The thing won't start. It turns over just fine, but won't start. The CHECK ENGINE light doesn't come on, the fuel pump isn't working (pressing on flap inside air flow meter on top of air filter housing with the ignition key on) and the heater/vent fan inside the cab isn't working. All the fuses check out as good (with an ohm meter) including the three under the hood and the 20A fuse for the heater/vent fan. Ignition switch is good. Fusible link is good. 12.55 volts from the battery. Fuel in tank. Ground from battery good. All turn signals, brake lights, head lights, dome lights, door buzzer, and other dash lights work.

When I bought the truck in 1985, I installed a kill switch that went to the EFI relay located in the fuse block to the left of the clutch pedal. When the switch was off, the CHECK ENGINE would be off and the truck wouldn't start. I've removed the switch and soldered the OEM wire back together. Still no CHECK ENGINE light.

The truck died from a stop sign after letting out the clutch. I noticed the CHECK ENGINE light was off. I eventually cranked the engine with the tranny in gear and the truck started. 1/4 mile later I parked it, finished my errand, and it started right up. I let out the clutch and it stopped running (CHECK ENGINE light off again). Nothing could bring the truck back to life. I recently replaced the clutch master cylinder with an OEM unit.

Any ideas?

Dan

ggouletster@gmail.com

 

well i think you said it, fuel pump doesnt work.... have you tried looking at the 85 fsm at how to test the fuel pump with the diagnostic terminal??

 

Hey Dan, welcome to Yotatech. Hopefully these guys can shed some light on your problem. By the way, you missed a nice BBQ on Sat. Dennis cooked up some good tri-tip and chicken.

 

Fuel Pump test jumper info:
- http://www.4crawler.com/4x4/CheapTri...shtml#FuelPump

 

Well guys, still doesn't run. The fuel pump test plug trick didn't turn on the fuel pump (ignition switch on) and the 20A fuse is good. If I replace the fuel pump, will the CHECK ENGINE light and heater blower start working too? I'd like to know how to get the CHECK ENGINE light to come on first. BTW, no spark from the spark plugs and the ignition switch tested good. Thanks

 

As I replied by e-mail:

I would suggest looking at the wiring diagram for the fuel pump to work out that issue, no fuel = no start:


As you can see, it is a pretty simple circuit, battery feeds power to the 15A EFI fuse, then to the main relay that is turned on by the ignition switch. Then that feeds power to the circuit opening relay which is turned on either by the ECU's STArt signal (i.e. while the STArter is being used) or via the AFM flapper Fc contact or via the test jumper. If neither the AFM or the test jumper turn on the CO relay, then the CO relay may be bad. Check it out and work your way back to the battery. Changing the fuel pump when the old pump is not getting power will do nothing but lighten your pocket book, unless you have otherwise determined the pump itself is bad.

The heater blower is probably totally unrelated, maybe it has a bad switch or relay (in the center console area, passenger side). Or study the FSM wiring diagram and see if there is anything in common between the things that don't work, like do they get power or ground from a common connection?

 

any word on this yet?