496 Mag backfiring?
 

My dad boat, 330 SS formula. (T-496 Mag's, W/Bravo 3's) randomly started a problemp once motor has a load on it. will idel fine, and will get on plane but you cant push it over about 25 ish or it starts hicupping.


throwing these codes.

191 Fuel level 2
118 steer ch hi
75 fuel level ckt hi
94 pikot low

I know the frist 4 are normal but these.....

36 Sea Pump Cont Hi
152 IAC OUTPUT
151 Fuel Pump Relay Ck
77 Cam Sensor
152 Cranksensor.


whats going on?

Wow! That's a lot of codes all at once.

Did you try clearing them to see if the return?

I will. But iw as not on the boat when it happend.

I know the first 4 are allways there. but the other 5 at once sucks..

No one has any help here?

Rylar? nothing?

A guy who went by dave_n used to be on here all the time and he knew everything about the 496's.

When I had a 496 I remember seeing the cam and crank sensor warnings occasionally. I don't think that's anything to worry about. The IAC seems to only effect the performance at idle. I don't know about the sea pump warming. Some of those warnings could have occurred a while ago. Diacom shows what hour they occured at. So, if you reset the codes, some might not come back.

Are you getting any alarms? I have the pcm 555 manual in front of me but it is real vague. I would make sure the harness is plugged in tight to the ecm, and check all other connectors.

swap out relay with other motor,,,put your hand over motor with good relay,,,have someone else turn on key,,,do not start just turn key to run,,,you will feel the fuel pump relay engage for two seconds then click off,,,swap it to the motor your having trouble with,,hope this helps

Can't take those codes at face value. Is it starving for fuel?

Clear it and read it again. The cam and crank faults appear seemingly when the wind blows. what does the freeze frame data say?

need more info. How are you able to determine that all 5 happened at once?

The starboard engine is running rich but seems to have no power. It will not go over about 3100 rpm even in neutral. It seems to vibrate when accelerating. The port will go to about 3300 but then starts to backfire

Checking the codes with the scan tool showed many codes; several are just because we do not have that part or sensor so I have tried to omit those.

Starboard:
152 I A C output
151 Fuel pump relay ck
77 Cam sensor
132 Crank sensor

The port doesn't have any except the ones for no sensors.



Starboard Port
Flow rate. 4.91. 4.99-5.1
Fuel level. 1022. 1022
Sensor power. 4.97 VDC. 4.97 VDC
Sea pump press. 24 KPA. 25 KPA
Spark advance. -5 + 4. All over. All over
IDC D Cycle. 34-36 34-37

Whatever it is affects both engines at roughly the same rpm and load. Highly unlikely that both engines develop faults at the same time so check what they have in common such as fuel delivery. Perhaps you have a partially clogged fuel pickup or something similar.

Good luck,

Dan

I have ben telling him fuel for the same reasons.... bad gas, fuel filters something....