The phone just rang... (Triumph project)
in [Motorcycles]
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From: TOG on 16 Mar 2010 05:54 <snip> And right on cue.... Took the Triumph out from the garage this morning. It started fine a couple of months ago, when I ran it up, but it wasn't having any today. Battery had fallen below 'criticial FI volts requirement' level. Jump-start from the car, then, on the expectation that it'd charge up on my 45-minute run to work. Only I didn't foresee some git in a white van jumping a red light and me jamming on the brakes and stalling it, just two miles up the road. When it hadn't charged up enough. That's when I confirmed that no, you really can't bump-start an FI engine. So I reached for the phone to ask my wife to come out in the car with the jump leads. Guess who left his phone on his office desk yesterday? Bah.
From: Mark Olson on 16 Mar 2010 06:20 TOG(a)Toil wrote: > <snip> > > And right on cue.... > > Took the Triumph out from the garage this morning. It started fine a > couple of months ago, when I ran it up, but it wasn't having any > today. Battery had fallen below 'criticial FI volts requirement' > level. Jump-start from the car, then, on the expectation that it'd > charge up on my 45-minute run to work. > > Only I didn't foresee some git in a white van jumping a red light and > me jamming on the brakes and stalling it, just two miles up the road. > When it hadn't charged up enough. That's when I confirmed that no, you > really can't bump-start an FI engine. Actually I would venture an educated guess that it is possible for a battery to be weakened to the point it won't supply the high current needed by the starter, yet it still has enough oomph to run the relatively wimpy fuel pump.
From: TOG on 16 Mar 2010 06:42 On 16 Mar, 10:20, Mark Olson <ols...(a)tiny.invalid> wrote: > TOG(a)Toil wrote: > > <snip> > > > And right on cue.... > > > Took the Triumph out from the garage this morning. It started fine a > > couple of months ago, when I ran it up, but it wasn't having any > > today. Battery had fallen below 'criticial FI volts requirement' > > level. Jump-start from the car, then, on the expectation that it'd > > charge up on my 45-minute run to work. > > > Only I didn't foresee some git in a white van jumping a red light and > > me jamming on the brakes and stalling it, just two miles up the road. > > When it hadn't charged up enough. That's when I confirmed that no, you > > really can't bump-start an FI engine. > > Actually I would venture an educated guess that it is possible for > a battery to be weakened to the point it won't supply the high > current needed by the starter, yet it still has enough oomph to > run the relatively wimpy fuel pump. That's what I thought, too, but it didn't seem to happen that way. The FI warning light came on. There wasn't even an attempt on the part of the starter to turn. No "chia-chia-chiaaaaa*click*" at all. Not even a click from the starter relay. Just nothing. The idiot lights didn't even dim when you pressed the button. When I stalled it, there was enough charge for maybe one second's turning of the starter motor, and then it closed down as above. My guess, then, on this evidence, is that the FI computer reads the voltage, says: "Not enough magic electrons, mate" and simply shuts down the system. I don't know whether the computer itself requires a minimum voltage to work properly - my guess is that it does, but I really don't know computers, so I throw that one open to the floor. Anyway, got to work OK, switched off, switched on again and it fired up perfectly, so it's obviously taken a charge. I've got the jump leads with me, mind. And I'll put the battery on the charger tonight.
From: Mark Olson on 16 Mar 2010 07:27 TOG(a)Toil wrote: > On 16 Mar, 10:20, Mark Olson <ols...(a)tiny.invalid> wrote: >> TOG(a)Toil wrote: >>> <snip> >>> And right on cue.... >>> Took the Triumph out from the garage this morning. It started fine a >>> couple of months ago, when I ran it up, but it wasn't having any >>> today. Battery had fallen below 'criticial FI volts requirement' >>> level. Jump-start from the car, then, on the expectation that it'd >>> charge up on my 45-minute run to work. >>> Only I didn't foresee some git in a white van jumping a red light and >>> me jamming on the brakes and stalling it, just two miles up the road. >>> When it hadn't charged up enough. That's when I confirmed that no, you >>> really can't bump-start an FI engine. >> Actually I would venture an educated guess that it is possible for >> a battery to be weakened to the point it won't supply the high >> current needed by the starter, yet it still has enough oomph to >> run the relatively wimpy fuel pump. > > That's what I thought, too, but it didn't seem to happen that way. The > FI warning light came on. There wasn't even an attempt on the part of > the starter to turn. No "chia-chia-chiaaaaa*click*" at all. Not even a > click from the starter relay. Just nothing. The idiot lights didn't > even dim when you pressed the button. When I stalled it, there was > enough charge for maybe one second's turning of the starter motor, and > then it closed down as above. My bike would definitely energize the starter relay whether the computer was hooked up or not. So our EFI systems are different in that respect. > My guess, then, on this evidence, is that the FI computer reads the > voltage, says: "Not enough magic electrons, mate" and simply shuts > down the system. I don't know whether the computer itself requires a > minimum voltage to work properly - my guess is that it does, but I > really don't know computers, so I throw that one open to the floor. > > Anyway, got to work OK, switched off, switched on again and it fired > up perfectly, so it's obviously taken a charge. I've got the jump > leads with me, mind. And I'll put the battery on the charger tonight. I'm not disputing your experience, but not all EFI designers make the same choices, hence some systems will be better at coping with lower voltage from the battery. Generally, EFI computers are very robust and work with even a very low battery voltage, you want the thing to work no matter what, best effort, all that sort of thing.
From: Aham Brahmasmi on 16 Mar 2010 08:57
On Mar 16, 4:27 am, Mark Olson <ols...(a)tiny.invalid> wrote: > I'm not disputing your experience, but not all EFI designers make the > same choices, hence some systems will be better at coping with lower > voltage from the battery. > > Generally, EFI computers are very robust and work with even a very > low battery voltage, you want the thing to work no matter what, best > effort, all that sort of thing. My 280Z had a Bosch fuel injection system. I don't remember if it even *had* a computer, but the car would sit for months and months without being driven and, if there was enough "juice" for the starter to turn the engine over even *one* turn, the engine would always start... |