Afeef Posted March 21 Share Posted March 21 My 1998 Honda VFR 800 sat idle for over a year, and now it won't start. The fuel pump isn't activating, indicating a potential issue with the ECU unit. To troubleshoot, I swapped in the ECU unit from my 2003 VFR. While the bike now starts, it lacks power and stalls after moving just 5 feet. The FI light blinks intermittently, and the RPM behaves erratically. When I loosen the fuel screw, the fuel pump pressure seems fine. Any assistance would be greatly appreciated. 1 Quote Link to comment Share on other sites More sharing options...
Member Contributer Grum Posted March 21 Member Contributer Share Posted March 21 4 hours ago, Afeef said: My 98 Honda VFR 800 was parked for over a year , but now when I try to turn it on , it doesn't go on . The fuel pump doesn't go on , so I realized that there might be a problem with the ECU Unit, so I used my 2003 vfr ecu unit to see if the problem will be resolved. You swapped a 1998 5gen ECU with a 2003 6gen ECU!!!! NOT possible! Different connectors, different wiring, different sensors etc !!!! What checks did you do to "realize a problem with the ECU Unit"??? OR.... Are you saying you swapped the FCR (fuel cut relay) with the one from your 2003? Do you have the Service Manual or a wiring diagram to work with? With the Sidestand down, Ignition to On, what is the Fi code being flashed by the Fi light?? 1 1 Quote Link to comment Share on other sites More sharing options...
Afeef Posted March 21 Author Share Posted March 21 38 minutes ago, Grum said: You swapped a 1998 5gen ECU with a 2003 6gen ECU!!!! NOT possible! Different connectors, different wiring, different sensors etc !!!! What checks did you do to "realize a problem with the ECU Unit"??? OR.... Are you saying you swapped the FCR (fuel cut relay) with the one from your 2003? Do you have the Service Manual or a wiring diagram to work with? With the Sidestand down, Ignition to On, what is the Fi code being flashed by the Fi light?? Well , the ECU units in both models are identical in shape and also the connecters are the same . The fuel pump was not working at all , but as soon as I swapped the ECUs , it worked fine , As for the code , I don't really know how to read it . It is just flashing and sometimes it goes away. Quote Link to comment Share on other sites More sharing options...
Member Contributer Presson Posted March 21 Member Contributer Share Posted March 21 Welcome Afeef! Can you post a photo of the ECU unit you swapped over. Also as Grum asks - With the Sidestand down, Ignition to On, what is the Fi code being flashed by the Fi light. It's the number of flashes in the sequence 1 Quote Link to comment Share on other sites More sharing options...
Member Contributer raYzerman Posted March 21 Member Contributer Share Posted March 21 You really need to put the original ECU back in. To read codes, find the two-way connector on left side under the seat, near the rear, and jumper it, or find a mating connector and put a switch in your jumper so you can conveniently use it when you need to. Follow the service manual procedure to read the codes, correct the issue and clear them. Again, with the original ECU. As for your initial problem of no fuel pump running, time to check all the connections of regulator/stator, clean them up, and especially at the starter relay. Check all fuses are good... what do you see first with ignition on and bike in neutral? 1 Quote Link to comment Share on other sites More sharing options...
Afeef Posted March 21 Author Share Posted March 21 2 hours ago, Presson said: Welcome Afeef! Can you post a photo of the ECU unit you swapped over. Also as Grum asks - With the Sidestand down, Ignition to On, what is the Fi code being flashed by the Fi light. It's the number of flashes in the sequence Thank you, Initially, the FI indicator remained constantly illuminated without blinking, indicating a problem with the ECU unit. Subsequently, I replaced it with the ECU unit from another motorcycle, which resolved the issue, allowing the engine to start and the FI light to turn off. However, upon starting to move, the engine became weak, accompanied by random blinking of the FI light. Despite attempts to accelerate, the RPM did not exceed 2000 and trying to turn off as if there were no fuel. The attached image shows the motorcycle from which I borrowed the ECU unit. I'll post a photo for the ECU being used later . This ECU unit is downloaded from the internet but mine is similar to this Quote Link to comment Share on other sites More sharing options...
Member Contributer raYzerman Posted March 21 Member Contributer Share Posted March 21 A constant on FI light can mean things other than a faulty ECU..... check service manual for the list....... being it sat a year, I'd be checking all connections first. 1 Quote Link to comment Share on other sites More sharing options...
Afeef Posted March 21 Author Share Posted March 21 13 minutes ago, raYzerman said: You really need to put the original ECU back in. To read codes, find the two-way connector on left side under the seat, near the rear, and jumper it, or find a mating connector and put a switch in your jumper so you can conveniently use it when you need to. Follow the service manual procedure to read the codes, correct the issue and clear them. Again, with the original ECU. As for your initial problem of no fuel pump running, time to check all the connections of regulator/stator, clean them up, and especially at the starter relay. Check all fuses are good... what do you see first with ignition on and bike in neutral? Thank you, Why does the engine start when I install my other motorcycle ECU Unit !? That's a sign that the old unit is defected, isn't? Quote Link to comment Share on other sites More sharing options...
Member Contributer Presson Posted March 21 Member Contributer Share Posted March 21 Not necessarily as there could be differences between no start situations between the different models. Here is the link to the service manual in the downloads section of this site. I strongly recommend putting the original ECU back in and then following the FI code process described by raYzerman and in the manual . 1 Quote Link to comment Share on other sites More sharing options...
Afeef Posted March 21 Author Share Posted March 21 2 hours ago, Presson said: Not necessarily as there could be differences between no start situations between the different models. Here is the link to the service manual in the downloads section of this site. I strongly recommend putting the original ECU back in and then following the FI code process described by raYzerman and in the manual . Thank you for your help. I'll have a look and follow your instructions. Quote Link to comment Share on other sites More sharing options...
Afeef Posted March 22 Author Share Posted March 22 12 hours ago, raYzerman said: A constant on FI light can mean things other than a faulty ECU..... check service manual for the list....... being it sat a year, I'd be checking all connections first. By the way, I have noticed that the fuel return tube is always empty!! Quote Link to comment Share on other sites More sharing options...
Afeef Posted March 24 Author Share Posted March 24 On 3/21/2024 at 7:56 PM, raYzerman said: A constant on FI light can mean things other than a faulty ECU..... check service manual for the list....... being it sat a year, I'd be checking all connections first. By the way, I have noticed that the fuel return tube is always empty!! Quote Link to comment Share on other sites More sharing options...
Afeef Posted March 24 Author Share Posted March 24 Update: There's good news! I was able to fix the problem and the motorcycle is running great now. It turned out there was a small cut in the pipe connected to the fuel pump inside the fuel tank. I replaced the pipe, and that seems to have resolved the issue (although the FI light might still be on for now). I appreciate all the help from everyone! 1 Quote Link to comment Share on other sites More sharing options...
Member Contributer JZH Posted March 24 Member Contributer Share Posted March 24 Welcome Afeef! Glad you got it running again. Did you know that you have an RC49, the police version of the RC46? The bikes look very similar, but I'm sure there are many hidden differences, too. Just keep that in mind when you're using the VFR800Fi RC46 repair manual! Ciao, JZH Quote Link to comment Share on other sites More sharing options...
Afeef Posted March 24 Author Share Posted March 24 49 minutes ago, JZH said: Welcome Afeef! Glad you got it running again. Did you know that you have an RC49, the police version of the RC46? The bikes look very similar, but I'm sure there are many hidden differences, too. Just keep that in mind when you're using the VFR800Fi RC46 repair manual! Ciao, JZH Yes bro , I know that . Thank you for mentioning it. Quote Link to comment Share on other sites More sharing options...
Afeef Posted March 24 Author Share Posted March 24 VID-20240324-WA0029.mp4 My FI light came on and showed error code 23. I checked the manual, but couldn't find any information about this code. Does anyone know what code 23 means for a 1998 Honda VFR 800. Note : I didn't jumper it Quote Link to comment Share on other sites More sharing options...
Worfje Posted March 24 Share Posted March 24 Faulty oxygen sensor heating element, according to Haynes service manual. Quote Link to comment Share on other sites More sharing options...
Afeef Posted March 24 Author Share Posted March 24 1 hour ago, Worfje said: Faulty oxygen sensor heating element, according to Haynes service manual. But 1998 Honda VFR 800 does not have oxygen sensors ! Quote Link to comment Share on other sites More sharing options...
Worfje Posted March 24 Share Posted March 24 Agreed, so it might be that the ECU you are using isn't the original one (but one from later years that expects oxygen sensors)... or oxygen sensor were applied in the police version 😉 1 1 Quote Link to comment Share on other sites More sharing options...
Afeef Posted March 25 Author Share Posted March 25 8 hours ago, Worfje said: Agreed, so it might be that the ECU you are using isn't the original one (but one from later years that expects oxygen sensors)... or oxygen sensor were applied in the police version 😉 Yeah, it could be Thank you Quote Link to comment Share on other sites More sharing options...
granderpete Posted March 25 Share Posted March 25 Or it could be that the code is being read incorrectly? 23 flashes is 2x long(1.3secs each) and 3 short? Quote Link to comment Share on other sites More sharing options...
Member Contributer Grum Posted March 25 Member Contributer Share Posted March 25 5 minutes ago, granderpete said: Or it could be that the code is being read incorrectly? 23 flashes is 2x long(1.3secs each) and 3 short? ?? Did you see his video of the fault code? Sure looks like a 23 to me. 1 Quote Link to comment Share on other sites More sharing options...
Worfje Posted March 25 Share Posted March 25 You can check if you have oxygen sensors on your bike when looking at the exhaust manifold (see below image). Quote Link to comment Share on other sites More sharing options...
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