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MACS5RDR

.040 Over
Joined
Nov 23, 2007
Messages
55
Location
Mass
Was riding to work last Monday when out of the blue the Low fuel idiot lamp lit, about 10-15 seconds later the bike shutdown at idle. Re-started it and the same thing happened about 10-15 seconds later. None the less it was a long ride home, having to pull the clutch and restart the beast every so often. Seemed that as long as I applied throttle to it it would run a bit longer but not much (30 sec maybe)

Got her home, linked up my PC w/TuneECU, fault code was P0460, Fuel level sensor circuit. Tried to reset the fault but was unsuccessful, idiot lamp stayed on. Then performed all the continuity checks as the service manual calls for, everything looked fine. Ran the limited tests that TuneECU can perform,,,,, fuel pump passed w/o issue. Also checked the TPS, reading was within spec at .059V. At that point I pulled the tank off, then the sending/fuel pump unit out to check the float assembly. The float resistance read variable from end-to-end from 10 to approx. 100-150 ohms. Although functioning correctly as a rheostat, without analyzing the circuit it goes to or knowing what the values should be, hard to say whether good or bad. While the tank was off I went thru all the wiring connections on the bike, checking for wiring issues, cleaning and coating the connectors. Checked and cycled all the relays on the bench, pulled the ECU to do a quick visual on the interface connectors. I then cycled the fuel pump on the bench real quick while immersed in fuel, seemed fine. Everything checks out in stand-alone testing. The only thing in the tank that couldn’t be tested is the fuel pressure regulator.

I then reassembled & reinstalled the fuel tank. When the key is turned to on, you can hear the system going thru its power up self-tests but the low fuel idiot lamp is still lit as well as the P0460 fault is still present. Fired her up, she sounds fine but 10-15 sec later she just shuts down.

Just to step back about a week or 2, there were times while riding I did tend to get a faint fuel odor. Checked the beast out but found no fuel leaks and all the lines look fine, figured it may have come from the vent line.

A bit stumped at this point as I’ve found nothing electrically wrong, that I can tell, with her as of yet. One question is though, if the fuel regulator were to fail, can that in itself be a cause for this issue? Looking for opinions & any assistance is greatly appreciated.

Bringing her (trailering) to my dealer tomorrow as the triumph scantool is significantly more comprehensive in its insight into the system than TuneECU.
 
35K miles on this one. Didn't mention in the original post but have one on order. Was going to change it while apart figuring that restriction can reduce fuel pressure. Thanks for the input.
 
i would guess that it is probably either a short or an open in the fuel gauge asy then the computer turns off the pump. when you turn key off then on it resets computer and your on your way till the p0460 shows up. you can check the ohms for an hour and they look good but sometimes you put heat (hair dryer) on what you are testing and the ohms could go up a 1000 times. Also the computer can sense a little glitch and that's all it takes. i can see the comp. shutting it down, like who wants a short in the gas tank!
herman
ps let us know what you find.
 
Well, after extensive troubleshooting it looks like the fuel lamp was caused by a bad float assembly in the fuel tank. The low fuel sensor circuit sense input at the ECU regarsd an input of 2.5 - 5.0 volts as above the low fuel level mark. Anything below 2.5 volts will light the idiot light on the tach. I regards to the bike shutting down, manipulation of the ignition wiring when inspecting the connectors on the main cable assembly seems to have cured that as that problem has "mysteriously" gone away. Basically, if it ain't broke, you can't fix it. What I did do was when re-securing the ignition connector on the front left side of the tank, under the plastic cover, made sure that with the handlebars turned fully to the right that there was no tension being placed on the ignition cable, both in front and behind the connector assembly. Per the Triumph factory reps, the ignition system (cable) is the only part that will cause the systoms that the bike had. Crossing my fingers for my 2500 mile trip in 2 weeks. So far, so good.
 
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