PDA

View Full Version : 350 MAG running at 90%, needs help!



FISHIN SUCKS
06-28-2015, 12:08 PM
My starboard 350 mag is feeling ill, not sure why. While the port motor is turning 5000, the starboard is running around 4200. I don't recall this being the case last fall when we put her away for the winter. 400 hours, plugs are 200 hours old, never changed the plug wires or cap. I can do this, just wondered if there is something else i should be looking at.

Where can I find RED plug wires? black and gray just dont get it.

thanx in advance for any help or suggestions,

tom

Morgan's Cloud
06-28-2015, 12:27 PM
My friend who had a 28ZXO with 350 mags never had any internal issues that caused fluctuations in performance between engines . Every time he had service work done though the mechanic always discovered that the distributor caps were suffering from corrosion issues.
Changed them , and boom ! Back in business again .

Of course you may get different results ....

Ed Donnelly
06-28-2015, 01:15 PM
MSD.. Red plugs,caps, rotor might help too.
Make sure to check the timing..Ed

Ed Donnelly
06-28-2015, 01:19 PM
Mallory and Acell ( Acell owns Mallory) also have all the red goodies..Ed

BUIZILLA
06-28-2015, 05:42 PM
change the fuel filters?

FISHIN SUCKS
06-29-2015, 09:52 AM
Thank you brothers! I have heard the distributor cap a couple times now, I'll start there. Have not changed the fuel filters, i'll do that too.

Stoopid question, is there a difference in plug wires....meaning marine or not marine?

Thanx again,

Tom

Pat McPherson
06-29-2015, 10:34 AM
I change my Fuel Filter once or twice per year. My Plugs, Cap, and Rotor get changed every 2-3 years depending on use. Wires last a long time and there is little difference between "marine"; I'd use 8mm.

FISHIN SUCKS
06-29-2015, 09:09 PM
Many thanx Patrick!

FISHIN SUCKS
07-05-2015, 09:50 AM
Okay, we're in business!!! replaced the fuel filters in both motors, the starboard one was nasty, port was good. replaced the distributor caps and rotors, both were corroded. Many thanx to all,

tom

FISHIN SUCKS
07-15-2015, 10:09 AM
S.O.B., spoke too soon! back to the same issue again, but now it seems intermittent. Port is running strong, but Starboard is running at 4000, then 4800, and back to 4000. WTH is going on here? I know it's not my tachs because I can hear the motors harmonizing and when they are not. I even talked dirty to them, still no change. thanx in advance for any input,

tom

Pat McPherson
07-15-2015, 12:02 PM
If the engine detects a knock it will retard the timing 10deg and you will loose power.
I had a bad knock sensor make the engine act like this on a 96 EFI engine.
Have you checked the base timing?
Have you checked for trouble codes?

Morgan's Cloud
07-15-2015, 01:37 PM
Odd thing is , the same time this thread was started there was a similar discussion on OSO with the identical problem on a pair of 496s (I think)
It was commonly suggested that it was the position indicating sensors on the flywheel.
Don't know if the Mag350 has them , but it wouldn't surprise me.

Pat McPherson
07-15-2015, 03:58 PM
Odd thing is , the same time this thread was started there was a similar discussion on OSO with the identical problem on a pair of 496s (I think)
It was commonly suggested that it was the position indicating sensors on the flywheel.
Don't know if the Mag350 has them , but it wouldn't surprise me.

350s have 1 coil and a distributor (old school), 496s have individual coils and the firing is completely computer controlled.

Still comes back to a similar issue of timing...

donzidon
07-16-2015, 08:57 AM
If it was ugly the first time, maybe it loaded up again.

tmdog
07-16-2015, 10:17 AM
If it was ugly the first time, maybe it loaded up again.


What he's saying. Filters.

joseph m. hahnl
07-20-2015, 07:51 PM
Switch the ignition coils and see if the problem goes to the other engine.:rolleyes: