98 mariner efi engine trouble

[Tim_eubanks]

I have two 98 mariner 225 efi offshores one runs like a champ and the problem child runs like crap motor cranks and idles fin for Manet 40 seconds if you try to throttle it up it will rev up for a few seconds and start breaking down like it’s loosing fire … if you watch the tach when it starts it will randomly drop out and come back it’s almost like you cut the key off and cut it back on before the motor stops spinning. I have swapped every part including the key switch harness from the good running engine to the bad one and no change at all. Has any had or heard of these symptoms?

 

[Faztbullet]

Checked fuel pressure?

 

[Tim_eubanks]

Fuel pressure is in spec I have swapped every electronic component from one engine to the other and I did find out that the alternator was over charging although I still have the same problem with the good alternator fuel injectors have just been serviced (cleaned and flow tested) they were all within 2% of each other vst has also been cleaned. I also visually checked the stator as well as with the fluke meter it is within spec and only 2 ohms difference between the good running engine. I am leaning toward the possibility that it is in the motor harness

 

[Tim_eubanks]

Fuel pressure is in spec I have swapped every electronic component from one engine to the other and I did find out that the alternator was over charging although I still have the same problem with the good alternator fuel injectors have just been serviced (cleaned and flow tested) they were all within 2% of each other vst has also been cleaned. I also visually checked the stator as well as with the fluke meter it is within spec and only 2 ohms difference between the good running engine. I am leaning toward the possibility that it is in the motor harness

Also did a compression test 118-122

 

[Faztbullet]

What about pressure regulator?

 

[Tim_eubanks]

What about pressure regulator?

New and working correctly

 

[Tim_eubanks]

Good news everyone I have found the problem apparently I have a broken wire inside the motor harness… I replaced it today on a whim and motor is now running like a champ!!! Side note my motor is apparently doesn’t like ngk plugs