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Re: Ur-q fuel system troubles
Hi, I posted about this a couple of days ago but got no responses so I thought
I'd try again with some new information. My Urq is running very lean. It
doesn't like to start very much when it's cold and really doesn't start very
much when it's hot. Power is also greatly diminished, although at certain
times the power comes back for a little while and then goes away again. What
does this sound like? System or differential pressure regulators? Pump? Check
valve? Distributor? I'd really appreciate any help, and soon, please. I'm
supposed to be taking the car somewhere a good distance away tonight:(!
Private responses would be best as they get here faster than the digest.
Thanks so much (fingers crossed),
How do know it's running lean? Measure CO/CO2? Voltage at O2 sensor (it
should be constantly bouncing around between roughly .3 to .7 volts)?
Duty cycle on Freq Valve (should be bouncing around 44 to 55%)? What makes
you think your O2 sensor is any good? (30Kmiles can do a number on the
older 2-wire models...)
Assuming you don't have a clogged/crimped fuel line, my suspicion for
lean mixture would be the <expletive deleted> Control Fuel Pressure Regu-
lator (that wart on the side of the block opposite the fuel distributor,
with multiple fuel, manifold, and electric lines running to it), followed
by the fuel pump itself. These were the primary physical culprits on my
beastie. The injectors were a minor culprit (once I got 5 of the *same*
injector installed, the engine ran a little smoother too...)
Dirty grounds were the major "erratic" behavior gremlins -- there are
two spider-web-grounds in the engine compartment, one which goes to the
top of the valve cover in the rear, and then just behind that one there
is another multiple ground connection up by the coil. Very *VERY* good
odds these connections are junk, time to cut them all off and solder on
a new connector(s) and clean up the ground point(s) and bolt them back
Cold start [almost] has to be the cold start injector, or a really
low fuel system pressure.
Hot start [almost] has to be the cold start injector too! Those cars
are really subject to vapor lock problems (something about hanging
the fuel injection system on top of the exhaust manifold and turbo...),
so there is a "Hot Start Pulse Relay" that should throb the Cold Start
Injector about every three seconds when starting a warm engine -- you
should be able to hear the relay click-clacking away as you crank a
That should be enough to keep you occupied for awhile . . .