'90 Ranger 2wd: Dies when warm.

[AZCustomCarCare]

Hi I recently bought and fixed a '90 Ranger 2wd for work. I noticed it started to die coming of the freeway Monday. It was the longest I had driven it like 20 miles. Then later I charged the A/C and left it running when completely died. Soon I went to pick up the kids and it started dying at stops in traffic then it wouldn't start after I picked up new plugs at the parts store. After it cooled it started but had to limp it, punch it, keep it from stalling.

Things I noticed.
It felt like it had 3 dead cylinders when accelerating.
The idle seemed to drop down slowly as if the computer was doing it.
It seemed to be heat related.
It smelled rich/flooded.

Things I did.
I changed plugs to platinum.
Redid my vacuum hoses.
Checked Fuel pressure visually by pressing valve
Cleaned the Fuel relay connections
Repositioned and zip tied engine harness away from engine.

What I think:
I ran the truck this morning it runs like a champ but it not hot so being AZ Ill have to wait till we get those 100+ degrees to see if my hunch about wires resting on engine over- heating and causing a bad signal to distributor or;

The Oxygen Sensor is bad. Since I have been smelling a rich mixture lately and my truck had developed a misfire I think it may have started dumping more fuel. My theory is that once the engine warms up it then begins to base the fuel trim on the O2 sensors readings. So if its bad it can tell the computer the trim is lean and will dump more fuel drowning and eventually killing the engine.

It did rain here tremendously this last week maybe that leaking windshield problem caused a damaged PCM this is first on my list before replacing O2 sensor.

Or bad wiring. The wiring is all to crap. I read one guy put all aftermarket ignition and fuel components and never had a problem since.

No I don't think it's the Pump. Regulator. Filter. TPS. IAC. MAF

I will try this later if its not fixed already. Ill follow up as I'm determined to fix this cause I need a reliable truck.

 

[RonD]

The Ford TFI ignition system is infamous for heat related issues.

Click on this link:
http://www.therangerstation.com/tech_library/TFI_Diagnostic.html

Print the Worksheet and follow the steps.

Some go as far as relocating the system to reduce heat exposure.
Click here:
http://www.therangerstation.com/tech_library/remote_tfi.htm

But I don't think you need to go that far.


O2 sensors do wear out and they wear out "rich", so that is often a sign.
But Fuel Pressure Regulators(FPRs) can also leak fuel into their vacuum line causing a rich smell and lower MPG.

 

[AZCustomCarCare]

Truck still dies

So after reading an article explaining how all the same symptoms i have are caused by the TFI Module. I picked up a used distributor set the timing and checked the ignition wires. It still dies after 20 minutes once engine wormed up especially at idle.

I don't have a DVOM right now cuz I left it in the rain so, I'm just gonna buy that o2 sensor as soon as I get money. I gotta replace the u-joint also so I'm not happy.

 

[RonD]

Buy a DVOM first, $15-$25.

Then check the OHMs of the Coil, when it is cold then when it is hot

O2 sensors come into play before the 20 minute time frame and can't cause engine to die and for sure not restart.
O2 sensors need to be at 600degF to work, so even if engine is warm the computer ignores the O2 sensors during start up and then for at least a minute after starting.