Smarty pants, I really could use your help! 350 Mag trouble SOLVED?? MAJOR UPDATE

rasbury

why would that become clogged? It's just vacuum right? Perhaps more likely dried out and sucking air??

Wildboating

We made some progress today however I did not have the opportunity to engage Al just yet, Al requested some Info be on hand during our discussion.  I hope to have this gathered by tomorrow.

Reminder working with new tech- this guy is independant and heavily engaged by shops all over the north east as a go to guy for problem engines.

Tech pulled plug and felt they were very, very lean appearing.  Both engines he felt were alittle lean looking however the Starboard motor was significantly worst.  He verified that the plugs were the correct 41-933 plugs and they were gapped at 60 thousand's.  A merc engineer he was on call with today suggested that they have recently found heavy amounts of pre-detonation happening with these plugs and provided him with a new part number that is Iridium as a safetly precaution to help prevent engine destruction / damage.  Has anyone heard this?

Fuel pressure was tested and passed, I believe he stated 43psi and the book said 38-43 for this motor.

A fuel sample was taken back to the shop to be tested for ethanol levels.  This data will be back tomorrow.  

It was suggested by the Merc engineer and decided on by my tech to perform an exhaust back pressure test.  We were unable to fufill this today and will perform tomorrow due to some tools needed to accomplish.  The Merc engineer suggested the Bravos be upgraded to a HP exhaust bellow.  Has anyone heard of this?

The tech mentioned to the Merc engineer that the IAC was acting abnormal to the suggested good motor the Merc engineer told us to ignore those readings at WOT.  These are used for Idle testing  and a number of factors can effect the IAC readings at WOT including pressure in the manifold during WOT conditions.


Oddly, when asking about the Spark Control Module and its direct function to how it relates info to the ECM and wether or not we would see a reduction in the Spark Advance via the 555ecm we were never really given an answer.  As a matter of fact, it seem like we would get subject changes.  So Im taking this as a matter of a subject he had no idea on.  We decided to swap the Spark module and the spark knock detector from one block to the other to test.  


Also,  I never paid much attention to it but the Merc engineer and my tech found great interest that my ECM shows in the first 650 hours of this boat, it has never been over 4100 rpm.  Only 1 hour falls in the 4000-4100 range.   I contributed this to the older couple I purchased from who used in on a river in PA.  They told me they only did leisure cruises and towed the kids on toys.


I will be sure to check the vaccum hose at the regulator right away, the Merc engineer was talking about that today on the phone but not saying to check it but they put it there as a way to regulate fuel pressures at Idle I believe.  I will check right away.   I also will swap coils to see.   SInce we are running lean on the engine this does not seem to be the problem though.




AS ALWAYS, THANKS TO THIS FORUM FOR THE CONSTANT SUPPORT AND HELP!!!!

Black_Diamond

Glad we can help. Big benefit has been your feedback so we can all learn too. 

It is amazing on other sites people who never respond with solutions. 

Liberty44140

Yes on the iridium plugs, that is what I use as it is the merc recommended replacement/upgrade 

randy56

Good info Wild, what an ordeal, sounds like you have the right guy.

Handymans342

Man I'm glad I don't have to worry about all this stuff

Wildboating

So I just came down to check the vacuum line off the fuel regulator underneath  The flame arrester.    The vacuum line coming off the regulator goes into the tea one side goes to the intake manifold and the other side goes down around the back of the motor to the cool fuel 2 module.  Attempting to blow or suck in that vacuum line into the intake manifold is all clear if I unplug the line adapter near the cool fuel module in attempt to blow or suck into the cool fuel module I am on able to move either direction.   There is a possibility I'm pinching the line after I separate at the adapter near the cool fuel module.  I tried to separate the Vacuum Lind up near the intake manifold but it wouldn't pull apart.

rasbury

I heard that trump was going to raise the taxes on diesel so the cost was going to 8 dollars a gallon...

Wildboating

Pressure- 38 to 43 psi. We are getting 40 +.  

 Volume into the cylinder is controlled by pulse width of the injector at a given fuel pressure.

if plugs are lean what is telling the ecm to spray less fuel?

Wildboating

Ethanol test came back 7%.  I'm told anything under 10% is fine. 

Wildboating

New injectors trying to solve this problem.  Didnt help.  I have cool fuel 2.   Filters are good, both have also been replaced diagnosing this issue.

Handymans342

Why would they paint the inside of a fuel system component? That is so retarded

Black_Diamond

The paint unto itself was not the issue, it is the ethanol in the gas that caused the paint to peel/flake off. 

Handymans342

Well they knew ethanol has been in the gas for many years

Handymans342

There is not one fuel related part in an automotive system that has paint inside that I am aware of. 

Dream_Inn

Oh boy, if it's the ole paint issue.  Been there done that one twice now!  New fuel coolers this past spring.  My neighbors 420, same thing.  His happened on the way back from Rinkervous!  This will be his second time changing out the fuel coolers/pump.  I didn't know the cool fuel 2 would have the issue as well.

Wildboating

I need some help direction.  Mechanic can't come back until next week now. 

How do we truly start eliminating systems.

Fuel System has 43psi at fuel rail.  If the duration of the spray is controlled by the ecm How do I confirm 100% the fuel system or any component within it is fully functioning so we may eliminate this system.  

Wildboating

@Alswagg
@212rowboat


So I was able to complete some more diagnostics this weekend.   I only was able to look at my starboard motor which is the motor that runs out of power at 60% throttle.  Here are the compression numbers from each cylinder measured with a new OTC compression gauge.  Somehow i misplaced a few photos but each and everyone of the plugs are identical in color. a reddish tint with some white.   I have some thoughts, but **** if i know how yet.   What are you thoughts?

Fuel pressure is 43 on the rail.   Water fuel seperator was dumped into seperate containers, the water chamber only had fuel and no water at all.

Ethanol test came back at 7%

I double then tripled checked firing order.  Again, we have new wires and dist cap/rotor. Checked gear.  Obviously this does not look like an ignition issue though.  

Compression Numbers:   Is this a bit high for a 350 mag?  Im not sure what a new longblock with 100 hours should read.  Atleast they are all together.

1: 210

3: 210

5: 210

7:206

2:211

4: 210

6:210

8:204

Clyinder photos taken with borecam just to verify interior condtions.  These may or may not be helpful.

Cylinder 1:

Wildboating

Cylinder 3:

Wildboating

Cylinder 4:

Wildboating

Cylinder 5:

Wildboating

Cylinder 6:

Wildboating

Cylinder 8:

Wildboating

Exhuast flapper are intact on the exhaust pipe.  My borecam died before i could scope the exhaust y pipe.  I will follow back up with that one.

Wildboating

This the fuel brand I am running.   One of the main marinas in Cleveland, Edgwater. http://www.valvtect.com/marineFuelGasoline.asp
 

Handymans342

If not ignition then its a fuel issue

Black_Diamond

++ @Handymans342. I bet you have a fuel flow issue, not the same as pressure. Collapsing fuel line, one of the 2 fuel pumps. Pressure regulator, restricted fuel vent line. 

Check your fuel lines where they pass thru the firewall. Mine were pulled tight around the corner, virtually kinked. I replaced both lines from the tank to the shutoff valve and made that corner a loop in the line. 

Wildboating

So I also am highly suspect of the volume that is being delivered.  However pressure at WOT should fall off if volume is not able to be delivered under load.   Eitherway, I ordered a graduated cylinder which arrives tomorrow.  I am going to do a 5 second test on the output from the cool fuel module.  I will convert that output to gallons per hour.   I found info stating that the 350 Mag Mpi requires 23gph at 300 horsepower and 5000 rpms.   I am only getting 17gph out of my starboard and about 19gph on my port.  This explains why the port runs a few hundred rpm higher.

Neither one of you made a comment about the reddish tint of the plugs.  is this a normal condition to you??

Handymans342

I can tell if its a fuel issue if I could smell the exhsust

Wildboating

@Alswagg

Yes, the tank was done last year and it made no difference.    What are your thoughts of the spark plug color?