575sci's Advice

[Quinlan]

OK, Where to start. 02 575sci's
Port motor was acting up this weekend only gunning to 4k rpms. So pulled plugs and they were fouled pretty bad (about 20 hrs on plugs) Cleaned up and ran better. Runs rich most of the time. I am replacing the t stat, sender and ECT.

St board It is always hell to get warmed up. Pulled plugs not fouled near as bad but cleaned anyway. When cold it hardly idles at all. Always poping and dies. Replacing all of the cooling senders and t stat also.

At this time I have both throttle bodies off and at a shop having the injectors cleaned and flow tested. Also I have been told to send in the ECM to have reflash.
I had both blowers rebuilt this past winter. Have done compression and leakdown and not to bad on either. Both have about 400 hrs, but Port was rebuild right before I took delivery and I plan on going thru both this fall.

Boat runs like a bat outa hell when warmed up. :sifone:

Am I even on the right page? Any suggestions would be great.

Thanks Quinlan

[Geronimo36]

starboard engine with the 400 hrs might be popping due to bad valve springs. 400 hrs is a lot on original valvetrain. does the popping go away after its warm??? Is it popping out the exhaust or in the intake plenum?

Not sure about the port engine but it seems you're in the right direction. Anyone get a scan tool on it to see what's happening?

[Quinlan]

The intake. When I pulled the Throttle body on that one there was raw gas on the blower blades, looks like injectors are just dripping fuel.

I forgot to mention that the top end has been rebuilt on both motors less that 100 hrs ago.

[J.T.]

Did you ever figure out anything on this ?
http://www.seriousoffshore.com/forums/showthread.php?t=7099

Is the engine with gas sitting on the rotors the one that had the
pressure problem ?

[Quinlan]

Yes it is.
I did find a loose wire, I think it is the fuel pressure sender on the front of the throttle body. Not sure if that is the problem as I have not had it fired up yet.
The popping is only on idle when I advance the throttles, one pop then dies.

[J.T.]

I was thinking maybe if it truly was excessive fuel pressure
it would be dumping in way more fuel than it could deal with,
but, if it was just a sender problem, that blows that theory.

One of mine has had an intermittent problem with sneezing and
dying when coming off of idle, the other one will occasionally do it too.

They do run great off idle, but when they're cold, or it's hot and
humid out they suck......my carb HP500's behaved better than these.

I've just learned to deal with some of these quirks.

But hopefully, these quirks will go away after the head,
cam and ecm mods Dean Gellner is doing for me

[Quinlan]

Keep us updated on the mods.

[TxHawk]

I was thinking maybe if it truly was excessive fuel pressure
it would be dumping in way more fuel than it could deal with,
but, if it was just a sender problem, that blows that theory.

One of mine has had an intermittent problem with sneezing and
dying when coming off of idle, the other one will occasionally do it too.

They do run great off idle, but when they're cold, or it's hot and
humid out they suck......my carb HP500's behaved better than these.

I've just learned to deal with some of these quirks.

But hopefully, these quirks will go away after the head,
cam and ecm mods Dean Gellner is doing for me

I have had to learn to live with the 575 quirks on the ones I have operated too. I understand the pop through the intake at idle when advancing to be a lean pop. They are just kind of rough engines. The do run great once you get them going.

Can you get a mechanical fuel PSI gauge on them?

[J.T.]

You can plug a mechanical gauge where item
#25 plugs in to.
http://www.mercruiserparts.com/Show_Pictures3.asp?dnbr=881752&ivar=images/COMMON/26656.png&inbr=5419&bnbr=80&bdesc=Intake+Throttle+Body+Assembly

I thought that maybe the tps might be the problem
with the sneeze, but I've never got around to trying one.

[Quinlan]

Got the gasket kit for the throttle bodies today and went by shop working on injectors, they said that 4 were less than 100 ( I guess psi?) flow when they should be 115.
So that might explain the lean pop you guys mentioned.

Any recomends on some Mech fuel gauges? I think I need for peace of mind.

Hope to have it back together by weekend! Will see
Quinlan

[Quinlan]

Well we got it all back and installed. We will see what happens!!!

[Quinlan]

Went out Sat and ran da pizz out of it. All seems good, still might be fouling plugs tho. Will pull to check this week.
Fuel pressure issue must have been the missing nut!

[Quinlan]

Faaak

[J.T.]

Faaak

???

[Quinlan]

Was running great after all I had done. Idle great even the transom was fairly clean. Then I think I lost a head gasket.
At brad smiths now. Refresh on both. Hopefully by Shootout.
O well guess I be hangin in the cruzier and the A/C for a month or so.
I will relay what they tell me.

Quinlan

[Quinlan]

Eat an exhust valve and spit it out. Not to pretty. But by god they will be when finnished!!!
Go Brad!

[Geronimo36]

Check your exhaust system for water leaks

[J.T.]

Did it loose a valve seat ?


My heads were cracked by the seats, and the risk of
valve seat falling out is what led me to get new heads.

[OBNOXUS]

got to love our oyxgenated fuels

[PrecisionPower]

If interested we do an upgrade package to the 575SCi that includes: Cylinder head work, good valves, hydraulic roller camshaft, good head gaskets/bolts, blower mod.(stock pulley), and new ECU program. Makes 675HP @ 5500 and 675ft/lbs. @ 4500, cleans up idle, doesn't "pop" or stall. Did 3 in a 50 Hustler 3 years ago and solved all issues related to the 575. 616-844-1000 -Ben

[Quinlan]

Did it loose a valve seat ?


My heads were cracked by the seats, and the risk of
valve seat falling out is what led me to get new heads.

I am not exactly sure what gave up, but I know the exhaust valve is gone.
Also the water passages on the manifolds are VERY corroded. New manifolds too.

Saltwater boats Live and learn.

What heads did you do? Brad is suggesting Alum. heads.
I will be 99% freash water running and the extras sound worth it.

[J.T.]

I am not exactly sure what gave up, but I know the exhaust valve is gone.
Also the water passages on the manifolds are VERY corroded. New manifolds too.

Saltwater boats Live and learn.

What heads did you do? Brad is suggesting Alum. heads.
I will be 99% freash water running and the extras sound worth it.


I went with Dart Iron eagles, basically so I didn't screw up the
center of gravity of the boat. ( It doesnt need any more weight removed
from the a$$ end)

On a twin step, I doubt it would be as much of an issue though.