Hard starts when cold

[christian1]

I have a 96 Ranger 3.0 AT 2WD that is very hard to start when cold (below 40 deg ). I can crank of and on for a few minutes before it starts. I checked fuel pump and it has good pressure and holding. Once it starts it can be shutoff and will start right up. Any suggestions ?

 

[Dune Runner]

What weight oil are you running? What is the battery voltage before you start cranking on it?

 

[RonD]

Try this simple test first.
On cold engine, turn key on and count to 3, turn key off, repeat this 3 times, then crank engine.
Computer turns on fuel pump for 2 seconds each time key is turned on, so what you are doing is testing if Fuel Pressure Regulator(FPR) or fuel pump check valve has a small leak, sitting for 6-8 hours leak, not a fast leak.
If engine starts right up after priming system 3 times then you do have a leak.

Also check Vacuum line on the FPR, remove it and smell it for gasoline smell, FPR diaphragm can crack and fuel leaks into vacuum line, when you start it after sitting engine gets flooded until cleared by repeated cranking.

Fuel injected engines can't use a Choke plate, they have no Jets to suck extra fuel from when cold starting.
So they use an electronic "choke".

This is an engine temp sensor and the computer.
When you turn the key on the computer checks the resistance of the ECT sensor, if is shows high resistance(low voltage) then computer sets "choke mode", rich fuel mix, advanced timing and high idle.
The Engine Coolant Temp(ECT) sensor is a simple resistance sensor, similar to the 1 wire sender used for the dash board temp gauge.
The ECT has 2 wires, it is easy to test with an OHM or Volt meter
Info here on the ECT sensor:
http://oldfuelinjection.com/?p=28

Good site for all sensors.

ECT sensor rarely fails, so probably not your problem, but it is easy to test.


There is also the MAF(mass air flow) sensor and IAT(intake air temp) sensor.
Both are used to set mixture of fuel/air, a cold engine needs a rich mix to start.

Before starting cold, unplug the MAF sensor, then try to start, if it starts right up then you should check voltages at the MAF.
Read here for that:
http://www.therangerstation.com/tech_library/CleanMAF.html

Always worth cleaning MAF as well.
Unhooking the MAF makes computer use preset fuel/air which will be rich by default, Check Engine Light(CEL) will come on, that is OK, it will go off when MAF is hooked up again.

IAT sensor is like the ECT sensor in that it is east to test with OHM/Volt meter
read here:
http://oldfuelinjection.com/?p=29


And then we have spark, when cold starting all the above make the fuel mix rich, if they are working correctly, so to start up right away the engine needs a good hot spark or plugs will foul out and will need to heat up, by repeated compression strokes, before they will spark enough to ignite the rich mix.
So worth a look at the spark plugs, if they have a black coating then they are getting carbon fouled, so not sparking hot enough or engine is running to rich all the time, what's the MPG lately