There have been too many threads over the years that have gone this course.

You could do a fuel system pressure check to see if it is within spec. Otherwise, you are best to get the computer diagnostics hooked up as see what is going on.

 

[AH1Cobraguy]

Have a motor serial number?
Does the alarm work on the boat?
Meaning do you get any beeps when the key is turned ON?

If you do, check your fuel pressure at the rail

Engine serial number is: 1A065287

 

[AH1Cobraguy]

Engine serial number is: 1A065287

Alarm works , but no alarm has signaled a problem.

 

[AH1Cobraguy]

Have a motor serial number?
Does the alarm work on the boat?
Meaning do you get any beeps when the key is turned ON?

If you do, check your fuel pressure at the rail

The engine has only 254 hrs on it. I bought is 5 years ago with only 34 hrs on it.

 

[Alumarine]

What speed are you getting at 3200 rpm?

 

[alldodge]

The 3200 rpm could be the In-Gear switch but your not getting an alarm. The switch is on the shift plate and you can disconnect it to see if the issue goes away

Would be best to scan for codes, but without need fuel pressure reading

 

[kenny nunez]

Do you have a water pressure gauge?

 

[AH1Cobraguy]

What speed are you getting at 3200 rpm?

22 mph

 

[Fun Times]

Are there any noticeable sound differences between what used to be normal to now getting up to and trying to go past 3200 RPM within the engine?

It seems you’re starting all within the possible right directions such as spark plugs, Cap/Rotor/ignition system to know their conditions plus like mentioned check fuel pressure, checking for water in fuel and/or maybe paint deterioration within the cool fuel module / under the fuel regulator as some were susceptible to these issues which can reach all the way up to the fuel injector tips.

 

[Stinnett21]

Just curious, when you attempt to go past 3200 what happens?

 

[AH1Cobraguy]

Just curious, when you attempt to go past 3200 what happens?

Nothing. It will not accelerate further beyond 3200 RPM.

 

[LundAngler1650]

Have you checked the tank for an in tank filter as well, incase it has one. That is clogged, well guess what could be your problem.

 

[kenny nunez]

Have you replaced the water pump impeller recently?

 

[QBhoy]

Hi. I’m not even going to say what I always say about what causes this, haha. I’ll get a ripping for it. So I’ll leave the obvious Diz cap answer aside (oh oh...I just did...)
So is it always just getting to 3200 exactly and not going further ? Or is it irregular?
is it popping when it gets to this rpm and no more ?
Any vibration or misfire at all when it does ?
Temperature ok and normal at 150-160of (if alpha one) when this happens ?

 

[AH1Cobraguy]

SUCCESS!!!!! Our 2008 Mercury 5.0 MPI has only 230.7 hours on it. (My earlier 264 was incorrect) It was acting up the last few runs. When trying to hole shot a waterskier it developed a very new & noticeable vibration at around 1500 RPM and then literally NO acceleration above 3200 RPM...... thus not pulling out the salon skier. Normal water temp (160), normal oil pressure (40-65 psi). As per some suggestions we changed the following: new distributor cap, new dist. rotor, new spark plugs (NGK ITR4A15), and new plug wires. The points and rotor contacts had significant corrosion. Just returned from the lake....UNBELEIVABLE difference.... The engine runs very smoothly. It accelerates great from idle/just forward of idle to 4600-4800 RPM without hesitation very smoothly. Extreme improvement! We are only the 2nd owner of this boat and literally only have a total of 230.7 hrs on it when this problem occurred. Bought it 4 years ago with 44.0. Hrs. So thanks to any suggestions I have read. The above parts fixed the problem completely. Even a rep from Mercury @ Fond du Lac suggested this as step one to fix the problem.

 

[nola mike]

SUCCESS!!!!! Our 2008 Mercury 5.0 MPI has only 230.7 hours on it. (My earlier 264 was incorrect) It was acting up the last few runs. When trying to hole shot a waterskier it developed a very new & noticeable vibration at around 1500 RPM and then literally NO acceleration above 3200 RPM...... thus not pulling out the salon skier. Normal water temp (160), normal oil pressure (40-65 psi). As per some suggestions we changed the following: new distributor cap, new dist. rotor, new spark plugs (NGK ITR4A15), and new plug wires. The points and rotor contacts had significant corrosion. Just returned from the lake....UNBELEIVABLE difference.... The engine runs very smoothly. It accelerates great from idle/just forward of idle to 4600-4800 RPM without hesitation very smoothly. Extreme improvement! We are only the 2nd owner of this boat and literally only have a total of 230.7 hrs on it when this problem occurred. Bought it 4 years ago with 44.0. Hrs. So thanks to any suggestions I have read. The above parts fixed the problem completely. Even a rep from Mercury @ Fond du Lac suggested this as step one to fix the problem.

Points?

 

[AH1Cobraguy]

Points?

8 Contacts in the distributor housing assembly. They were corroded.

 

[nola mike]

8 Contacts in the distributor housing assembly. They were corroded.

Distributor cap