Mercruiser 5.7l MAG MPI 350 won't start, smartcraft guages going haywire.

[captnvinny]

[FONT=Helvetica Neue, Helvetica, Arial, sans-serif]I have a mercruiser 350 mag mpi I/O. Replaced the starter a month ago and seems to be working jus fine. However when I turn my battery switch to BOTH, I get the beep from the smart gauges, and the gauges are erratic when I turn the key, the fuel pump relay does click, the engine cranks but does not start. I checked all the fuses, I had one burnt that was tied [/FONT][FONT=Helvetica Neue, Helvetica, Arial, sans-serif]directly onto the battey, replaced the 5amp fuse. Not even sure if it is related to the issue. Seems like fuel is not getting to the engine?? I also replaced the filter but not the basket. Basket needs replacement, I just don't have one. I used to be able to smell fuel in lower hatch compartment but now I can kind of smell a little egg/sulfur stench but not strong. I have added fuel twice since the 1/2 I had in there during the winter but that 1/2 tank of gas was never stabilized (my bone head error). I had the boat out twice this year, but the third time I had to change my battery switch to #1 to get going. The batter switch when turned to BOTH acted weird. That trip did not go well as the engine never started since the 1st time that day. Don't know where to go with on this issue???[/FONT]

 

[alldodge]

[FONT=Helvetica Neue, Helvetica, Arial, sans-serif]I have a mercruiser 350 mag mpi I/O. Replaced the starter a month ago and seems to be working jus fine. However when I turn my battery switch to BOTH, I get the beep from the smart gauges, and the gauges are erratic when I turn the key, the fuel pump relay does click, the engine cranks but does not start. I checked all the fuses, I had one burnt that was tied [/FONT][FONT=Helvetica Neue, Helvetica, Arial, sans-serif]directly onto the battey, replaced the 5amp fuse. Not even sure if it is related to the issue. Seems like fuel is not getting to the engine?? I also replaced the filter but not the basket. Basket needs replacement, I just don't have one. I used to be able to smell fuel in lower hatch compartment but now I can kind of smell a little egg/sulfur stench but not strong. I have added fuel twice since the 1/2 I had in there during the winter but that 1/2 tank of gas was never stabilized (my bone head error). I had the boat out twice this year, but the third time I had to change my battery switch to #1 to get going. The batter switch when turned to BOTH acted weird. That trip did not go well as the engine never started since the 1st time that day. Don't know where to go with on this issue???[/FONT]

The first thing I would do is have both batteries tested. One is either bad or about dead. How does the batteries get charged when your engine is running, and do you have a 2 or 3 bank battery charger?

 

[captnvinny]

The first thing I would do is have both batteries tested. One is either bad or about dead. How does the batteries get charged when your engine is running, and do you have a 2 or 3 bank battery charger?

I have 2, one is 4 months old and is a 27DC 13.30 currently, the other is a SL34 magnum 12.62, no on board battery charger charger, never needed one.

 

[captnvinny]

Also if the battery was bad, why would it crank? I just cant understand why the gauges seem so erratic when starting? What am i missing?

 

[Bondo]

I just cant understand why the gauges seem so erratic when starting? What am i missing?

Ayuh,.... Welcome Aboard,...... My WAGuess is a Bad ground, or Bad corroded wirin' connections, Somewhere,.....

 

[alldodge]

little egg/sulfur stench

That's sulfuric acid smell, maybe the battery is bowling.

Also if the battery was bad, why would it crank?

It only cranks when on battery 1

I have 2, one is 4 months old and is a 27DC 13.30 currently, the other is a SL34 magnum 12.62

A fully charged battery should read 12.6V, where is the 13.3 coming from?

Agree with Bondo, the WAG might be a ground

 

[Bondo]

That's sulfuric acid smell, maybe the battery is bowling.

Ayuh,.... I wonder what it got for a score,..??..??

 

[captnvinny]

Ayuh,.... Welcome Aboard,...... My WAGuess is a Bad ground, or Bad corroded wirin' connections, Somewhere,.....

Checkin grounds, i did find a wire w/inline fuse that goes back to the starter switch that is loose. The engine still cranks, the pump primes, the fuel relay clicks....still scratchin?

 

[captnvinny]

Also that sulfuric odor is in the mid hatch, where i used to smell fuel from the gas tank

 

[Fun Times]

AllDodge

Ayuh,.... I wonder what it got for a score,..??..??

Lol, Well if we're still talking battery power than captnvinny batteries needs to score at least a minimum of 750+ cold cranking amps in order to win at starting a MPI engine model that he has.

captnvinny, According to Mercruiser, you are supposed to have at least one starting battery that's not deep cycled that produces at least 750 CCA or it could very well cause problems such as you are describing above. You'll want to read the labels on the batteries to see what CCA they are.

Also like mentioned above by AllDodge concerning the battery that is showing 13.30 volts. That is really to high of a voltage while at rest. That's more of a reading you'd see if the engine was running.

However when I turn my battery switch to BOTH, I get the beep from the smart gauges, and the gauges are erratic when I turn the key, the fuel pump relay does click, the engine cranks but does not start.
But the third time out, I had to change my battery switch to #1 to get going. The battery switch when turned to BOTH acted weird. That trip did not go well as the engine never started since the 1st time that day.

This could be due to one of the batteries has an internally shorted cell. If one battery is good and the other one is bad and you try to use both, then the good battery may try to compensate for the bad battery which may be just enough to power up some boat items but not enough to power up the complete system.

Be sure the battery cables aren't connected in reverse order and then try disconnecting one battery completely and see if things return to normal. I'd disconnect the battery with 13.30 volts as it seems that may be the problem thus far.

Do you have two separate black ground cables going to the engine or do you have one short ground cable jumping between the two negative sides of the batteries and then one long ground cable going to the engine block?

Here's some other basic battery info you may need to know about. https://answers.yahoo.com/question/i...8151938AAdJNTo

 

[thumpar]

I think you have the info you need to figure out the problem but if it is really a 350 MAG it it is a 5.7l.

 

[captnvinny]

Fun Times and ALL Dodge thanks for the response! Your SOLID FEEDBACK is GREATLY APPRECIATED! The one battery 27DC is 575 CCA and 2 months old. Should I replace with a more powerful one? I also rechecked the batteries this AM for voltage, 12.6 and 12.7 is the DC, Thumpar, u r correct, it is a 5.7L. So I noticed during one start (when it actually did) I was not able to crank over when set to BOTH on the battery switch, I changed to #1 and it started. So I researched troubleshooting the switch and did a continuity check. When I have the switch to #1, I get NO continuity, but #2 and BOTH do have continuity. I pull off the switch and open it up to find some plastic had melted (not alot but you can clearly see). So I plan on replacing the switch but why would it melt inside?

 

[hnt]

I have found that ground problems are very common in boat electrical systems and often cause weird things to happen.

My father would tell me to always make sure the ground is good first and now I'm old enough to see he was usually right. Too bad I can't get my 19 and 21 year old sons to recognize any of my wisdom improving yet.:facepalm:

 

[Fun Times]

I have found that ground problems are very common in boat electrical systems and often cause weird things to happen.

My father would tell me to always make sure the ground is good first and now I'm old enough to see he was usually right. Too bad I can't get my 19 and 21 year old sons to recognize any of my wisdom improving yet.:facepalm:

Somewhere I've read a forum members signature line that reads

When I was a boy of fourteen, my father was so ignorant I could hardly stand to have the old man around. But when I got to be twenty-one, I was astonished at how much he had learned in seven years.

^ So it shouldn't be all that much longer before the changes begin to happen.

When you located the melted switch, did any of the cables seem loose as a really loose cable could allow them to get hot or accidently connecting up a battery backwards could cause it, or an internally shorted battery as well. http://forums.iboats.com/forum/boat...otors/618003-melted-battery-posts-please-help

Keep an extra eye on the battery that had 13.30 volts. It don't seem trustworthy.

What happen to the original starter?

What year is the engine/boat?

It's your call on the battery being 575 CCA's but with your engine model, it is considered too small and known to cause starting issues with MPI and smartcraft systems especially as the battery gets a little older having less CCA power but still showing 12v power....But your main problem is the melted switch and to find out why.

Also just in case, check the orange wire at the back of the Alternator to make the wire is not cutting into any engine parts.

Possible Chafing of Orange Alternator Wire on 5.0L/5.7L/6.2L MPI Engines. Mercruiser service bulletin number 2006-02.
Situation:
On the units identified above, an orange wire attached to the output terminal of the
alternator (the orange alternator wire) was routed by MerCruiser in one of two ways. One
way was correct, the other was incorrect.
The incorrect routing places the orange alternator wire between the oil dipstick tube and
the alternator. With that incorrect routing, it is possible that the insulating material will be
chafed by the dipstick tube or the alternator, which could cause the wire to fail. If the wire
fails, it could become an ignition source. See the "incorrect routing" photographs below.
The correct routing passes the orange alternator wire beneath the alternator, not in contact
with the dipstick tube, which eliminates the opportunity for chafing and failure identified
above. See the "correct routing" photograph following.
In addition to the two orange wire routings described above, many boatbuilders modify or
disconnect the orange wire to facilitate the installation of battery isolators. Boats that have
been so modified will not require the corrective action outlined below.

 

[captnvinny]

Funtimes, THANKS again for the response & help. The battery was tested with a volt meter, but I will keep an eye on it. I'm just gonna replace it with the info you gave me. So I initially bought the battery April b/c the old one was 7yrs old. Then when decomissioned the boat end of April the starter would click but not crank, so I replaced that. Figured it was time for a new starter. When I pulled it off it had alot of corrosion from the bilge and only the solenoid would jump up but gears would not spin. the boat and engine are a 2007. The cables were tight on the switch and batterys, Im gonna go over every inch the cables today and look for damage. I'll look into the alternator wires and report back.