4.3 fi Merc Problem

[Britt]

I have the same problem with my Merc 4.3 every year. There seems to be a miss and major loss in power. It backfiresand the Rpm gauge is all over the map. No one has n=been able to figure it out. Can anyone help.

 

[achris]

Re: 4.3 fi Merc Problem

Hi Britt,<br /><br />Welcome to iBoats.<br /><br />The major clue here is the tacho flying around. Start looking for dirty battery connections or loose wires. Sounds like the EFI computer is being starved of volts. IMO<br /><br />Chris.............

 

[Britt]

Re: 4.3 fi Merc Problem

My battery connections are good. I have run over wiring as well. Could this be a dirty fuel problem?????

 

[snapperbait]

Re: 4.3 fi Merc Problem

Has anyone ever checked the computer for codes? Fuel pressure?

 

[Britt]

Re: 4.3 fi Merc Problem

I have someone doing this and they have now told me water in Cylinders 3 & 5. How does something like this happen??

 

[snapperbait]

Re: 4.3 fi Merc Problem

Leaking exhaust manifolds, blown head gaskets, reversion (engine sucking water in thru the exhaust).. Few possible causes for water in cylinders...<br /><br />What model year is the engine and is it used in saltwater, freshwater, or both?

 

[Britt]

Re: 4.3 fi Merc Problem

It's used in both salt & Fresh water. The engine is a 1999 4.3L EFI Mercury with fresh water cooling.

 

[snapperbait]

Re: 4.3 fi Merc Problem

I'd be looking at a leaking port side exhaust riser as being a good reason for water in 3 & 5...

 

[Britt]

Re: 4.3 fi Merc Problem

Thanks snapperbait. Could it be Heads? Cracked head?

 

[snapperbait]

Re: 4.3 fi Merc Problem

Hope not, but yes, that is a posibility...

 

[Blk-n-Blu]

Re: 4.3 fi Merc Problem

Britt, read this article on water in engine:<br /> http://www.marinemechanic.com/site/page88.html <br />Good luck

 

[Britt]

Re: 4.3 fi Merc Problem

Thanks again guys. The water I'm getting is not water from the cooling system (NO ANTIFREEZE) so this must rule out the Heads Right? When I cranked it over with plugs out and re hooked up to the hose the water re appeared. ????

 

[snapperbait]

Re: 4.3 fi Merc Problem

Yep on the head...<br /><br />If the exhaust manifolds are plumbed in as part of the closed cooling system, I got my $$$ on a leaking exhaust riser.. Riser would be the only part subject to raw water...

 

[Britt]

Re: 4.3 fi Merc Problem

Get this snapperbait. I went to see my mechanic today he said he thinks I have a blown exhaust manifold gasket. The cooling system in my boat was just replaced last year. This sounds like a very good posibility. He will have the answer Friday. <br />Your input has been a big help. You have no Idea the troubles I've had with this boat.<br /><br />This puts alot of things to rest. I've had 2 warranty jobs on this thing. Both replacing the engine and on the first trip out this season this is what happened.<br />It will be a big releaf.<br />

 

[Britt]

Re: 4.3 fi Merc Problem

We'll now I've been told there is no compression. Is this making any sense?<br />The mech checked the exhaust manifold and it was fine. What could be doing this?<br />