I need some Help (Stage 1 RX-1 MPI SC) Found Problem

[BlgsRX-1mtn]

My sled caused me to have a 3 mile walk on New Years Eve @8000' elevations.

Here's what happened;

Sled was running great (mid 13s on the A/F) as I was cruising down the trail @ mid throttle. I opened her up going over a roller and the a/f went to uper 12s. All of the sudden the sled lost power (almost like when the I/C & Carbs separate) and my A/F went to 20s and the motor died.I tried to re-fire the machine and it would start but as soon as I wicked the throttle, it would die. I walked 3 miles to our room and get the wif'e dressed so we could tow it in (got to bed @ 3 AM).

After some sleep; I checked the belts and both are good. The engine still cranks over just fine but wouldn't start after sitting while I slept. Towed it out to trailer and will be starting to try and diagnose what went wrong.

I am suspecting that the electric fuel pump croaked due to the instant change in A/F readings right when it lost power but I will be doing a leak down test and compression test. What is acceptable for both on a stock '03 RX-1 motor? Any other ideas on what to look at?

Thanks, Jim

 

[Ted Jannetty]

Re: I need some Help (Stage 1 RX-1 MPI SC)

My sled caused me to have a 3 mile walk on New Years Eve @8000' elevations.

Here's what happened;

Sled was running great (mid 13s on the A/F) as I was cruising down the trail @ mid throttle. I opened her up going over a roller and the a/f went to uper 12s. All of the sudden the sled lost power (almost like when the I/C & Carbs separate) and my A/F went to 20s and the motor died.I tried to re-fire the machine and it would start but as soon as I wicked the throttle, it would die. I walked 3 miles to our room and get the wif'e dressed so we could tow it in (got to bed @ 3 AM).

After some sleep; I checked the belts and both are good. The engine still cranks over just fine but wouldn't start after sitting while I slept. Towed it out to trailer and will be starting to try and diagnose what went wrong.

I am suspecting that the electric fuel pump croaked due to the instant change in A/F readings right when it lost power but I will be doing a leak down test and compression test. What is acceptable for both on a stock '03 RX-1 motor? Any other ideas on what to look at?

Thanks, Jim

You didn't say if you checked the carbs. (almost like when the I/C & Carbs separate)

This would be my first guess based on your description of events.

Or a blown fuse for the fuel pump or the curcuit the fuel pump is tied in to.

Ted.

 

[BlgsRX-1mtn]

Ted, when I pulled the I/C to check the secondary belt; I manually slid the slides up on each individuall carb. The needles on all four carbs moved when I moved the slides and I could hear air moving through the venturi that creates vacuum for the rubber diaphragms. What else can I check in the carbs? The cable is still good. I havn't changed anything since dialing in the jetting two years ago.

This is my third time riding in the mountains this season (~300 miles total) with no issues until this. The sled since the SC install has ~2000 miles on it. I called MPI and they (like you) said to check the connections (for moisture) and to check the fuses since I couldn't hear the fuel pump cycle when turning the key on and off.

I'm workin 12 hr shifts for the next four days so I won't be able get to the sled right away. Just trying to get some ideas so I'm not "chasing my tail" trying to find the problem. I should have added that when the sled re-fired; I had to use the choke lever (about 1/8 on), it barely ran (~650 RPMs) and usually the lights would not come on due to the low RPMs.


Thanks again, Jim

 

[BlgsRX-1mtn]

Well, the sled runs fine now. Here's what I found . The sled had actually flooded out the CAC tube with fuel and prevented the bowls from geting any pressure from the SC. I have experienced this on hard landings but didn't think that the landing from the little roller was bad enough to cause this.

It's a good thing I run clear tygon tubing from the CAC tube to the carb bowls. The fuel blowing through it when I started it today was the only indication of what happened unless I would have looked down the CAC tube New Years day and spotted the fuel when I had the IC off .

Jim

 

[tko47]

the sc RX-1 I had would do that , when you landed hard would stall dead and I bent the floats down I can't remember the spec it was a couple mm's , MPI should have it and it cured that problem....

 

[BlgsRX-1mtn]

the sc RX-1 I had would do that , when you landed hard would stall dead and I bent the floats down I can't remember the spec it was a couple mm's , MPI should have it and it cured that problem....

Yeah my floats are set to MPI Specs. I might try changing for a little less fuel level to see what happens. By all means it shouldn't have done that off this little roller. I have hit harder than that and never had it happen.

Usually I'm never looking @ the A/F Gauge when I know that (flooded CAC) is what happened because I'm usually launching off something or cresting a big hill with the skis in the air. I assumed that every time it did flood my CAC with fuel; the A/F went extreme rich and not to mid 20s like it did New Years Eve.

When it does flood out the CAC tube; I just tip the sled to the right side and feather the throttle until it clears out. This will allways be what I try first from now on. That 8000' elevation, 3 mile (1 1/2 hr) hike to the guest ranch I started @ 12:15 AM sucked. Especially when I was dressed for New Years Eve and left the FXR Pants and RU Outside Boots in the room (wearing jeans and hiking shoes).

Jim

 

[kinger]

Had to be darker then a sack of black cats out there at that time wasn't it?

Cell phones don't work either? That is a long azz hike. Just had a buddy die in a avalanche in CO so glad you made the hike back ok.

 

[BlgsRX-1mtn]

Had to be darker then a sack of black cats out there at that time wasn't it?

Cell phones don't work either? That is a long azz hike. Just had a buddy die in a avalanche in CO so glad you made the hike back ok.

Yeah it was dark that night. Wife had the cellular phone with her . Sorry to hear about you buddy. Luckily for me; I was riding from the town of Cooke City back to the guest ranch 4 miles out rather than out boondocking in really deep powder and in bad terrain.

Only problem was; I took an alternate trail that doesn't see as much traffic (hence a smother ride) because the groomer hadn't left town yet. Had I stuck to riding on the main trail; I would have known it was a closer and downhill walk back to town to have Geno (formerly mmwildman) or another riding buddy give me a ride home rather than walk the direction I was initially heading.

I did have incentive that probably pushed me to walk faster; in the fact that two guys on sleds went smoking right past me heading the same direction (that pissed me off). I guess they don't like Yamaha riders (had my Yamaha FXR Racing Team Jacket on and was carrying my helmet) since they didn't even slow down.

Jim

 

[nitro express]

Nice guys