1999 Ski Nautique GT40 Electrical Issues

[BrainerdDave]

Hello, I am hoping there is help out there for me. I am at my wits end.... The problem started with the boat dying in the water, cranks no spark. I checked the fuel pumps and neither were running. I went to the relays and put a new relay in for the fuel pump, at least I thought it was the fuel pump based on other threads however on my boat the starter relay and the fuel pump relay were reversed. This caused me to try everything. I swapped relays and what do you know, the low pressure pump turned on when I turned the key. While I was pulling my hair out before I realized I was working on the wrong relay, I pulled the cable harness out of the high pressure fuel pump, realized that was a bad decision. Low pressure pump working with the new relay, high pressure pump just needs to be reattached, I was thinking, great, this should solve it. Drained the high pressure pump, bought a 24in pipe wrench after I broke two strap wrenches trying to get the housing loose, reconnect the cables to the wiring harness, hooked everything back up. Turned the key and a puff of smoke arose from the starboard (drivers side) back of engine. Now nothing is working!!! I leave the key turned on and find the wiring harness is melting at the two cables with diodes that come off the solenoid. One of the two purple cables attached to the diode pulled right out. I jumped the wires and still nothing. Now there is no power at the ECM, fuel pump relays don't open, even when I jumped the ground on the ECC test. I have power at the solenoid battery cable, power at the purple/black cable that is hooked up to solenoid post just below the battery cable, no power on the post that has the purple wire attached which was previously melting and now jumped. Any help would be greatly appreciated.

[BrainerdDave]

partially solved. The other diode in the picture was also bad. I jumped that and with just that wire connected the fuel pumps came on and the boat started. I jumped the other purple wire coming from the solenoid post opposite the battery cable and nothing happens, except the battery drain goes from 14v down to 10v. Guessing this is what burned out the diode in the first place. What could be causing this?

[BrainerdDave]

Here is a picture of the wiring diagram from the owners manual. The two purple wires with diodes indicated coming out of the assist solenoid. I am seeing 12V with the key on coming into the yellow/red wire post that is on the assist solenoid. The owners manual says both purple should be sending out to the system relay. One is going out the other is coming in. The diode overheated on that wire and melted. Can't figure out why/if the voltage should be flowing into the assist solenoid.

[BrainerdDave]

Solved it by buying IN4003 diodes off of amazon.com. Put the diodes back in line, all fixed up!

[gun-driver]

Thanks for the follow up, good info. I have heard of the diode failing on the fuel side in the past.