Mercruiser 5.0l MPI dont rev out?

[Jeff Delbuono]

I have twin 5.0 efi without a shreader valve. Was told its the only way t . Check fuel pressures

 

[Zim]

I had a similar issue, couldn't get past 2k rpms on port engine. Turned out coil wire and 2 other spark plug wires had some shafing and arking to ground. The coil wire was the worst. So i recommend you pull all wires and visual inspect. Good luck.
Good luck

 

[Memike]

Now i nearly got all new parts, waiting for the cap and rotor.

Then we have the answer if it is a gasoline or electric failure or worse somthing more mechanic with the engine.
I´m going to change following and have already change.

Going to change:
* Rotor + cap
* Ignition wires
* Map sensor
* Knock sensor
* High pressure fuel pump + the gasoline lines

Have change:
* spark plugs
* Inline filter
* Water separate filter


After that im out of ides what it could be, off course i will check the compression of all 8 cylinders as well.

Coming back with update when i have try this out

 

[Memike]

Long time no see guys. I just forgot to update my thread here at CSR. But this problem was deeper than filter, fuelpump, etc etc. It was a leaking cyl top and the valves was like chantarelles. My mechanic sad it was cheap shit from china that someone has put in there before i buy the boat

But anyhow now is the top planned, new valves are in place (From USA original stuff) The transom is leaktested, all the gasket is new, the propp shaft is measured, all the bearings is replaced and so on. What can go wrong

The backside of the coin is, i are oing to have monster bill to pay now.... But hey, the boating is worth it, as long as you divide the cost by 10 to the wife

Have a nice friday. Now it is beer a clock in Sweden.

 

[aerobat77]

I dont think this is the problem because the engine is going well and sounds nice i "neutral" mode and Can rev up in 5k rpm.

it sounds very odd you ever rev a 5.0 MPI to 5k in neutral since afaik the engine has a rev limiter in neutral to prevent such excessive reving being in neutral .

whatever - good you have a healthy engine now !!!