RX DI issues + absolute beginner advice

[seadoobear]

Hi,

I'm new to the sport and we got a used 2001 RX DI. Since we had no time at all, it has been standing in the garage for two years until this spring. Now that we can take it out, we encountered some issues and I'd like to ask some questions that are swirling in my head.

The situation:

- When I bought it, it ran fine and showed no issues, it did, however, rest in our garage for two winters with freezing temperatures. We didn't specifically empty the water with pressure, though (please remember: we just had boats so far which naturally drain if lifted out of the water).

- When tested it in the spring, it was still cold. It immediately started, ran for 15 seconds and died. Restarting it didn't work. Cranking but no successful ignition. When I tried to call a repair shop, they told me to f' off with my "old junk". Fair - but as an East-German citizen, I really like 2-strokes .

- Since the fuel was old and the battery was really shitty, I now changed the battery. That made it start immediately on the trailer. I also changed the fuel, out of precaution. (E5 95 octane - is 98 or 101 octane better?). Spark plugs are okay, they look like it runs a but rich, though (black residue on insulator but not excessive).

- We ran it yesterday and it started fine multiple times and ran great for hours. 90 km/h tops. Switching it off midway and restarting, however, sometimes lead again to cranking with no successful ignition. Sometimes it worked fine. I did, however, just have a 20 Ah LiFePO4 battery with some tiny wires and a 50A Anderson plug. One time, after normal start, the red LED started blinking, and the display showed some weird text. Nothing that the manual describes or I could decipher. It stopped after 10 sec or so.

- Since the cables on the inside are not in great shape, I'll replace all grounding wires and the battery for a proper power sports AGM one and remove corrosion / renew connectors. I also flushed the inside with Salt-Away since there are salt residues that have led to corrosion on hose clamps and stuff.

Now the questions:


1. Any likely culprit for the starting issues other than battery or corroded contacts? Impeller and liner are new, motor was rebuilt, though, I hope there is no offset at the seal etc. that causes drag. Can I check that somehow? My resoning so far is that voltage sag caused the ignition to be disabled, which leads to cranking but no ignition. Is that a reasonable idea?

2. There are two ground cables in the engine compartment. One is attached to the bolt connecting engine body and exhaust towards the front, one is attached to an engine bolt towards the back. The one in the front is not connected to the battery. Should it? I don't find these grounding cables described in the shop manual.

3. Does it make sense to buy a diagnostic tool? If yes, which one?

4. Should I spray the inside with the fogging oil as prescribed or rather corrosion inhibiting wax like in my outboards?

5. Does anybody spray the fogging oil into the little nib in the air intake after use as prescribed by the manual? Does it even make sense to do it in freshwater?

6. Are there parts/stuff to watch or replace regularly that will keep it from suffering catastrophic damage, like oil pumps etc?

Any advice is highly appreciated!

Best,
Michael

 

[WaarrEagle]

You may also have a battery charging issue as rectifiers are known to go bad, especially on DI's as they use more power. Check the voltage on the rectifier using the shop manual procedure.

 

[seadoobear]

Thanks for the suggestion! I was also having the lingering suspicion there might be something amiss, as the battery didn't seem as full as I expected after the last trip, but given the low electrical power the RX has, I didn't think too much of it.

 

[seadoobear]

I checked the starter wiring and found that there is no ground cable connected to the grounding point, only way higher to an engine bolt - after a gasket and using crappy automotive crimp eye. That probably doesn't help... Is there a way to attach the proper ground wire and clean the red starter wire connection without taking the tuned pipe out?
I also rechecked spark plugs - after the last trip they're now pristine, textbook. No more black deposits on the ceramic.

Edit: I added the proper ground to the M10 thread next to the starter. Whole ground cable is now 2 mOhm from battery into the engine block. The red cable to the starter is also around 2 mOhm from solenoid to starter connection.
I also checked to turn the engine by hand, turns fine in my book, of course one can feel TDC. Jet pump has no crazy resistance or anything.
Starter current is about 110 to 120 A under load, which fits the datasheet.
Battery charge current going back to the battery at idle is 4A, couldn't measure voltage well because it's still connected to a huge lithium battery with minimal internal resistance and I didn't want to rev the engine up when not in water.

 

[seadoobear]

Yep, new ground and new red battery cable fixed it. Starts perfectly now! Putting in the ground without pulling the motor was painful though. 1,5h to screw in one single screw. Battery also gets charged properly during use, so magneto is fine. I also put in a 175A Anderson plug quick disconnect to avoid having to mess around with the battery terminals and have ready access to the battery for charging and measurements.