Throwing in the Towel - HELP!

[Doc_Vegas]

OK guys:

My 2001 2700 SCR with 7.4 MPI motor has lost much of its power. I changed the fuel/water seperator filter, cleaned the air intake, and looked at the distributor cap/wires. Everything seems fine, but still not much power. Temp is fine, oil pressure is fine. Just doesn't have the power. I do not think the prop is slipping, since the engine can not build the RPMs. I may try to check the wires on the spark plugs, but I doubt one came off. It does feel like a piston may not be firing, but at idle it sounds and feels normal. That said, it also seems to have a bit of a rich smell, like there is excess fuel in the exhaust (maybe).

I do see the tach. occasionally drift high for no reason, then come back down - but there is a recent post that indicates that problem may be dirty tach leads...?

The marine shops around here are uber expensive, and my wife and I are considering a major relocation, I hate to get deep into the boat - especially now. That said, I have no trailer and I am pretty much stuck to things I can do at the dock.

Any last minute ideas before I throw in the towel and call the shop?

Thanks

 

[Glastron_V210]

Re: Throwing in the Towel - HELP!

Sounds like you have dropped one or more cylinders.

Try this...


It idle, pull 1 spark plug lead at a time (Maybe use insulated pliers if you don't like the occasional zap)

The engine should run rougher...does it? If not, the cylinder is not contributing power...now find out why. If it does run rougher, then the cylinder is getting spark and it burning, at least at idle.

Is the spark plug getting spark? If not, fix it. If it is, then compression test is your next test.


Let us know the results.

Chay

 

[Don S]

Re: Throwing in the Towel - HELP!

There are a LOT of things to check on an MPI engine that could cause your problem. Is this a Merc or Volvo? What is the SN, year doesn't mean much on either one.

 

[Richard Carlson]

Re: Throwing in the Towel - HELP!

1.Check the fuel pump pressure.
2.Check that the inline fuel filter is not plugged. I would replace it. (cheap)
3.Clean the carburetor jets or have it rebuilt (around $200).
4.Check the timing.
Hope it's one of the above.

 

[Don S]

Re: Throwing in the Towel - HELP!

.Clean the carburetor jets or have it rebuilt (around $200).

It's an MPI, no carb.

 

[Doc_Vegas]

Re: Throwing in the Towel - HELP!

Thanks guys. It is now in the hands of the pros. I really did like the idea of pulling the plug wires, I should have tried that; however, I feel very uneasy being in the engine compartment with the motor running.

Regardless, I will post up the results when they come in... I also agree that it seems a piston (or two ) is not firing.

Oh yeah, it is a Merc.