1996 ranger troubleshooting

[fa5tfox]

Hi guys, I am having some trouble with a truck I have bought. It is a 1996 with a 2.3 four cylinder, and is a five speed truck. The truck started and ran by itself a few weeks ago, but it has now developed a no start condition. I have checked for spark at the coils, and found none so I then replaced the computer with another of the same number and year of truck, as I have read that the coils on this truck are fired directly from the computer. The truck now has spark at the coils and I have also replaced the crank position sensor, as I believed it to be the cause. I should also add that I just replaced all eight spark plugs and wires as well.

Next, I moved to checking for fuel, the truck has forty pounds of fuel pressure at the fuel rail when cranking, but I did check the fuel pump to ensure there were no leaks in the rubber hose connecting the fuel pump to the hanger. I then thought that the fuel injectors may not be working correctly so I primed the fuel with the key and jumped power to the injectors one by one to see the pressure drop, and they do seem to spraying fuel, as the pressure on the gauge drops.

I can run the truck on starting fluid, but it dies out as soon as you stop feeding it, making it seem as if this is a fuel related issue? I an not sure where to go from here so any help would be greatly appreciated.

 

[tomw]

Borrow some 'noid' lights and test for signal from the computer to the injectors.

There should be 12v at the injector connection with the key ON, and the computer will supply ground to make the injector open.
You can check for injector signal with a noid or a meter.
tom

 

[RonD]

Welcome to TRS

Yes, first test you should do when you have a crank but No Start is the 50/50 test
Spray fuel into the intake and crank engine
If it starts and dies you have spark but no fuel
If it doesn't start you have no spark
50/50

Crank sensor starts/times, spark and fuel injectors
So you have spark, and crank sensor is working

In most 2.3l/2.5l Limas only the exhaust side coil/spark plugs work when starter motor is on, gives a hotter spark if only 1 coil pack is active.

On the upper intake is the Throttle Position Sensor(TPS) it has 3 wires connected, unplug this connector, then try to start engine.
TPS is part of the Clear Flooded Engine routine

TPS gets 5volts from computer, if throttle plate is closed it sends back .69-.99volts to computer, if throttle is Wide Open it sends back 4.5-4.9volts
With key on and 0 RPMs if computer sees 4.5volts from TPS then it will enter Clear Flooded Engine routine, this leaves spark ON, Fuel injector OFF
So a shorted TPS will turn OFF fuel injectors


Other thing is how old is the gas in the tank?
And how long has truck been sitting?
All gasoline from gas stations will have water in it, all gasoline, "bad gas" is when there is too much water in it.
Water and gas can't mix, and water is heavier than gasoline
So if vehicle sits long enough all the water in the tank will settle to the bottom of the tank
And thats where Fuel Pump sucks in "fuel", so if there is a bit of water in there then it will be sucked in and cause a no start until it is cleared out and gasoline replaces it in the fuel lines

 

[fa5tfox]

Okay, so I tried unplugging the TPS, and it still does not crank. The truck had set for around one year, not running. I put a radiator in it and drove it to work for a week before the clutch master cylinder went out, so I replaced that as well. The truck ran like a champ till two months ago, and I drove it to where it sits now, so the gas is only a couple months old.

I also used a probe on the injectors to verify that they are firing, so no problems there.

 

[Tlaurin3]

Any chance that the crank sensor is sending the signal at the wrong time?

 

[tomw]

If you can get it started on ether - starting fluid - can you open the throttle/step on the gas to keep it running? If not, then you have a fuel supply problem.
The pump is powered for a few seconds when the key is turned to ON. Listen for the pump to run. If you do NOT hear the pump, don't bother trying to start the engine. It may start, but will quit in a few seconds, which is 'ho hum, so what'.
If the pump does run for a few seconds, it will stop, and once the computer gets the signal the engine is running, it will re-enable the pump. I do not know what the EEC-V system looks for to re-power the pump after engine start, but most look for ignition pulses, crank sensor rotation continuing, or maybe cam. Dunno.
Either way, the pump will shut off until engine start, and if the signal shows, and the computer is good, and the relays functional, the pump will be powered. Otherwise you have the situation you are experiencing.
tom