Microsquirt CB900F random stall

[NickC]

Hi all,

So I have been riding my bike quite a bit lately, and tuning it. Everything was going great, using VEAL and all was going good but recently, I have been getting random stalls. Does it at Idle and while running. I am almost certain that it is fuel because my WB gauge goes way lean when it happens while riding. Funny thing is, when it is idling and then just stalls, keeping en eye on my fuel pressure, it does not drop at the time of the stall?

So, attached is my MSQ as of tonight and a datalog from letting it idle and then stall. Last time I was riding it, I had VEAL set to auto tune, so the VE table is currently rough, but I was hoping to get someone to have a look to see if they see anything that could cause the stall? I can't seem to see anything, but I am not a super expert either.

Any other suggestions would be great. I did have an issues with crap in the fuel at the begining of the year, so if no one can see anything obvious in the datalog, I guess next step would be to check if any debris made it past the filter and is now at the fuel rail/injectors?

Thanks
Nick

[Matt Cramer]

That motor must have a very light crank - it's shutting off like a light switch! And it doesn't appear to be a loss of sync, either; the MAP goes from running to atmospheric pressure in the tenth of a second between idling and off. That would seem to be nearly impossible on an automotive engine, but on a bike...? Probably for real.

The one thing I noticed is that the battery voltage drops a fraction of a second before the stall. Not sure why, but a block in the fuel system might make a fuel pump push harder.

[NickC]

Thanks for taking a look Matt,

That is a good observation with the voltage, maybe a loose battery connection? It does seem to be completely random???

I will take the fuel rail appart tonight I guess, in hopes to discover a smoking gun answer. I will look at my battery connections too.

Any other expert mind having a look at this?

Thank you all in advance !!!

Nick

[NickC]

So i took appart the fuel system, and although I did find some foreigh stuff in the fuel rail, it was not what I consider enough to casue a stall like I am experiencing. I cleaned everything, put it all back together and still has the stalling issue.

Looked at connections, and all seems good. Thing is, it runs great when it runs, but then it just dies, like "a light switch". I know it's not fuel pressure. Everytime it stalls, it starts right back up????

Any thoughts? Frustratiung, to say the least...

Nick

[grom_e30]

could you be losing power to the coils?

[24c]

Nick,
Is anything getting hot?
Do you have any safety devices still wired up, I'm thinking an intermittent fault, like a faulty kill switch, side stand switch wire etc, because if one of these was going to ground, it would have the same effect, kill the coils etc or if wired up kill the fuel pump possibly. It just doesn't seem it could be one of these though, because it starts right up after stalling!
Could it be a starter relay glitch, my OEM one was corroded internally, and the bike had a similar running fault, that was before the link terminals burnt out and there was no power to the system, then I found the cause!
Just a 2¢

Mike

[NickC]

Thanks for the input guys,

I checked the items you outlined, and nothing seems off. I am starting to think it might be my charging system. Although I can start the bike right back up, today, after 30-40 min of letting it idle and re-starting after stall, battery had no more juice to start it back up. That and I noticed that now my fuel pressure was at 40psi instead of the set 42psi, perhaps due to the low battery.

I will let it re-charge and then check out that side of things.

One thing I noticed in my datalogs, is that I seem to get a Sync Loss reason of 2.0, "missing tooth at wrong time" ? It is not every single time that it stalls, but it has been showing up in the logs. Could that just be related to the stall?

Keep you all posted. Any thought in the meantime would be appreciated.

Nick

[grom_e30]

if you have added a lot of extra electrics, fuel pump, wideband ecu ect maybe your charging system may be strained a little,i had this same thought when i did my bike, there is an injected version of my bike and it has a higher output charging system than the carb bike, the engine stalling will cause the sync loss, if the sync loss happens in the log before the stall then you should be worried but was not the case in the log i saw.

[NickC]

Thanks grom_e30,

That is what I though about the loss sync. The original charging system on my Honda are notorious for being crap, so when I did the FI conversion, I swaped out the charging system for the charging system out of a 2002 GSXR 1000. Swaped out the complete generator and the reg/rect. Parts were used but tested fine at the time of the install. It does seem to under charge, but the charging set-up should handle the Amp demand.

I will be looking into it in more depth.

Nick

[NickC]

So I went over the whole charging system, and all is good. The output of the AC generator is above spec in the Suzuki OEM manual, the regulator Rectifier Diodes all check out fine and at idle, the bike sits around 14V. Yet the thing seems to stall completely at Random????

Now after lurking in the wiring for some time and moving stuff around, it seemed to work better, and then I took it out for a 20km ride, and no miss or burp. It was running flawlessly???? WTF?

So i think I have a connection somewhere causing me this pain in the A**. It is after all, a mix of old 1982 wiring and new, spliced-in wiring for the FI install including Ignition. So I think at this point, I will try and finish the season with it ( about 3 weeks left I think), and over the winter, revamp the wiring on the whole bike.

Wiring gremlins are a real PAIN!!!

Nick

[ewflyer]

On my first fuel injection conversion project, an '05 Kawasaki EX250, I had a recurring problem that sounds just like yours. It ran great most of the time, but every so often the riding conditions (like stop-and-go riding on a hot day) would allow the fuel pump to heat up. The fuel pump would suddenly experience cavitation, due to fuel vaporizing inside it I guess, fuel pressure would drop to nothing. I have an air/fuel gauge on it and I could watch it suddenly go lean and stall. I figured out that if I waited a bit so the fuel pump could cool off enough and then rode home without stopping it wouldn't quit again.

I eventually rebuilt the fuel system with a Honda TRX500 pump and a return-to-tank flow for the excess fuel pump output. No more stalls.

[R100RT]

So I went over the whole charging system, and all is good. The output of the AC generator is above spec in the Suzuki OEM manual, the regulator Rectifier Diodes all check out fine and at idle, the bike sits around 14V. Yet the thing seems to stall completely at Random????

Now after lurking in the wiring for some time and moving stuff around, it seemed to work better, and then I took it out for a 20km ride, and no miss or burp. It was running flawlessly???? WTF?

So i think I have a connection somewhere causing me this pain in the A**. It is after all, a mix of old 1982 wiring and new, spliced-in wiring for the FI install including Ignition. So I think at this point, I will try and finish the season with it ( about 3 weeks left I think), and over the winter, revamp the wiring on the whole bike.

Wiring gremlins are a real PAIN!!!

Nick

Once you've wired every aspect of your project then you know what you have. Doing it over again is even fun. (I've started over with my main harnesses and outer runs probably 4-5 times since the first reiteration, never had failures but always seeing an improvement or wanting it better lol)

[NickC]

On my first fuel injection conversion project, an '05 Kawasaki EX250, I had a recurring problem that sounds just like yours. It ran great most of the time, but every so often the riding conditions (like stop-and-go riding on a hot day) would allow the fuel pump to heat up. The fuel pump would suddenly experience cavitation, due to fuel vaporizing inside it I guess, fuel pressure would drop to nothing. I have an air/fuel gauge on it and I could watch it suddenly go lean and stall. I figured out that if I waited a bit so the fuel pump could cool off enough and then rode home without stopping it wouldn't quit again.

I eventually rebuilt the fuel system with a Honda TRX500 pump and a return-to-tank flow for the excess fuel pump output. No more stalls.

Thanks for the reply ewflyer. I had that same issue first times out on the bike, but I have since fixed it with by relocating the fuel pump away from heat and putting heat insulation on the inside of the fuel tank and fuel lines that run near the engine. I don't think this is my problem because the symptoms I get also happen when the engine is dead cold??? But it behave the same as vaporlock in fuel system...

[NickC]

So I had some time today to have a quick look at it and I was poking around the harness and nothing jumped at me.

I was then looking at the datalogs, and it appears that just before the stalls, the battery voltage drops slightly and the "Timing Err%" spikes up to 12.7%?

Any thoughts on that? Is it normal to have the timing err% oscillate between -2 and +2? cause that is what I see when it is running. But then when I get this random stall, it jumps up to 12.7% right before it quits?

Help!!!lol

[grom_e30]

+-2 is a fairly normal number, i think the timing error relates to when the ecu is expecting the next tach input iv had higher numbers if im crusing and pull clutch and engine speed shoots up or down really quick. i would expect the jump in that is a result of the engine staling.