lancesrepair

i have an 85 it seams to have no power to some motor componets.the (9th) inj is not switching to start if i add power with a power prob car will run.without doing that it starts and dies in seconds.also when i turn key on to start the car the fuel press gauge is normal till i turn the key then it drops to 0.im lost any help would be apreciated

Cliff Harris

The 9th injector only works while the engine is CRANKING. It gets its power from the starter solenoid.

When you turn on the ignition the ECM runs the fuel pump for 2 seconds to prime the fuel rails for starting the car. It turns off the pump so it won't run continuously if you turn on the ignition but don't start the car.

The fuel pump gets turned on again under two conditions:
1 - the ECM receives DRPs (Distributor Reference Pulses) from the distributor. This happens while cranking and when the engine is running.
2 - the oil pressure switch will supply power to the fuel pump when it sees more than 4 PSI of oil pressure.

In either case you should see fuel pressure after cranking for 5 seconds or so.

Do you get any error codes?

lancesrepair

no error codes at all.someone put a jumper wire on the fp fuse so it stays on and has pressure could it be the anti theft causing this prob

Cliff Harris

How could the fuel pressure drop to zero (as you said in the original post) if the fuel pump is on all the time?

Disconnect all the injectors and see what happens when you turn on the key. The only way I could see the fuel pressure going to zero is if there is a short in the injector signal line that's turning all the injectors on all the time.

The anti theft system disables the starter. It doesn't produce the symptoms you're describing.

lancesrepair

fp stays solid but when i turn the key to crank it over it drops to zero its like there is a short in the switch that it loses power.its definatly a fuel delivery prob its not getting fuel inj ohm good and a noid light blinks so they are getting a signal.