[V8] Dumping Fuel

Buchholz, Steven Steven.Buchholz at kla-tencor.com
Thu Mar 10 17:38:43 EST 2005

... my recollection is that indeed the injectors are doubled up on the
V8 ... i.e. each injector driver on the ECU drives two injectors.
Unless he looks around and finds another cylinder that is wet I'm
skeptical that it is the ECU proper.  

Which cylinder does the vacuum signal for the FP Reg come from ... isn't
it #3?  I know the report is that the FP Reg was replaced, perhaps the
replacement part is bad too.  I'd pull the vacuum line for the FPR off
to see if it was wet.  If there does not seem to be an issue with the
drive from the ECU he could always simply jumper the Fuel Pump Relay and
find out where the leak is coming from.  When I installed the
replacement engine on #2 I found out how simple a matter it is to unplug
all the injectors and fuel rails from the engine ... it is just 4 bolts
that hold the assembly in place.  You could try running the fuel pump
with the injectors off the engine ... but be careful if you don't have
all the proper clips in place (don't ask how I know what happens :)

Steve B
San Jose, CA (USA)
> If the #3 injector is unplugged, does the motor run OK (no 
> fuel pouring out the
> tail pipe)?
> If so, it would seem the only choices are a short somewhere 
> or a bad ECU.
> You seem to have ruled out the injector already. Never hurts 
> to double check
> things though - especially when there is a language problem.
> If I remember correctly, the ECU bank fires the injectors - 
> in other words, two
> injectors fire at once so if #3 is stuck on, its mate (which 
> one I dunno) should
> also be stuck on.
> If I am wrong, and the ECU fires each injector individually, 
> it is plausible the
> ECU is bad. It may take a tool like an Oscilloscope to really 
> see what is going
> on though. I suppose there is some bizzare failure mode the 
> driver transistor
> could be in.
> Dave
> Quoting cobram at juno.com:
> > A member of the V8Q brotherhood from Nicaragua, of all 
> places, found my
> > meager web site, and after a little correspondence, has me 
> stumped.  I
> > asked him to join our list, but he doesn't speak a word of English.
> >
> > 1990 V8Q with a 7/89 build, 190K kilometers, used to be 
> some ambassadors
> > car, dealer maintained till the day he got it.  He says one 
> morning the
> > car started billowing smoke out the tailpipe along with raw 
> gas blowing
> > out the tailpipes.  He shuts it down, replaces Fuel 
> Pressure Regulator,
> > pulls codes (all 4444's-no codes)  starts it up again, and 
> she's still
> > smoking like crazy, and spitting raw gas out of the exhaust.
> >
> > At this point I tell him to check the plugs....#3 cylinder 
> is SOAKED,
> > rest of the plugs look alright.  Bad injector I tell him, 
> but I also tell
> > him to check the pulse first.  I am astonished that he 
> didn't hydrolock
> > the engine.  He tells me the "noid" light is blinking fine 
> when tested
> > via the self check and when cranking (with the plugs out of 
> the engine),
> > BUT, he's getting a big gasoline fog cloud out of #3 
> cylinder that stunk
> > up half the neighborhood.  Damn, so I have him swap the new 
> injector for
> > one of the others, he puts the plugs back in......and the 
> thing is still
> > smoking like a deranged crop duster, still at #3.  He says he went
> > through 5 liters of gasoline in about 3 minutes running the car.
> >
> > Anyone have an idea of WTF is going on here???  The 
> injector pulse is
> > normal, if it was a fuel rail problem it would effect more than one
> > injector, if it was the computer he'd get a solid pulse at 
> the injector.
> > Or is my logic off here somewhere?  I've never come across 
> nor heard of
> > anything like this on a V8Q before.
> >
> > Muchas Gracias and BCNU,

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