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Bike Power Dropped During Riding and Won't Start

Old 07-07-2018, 03:00 PM
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Default Bike Power Dropped During Riding and Won't Start

Hey all, I have a 2003 CBR F4i with about 8000 miles on it. It was a previously wrecked bike that I got running about 6 years ago and has been pretty solid other than the usual battery replacements.

I have an issue with the bike that is really boggling my mind. I rode the bike about 40 miles a few days ago and the bike suddenly just lost all power at about 30 mph. However, all my instruments appeared to be working just fine. I pulled the clutch and drifted to the side of the road. There were no other warning signs previously during my ride that would have tipped me off to such an issue. I tried to restart it, but it would not start. However, the engine was turning over just fine (also could hear the fuel pump priming). I ended up pushing the bike about 2 miles home once this occurred.

In the meantime, I have been troubleshooting this issue to no avail. I have tried the following things:

1) Hooked up to a battery tender and have ensured that there is good battery voltage and measured with voltmeter.
2) Verified again that the fuel pump is priming. I have had issues with the pump before, but it appears to be running just fine since I have replaced it.
3) Verified there is a spark from one of the cylinders. Grounded the plug to the case and started engine. Spark was seen.
4) Installed a noid light on the ignition coil connections and can verify that all 4 coil connections are lighting (albeit kind of weak and fast, but don't think that is abnormal).
5) Removed fuel line and then turned on fuel pump (I know, not the smartest idea) and was sprayed with a lot of fuel.
6) Removed vacuum hose line from fuel pressure regulator. There was no fuel dripping from the FPR. I have also seen this issue before and previously replaced the FPR.
6) Moving on to the injectors... Placed the noid light on all injector connectors and verified a dim/weak light when pressing the start switch (not sure if this is a bad sign since I was starting the engine during this test. I assume there would be a little voltage drop during the start).
7) More injector testing. I placed a piece of paper in all of the cylinders (it's not firing anyway, so why not?!?!) and pressed the start switch. Pulled piece of paper out and verified that they were all being sprayed with fuel.
8) Now I am getting desperate and I sprayed starter fluid into the throttle body and then tried to start it. It isn't really doing much of anything different, but occasionally I get a slightly different noise as if it almost starts.
9) Checked all fuses to be good.

In all cases, the engine just turns fine but won't actually start. I am really at a loss as to what to try next. There are no error codes from the PGM-FI. Does anyone have any ideas as to what would cause this?

I am about to replace all the spark plugs anyways since it definitely won't hurt my endeavors and they are quite old, but I can't see how all 4 spark plugs would have instantaneously gone bad and then cutoff my engine during my ride.
Old 07-07-2018, 06:15 PM
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Update: Spark plugs changed and still no difference. However, I sprayed some more starter fluid in the throttle body and did hear it begin to start and then quickly die. I am thinking there may be something clogging the fuel pump just enough to not fire the engine but still allow fuel flow.
Old 07-08-2018, 12:39 AM
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Last Update: Fixed!

I ended up pulling out the fuel pump from the tank to see if there was anything obviously wrong in there. Low and behold, the inline hose connection for the fuel pump had completely disconnected. This makes some sense as to the behavior that I was seeing. While the hose was disconnected, it was still somewhat aligned with the pump and thus there was some fuel flow (as I had previously stated) but not enough to fire the engine. After reconnecting the hose and clamping it, the engine is running again! Hopefully this is helpful to anyone else in the future who may see some of the same symptoms as me.
Old 07-08-2018, 03:36 AM
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Location: UK
Posts: 2,051

Well done matey, you did all that while I was in bed (UK)
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