what fires the injector?

[sylvesterkitty]

i am working on a 89 k1500 and i got gas up to the injectors but not through them and this may be a stupid question but what fires the injectors? the diagram shows the ecm but what tells the ecm? all the fuses are good as are the grounds the truck ran fine until i shut it off now it won't start unless i trickle gas down the throttle body. the fuel pump works good and the filter is new the only test tools i have is a meter and a test light and all the youtube videos show hooking it up to scanners.

[sylvesterkitty]

is this a hard question? how is somone suppose to learn if no one answers?

[barry G]

idle circuit.

not sure if ECM for TBI tells idle to stop via the TPS or not.

it may be a gadget problem right on the unit.

 

try cleaning or something. Idle is a tiny place.

[sylvesterkitty]

i was thinking it might be the module in the dist. the ecm turns the fuel pump on but it needs a rpm signal to keep it firing i think . the diagrams don't say much and it is a muddy subject. i have power to the injector and gas to the injector but to make it cycle on and off is a mystery.

[grampadirt]

Make sure the oil pressure is at least 4psi,if the ECM sees no oil pressure it won't let the fuel pump run.One of the wires going to my oil pressure sensor once grounded out by laying on the exhaust manifold and melted,grounding out the sensor....there no signal to the ECM and no fuel.Something to consider.

[sylvesterkitty]

it has plenty of oil pressure and a new switch.

[jamestt600]

The pick up coil in the distributor provides the pulse for the injectors. Had a few go out on me.