2004 350MAG MPI – lost port engine while underway

[Alex F]

Today I lost my port engine while underway. The problem occurred first by extra fuel smell, then gradual loss of RPMs and finally port engine stole.




My troubleshooting steps:

• Since I had clunk of seaweed blocking scoop strainer the day before I checked the condition of seas strainer and dove to see if the scoop strainer wasn’t clogged. So, this had confirmed that there were no issues with water intake.
• I tried to start the port engine, it starts, idles for few seconds and stoles again. If I apply throttle it wouldn’t even attempt to start. If I keep the throttle at idle the engine again will start for a moment and quit right away.
• Got back in the slip on one engine. Went to discuss the issue with marina owner. Knowing that I always try the DIY methods he suggests to do a fuel test. I took the fuel water separating filter out, poured it in the small bucket and waited for 10-15min. I saw some water collecting at the bottom, but marina owner and another mechanic said that this shouldn’t be enough to stop the engine. So, marina owner gave me new filter to give it a try.
• I changed the fuel water separating filter (only the white one on the bottom, I'm not sure but I think the filter SAE J1171 is for return, at least that's how I was told) and engine starts right up and for the next 1-2min I was happy again, but then it stoles again and the symptoms are back to the way there were prior.
• 
• I go back to marina owner to report the results, this time he suggests changing inline fuel filter.
  

His theory is that there’s something that prevents fuel to be delivered to the engine. He finds the inline filter and I make the switch. This was another misfortune, because nothing had improved and engine behaves the same.

We ruled out the fuel pump being a problem only due to results from #4 (changing fuel filter). If the fuel pump was bad I’m thinking that the engine would not work for 1-2min.

At this time we also think that this is not an electrical issue due to the results from #4, but I can’t be sure 100%. I should also mention that there are no codes displayed on SmartCraft display.

I would really appreciate some suggestions. I hope to avoid changing all fuel related components as a process of illumination. However, is worth the shot to change the skinner valve?

Thanks,
Alex.

 

[osd9]

Alex....the 'Skinner' valve, as I understand it to work, is either open or close. It has a solendoid that turns that 'knarlly' knob when you put the ignition on/off. Is it opening and closing? You can manually open/close to test.

Check to see how the other side is working and then confirm the same operation on the trouble side....if not sure, you could swap.

 

[hack4alivin]

Did you check the relays that are used to turn on the fuel supply solenoids for any signs of problems with connections at the socket? Also just swap them around to see if the problem moves to the other engine. They are easy to replace, and a bad contact in the relay could be affecting the fuel supply solenoid you are showing in the picture.

 

[Alex F]

Dom,
The knob was turned all the way to the left (just like on the other side). Now that you had explained that when egnition is on the knob should turn to open the valve it gives me the clue that it should turn all the way to the right. So, this is something to check as my next step.

I was thinking, to illiminate fuel delivery issue theory is there a way to use cross-over fuel delivery from the other tank. I thought I've seen some descussions that modern boats have cross-over feature in case if one side is low on fuel. If I can do this then I would also have better understanding if the fuel pump is part of the problem or not.

Does anyone know how to the cross-over (I'll be checking my manual trying to understand if my boat is equiped with this feature)?

Thanks,
Alex.

 

[tdappleman]

The item labeled as J1171 looks like the fuel pump vs. being a fuel filter. It should have a 2 wire connector going to it and it should run for a few seconds when the key is turned to on but not the start position. This allows the system to prime and build up pressure. It looks exactly like my fuel pump on my carb'd 4.3 - runs at about 6psi. Maybe it's a booster pump if you have the fuel injected motors in your signature.

 

[Alex F]

The item labeled as J1171 looks like the fuel pump vs. being a fuel filter. It should have a 2 wire connector going to it and it should run for a few seconds when the key is turned to on but not the start position. This allows the system to prime and build up pressure. It looks exactly like my fuel pump on my carb'd 4.3 - runs at about 6psi. Maybe it's a booster pump if you have the fuel injected motors in your signature.

Yes, these are fuel injected engines.

 

[skolbe]

My dock neighbor had a similiar issue this weekend - he replaced fuel filter, thermostat, spark plugs, coil wire... The engine was running rich and he noticed the thermostat was open - He said he was having trouble getting the engine to keep up. So, he is having a compression check on his done. The mechanic was concerned about the valves from carbon buildup from running rich.

 

[Alex F]

Thanks skolbe,

Looks like I have to arrange the trip to MM and let them do the their thing. This appears to be more complicated issue than I originally thought and requires special diagnostic tools and expertise.

 

[skolbe]

Thanks skolbe,

Looks like I have to arrange the trip to MM and let them do the their thing. This appears to be more complicated issue than I originally thought and requires special diagnostic tools and expertise.

My friend was doing everything you described and he finally realized it was over his head. He had tried Quickleen - Fuel Treatment. After he discussed with a Merc tech, he realized it may be over his head. Another boat in our marina spent over $1k to diagnose his 350MAg - basically it ended up being Carbon Build Up on the Fuel Rail - causing the boat to miss in the 2000 RPM - range - he also had tried just about everything himself. The Marina - I buy fuel has Valvtec in it. But seeing a few boats in my area having carbon build up issues got me thinking, maybe I need to run a cleaner a couple times a season.

 

[Alex F]

Skolbe,

Thanks for the info. This is the reason why I'm thinking to stop waisting time and just get the boat to MM. I never had put any treatments during the season. This is something to reconsider, but I'll see what they going to find as a cause.

 

[Stray Cat]

Alex - FYI for future...when energized the coil on the Skinner solenoid valve creates a magnetic field to pull an internal plunger off of it seat to allow fuel to flow. With the ignition switch on, you can test the coil by using a steel rule or a small screwdriver to test the magnetic pull on the coil housing. A good coil will provide resistance when you try to pull the steel rule away from it. The knob is a manual overide you can turn in the event the coil fails....atleast that is the way other Skinner valves are designed. Though I have not physically watched it, I don't think the knob moves when the ignition switch is turned on.

My Merc Tech has told me that he has experienced a rash of failures of the air idle control on late model 350 Mags. It is located on top of the intake manifold behind the throttle body, has a couple of wires running to it..has some kind of DC motor that takes a dump and causes the engine to intermitently stall, and idle very ruff...good luck on your diagnosis.

 

[Alex F]

Stray Cat,

Thanks for the info. As for IACVs, I had them replaced on both engines in July. The simptoms with IACVs are the engine works just fine but wouldn't idle. If you apply a touch of thruttle the engine will stay on just fine, but double beep alarm will sound letting you know that something is still wrong. In my situation, if I apply thruttle the engine wouldn't even try to start. If I don't touch the thruttle the engine starts, but shuts in few seconds.

 

[skolbe]

Met my friend at his boat tonight - sprayed Mercury Power Tune into the throttle body - a whole can. The engine started picking up RPM's when we stopped half way through the process. Letting it sit over night after spraying the rest of the can - the boat went from 1200 RPM's to 1600 RPM's within a few seconds of stopping spraying the stuff half way through. So far the stuff seems to be working in breaking up the carbon. Going to take the boat out of the marina on one engine and run it tomorrow once we can get out of the idle only areas and try to blow out the crud. Then repeat the process. Our assumption is that a valve was stuck and therefore the boat was running bad. So, far I am impressed. His boat is a Throttle Body FI not a MPI.

 

[Alex F]

Alex - FYI for future...when energized the coil on the Skinner solenoid valve creates a magnetic field to pull an internal plunger off of it seat to allow fuel to flow. With the ignition switch on, you can test the coil by using a steel rule or a small screwdriver to test the magnetic pull on the coil housing. A good coil will provide resistance when you try to pull the steel rule away from it. The knob is a manual overide you can turn in the event the coil fails....atleast that is the way other Skinner valves are designed. Though I have not physically watched it, I don't think the knob moves when the ignition switch is turned on.

Here's the update on the fix.

Stray Cat, your tip above was very close to finding resolution. I have never worked with these types of valves, so I couldn't perform detailed analyses properly. However, before heading out to MM, I did the following test:

1. Turned the knob in one direction and then back to original position.
2. Noted the position of the knob, turned the ignition on and observed that the knob did not turn.
3. Check the same thing on the other side and it performed the same, so I concluded that it's normal for the knob not to turn.
4. The next and final test was to (what I guess you described as manual override) manually turn the knob and attempt to start the engine. This didn't improve anything, thus at this point (with the assumption that I did use manual override) I had concluded that the valve should be fine. Thus, I made the decision to hand it over to MM techs.

The final fix was this exact skinner valve (you can imagine my frustration :smt013). I was told that it took technicians over 3hrs to diagnose the problem. It’s very strange that manual override didn’t do the trick, unless turning the knob manually is not enough to do proper override.

The valve is part#MM1157475 “Valve, Brass fuel S”, costs $160.99. The final cost with taxes, etc. was $543.

Very interesting and new to me charges were:
- Environmental Surch $5
- Freight external $11.27

I hope this will help someone else to resolve the same issue with only $160.

Alex.

 

[rondds]

Alex
All in all, not that costly a repair. Yet very frustrating when the part is that cheap. But hey, sometimes the diagnosis is the most difficult and time consuming thing. Glad it's resolved!

 

[Alex F]

Thanks Ron,

I guess the only question remains open what is it I didn't do to complete the override function of the skinner valve? I guess, it's always a possibility that the valve was clugged up or stuck to the point where even override couldn't help.

 

[Stray Cat]

Alex, I work for a Parker Hannifin distributor, I will give the Skinner Valve Division a call tomorrow to see exactly how that overide functions....we should all know how that overide works. I was in my ER today and was looking mine over....mine have a little arrow on the knob to indicate inline flow with the pipe stream, but I'm not certain what position overides the coil to hold the plunger open.

I have the Parker part number somewhere.....I'm certain it is proprietary for either Brunswick, S/R, or Merc....

I have 3 of the little gems on my boat, the genny has one too.

 

[Alex F]

Jeff,

That would be awsome if you can get detailed info for our education. I don't recall seen arrows on mine, it's more of a groove for regular screwdriver on the knob. I was able to turn it clockwise and back when I was in the middle of troublshooting.

Thanks,
Alex.

 

[Stray Cat]

Alex, spoke with Tech Service at Skinner Valve this morning. The knurled knob with the screwdriver slot should also have an arrow on the knob face. (I checked mine yesterday and they all do.) Under normal operating conditions with the coil being used to open the plunger, the arrow points in the direction of flow. With the valve mounted for flow from right to left, the arrow points at 9 o'clock. If the coil fails, or 12 VDC is not present to the coil, the plunger can be overridden by turning the knob 180 degrees to the 3 o'clock position. There is an internal fork that lifts the plunger off of its seat to allow fuel flow. Turning the knob multiple times doesn't help. The screwdriver slot position doesn't mean anything.

Next weekend, I'll take a close up picture of one of my fuel solenoids and then post a thread on the how to. Take a closer look at the solenoid MM just installed. It should have an arrow stamped onto the face 90 degrees to the screwdriver slot.

 

[Alex F]

If the coil fails, or 12 VDC is not present to the coil, the plunger can be overridden by turning the knob 180 degrees to the 3 o'clock position. There is an internal fork that lifts the plunger off of its seat to allow fuel flow.

Jeff,

Thanks for the update. The above statement sounds like exactly what I did, but that didn't help. Next weekend, I will also observe closelly how the skinners (old and new work) and will let you know.

Alex.