Stalling engine help needed

[DJ Tomás]

I have a '21 500 RR-S that won't run. I'm no pro mechanic, but have done some troubleshooting. Here's the story...I bought a new 500RS and swapped a bunch of the upgrade parts from the '21 to the '24 including the fuel tank. The '21 ran fine before the swap. I put the stock parts back on the '21 to sell and did the 150 hr. maintenance including checking valves and removing the spark plug. I had to swap the tank internals back over to the stock tank from my IMS tank that was in use and replace the fuel filter. I did disconnect the battery for a few minutes to remove a pigtail. After assembly, the '21 bike starts and runs for about 15-20 seconds, then quits. Here's my troubleshooting finds so far.
1. error code p0231 fuel pump relay- circuit low (as in photo from car scanner)
2. fuel pump runs and pushes fuel upon key on
3. I'm getting voltage all the way to the fuel pump
4. all fuel and electrical connections seem to be intact and working

What am I missing? Where is the fuel pump relay?

[Trail Rider]

I dont own one of these bikes so really cant help all that much. As far as "where's the relay"? I'd check the electrical wiring harness parts diagram.

[DJ Tomás]

Update...found the relay and replaced it. No change. Swapped tanks and batteries from the '21 and '24. Same problem persists on the '21. Batteries read the same voltage measured on the bike. The '21 shows 12 something volts going to the Trailtech Voyager. The '24 shows nearly 14 volts going to the Trailtech Voyager Pro mounted on it.

[webmaster]

Suggest you check your ground connections and all other connections as well... - Corrosion is your enemy.

You can clean all electrical connections using Deoxit D5.

Inspect all wiring closely looking for insulation chafing, etc.

The first code stating "circuit low" I would take as a clue that either the power or ground isn't good, or your voltage generated is poor in same way (voltage regulator and stator...) I would start with chasing the power and ground connections for the fuel pump back to their source and go from there. Clean every connection along the way...

As a sidenote - After getting things cleaned up, I have never used dielectric grease, but maybe I should start?

Jeff
aka Almost retired electrical engineer...

[DJ Tomás]

Update...Found problem. Cracked porcelain on spark plug. New spark plug in and she runs fine now after chasing down possibilities with a mechanic friend of mine. I knew it had to be something simple...