88sand442s

I picked up an 89 S-10 4x4 with a 4.3L. I replaced the fuel pump in the tank and it will work off a battery, but not off the ignition or at least not long and only a little while cranking. Engine will start if I spray gas down the TBI and run for several seconds, but tbi will not send fuel down throat. Does the Ecm control the fuel pump ignition and throttle body? If Ecm was bad would ignition still allow me to start for a few seconds? any help would be appreciated. Thanks for any info.. Is there a way to wire the Ecm direct and bypass all other wiring?

MT-2500

No on direct wiring.

Does it have good hot spark to plugs?
Has it got proper fuel pressure?
Has it got good injector pulse?
Also check all hot key on fuses for 12 volts both side.

__________________
Remember proper testing gives us the answer to many problems.
MT

88sand442s

Good spark, fuel pessure is good if I run pump direct off battery, but not if connected through car wiring. Only momentary slight pressure when key is turned and then only a little during cranking sequence. Don't know how to check pulse on injectors and already checked fuses for hot, but will do so again. Had a Viper alarm and I had no info on it so I removed it and all related alarm wiring, thought it might have disabled fuel pump also.. I cannot find a fuse for the fuel pump nor do I have wiring diags for specifically my model. Thanks,Ray

MT-2500

Find the fuel pump relay and oil pressure switch.
Check for 12 volt power key on on orange wire from EMCB fuse to relay and oil pressure switch.
If power there the relay should switch power to the fuel pump on tan/white fuel pump feed wire.
Key on or cranking cranking.
When oil pressure comes up the oil pressure switch also feeds power to the fuel pump tan/white wire.

Where are you jumping fuel pump and how much pressure does it have jumped and running?
Will engine start and run with fuel pump jumped?

__________________
Remember proper testing gives us the answer to many problems.
MT