99 200 EFI shutting down at WOT

[Tx 201]

Serial number 0G946241 Timing and idle module removed, oiler removed, heads shaved and front half cut, timing set at 23.5 if I remember correctly. I have sent the ECU to Simons to rebuild all drivers, rebuilt the pulse pump, changed the fuel line to the new gray line with blue lettering, (purchased from Don) have changed regulators to the newer style to prevent tach jump bouncing. I think the tach just needed to have the adjustment on the back rotated back and forth, set on original position and reads correctly without bouncing. Have spread the pins on the plug into the ECU and also the connection on the starboard side of the motor. Have cheked for loose ground wires, nothing stands out.

Starts great, runs strong all the way through 3/4 throttle. WOT and trimmed up it may run for up to a couple minutes, and then shuts down. Will start right back up and may run fine the rest of the day, just don't go WOT. I understand if the voltage gets too high it will shut off the fuel driver in the ECU to prevent damage, at what voltage would that occur? I thought I had it fixed, one of the regulator bullet connectors I was able to seat a little better and had two trips to the lake without issues, but did not run it hard for long distances due to weather conditions. Third and final lake test WOT for about five minutes, thought it was resolved and then it shut down, as it was shutting down, probably about 3-4 seconds into shutting down my graph read 14.9 volts, did not see what the voltage was as it started shutting down because it caught me off guard thinking I had fixed the problem At what voltage would the ECU shut off the fuel driver?

I don't think I had this issue until I changed regulators, I have the old ones and may re-install those and check again. I know it is rare to put in a new electrical part that is not good, but I am thnking one of the new regulators (with the fuse) is bad. Thoughts? Thanks gentlemen!

[JOE54]

have seen some ecus shut off at 15 then others overcharge and never shut down some just seem more finicky than others , pull fuse on one reg go run it ,cut system in half

[EuropeanAM]

+1... I'd be wiring a DVOM directly to the battery and monitoring to see if voltage is climbing beyond 14.6 VDC. EVEN if you have "new" regulators,

[Tx 201]

Thought by now I would have been able to test without a fuse in one, but work and weather has kept me off the water. Three questions if you don't mind.
1. If it runs at WOT with just one regulator without shutting down, what would the long term effect be if I kept running it that way? I usually don't run long distances when fishing, at least not enough to do much recharging of the battery.
2. I have the volts shown on a newer Lowrance graph, is this reading not reliable enough and I need to rig a DVOM to get an accurate reading?
3. Are regulators like every other electrical part and need to be replaced in pairs if this turns out to be the issue?

Thanks gentlemen!

[EuropeanAM]

Thought by now I would have been able to test without a fuse in one, but work and weather has kept me off the water. Three questions if you don't mind.
1. If it runs at WOT with just one regulator without shutting down, what would the long term effect be if I kept running it that way? I usually don't run long distances when fishing, at least not enough to do much recharging of the battery.
2. I have the volts shown on a newer Lowrance graph, is this reading not reliable enough and I need to rig a DVOM to get an accurate reading?
3. Are regulators like every other electrical part and need to be replaced in pairs if this truns out to be the issue?

Thanks gentlemen!

This method of testing is NOT something I would recommend. System is designed to have two regulators ONLINE and functional. Attempting to run one of these engines with faulty (or non-functional) regulators can potentially result in some nasty problems that Smokey the Bear did not refer to as a "minor thermal event".

Use a DVOM connected to the BATTERY, and monitor voltage if and when it shuts down. 14.6 VDC and below are JUST FINE.

Regulators should be replaced in pairs for best results.