Bike Stalls Once Warm and over 5500 RPM

[Fast Eddie]

My '93 907 is still stalling after about 25 miles and its taken over 5500 RPM. It will come sooner if I get on the throttle hard. The odd thing is when it stalls all I hace to do is turn the key off and then back on at it will start right back up. I checked and cleaned the fuel pump and tank. I've run two bottles of Sea Foam trough the tank. I've replaced both fuel relays. Now my next step is replacing the coils. Does anyone have a part number of a replacement coil? If the coil doesn't fix it then my next step is the ECU.

[907pasonut]

hi Ed... if I remember correctly you've had this problem for a while, the tank and pump are clean, did you replace the fuel filter, as this is very similar to what I had on my bike.
if the tank was dirty, change the filter again...my 2CW
I doubt its the coils, and very unlikely the ECU

[higgy]

It it most likely a bad connection, check those grounds and everything else

[Fast Eddie]

hi Ed... if I remember correctly you've had this problem for a while, the tank and pump are clean, did you replace the fuel filter, as this is very similar to what I had on my bike.
if the tank was dirty, change the filter again...my 2CW
I doubt its the coils, and very unlikely the ECU

Pasonut, you're right. I've had these problems since the fall. The fuel filter was the first thing I changed and have changed them twice since then. The last was very clean but changed it anyway since I had it out.

[Fast Eddie]

It it most likely a bad connection, check those grounds and everything else

I was thinking wiring too. Changed the relays. What's odd is that it will run fine for about 20 miles and then its over. I figure I'll start with the wires at the relays, where else should I check for wiring and grounds?

[higgy]

The connector at the bottom of the Ignition switch and every other connector. No easy way out,gotta get your hands dirty. One good thing once you check and fix them they tend to stay fixed for a long time

[Tamburinifan]

Just a +1 on NOT the coils,
most unlikely both go bad at the same time.

[ducinthebay]

Coils will fail in a similar fashion, but it wouldn't change if you were on the throttle or not, it would be mostly time based.
This sounds more like a fuel problem. One thing to check is the vacuum line. If its pinched or clogged it will give you this behavior. As soon as you turn off the engine, the pressure equalizes and everything is back to normal. One easy check is to just pop the gas cap and see if it continues running as it should. I had a similar problem and found my vent tube pinched.

Also check the gap on the timing sensor. If its dirty or the gap is big, it will get worse when hot.
Good luck.

[Fast Eddie]

It does make sense that the tank pressure could be causing the problem. The person I bought it off of, who is mechanically inclined, checked that. What does concern me is that he disconnected the hose at the fill hole, which he believes was to keep water out of the tank, and plugged it and the hole at the gas cap. He said that the nipple inside the tank where that hose clamped onto would not hold and therefor would then suck fuel and spill fuel on the bike. I am going to try to open the gas cap (of course with a half tank of gas) and see if the problem is still there. I really love this bike. Even with it's problems I ride it more than my other bikes. I just feel so much more comfortable on it and the grin factor is very high. I can't imagine how big my smile will be once this is sorted out.

[ducinthebay]

I don't have a 907, so I can't comment directly on the set up of that bike, but I do have a ST4s and had an ST2. One line off the tank was for overflow during filling, or for water around your filler. That drained below the engine.
Another line was the vent for the tank. Originally that would go to the charcoal canister. If the tank is really full, and you leave it in the sun, you will get an overflow situation and some gas will drip from your bike, assuming you just ran the tube under your bike after you got rid of the charcoal canister.
Another line on the fuel injected bikes was the return line. If he hooked the fuel return line to the vent line, things will get interesting.

I think best that you prop up the tank, and trace all of the tubes running in and out of the tank.
In problem solving cars and motorcycles, always start with whatever the last person worked on. It will fix it 90% of the time.

Cheers,

[higgy]

Pressure or vacuum in the tank could be a problem,lines placed in the wrong place or if the bike came equipped with a canister and some body plugged the line to the canister.

Sounds like you are on the right track

[clay7185]

My bike did this also. It was the butt connectors on the yellow alternator wires they were shorting out but only at high throttle after running for awhile. I had them soldered together and it stopped happening. I figured it out after running for awhile I grabbed the butt connectors and I could feel the heat through my riding glove.

[907pasonut]

Ed, hows the grin factor going??
did you manage to find the problem?

[Fast Eddie]

My bike did this also. It was the butt connectors on the yellow alternator wires they were shorting out but only at high throttle after running for awhile. I had them soldered together and it stopped happening. I figured it out after running for awhile I grabbed the butt connectors and I could feel the heat through my riding glove.

Would your bike start back up right away after it stalled?

[Fast Eddie]

Ed, hows the grin factor going??
did you manage to find the problem?

Claude, not yet. But I do believe its electrical. Clay's problem makes sense so I'll be looking at that. The gas cap release didn't work and I checked all the hoses per the shop manual and they were correct and not pinched. I'm still grinning, just not 100%.