Engine Shut Off at Cruise

[bman2u187]

After a recent tune-up consisting of an oil, air and oil filters, plugs, coolant, and brake/clutch fluid change and a fuel injection cleaner to the gas and throttle body cleaner to the intake runners, my bike initially began to have power surges at cruise in all gears. It had no problem accelerating hard and no abnormal deceleration characteristics. From another post, suggestions were to check the plugs and their gap and torque. I triple checked it all to no avail. It still happened. Then one day, while cruising the engine totally turned off, tach registered 0 RPM, but light, speedo, etc all continued to work. It started to run again after approx. 3 seconds. It did this 3 more times on the way back to the house, same symptoms, but I could not duplicate the conditions to make it happen on command. This time I replaced the new set of plugs with another new set, checking gap, torque, vacuum hoses, etc. all again. The surging is still present, but very very minor, like if I wasn't looking for it, I wouldn't notice it minor. 2 days ago, it turned off again while cruising 5 times at no regular intervals, speeds, or RPMs. I cannot replicate the scenario to do it on command, very sporadic. That was 2 days ago. I have ridden 200 miles since and no more turning off, just the minor surging, but even that has deminished. Both times the plugs were changed, the battery was disconnected. I have scoped the TPS and it has a good waveform. I have scoped the CKP and that has a good waveform. I am at a loss. I am an automotive technician for BMW, I am very familiar with engine management systems. What am I over looking? Please help, Suzuki won't...they want me to bring it in.

 

[BlueHaya]

How about fuel pump?

 

[WuzzaCBXRider]

Some sort of vacuum leak or stoppage, such as a clogged gas cap vent or a seeping hose. Maybe a partially clogged injector? I've never heard of bad plugs or wires causing surging. Is fuel or air.

 

[Mr Bogus]

hmmm the tach read 0.. need to answer a question

was the bike still in gear? (engine being turned over even though stalled and no power)

Reason is this, the ignition system should still be working and the tach should still be reading IF it is a fuel pump problem.. The pump could still be having a problem running but there would be other issues involved, not just a bad pump

This "could" give you a head start n the source of the problem (mechanical or electrical)

 

[bman2u187]

The fuel system was my next area of attack. I was going to start with checking pressure and volume. I need specs though, anybody got the specs for the right pressure and volume the pump should be putting out?

Mr. Bogus, yes, the bike was still in gear when the tach went to 0.

Thanks for the input guys. I'll post my results once I get some specs to go off of.

 

[Jayslamms]

Check the kill switch on the kick stand. Mine did that once right after I did the kick stand mod. I was in the fast lane when the bike just dies. Scared the s*#@ out of me.

 

[Mr Bogus]

if the key was on, the bike was in gear and moving with the engine was dead, then the source of your issue is likely an electrical issue.

There was likely no spark, (and could very well be no fuel flowing) but checking fuel pressure is just a waste of time at this point.. I have not looked over the logic of the fuel setup but it likely must see a crank/cam signal to fire the pump relay.. But if there was no signal, then no fuel pump and no pressure. You need to find out where the failure is that had the tach reading zero.. (and probably no ignition even if there was fuel)..

not sure if this makes sense to you but the bottom line is that you more than likely have a failure in the ignition/sensor system that needs fixed, not a fuel system issue..

 

[bman2u187]

Jayslamms I think hit the nail on the head. I've bypassed the kickstand switch and havent had an issue with the bike turning off for the last 4 days. I do still however have the intermittant hesitation and power loss at cruise.

Mr. Bogus - I get what you were saying re: the sensor, pump, etc. I was thinking of the pump more on the lines of the intermittant power loss at cruise. I did not change the fuel filter and was thinking of the pressure and volume to see if it was substandard thinking the filter could be getting clogged. What do u think about possibly being the throttlebosies need to be resynced after the plugs and air filter change.

As always, I'm up for any advice and/or suggestions.

 

[illfirsdonill]

possible the oil pressure switch is going bad?

 

[MrGraffixx]

Hey Bman, I have a 99 and I had the exact same thing happen to my bike a few weeks ago after I changed the fuel filter. I barely made home from my shop and back up here the next day. It ran fine under load, idled fine but when I was on flat ground, it surge until I gave it more gas or was going up hill. As soon as there was no load on the motor, it surged really bad, and even turned off and on intermitantly. When I lifted the tank back up, I could find nothing wrong and thought I put the fuel pump back together wrong so I started to take it back out and realised the vacuum line on the fuel pump was not connected under the fuel rail and that was the entire problem. Hope this helps. I know we have a bunch of vacuum lines on our motors and as sensitive as ONE single hook up was, I would suggest going through all your lines looking for connections or pin holes......

 

[gaetano]

I am having the same issue with my 02.. Just started about a week ago and come to think of it, it started after I changed my air filter. Wonder if a line got pulled. Thanks for the info.. off to the garage now