Rookie Needs help! Mystery issues '93 4.0

First off, let me just go on record that I'm not extremely well versed in auto repair so forgive my ignorance. I bought a '93 Ranger 4x4 4.0L as a fun/project car and it's turned into quite the ordeal (289,000 miles probably doesn't help!). It had been sitting for some time, so that may have something to do with the issues I'm having, but I'm not sure. My uncle has helped a lot but he's exhausted his knowledge. Here's what I have going on....

Truck won't start without starting fluid if it's been sitting for more than an hour or so(what's weird too is that it hardly needs any starting fluid to get going as we can only spray it in way up front by the grill at an air intake).
Once it starts, it runs OK, but seems to be missing.
Idles around 1000 or so....seems high.
Battery reads 12V and seems okay.
There are "dead" spots that occur in certain gears when you try and give it gas nothing happens.
Once you shut it off, you can start it back up, no problem. This is what is so puzzling to me. If I could get it to start from 'cold' I could deal with it not running so great since it's quite old, but with it having trouble starting and the dead spots when accelerating, it doesn't give me much confidence on taking this bad boy out on the road.

Here's what we've done so far.....please note, a lot of this was my uncle guessing and me just going along for the learning experience
- Pulled gas tank; emptied out old fuel, cleaned thoroughly, and re-attached.
- Replaced Fuel Pump
- Replaced Fuel Filter
- Changed oil and oil filter
- Replaced air filter
- Replaced spark plugs
- Replaced coil/wire set
- Replaced fuel regulator
- Replaced fuel injectors (pack of 6 refurbished from ebay)

Are you pulling any codes from the computer? I know in my 94 Explorer (with the 4.0) when it went out I chased problems all over in it. I had to have FORD replace the fuel pump as it would run, and run well, but had a random no start issue (you have replaced yours though).

I would also start going through the relays and all the wiring (I know a giant pain), but an older truck, and maybe have some ground issues. They are great rigs when they are running and make you want to kick puppies when their not. Hang in there and keep doing one thing at a time.

Have you checked for vaccum leaks?

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I would start by cleaning the MAF, and replacing the coolant temp sensor.

The MAF being dirty could account for your 'dead spots'.

The coolant temp sensor can have many things go wrong for many reasons on an older vehicle, but it is used in calculating the fuel charge for starting and running and isn't super expensive. If it is telling the computer the engine is hot then it won't get enough fuel to start cold.

Ford Rangers with fuel injection only Prime the fuel system for 2 seconds when you turn on the key, but EACH TIME you turn on the key
So...........turn key on, count to 3, and turn key off, repeat 3 times and then try to start engine

1997 and earlier Rangers should have 35psi fuel pressure at the injectors, and that pressure should stay above 25psi for MONTHS when engine is off, not minutes, hours or days, MONTHS.
A 2 second run of the fuel pump = about 10psi, so plenty to start the engine IF pressure is holding above 20psi when engine is off, if not then turning the key on and off 3 times should get the pressure back.
So your cold engine start issue may be time related not temp related, i.e. if engine has a slow pressure leak it may take a few hours for it to drop low enough for a no start

But easy enough to test, just cycle key on and off a few times
Fuel pump runs Full Time when engine RPMs get above 400(engine started) which is why it doesn't take much starting fluid to get it running, one or two cylinders firing get above 400rpms pretty fast

I'm working on getting the MAF sensor off.

As for the coolant temperature sensor.....it seems I have two of these though and both of them have two wires coming into them. One is located near the front of the engine underneath the throttle body, and the other is located on the drivers' side of the block, much more accessible on top of the block, back near the firewall on driver's side.

Thoughts on this? I guess I could pull them both out and see what they look like. Maybe one is a different sensor? It looks like in Haynes, they show the front one under the throttle body should be the one I need to remove, but not sure.

Diagram here: http://www.therangerstation.com/forums/attachment.php?attachmentid=7525&stc=1&d=1336645275

#2 is the one the computer uses, #1 is for the dash board temp gauge only

UPDATE:
So i removed and replaced the coolant temperature sensor....also removed and cleaned the MAF (didn't look dirty, but cleaned anyway). Re-installed everything. Unhooked red cable from battery for 15 mins or so.

Still having the same issue when I tried to start the truck this morning. It won't start on it's own after sitting for more than a couple hours.

Any other ideas on what I might try to get this resolved? After a spray of starter fluid, and running for a bit, I'll turn it off, then wait a half hour and it starts right up like a champ! I wish it would do that all the time LOL.

Thanks everyone!

UPDATE:
Sorry, forgot to mention that I'm always trying to "prime" the engine by turning the key to on for 3 seconds or so to get the fuel pump going. Unfortunately, with the truck beeping, I can't really hear if it's turning on or not, but it's new so I would imagine it is?

Have to turn the key ON and the OFF, and repeat that 3 times

OP UPDATE:
Yes, I try to turn the key ON and then OFF, repeat 3 times; still won't start. Fuel pump is new. I've tried to repeat 4 or 5 times and start as well and still nothing. Very puzzling.

Would this be caused by a weak battery by chance? The battery seems to be okay, but it's dated from 2011.

Thanks everyone for your advice and help!

kpiztheniz said:

OP UPDATE:
Yes, I try to turn the key ON and then OFF, repeat 3 times; still won't start. Fuel pump is new. I've tried to repeat 4 or 5 times and start as well and still nothing. Very puzzling.

Would this be caused by a weak battery by chance? The battery seems to be okay, but it's dated from 2011.

Thanks everyone for your advice and help!

Click to expand...

If there's enough battery power to turn the starter motor, then there's more than enough for the fuel pump.

Have you tested the fuel pressure at the fuel manifold valve? Knowing if there's enough pressure there can really help with the troubleshooting process.

Easy enough to test battery

After it sits a few hours use volt meter on battery terminals, do not disconnect battery from truck
12.8volts + is a new battery
12.5volts is a 3 to 4 year old battery
12.3volts is 5 to 6 years old and time to shop for a battery sale

12.2volts or less is failing battery, you WILL get the "click, click, click", no crank, sooner than later

Ether, Starting Fluid, has a much lower ignition point than gasoline, which is why it is a good starting fluid, lol, for gas or diesel engines, it takes very little heat to ignite it.

So if fuel delivery is not the problem then Spark or compression is all that is left.
Compression is either Good or Bad, not intermittent.
But compression for starting is based on crank speed which is based on starter motor and battery power condition.
Metal cylinder walls, metal rings, metal valves and metal valve seats do not make good air tight seals
They are not suppose to, which is good because they can't, so they do leak air out during compression stroke, if crank speed is too slow then compression will be lower.

Liquid gasoline can't be ignited by a spark, only gasoline vapor will ignite with a spark.
Fuel injectors don't vaporize gasoline, only heat can.
That's were compression comes in, compression heats up the gasoline enough to turn some of it to a vapor, and if near the spark plug then it will ignite, vaporizing the rest.
A cold engine will have cold gasoline and cold metal parts, so you need Good compression(heat) to get enough vapor for the spark plug to ignite it.
Slow crank speed could lower compression enough so there is not enough vapor to ignite by spark.
Ether would ignite and once that happened faster crank/piston speed would get gasoline to vaporize.
So yes check battery

Spark also need to be "hot" for cold start
Because a Cold engine needs a certain percentage of gasoline vapor to start, Chokes were used to increase the amount of gasoline flowing into the cylinders which would increase the amount of gasoline vapor.
Fuel injection can't use a Choke Plate but a cold engine still needs the extra gasoline to start and run, so computer runs a Choke routine based on engine temp(ECT Sensor).
Now this extra gasoline does provide more vapor but also "wets" the spark plugs, so spark plugs need a "hot" spark to ignite the Rich mix.
During cranking the starter motor draws alot of power, so coil will only get about 10volts, so spark will be weaker but if battery is older and cranking voltage is dropping down to 9 volts............
So test battery voltage while someone cranks the engine, you want to see no lower than about 9.7volts

Just for giggles why don't you clean up the grounds/screws on the ICM? Some people even run an independent ground to the ICM.

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OP UPDATE:

Thanks RonD for all the information! I really appreciate it! I had some store credit at advanced so went ahead and got a new battery since mine was dated from 2011 and still no dice. I ran it yesterday after getting it going with some starter spray and this morning after letting it sit over night, it won't start on it's own without some spray.

At this point I'm at a loss. I'm taking it in for a safety inspection this week, so maybe I'll have the shop check everything out and make sure nothing looks bad/out of place.

I appreciate everyone's help and advice! I'm going to clean up the grounds/screws on the ICM as modelageek suggested and will keep fiddling with other things to try and figure this beast out. It seems like it'll be a great truck, just gotta get this whole starting on it's own thing figured out LOL

Thanks again all and if anyone has any other suggestions, I'm willing to try just about anything at this point