Suzuki GSXR Forum banner

1 - 20 of 23 Posts

·
Registered
Joined
·
16 Posts
Discussion Starter #1 (Edited)
I just bought a 2008 Gsxr 600 and when I test drove it, it ran like a champ. But after I got it home and did some cruising around the city I slowly started to realize that between 4-6k rpms constant speed (no matter what gear -but mainly 3rd, 4th, 5th, and 6th) that my rpms would do it to 0 and come back up shortly to whatever my throttle position was at. This sometimes made the bike jerk forward. I did a little digging and seen problems with kickstands, TPS, fuel pumps, rectifiers, etc. but let me show exactly what mines is doing HERE’S A VIDEO OF IT: Loss of power.mp4
With that being said... my bike has two recalls that need to be done. One is the rectifier and front brake master cylinder. I just dropped it off to get this done to it but I have a feeling this won’t fix my problem. Just explaining things to the techs, and also bringing up the fact that I’ve seen in previous forums that O2 sensors may be bad in them, they really couldn’t explain things either. Has anyone ever figured out a solution to this problem?? Or does everyone sell them and the next person (ME) gets the problem??? Any solutions out there? Please, anything would help...
 

·
SuperMod of the North
Joined
·
26,979 Posts
The side stand is a likely culprit for this. If the springs are weak or it is poorly lubricated, bumps may cause the arm to drop and allow the safety switch to open killing the engine momentarily. I have also seen people who found they had lost one of the two springs there. Have a look at that first. The other things you mentioned would tend cause problems all the time, not just intermittently.
 

·
Registered
Joined
·
16 Posts
Discussion Starter #3
The side stand is a likely culprit for this. If the springs are weak or it is poorly lubricated, bumps may cause the arm to drop and allow the safety switch to open killing the engine momentarily. I have also seen people who found they had lost one of the two springs there. Have a look at that first. The other things you mentioned would tend cause problems all the time, not just intermittently.
Thanks! That was definitely one of the first things I was going to do when I got the bike back. I always hit it with some lube and that helped out a lot. Because it wasn’t going all the way up on the first try initially. Now it’s popping back up with the help of the lube. So I think my problem is a little more complicated. Have you watched the video? Thanks.
 

·
SuperMod of the North
Joined
·
26,979 Posts
Yeah. The tach was hard to see on my phone and the wind noise was tough but it looked like you were on a road with some dips. Try sitting in neutral with the bike idling and tap the side stand with your foot to see if it cuts out. Another way is to zip tie the side stand up securely and road test to see if that solves the problem. Just be sure to have some side cutters in your pocket in case you need to stop while you are out.
 

·
Registered
Joined
·
16 Posts
Discussion Starter #5
Yeah. The tach was hard to see on my phone and the wind noise was tough but it looked like you were on a road with some dips. Try sitting in neutral with the bike idling and tap the side stand with your foot to see if it cuts out. Another way is to zip tie the side stand up securely and road test to see if that solves the problem. Just be sure to have some side cutters in your pocket in case you need to stop while you are out.
Yup. Tested that and the bike completely shuts off when dealing with the kickstand. Plus there is a bit of travel when the switch cuts the bike off and where the kickstand already has it engaged. Basically I would have to jump my bike 15ft off the ground to cause the kickstand to move that much to disengage the switch. No pothole or vibration will move the kickstand that much from new testing it. (It’s pretty tight) That’s in neutral or in gear. The reason I’m leaning more towards fuel problem is because of the when it happens and how it doesn’t come back to life until you let go throttle.
 

·
SuperMod of the North
Joined
·
26,979 Posts
OK. At least it is ruled out. I'll let the real tech guys deal with the fuel side of things. They should be along shortly.
 
  • Like
Reactions: Mr707hp

·
Super Moderator
Joined
·
9,411 Posts
Yup. Tested that and the bike completely shuts off when dealing with the kickstand. Plus there is a bit of travel when the switch cuts the bike off and where the kickstand already has it engaged. Basically I would have to jump my bike 15ft off the ground to cause the kickstand to move that much to disengage the switch. No pothole or vibration will move the kickstand that much from new testing it. (It’s pretty tight) That’s in neutral or in gear. The reason I’m leaning more towards fuel problem is because of the when it happens and how it doesn’t come back to life until you let go throttle.
It is not fuel.

The clue is the tach going to zero while the bike is still going 40+ mph and the engine is still spinning.

The tach going to zero is due to the ECM losing power. If you let the condition go on for about 3-5 seconds I'll bet that "CHEC" would pop up in the temp window indicating the ECM is off line and no longer sending data to the cluster. I can't see the cluster well enough in your video to see much.

I'll still go with what others suggested and that it is the side stand switch. Zip tie the side stand up tight and ride the bike. Next guess would be the kill switch or ignition switch becoming intermittent. The side stand relay has caused some issues, but they have been rare.
 

·
Registered
Joined
·
16 Posts
Discussion Starter #8
It is not fuel.

The clue is the tach going to zero while the bike is still going 40+ mph and the engine is still spinning.

The tach going to zero is due to the ECM losing power. If you let the condition go on for about 3-5 seconds I'll bet that "CHEC" would pop up in the temp window indicating the ECM is off line and no longer sending data to the cluster. I can't see the cluster well enough in your video to see much.

I'll still go with what others suggested and that it is the side stand switch. Zip tie the side stand up tight and ride the bike. Next guess would be the kill switch or ignition switch becoming intermittent. The side stand relay has caused some issues, but they have been rare.
Hmmm... you make a point there. Also when the tach is at zero there is no power at all, couldn’t the engine just be spinning off of momentum? It does slow me down quite a bit when this happens.
I will definitely try the zip tie as soon as I get the bike back. That would be crazy if that’s the cause. Lol.
 

·
Super Moderator
Joined
·
9,411 Posts
Hmmm... you make a point there. Also when the tach is at zero there is no power at all, couldn’t the engine just be spinning off of momentum? It does slow me down quite a bit when this happens.
I will definitely try the zip tie as soon as I get the bike back. That would be crazy if that’s the cause. Lol.
Yes the engine keeps spinning from momentum and being driven by the rear wheel.

You can simulate this whole scenario by moving your kill switch to "stop" while you are riding. It won't hurt anything but obviously, do it on a quiet road. See if it feels just like your issue. (The kill switch just cuts power to the ECM)
 

·
Registered
Joined
·
16 Posts
Discussion Starter #10
Yes the engine keeps spinning from momentum and being driven by the rear wheel.

You can simulate this whole scenario by moving your kill switch to "stop" while you are riding. It won't hurt anything but obviously, do it on a quiet road. See if it feels just like your issue. (The kill switch just cuts power to the ECM)
That’s good info! Thank God for these forums because that’s something I would have never thought about... but make prefect sense. I don’t know when I’m getting my bike back from getting recall work done. But I’m definitely trying this to see if this feels like my issue. I’ll keep you updated! Thanks!
 

·
Registered
Joined
·
16 Posts
Discussion Starter #12
So I've had the rectifier replaced, battery seems good as well. Checked the kickstand switch. After ordering a new repair manual, I kind of got it down to a few issues. This could be the STVA, TPS, EXCV actuator, or ISC valve malfunction. Because these things causes the ECM to cut power when signal is lost or malfunctioning. I think someone point it out, but also read you get the CHECK message (as shown in my video) on the cluster when ECM loses power for 5 secs. Something tells me it's the throttle positioning sensor. Maybe there's a dead spot in there from 4-7k rpms and when moving the throttle to another position, it comes back on.... I'm taking that off this week to test for it. Hopefully it's this instead of the entire throttle body that would have to be replaced if STV!
 

·
Super Moderator
Joined
·
9,411 Posts
So I've had the rectifier replaced, battery seems good as well. Checked the kickstand switch. After ordering a new repair manual, I kind of got it down to a few issues. This could be the STVA, TPS, EXCV actuator, or ISC valve malfunction. Because these things causes the ECM to cut power when signal is lost or malfunctioning. I think someone point it out, but also read you get the CHECK message (as shown in my video) on the cluster when ECM loses power for 5 secs. Something tells me it's the throttle positioning sensor. Maybe there's a dead spot in there from 4-7k rpms and when moving the throttle to another position, it comes back on.... I'm taking that off this week to test for it. Hopefully it's this instead of the entire throttle body that would have to be replaced if STV!
It think you mis-read the service manual. Failure of any of those items do not cut power to the ECM but just allow operation in fail safe mode. There is a table in the service manual titled "Fail-Safe Function" that lists how the ECM handles each failure and whether the bike will start and run. (in the FI Diagnosis section)

Actually, I can not think of any failure that shuts off power to the ECM. Even a TOS fault has the ECM turn off the fuel system but the ECM stays powered up.

As far as I know, the only way the ECM loses power is via the ignition switch, kill switch and side stand relay or a bad wire/connection between those components.
 
  • Like
Reactions: DEATHWISHRIDERS

·
Registered
Joined
·
16 Posts
Discussion Starter #14
You're right. I misread the TPS, but it looks like the others I listed will temporarily cut power....or am I misunderstanding this text??
 

Attachments

·
Registered
Joined
·
16 Posts
Discussion Starter #15
You're right. I misread the TPS, but it looks like the others I listed will temporarily cut power....or am I misunderstanding this text??
It says power from ECM is shut off pertaining STVA, EXCV, and ISC valve....
 

·
Super Moderator
Joined
·
9,411 Posts
It says power from ECM is shut off pertaining STVA, EXCV, and ISC valve....
Power "FROM" the ECM. Otherwise the ECM no longer sends power to the component. The ECM still operates.

Look at the two right columns, for start ability and run ability. The only "NO" is the CMP for running.

It's funny that they don't include the CKP on the list. That is a no start, no run item.
 

·
Registered
Joined
·
16 Posts
Discussion Starter #17
Power "FROM" the ECM. Otherwise the ECM no longer sends power to the component. The ECM still operates.

Look at the two right columns, for start ability and run ability. The only "NO" is the CMP for running.

It's funny that they don't include the CKP on the list. That is a no start, no run item.
Ok. Makes sense. I definitely misunderstood. I figured I was getting close since it occurred in certain RPM's ranges only. Do you think it would be a waste of time going down the TPS avenue?
 

·
Super Moderator
Joined
·
9,411 Posts
Ok. Makes sense. I definitely misunderstood. I figured I was getting close since it occurred in certain RPM's ranges only. Do you think it would be a waste of time going down the TPS avenue?
I don't think the TPS or other sensor is causing the engine to shut off briefly. Again the clue is the tach going to zero right away. That says the power is being cut to the ECM momentarily.

A bad ignition switch, kill switch, side stand relay (or the side stand switch that controls it) or wiring or connection will do this. I've not read of an ECM that does this on its own.

I think I said it already, but because it acts up at certain rpms (also a certain vibration) it is usually the side stand switch. There have been a couple of posts recently about the side stand relay failing also as the bikes get older.

If it was my bike, I would attack it in this order.
1. Bypass the sidestand switch temporarily and see if the problems goes away.
2. Bypass the sidestand relay (Jump between the O/Y and O/B) wires.
3. Open the kill switch and check condition.
4. Check the connector and pins on the ECM for corrosion or damage.
5. Check the right handlebar connector for damage.
6. Check the ignition switch connector for damage.
7 Last would be the ignition switch itself.
 

·
Registered
Joined
·
315 Posts
Did anyone suggest checking for tight battery terminal connections? I had a bike that ran fine and would randomly shut off at higher speeds. Turned out one of my terminals was loose lol.
 

·
Super Moderator
Joined
·
9,411 Posts
Did anyone suggest checking for tight battery terminal connections? I had a bike that ran fine and would randomly shut off at higher speeds. Turned out one of my terminals was loose lol.
Good thought. I've read posts of similar experiences also.
 
1 - 20 of 23 Posts
Top