There is a good reason for what he is seeing. During 88 models the FI wiring was changed to only power up the injectors when the fuel pump relay was on. Of course the ECU fires the injectors by pulsing the ground side of the injector. Earlier 2.1 had the injectors powered by the ECU power relay but during 88 it was switched over to the FP relay, as was the power for the idle control. So 88+ is different than earlier and this is not reflected in some of the diagnostic materials. Mark
David Beierl wrote: > At 03:47 PM 12/7/2013, Steve Cotsford wrote: >> Hi Neil. I did a little more checking. It seems that each FI >> plug does have a constant B+ on one side. For me it was showing >> 11.75 Volts As I was doing this testing with the pump relay in >> place, I noticed that the B+ was only present when the pump was >> running and when it disappeared and the pump turned off, this is >> when the injector sprayed. > > I'm having trouble following this part. Your injectors should fire > independently of the pump running; they're separate activities. > > The pump only runs during the period that the ECU is receiving pulses > from the distributor (and I'm guessing for a second or two after) as > a safety measure so as not to continue pumping fuel after an accident > or fuel-hose rupture. > > The injectors OTOH fire on each individual pulse from the > distributor. ... |
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