91 2.3 liter cold start problems
 

I just got my 91 ranger from my dad. When it’s 40 degrees or below outside it won’t start it just cranks. On a normal day I have to pump the gas while cranking to get it to start. Anyone got any ideas?

Welcome to the forum

There is no "gas pedal" on a fuel injected engine, its an "air pedal"
With a carburetor when you pumped the gas pedal your WERE squirting in extra fuel from the accelerator pump
With fuel injection you are just adding more air when you press on "gas pedal"


It reads like either your fuel pressure is dropping to 0 psi when engine sits over night, or that computer doesn't know to CHOKE the engine because its cold
First is easy to test for
When engine is cold, cycle key on and off 3 times, then try to start engine
If its starts up easily and idle is high then yes you are losing fuel pressure when truck sits long enough

Rangers have a safety system so the fuel pump only runs for 2 seconds when you turn the key on, 1991 needs 30psi fuel pressure, when truck is off fuel pressure should drop to maybe 20psi, and stay there for MONTHS
Fuel pump running for 2 seconds should add 10psi, so 30psi and ready for startup
If pressure is dropping below 10psi when engine sits for 6 hours or so then cycling the key on and off 3 times will build the pressure back up


The computer uses an ECT(engine coolant temp) sensor to get outside and engine temp for start up and running
All gasoline engines need to be CHOKED when cold, this means extra fuel, high idle, and advanced spark timing
So the ECT sensor tells the computer how much CHOKE to apply based on temp with key on

ECT sensor is just used by the computer, dash board temp gauge uses a SENDER, 1 wire
ECT sensor is 2 wires
ECT sensors can be tested but are not that expensive to replace

Not sure about the location of the ECT sensor on the 1991 2.3l

This shows it on lower intake: https://2.bp.blogspot.com/-geZJDf7eu...ant+Sensor.png
But Ford also used heater hose Bung


Computer controlled engines should need NO driver input for start up, cold or warm, so no need to touch gas pedal

When you turn on the key the computer boots up
It opens IAC(idle air control) Valve all the way for startup
It gets temp from ECT, and calculates air:fuel mix needed, how much CHOKE to use, if any
It runs fuel pump for 2 seconds

You crank the engine and when it fires RPMs should go above 1,500 because IAC Valve is open all the way
Computer then starts to close IAC Valve to set idle RPMs, 1,100-1,200 cold, 750-850 warmed up

IAC Valves can get dirty but are not hard to clean

The temp gauge doesn’t work either so I’m gonna try replacing the sensor and the sender. Thank you

I changed the ect sensor. It didn’t fix it. What should I try next?

Cycle the key

I’ve done that

And?

Elaborate, throw us a bone, lol

Does it run fine when it starts
Does it run better cold or warm

Is the idle high on cold start or does it stall

I go to start it and it cranks and fires but doesn’t start. If I crank it with the peddle to the floor it’ll eventually start and runs fine after it starts. Cold days it’s harder to start and sometimes won’t at all. When it’s warmer it’s easier to start. I changed etc sensor. It didn’t help. When I cycle the key it doesn’t make it any easier to start

It should NEVER start with gas pedal to the floor, that turns OFF the fuel injectors, its called the Clear Flooded engine routine, its in all fuel injection computers

So it reads like engine is not being choked on cold start
And you changed the TWO wire ECT sensor, and both wires looked OK

This sensor tells the computer how much Choke to apply
Liquid Gasoline can't be ignited by a spark, yes the movie guys take liberties with that one, lol
Only Gasoline Vapor can be ignited by a spark
This is why gasoline engines need to be choked
Choke means to add extra gasoline, so there is enough Vapor(30%) in a cylinder when spark plug fires
Cranking the engine warms up the cylinders(compression = heat), and heated gasoline has more Vapor, which is why it eventually starts after cranking a bit

And one more thing at play with 1991 2.3l
1989 to 1994 2.3l Ranger only uses the Passenger side's 4 spark plugs and coil pack when starter motor is on
The Drivers side is OFF while cranking, and starts to work above 400RPMs
This was done to give the 4 passenger side spark plugs a "hotter" spark when cranking(voltage at 9.5volts)

This 2.3l engine ran with just 4 spark plugs from 1974 to 1988, the extra set was add for better performance
So when running you can't tell if 1 spark plug is not working well, as the cylinder still fires with only 1 working spark plug

Where I am going with this is.............maybe passenger side spark plugs or coil pack is not 100%, which you would ONLY notice on startup

I would start and warm up the engine, then shut it off
Then unplug Drivers side coil pack's 3 wire connector, so those 4 spark plug are OFF
Then restart engine
If its misfiring or barely running then you have a spark problem on passenger side

Ok thank you. I’ll try that tomorrow

I found a 93 thunderbird 5.0 ho with aod transmission and 8.8 rearend. with 70000 miles. My truck has the 2.3l and its a 4 speed with OD. Would that be a good donor car? I found one for 1000. Just thought I’d check here before I made the purchase

No on the rear end, but sure on the V8 with AOD

I don't think the EFI intake will fit under the Rangers hood, but with AOD trans you can run carb and HEI distributor so no computer or sensor wiring needed

So you said my starting problem could be the iac valve. Should I clean it or just replace it? What do u use to clean it

Also, thank you for all your help

Clean it first

Look here: https://www.explorerforum.com/forums...-w-pics.84220/

If you replace it only use Motorcraft or Hitachi brand, other brands do not work well

And you tested that spark on drivers side is OK?

Not yet. There’s also this other sensor I found it when I was changing the ect sensor. It’s more on the top of the motor. I thought it was the ect sensor until I pulled it out. The plug and nut looks exactly the same. It looked horrible when I pulled it out. And I have no idea what it’s called. I’m gonna take a picture of it and post it maybe you can tell me what it is so I can change it

There should be no "nut" on ECT sensor, its a 2 wire plug

The Engine temp SENDER or oil pressure SENDER can use 1 wire with a stud/nut connection, these are only used for dash board gauges

All "sensors" use at least 2 wires, some 3 or 4 wires, and always use connectors, no mechanical connections like a stud with nut

This was a 2 wire plug but was identical to the ect sensor until you pulled it from the motor. The underside was different if that makes sense

Generally.........................ECT sensor will have cone shaped end, ECT sender will have a cylinder shaped end

SENDER: https://encrypted-tbn0.gstatic.com/i...F2zGJ&usqp=CAU

SENSOR: https://www.fuelinjectedford.com/images/ect.jpg

ECT sensor is only used by the computer
ECT sender is only used by dash board temp gauge

ECT= engine coolant tempurature

I replaced the ect sensor already. I have the sender just haven’t replaced it yet. I’ll pull the other sensor I’m talking about and take a picture of it

So I just tried running it with the drivers side coil unplugged. It didn’t run good at all. So would u suggest changing passenger side coil? I have already replaced plugs and wires

https://cimg3.ibsrv.net/gimg/www.ran...2d99b9a0e.jpeg
What is this?

That's an IAT or ACT sensor, and a real dirty one at that
IAT = intake are temp
ACT = air charge temp
same thing different names depending on the year of vehicle

I would swap coils, and see

Ok I’m gonna change that sensor and the coil

Just wanted to let you know that I changed the coil and the sensor and it starts up and runs so much better! Thank you for all your help. Now it’s time to start with the cosmetic stuff I wanna do. I’m hunting for a set of mustang wheels for it and I think I’m gonna attempt painting it myself. I got the truck for free from my dad so I think I’m gonna just have some fun with the project.