lakeman2

Need some help with my 575 sci.Last year the blower went bye bye.Had the blower shop rebuild it (new shafts.rotors and bearings).I also installed (2) new regulators in the throttle bodies.Mercury does not sell the regulators anymore and can not give me a GM part #.I matched them up at my GM parts store.I took the boat out for a text run and it is running a little rich.When i start it i get black smoke.It ran good but,every once and awhile it pops and surges.then cleans up.Iam running a super chiller w/3 1/2" pulley,areomotive fuel pump.Fuel pressure set at 28lbs at idle.The boat never ran rich before the blower went away.Iam thinking maybe the regulators are not the right ones or maybe the iac might be bad.There was a little bit of fine shaving's from the blower around the bottom of the t.b.s and i cleaned them before install.Were do i start?Does anyone have the right GM part # for these regulators?.Thanks

lakeman2

Anyone?

CB-BLR

Ask SteveZ over in the Nordic forum. He has a warmed over 575 with an innercooler that runs really strong. He is quite knowledgable, and a nice guy.

Chris

Pesky Varmint

I can tell you this. Fuel pressure in the 575SCi is not
regulated in the throttle body. The fuel pressure regulator is in the housing with the high pressure fuel pump under the front of the engine. I know, I've changed the pumps before.

Mercruiserparts.com drawing at (item 15):
http://www.mercruiserparts.com/Show_...nd+Fuel+Cooler

In the normal GM TBI car systems the regulator is in the throttle body and the throttle body has a fuel inlet and outlet. They plug the outlet on the 575SCi, so I don't know whats inside or the function of what would have been the pressure regulator in the throttle body. Hope I never have to find out.

Pesky Varmint

Steve Zuckerman

If it's early in the season (it is) and you are running cold water through your intercooler at idle or just above idle, your motor will act very cold natured and go rich. This can be eliminated by putting an adjustable water pressure valve on the intake side of the intercooler, so that it shuts off flow at idle. Other problems are as you mentioned a bad IAC.
Re FP regulator, it is near the high pressure pump. Is your fuel pressure OK (idle and WOT?)? Maybe you installed new injectors?? You may also have a bad map sensor. They are sensitive to backfires and popping.
The throttle bodies are not very strong, just cast aluminum and therefore they are prone to leaks and breakage. Take the flame arrestor off and check them out at idle to see if you see any fuel leaks.
For spare parts and modifications, I recommend CFM TECH.
They can rebuild these for you, and they have a few performance mods too. I'll see if I can find their website for you. Here you go www.cfm-tech.com
Your avatar doesn't say where you live. If we knew maybe could recommend a good technician.
Regards,
Steve

lakeman2

Thanks for the info.The boat is located in lake havasu,az.I found out that i had the wrong spark plugs in the boat (thanks to my service guy).Also when i did my first test run 3 weeks ago the thermostate stuck open.It was pretty corroaded.Talking with a merc tech he told me to change out the thermostate sensor.It might be telling the computer that the motor is cool and it needs more fuel.Iam going to change out the iac's and tps.Maybe the map sensor.I still need to know if i installed the right fuel regulator in the throttle bodies.There is one on each throttle body next to the injectors.It looks like a power valve on a carb.It comes with the top housing.I called Mercury racing today and they are trying to find a GM PART # for the regulator.My intercooler is plumbed with a force fed pickup on the bottom of the boat.It does not get much water pressure at idle.I will call cfm tomarrow and see what they say.

Linster

If your thermostat was stuck, you would be rich. The way a EFI works compared to a carb is simple. When the motor starts, it reads water temperture. It adds fuel to act like a choke. When the water temperture comes up, it cuts the idle fuel back. Dont change all that stuff you have stated, fix the thermostat. See how it runs. Probally will come back to you. Those sensors dont go bad that often.

The regulator is down on the fuel pump with the cool fuel

lakeman2

I changed the thermostat and plugs.It cleaned up pretty good.My merc guy said to also change the thermostat sensor.It still is rich on warm start up.There are also regulators in the throttle bodies part #852955.I have aftermarket fuel pumps,no cool fuel.

Boat Tech

I looked up what you are talking about.[imo] that part never goes out but you never know things happen.well I went to bam marine and i believe they still have one in stock, part # 852955 at $ 185.80. that is what there web site said.give it a try good luck.

lakeman2

I found that also.The regulator has a rubber diafram with a spring.With the great fuel we have on the west coast it ate up the rubber.Bam has one ,i need two.Mercury parts express has them online,I just need to check if they are in stock.I need to find out if the ones i picked up at my local gm parts store are the same regulator.They bolt right on.After i installed them the boat ran alittle rich.