kubagsx Posted July 29, 2022 Share Posted July 29, 2022 (edited) Hi It is my first post here My XX worked not very well last time. 20 000 miles done. Year 2002. Fuel consumption was horrible. I could do only 90 miles on a tank driving very calmly! I checked all the sensors and noticed that the voltage, which is delivered to the IAT sensor (is in the airbox) and to the engine coolant temperature sensor is only 0,44V ! Haynes manual says, that in both cases it should be between 4,5 - 5,5V. It is possible that bikes consumes so much fuel because of it. Manual also states that when low voltage is present, the ECU can be damaged. What should I do now? Maybe the manual is wrong and you had similar issue? What is the reason of it? Thank you in advance! J. Edited July 29, 2022 by kubagsx Quote Link to comment Share on other sites More sharing options...
rockmeupto125 Posted July 30, 2022 Share Posted July 30, 2022 What's the voltage at the battery, both off, and while running? Quote Link to comment Share on other sites More sharing options...
Guest Kubagsx Posted July 30, 2022 Share Posted July 30, 2022 Hi. Voltage at the battery is 12.9V. When the key is turn off, the Voltage at the sensor is 0. When I turn on the key, Voltage appears and is only 0,44V. Quote Link to comment Share on other sites More sharing options...
blackhawkxx Posted July 30, 2022 Share Posted July 30, 2022 Maybe someone can move this to the garage area so more people will see it. Quote Link to comment Share on other sites More sharing options...
superhawk996 Posted July 30, 2022 Share Posted July 30, 2022 First thing I'd check is the fuel pressure regulator, pull the hose off and see if there's gas in it. The 4.5-5.5 is probably with the engine running so if you're checking with the engine off that would explain it. Even if you're checking correctly, I doubt that being .1v below the minimum spec would cause that much of a problem. If either of those sensors is reporting super low it would make it run rich and unless it's a totally open circuit the computer probably would't know that it's faulty. Low voltage to the sensors would probably make it run rich, but I don't think .1 is enough to make such a dramatic difference. If your bike has an O2 sensor that 'should' correct a rich mixture, and if it's faulty it could cause the rich mixture. I'd avoid riding it 'till the problem is corrected. Quote Link to comment Share on other sites More sharing options...
superhawk996 Posted July 30, 2022 Share Posted July 30, 2022 Shit, I misread the voltages and thought I saw that you were getting 4.4. .44 is way off and if the sensors work as I think they do, that would cause a super rich mixture. Verify that you're testing correctly and try testing at the ecu to know if it's the ecu or a wiring problem causing the low voltage. Quote Link to comment Share on other sites More sharing options...
kubagsx Posted July 30, 2022 Author Share Posted July 30, 2022 Hi The problem with voltage was in the connectors. Some were seized. Cleaned them and voltage is ok now. I have ordered the fuel pressure regulator. Thx I don't have O2 sensor, while I installed power commander with O2 sensor eliminator. 2 Quote Link to comment Share on other sites More sharing options...
superhawk996 Posted July 31, 2022 Share Posted July 31, 2022 19 hours ago, kubagsx said: I have ordered the fuel pressure regulator. Thx Was yours leaking? Quote Link to comment Share on other sites More sharing options...
kubagsx Posted August 9, 2022 Author Share Posted August 9, 2022 On 7/31/2022 at 4:31 PM, superhawk996 said: Was yours leaking? I haven't checked yet :) Quote Link to comment Share on other sites More sharing options...
ironmike Posted August 9, 2022 Share Posted August 9, 2022 The FPR vent lines should be bone-dry; any residual fuel--even moisture--is a sign of a compromised FPR diaphragm, a pinhole would do it. This is one of the few weak spots in the XX. The original (FPR) design predates the proliferation of alcohol-laced unleaded fuel, which is thought to contribute to weakening/compromising the diaphragm; anecdotal reports, while falling short of empirical evidence, seem to support this conclusion. Fortunately, the fix (replace the FPR) is relatively inexpensive and easy to do (on the right end of the fuel rail). 1 Quote Link to comment Share on other sites More sharing options...
superhawk996 Posted August 9, 2022 Share Posted August 9, 2022 4 hours ago, kubagsx said: I haven't checked yet You don't wanna fuck it off. The gas all goes to #3 cylinder and can lead to a really bad time. Quote Link to comment Share on other sites More sharing options...
kubagsx Posted August 9, 2022 Author Share Posted August 9, 2022 (edited) 3 hours ago, ironmike said: The FPR vent lines should be bone-dry; any residual fuel--even moisture--is a sign of a compromised FPR diaphragm, a pinhole would do it. This is one of the few weak spots in the XX. The original (FPR) design predates the proliferation of alcohol-laced unleaded fuel, which is thought to contribute to weakening/compromising the diaphragm; anecdotal reports, while falling short of empirical evidence, seem to support this conclusion. Fortunately, the fix (replace the FPR) is relatively inexpensive and easy to do (on the right end of the fuel rail). 7 minutes ago, superhawk996 said: You don't wanna fuck it off. The gas all goes to #3 cylinder and can lead to a really bad time. What is an average lifespan of FPR? How quick FPR failure can lead to ruin the cylinder wall? Edited August 9, 2022 by kubagsx Quote Link to comment Share on other sites More sharing options...
Furbird Posted August 9, 2022 Share Posted August 9, 2022 It doesn't ruin the cylinder wall, it hydrolocks the engine. As in, the ENTIRE engine fills up with the contents of the gas tank. Been there, done that, got the t-shirt and the stains on the ceiling when I had to pull the spark plugs and pump the fuel out. That was quite the geyser. Quote Link to comment Share on other sites More sharing options...
XXitanium Posted August 9, 2022 Share Posted August 9, 2022 55 minutes ago, superhawk996 said: You don't wanna fuck it off. The gas all goes to #3 cylinder and can lead to a really bad time. No shit, these can hydrolock too?! Quote Link to comment Share on other sites More sharing options...
XXitanium Posted August 9, 2022 Share Posted August 9, 2022 37 minutes ago, Furbird said: It doesn't ruin the cylinder wall, it hydrolocks the engine. As in, the ENTIRE engine fills up with the contents of the gas tank. Been there, done that, got the t-shirt and the stains on the ceiling when I had to pull the spark plugs and pump the fuel out. That was quite the geyser. It's worse when a plug fires and jams a piston into a slug of gas that's in the cylinder. It bends the connecting rod. Quote Link to comment Share on other sites More sharing options...
superhawk996 Posted August 10, 2022 Share Posted August 10, 2022 5 hours ago, kubagsx said: What is an average lifespan of FPR? Somewhere between 5 seconds and 500 years. There's really no way to say, but if yours is factory it is absolutely suspect. This is a thing that seems somewhat particular to 'Birds, but it happens to all vehicles. 5 hours ago, kubagsx said: How quick FPR failure can lead to ruin the cylinder wall? Any excess gas is bad since it washes the oil off the walls/rings/pistons and dilutes the oil with something that doesn't lubricate for shit so everything suffers to some extent. The quick catastrophic potential is a hydrolock on startup which will possibly bend a rod and could break a piston. Quote Link to comment Share on other sites More sharing options...
superhawk996 Posted August 10, 2022 Share Posted August 10, 2022 5 hours ago, XXitanium said: It's worse when a plug fires and jams a piston into a slug of gas that's in the cylinder. It bends the connecting rod. I'm pretty sure the gas won't ignite. I think the damage happens from starter torque and momentum of the other parts. The same damage happens when an engine is cranked with too much water or oil in a cylinder. Quote Link to comment Share on other sites More sharing options...
XXitanium Posted August 10, 2022 Share Posted August 10, 2022 My CBX - slug of gas in cylinder 1, I hit the switch and one of the other cylinders fired and stalled it out. It's a sick feeling. Quote Link to comment Share on other sites More sharing options...
XXitanium Posted August 10, 2022 Share Posted August 10, 2022 The gas runs downhill the tubing to the lowest cylinder. Cylinder 1 is toward the right if the picture. I don't THINK the starter has enough juice to bend a rod. 1 Quote Link to comment Share on other sites More sharing options...
superhawk996 Posted August 10, 2022 Share Posted August 10, 2022 40 minutes ago, XXitanium said: I don't THINK the starter has enough juice to bend a rod. Probably not without some amount of momentum build up, but it has happened with many engines that had water or oil in the cylinders so it's not a fuel ignition issue. If a cylinder is full and already on the compression stroke the starter probably can't bend a rod, but fluid usually gets in through an open valve so there's going to be some amount of spin/momentum before the compression happens. It's a relatively common issue when someone does injector work on 7.3 diesels, some of the cylinders fill with oil and if they're not purged they're fucked. Quote Link to comment Share on other sites More sharing options...
SwampNut Posted August 10, 2022 Share Posted August 10, 2022 I bet Joe has an engine laying around that we could test this on. I see a drinking game at NeXXt. 2 Quote Link to comment Share on other sites More sharing options...
kubagsx Posted August 11, 2022 Author Share Posted August 11, 2022 Changed the FPR. Now xx consumes 5.5 liter per 100 km. Less than should Thank you for the advices. 1 Quote Link to comment Share on other sites More sharing options...
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