1986 pontiac fiero won't start, changed fuel pump and relay gas coming up, but no spray from injectors
Actually the injectors don't spray "all the time". They pulse open for a few milliseconds then close every time they are grounded by the ECM. The distributor has a pick-up coil (Variable Reluctance sensor) that provides an A/C (Alternating Current) pulse every 120 degrees of crankshaft revolution to the Ignition Control Module also contained inside the distributor. The I.C.M. amplifies, rectifies and passes along the pules as a +12V square wave to the ECM. The ECM uses these pulses to calculate RPM and determine when the engine is rotating vs. stopped. Together with this information and more from Coolant Temp., Throttle Position, Manifold Pressure and Air Temp. the computer constantly 'looks up' what the appropriate amount of time it should pulse the injectors for to deliver the required amount of fuel.
With that in mind, the injectors are supplied with +12V via a 3 AMP fuse labeled INJ 1 for 1 bank of 3 injectors, and INJ 2 for the 2nd bank of injectors. Make sure your injectors are getting +12V whenever the key is ON or they wont fire (or at least 3 won't).
If all 6 injectors have +12V and you have fuel pressure (checked by pushing down in the center of the Schrader (tire valve stem looking thing) valve and fuel SPRAYING out, and your still not getting fuel it is probably because the injectors aren't pulsing. They are probably not pulsing because the ECM is not receiving any reference pulses from the distributor. If you have spark then you are producing reference pulses.
I hope some of this explained from an actual '86 Fiero GT 2.8L V6 owner/mechanic will help narrow down your problem.
Mar 20, 2011 |
1986 Pontiac Fiero