Fixed with forum help (Died during idle wont stay running)

[1987ranger12394]

I have a 1987 manual 4x4 2.9l singlecab reg bed ranger.

Things I have replaced: injectors, fuel filter, fuel pump, fuel tank, fuel pump high pressure, spark plugs, cap and rotor, plug wires, coil, map, cylinder heads, lifters, rockers, water pump, thermostat, temperature sensor, all battery wires and battery cables, ignition solenoid, ingnition key.

I had the truck idling after head replacement off and on for 3 weeks. And the day of registration it idled for 1h 45m straight than died. Now it will only run if fuel is added to the intake. What am I missing? Both pumps work and I'm getting fuel at the rail 40 psi.(update: running but now dies when you put it in gear)

 

[adsm08]

Does it just not idle or does it not run at all unless you are bottle feeding it? If you can keep it running off idle by holding the gas pedal down a hair your IAC isn't working.

 

[1987ranger12394]

Not at all unless bottle feed. As log as I'm feeding it, it runs fine

 

[adsm08]

Could be an issue with power to the injectors, or with the computer.

 

[1987ranger12394]

I'll try that next. It's a one owner that I got for free. So far i have 700 in parts so I'm trying to avoid taking it to a shop.

 

[RonD]

Fuel injectors are not working, check the TFI Module plug on the distributor, it sends the injector timing pulses to the computer, no timing pulse no injectors

Test if you have 12volts at any fuel injector's Red wire with Key ON
If not the EEC Relay or its fusible link is bad

Next would be failed computer

 

[sheep herder]

Why in the f*** would you leave it idling that long?

 

[1987ranger12394]

Why in the f*** would you leave it idling that long?

Because it doesn't hurt it. That and letting it idle and play music while I change and blead the brakes and having it die is better than driving down the road and it die

 

[1987ranger12394]

Fuel injectors are not working, check the TFI Module plug on the distributor, it sends the injector timing pulses to the computer, no timing pulse no injectors

Test if you have 12volts at any fuel injector's Red wire with Key ON
If not the EEC Relay or its fusible link is bad

Next would be failed computer

Thanks saved me from Googling for an hr. I'll try all of this and post what I find

 

[1987ranger12394]

I tested a fuel injector red wire getting 12.7vdc. Tried turning over and it cranked ran one full cycle than died. Leaning towards tfi module will have to test in the morning when I have more light.

 

[wildbill23c]

Kind of wonder if the TFI is shot too, with all that idling and heat build up in a 30+ year old truck it may have finished off that poor TFI. I really need to replace the TFI on my 87 Ranger and 88 Bronco 2...but I want to do the remote TFI setup that is in the Tech section first.

 

[RonD]

TFI does the spark, I know Duh, but its autonomous, it doesn't need the computer for start and idling, and it was said that it would stay running if you kept adding fuel manually, so distributor pickup and TFI would be working

Its possible that TFI is passing on the timing pulse to computer, intermittently, and idling that long with hood closed would stress the TFI module(heat)

 

[1987ranger12394]

I'll check the tfi this afternoon may just replace it anyway wont hurt it. I guess the next thing would be all of my fuel injectors could be clogged? Seems unlikely though. Definitely a head scratcher. When I had it idle it was with the hood open and it was a good 50° outside but it could have heat soaked the tfi. I dont know if it could be the ecu with it running on intake added fuel.

 

[RonD]

The TFI spark system runs off the ignition switch power and doesn't need computer for startup

The computer, and injectors, get power from the EEC Relay, but it shows power
The computer also needs the timing pulse from the TFI or it doesn't even know you are trying to start the engine, it has no connection to starter system
So when the computer "sees" the TFI pulse it starts to Ground the injectors, open them
Its a Batch Fire systems, so it opens 3 injectors at the same time on a V6 engine
So unlikely to be clogged injectors

Can you confirm fuel in the rail, not just pressure

 

[cbxer55]

I heard that if idled too long, the IAC gets overworked and can go bad. Ford IACs are known to be weak in any event. I had many Auto Zone made in Mexico IACs go bad on me, usually right around the end of the one year warrantee. I finally found that AZ offers a "Premium" IAC, made by Hitachi in Japan. Got one in 2015. Haven't touched it again since. My Lightning also has one since it's original went out at around the six year mark, in 2010. I also went through two made in Mexico units on it, before replacing it with the Hitachi, haven't touched it again since.