Mercruiser Mag Mpi Horizon W/Bravo3

Grahamu

Oops I assumed you were twin engine, you will need Mercruiser 10 pin yellow terminator 859318T1 which doesn't come with the module. If you are going to mount it outside of the engine compartment  an extension cable is needed.

NickCruz

Just got the kit in this afternoon. Will look to make sure I can even use it, but I thought there would be a terminator on the plug on the boat. Oh well I'll order it to have it here. Thanks

NickCruz

Can anyone tell me about how much movement the outdrive should have side to side by hand or if any at all.

LaRea

Maybe a half-inch at the propeller.  If it's more than that, time to investigate. 

NickCruz

Ok thanks LaRea I guess its time to investigate, always something.

NickCruz

OK everyone here I go again, need brain storming.  I'm still having the problem of WOT 4200 rpm. I have since installed Vessel View and verified RPM gauge and speed.  I also bought a merc 21P 4x3 Recommended by Mercury Marine.  I still got the same RPM maybe 200 more to 4400 from my 24P. My new question is I just did a fuel pressure check.  Recommended is 43 pounds and of course I am running at 80 lbs.  Steady.  Can someone tell me what that means?  Thanks

Grahamu

The pump is designed to put out 80 PSI, you probably have a rusted fuel pressure regulator which is not controlling fuel pressure. Another cause might be a kinked fuel return line from the rack.
What is your gear ratio on your drive, boats never get lighter over time but heavier and I believe Mercury around 2005 made available gear sets with higher ratios to address this.

NickCruz

That is about right on fuel pressure regulator,  I am going to get my injectors Professionally cleaned .  I have a 2.2 gear ratio

Grahamu

Probably best that you make sure the engine is putting out full power, changing ratios is expensive. Have you done a compression test, I don't see mention of it in the post?

NickCruz

The compression test was supposedly done when I bought the boat.  During the sea trial the boat overheated so I had it repaired at a marina and asked for a compression test to be done.  They said it was good I believe it was all in the 140s or 150s. But anyway I am going to do it again. Just in case.

NickCruz

Hi everyone, I'm back with the same problem I had from the beginning.  Since the last time I wrote I still have not done the compression check, hopefully in the next few days it will be done.  But just some info.  I had the fuel injectors cleaned and rebuilt, and I bought a new set of mercruiser 21P props and tested them.  Believe it or not it made absolutely no difference maybe 100 RPMs.  This does not make any sense at all.  I believe everyone with a 270FV said they had 22Ps and they got between 4800 and 5000 RPMs.  I took the props back and they Refunded the money.  Any more Ideas??   

aero3113

Is your throttle cable adjusted correctly? It’s possible it can be out of adjustment and not giving you full throttle.

NickCruz

It should be it opens the butterfly in the air intake all the way open.  Also I had a mechanic check it with the computer and it showed throttle position at 95% and he said that is a good reading.  I hope to do a compression check tomorrow if all works well. 

NickCruz

Update, Just did the compression test and all cylinders were 185-190.  But the spark plugs were all black like running very rich.  Might be from before injector cleaning.  Will find out when I take it back out.

NickCruz

@Grahamu is it possible to over pressurize the fuel injectors. If running 80 psi all the time might be reason plugs are fouled as if running rich.

NickCruz

The plug that Mercruiser  recommends is ac-41-932.  I guess they don't make those anymore could someone tell me what they are using or what works.  Thanks

Handymans342

They should have a cross reference for that plug

NickCruz

Yes they gave me all these different plugs that were over 10 dollars each.  The ones I had in the boat which I put in not to long ago were the 41-993. they said those were a cross for the others.  I just wanted to make sure those were good because, I'll send a picture, they were really burning rich.

Grahamu

@NickCruz just saw your post I will check tomorrow with my Mercury Guy, also check what we substitute for the plugs.

Grahamu

The replacement plug is NGK ITR4A15 Not sure of US$ price but probably around $4.75 ea. The plugs you have AC41-993 were the plug used by Mercury previously and now changes up to NGK. Did you change the fuel pressure regulator?

Dream_Inn

Those are definitely running rich.  Some of the blackest plugs I've ever seen.

NickCruz

No @Grahamu I just went out to remove the fuel cooler so I can get to the regulator and I just came in because I did not see one on the right back side of the engine. Came to make sure I was looking correctly.  My back does not allow me to bend to much so I may have to have a mechanic do it. @Dream_Inn You think! LOL especially I just put those in less then 10 hours ago engine time.  NGKs are expensive 80 dollars or more.  I already ordered delcos so if they don't work I will get the NGK they all cross over the same. I'm hoping fuel issue is from either the regulator or the injectors which were already done.

NickCruz

Well I figured out I was way out there.  I found the fuel pressure Regulator on the fuel rail of the injectors.  I took it off to get some numbers off of it.  Can you believe boats.net wanted over 300 for it I found one for 29 looks Identical

Aqua_Aura

Looks identical and Are identical can be two different things. The only difference in them if they "look" identical would be the spring inside for different pressures. Just make sure it is the correct pressure setting for your engine. 

reneechris14

There is also a regulator on the fuel cell. 43psi is what my 05 350mag was.

NickCruz

Mine was running at 80psi even at idle and I went to 3000 and did not move.  The one I ordered says it is for that engine.  We will see.

Liberty44140

I used Delco 41-933 platinum in my 2006 mercruiser 350 mag mpi horizons. Ran great for me for 4 seasons and new owner is still running them...

J3ff

my 383 runs VERY rich, you can smell the gas at idle. It always has run that way.. 

NickCruz

@J3ff did you ever check your fuel regulator or fuel pressure.  Thats exactly what I smell also. Mine ran decent except never reached proper RPM.  But now I have done everything possibly associated with the low rpm.  Today I'm putting in the new plugs and new regulator. I will check my fuel pressure.  Then take boat out for trial run when it stops raining around here.