KCG

iTrader: (1)

I'm working on putting a 89 IROC back together that someone else tore apart.
It's a 305/T5. Its been sitting for some amount of time. Long enough I had to replace the gas tank it was so corroded. Here's a quick run down of what I've done so far,
I've installed new fuel filter. New pump. Ran some gas thru the lines to get rid of the old gas. Cranked it over, and nothing. Checked the valve on rail and have pressure. Don't know how much, need to get adapter for the gauge I have. Checked for voltage at the inj's and have 12v on all of them. Lifted the rail and cranked and no fuel is being sprayed. So, I'm thinking is the rail/inj so clogged up they're not spraying?...or not being told too. I back probed with a 12v test light and cranked it over thinking I'd see the light go out when it fired, but didn't happen. One weird thing is, I measured 12v on both wires of the inj connectors with key on.
So next I tried to apply 12v & a ground directly to each injector. One sprayed. One dribbled some fuel. Nothing out of the others.
So, I evidently have several bad injectors.
First question, could these bad ones effect the others (at least the good one) from firing with the ECM?
Second, why am I measuring 12v on both wires?

rgarcia63

The injector drivers in the ECM drive the injectors coils to ground so you need a constant 12v on the other side of the injector coil.
Yes, since the injectors are grounded in banks of 4, injectors(s) in a bank can draw enough current to keep the other(s) from firing as long as the current draw doesn't blow the injector bank fuse. Never maually ground the injectors especially if they're good injector because you can't match the frenquency at which the ECM switches the drivers and you're taking a chance on burning out the injector coil(s). To determine if the ECM is firing the injectors, use a Noid light it takes the place of the injector coil.
In this case the injectors are most likely in need of a rebuild, or replacement.
You want all 8 injectors flowing the same amount of fuel. Do youself a favor and replace them with new, or refurbished injectors.
Before installing the injectors I would also pull the intake base and get it cleaned out, test the fuel pressure and flow requirements.
-RJG

rgarcia63

and don't forget to clean out the fuel rails as well

KCG

iTrader: (1)

Thank you. That sounds like good advice.
I'll update when I get my new injectors.

KCG

iTrader: (1)

just to close this out....I replaced all injectors with good ones and they are now operating as they should.

Thanks

Edward63

Question, I have a 89 GTA with the 5.7 TPI engine. The engine rotates over but will not start. The car was running a couple days ago but now it will not start all. At first I thought it was the timing so I rotated the distributor trying to get it started. No luck. I've checked the fuel pressure at the rails and it was at 40 PSI. So I'm getting good fuel pressure. So I thought it was the ignition module or coil. I'm getting sparks to the plug. The only other thing I think it could be is the ECM/PROM that's not opening the injector. Should I replace the computer and or the PROM?

bigal55

iTrader: (1)

You should probably start your own thread, but in the mean time, check voltage to the injectors. You should have battery voltage at the injectors with the key on. Could be injector fuses or wiring. Probably not a VATS problem if it cranks as the ECU disables crank and injector firing. HTH!

FaithTerry

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