boat ran fine yesterday, now wont fire, help por favor

[natedog]

oh i know, i am simultaneously checking correct craft fan for help over there as well, cant hurt to ask as many people as possible, but honestly DanielC has given the best info i think. im also waiting for a pcm tech to get off work so he can come by if he has time after work but i would like to diagnose the problem myself and hoping to fix it myself.

[horkn]

fwiw, on these gt40 efi motors, there are less marine specific items than on a carbed marine motor. The starter, alternator, exhaust manifolds and no o2 sensor are the biggest main differences between an gt40 PCM and a lets say a first generation ford lightning pick up. That 1st gen lighting is about as close as you can get to a pcm gt40.

Even then, many parts of a marine carb are the exact same as on an automotive one, but there are some key marine additions to carbs to make them marine, and some of those differences were not always used, like J tubes.

The distributor on a 5.0 mustang looks exactly like the ones on a gt40 in a nautique. If PCM/ CC techs say it's the same, I would figure it to be true. A simple part number check would confirm that.

Well, at least you checked and ruled out the TFI. If you don't have power at the coil, that is the real issue, or something before it. A distributor as mentioned above simply puts electrical energy to the proper cylinder.

[natedog]

that is basically what the pcm tech said and i am thinking hoping its the 12.5 amp breaker is the culprit, an online service manual explained this is the breaker for the ignition system. it was a pcm manual, i am hoping it is correct.

[horkn]

Those breakers are cheap and easy fixes. They are also very common to go out. I would buy a spare or 2 and keep them in the boat, along with the tools to replace them.

[natedog]

i had my brother crank the motor while i used a test light, i am not getting power at the 12.5 circuit breaker or the 15 amp breaker which are the ignition breaker and fuel pump breaker but i am getting power at the 60 amp breaker which is the breaker for the whole electrical system

as well i am getting power at on relay and not the other relay under the ecu and i have tried using a brand new relay and still no luck, if i cant find another fuse my only thought is the wire itself is bad from the battery to to the relay which in turn goes to the breakers then ignition coil

[crobi2]

Do you have a solenoid under the ECM that the main cable from the battery goes to?

Our 2000 SAN has a solenoid that just passes a smaller hot cable straight through to the starter but switches on/off power for the ECM/fuel system. The solenoid is switched on by the ACC/Run position. It may be specific to keypad style keyless systems though.

Oops, sorry, I just re-read that you are getting power at the 60 amp breaker. Just trying to help.

[DanielC]

You can down load the GT-40 service manual from the downloads section on this web site.
Do that now.
In section 6 of the service manual, there are diagrams of various electrical systems. They are on page 284, and 285.
Pin 87 of the EEC relay supplies power to the engines ignition coil. Pin 87 of this relay has a purple, and black wire on it.
It looks like there is a direct connection from this relay to the positive side of the ignition coil. At the coil, the positive wire is gray and blue. Make sure you have power there, with the key on.