Another "Get It Started" thread... '93 4.0L Ranger

[TheBobmanNH]

Hey All,

I know there are a million "help me get my truck started" threads with all the same advice. I've read many, many of them, but I'm hoping I have enough stuff here to justify a new thread. I'll try to keep it brief.

DETAILS : 1993 Ranger, 4.0L, Manual 4x4

HISTORY : Inherited it last fall from my future brother-in-law for free. Ran OK, needed work but it started. Then randomly decided it didn't want to run anymore.

SYMPTOMS : Cranks just fine. Never even sputters or tries to catch. I don't have a pressure gauge, but checking the schrader valve on the fuel rail managed to squirt me in the face with gas two feet away, so I feel like I have good fuel pressure. Old plugs were black and reeked of gasoline before I replaced them.

The only other thing that I hope is a clue is that 3 out of 4 times when I try starting it, after I stop cranking the starter, it kind of backfires. Not a loud pop, but an obvious release of air pressure from somewhere; I haven't figured out where yet.

REPLACED : Plugs, wires, PCV, fuel filter, air filter, fuel pump relay. Bypassed the inertia switch (that had popped once before causing this exact symptom). Disconnected the MAF sensor.


Anything else I can check?

Thanks for any tips.

 

[tmcalavy]

Fire, fuel and air in the right sequence is all any engine needs. When one won't start, check for air (can it breathe?), does it have spark (fire), is it getting fuel? Sounds like you have a lot of fuel pressure...maybe too much since the old plugs were gas fouled. I'd start with the basic three and by checking for any codes.

 

[doorgunner]

and smell that gas to see if it has a "varnish-like" odor! Remove a spark plug and plug it into the plug wire/lay it on the maniflod where it can ground itself/crank engine to see if it has a good spark.....

 

[bigtruck94]

replace your spark plugs. That could help maybe. Also check you IAVC (Idle Air Valve Control). If it runs rough, you could try and clean it up and maybe it will idle a little better.

 

[97RangerXLT]

Check the coilpack and see if it is giving power to the spark plugs.
Make sure the airbox is clear of any rodents/animals that may have taken residence and blocked the airflow into the intake. I would hook the MAF sensor back up, as it is probably not the issue.
Sounds like you have fuel pressure.

with wet plugs, it sounds like you are either not getting any spark at all or no air to aid combustion or as someone previously mentioned you are getting waaay to much fuel. you might want to check the fuel pressure regulator while you are at it.

AJ

edit: I see you replaced the air filter, but check the pipe coming into the airbox, maybe you ingested a bird lol... but I would check the spark tho for sure.

 

[RonD]

I would get a can of Quick Start, ether, and spray some into the intake and see if it fires up, if it does then fuel is the problem, if it doesn't then spark is the problem.

On the lower front of the engine is the CKP sensor, Crank Position sensor, located next to the crank pulley.
This sensor tells the computer(PCM) that the engine is turning over.
If the sensor or it's wiring has a problem then the computer will not send spark or fuel to the engine, engine will crank but won't start, computer doesn't know you are trying to start the engine.

The PCM runs the spark and fuel via Grounds not power, the coil and the injectors will have 12v when key is on.

The PCM then Grounds the coil or injector when it wants it to fire.
So a loose Ground inside near the PCM may prevent a good ground to fire the component.
Coil has 4 wires, 1 will be 12v, the other 3 are to fire(ground) one of the 3 coils inside.
Injector has 2 wires, 1 will be 12v the other is to fire(ground) that injector.

 

[TheBobmanNH]

Thanks guys. I realize I should have tested for spark before coming here. That process always made me a little nervous. Been zapped by electricity one too many times in my life, I guess

Good thinking on air obstructions too.

I'm hoping it's not something along the lines of the crank position sensor just because I don't particularly want to take apart the front of the engine but I guess there are worse things.

 

[adsm08]

Dont' worry about getting hit by the ignition coil. It is about 40,000 volts at .1 or .2 amps. It makes your arm go numb but isn't enough to kill you if you aren't holding the plug in a cut and holding your other hand on the vehicle body with it bleeding all over.

 

[JC 97]

Fire, fuel and air in the right sequence is all any engine needs. When one won't start, check for air (can it breathe?), does it have spark (fire), is it getting fuel? Sounds like you have a lot of fuel pressure...maybe too much since the old plugs were gas fouled. I'd start with the basic three and by checking for any codes.

An engines needs 4 things to run: fuel,air, spark and timing. It always puzzles me why everyone says it just needs 3 things.

 

[TheBobmanNH]

I finally got around to playing with my truck yesterday (two months later....) and had some really confusing results.

Pulled one of the plugs to test for spark. Grounded it out on the block, had the girlfriend crank the starter. Saw a spark... but more importantly the truck sputtered to life for a second! First time it's done anything but crank since before the winter.

Put the plug back in, no sputter.

Took off just the wire (with the plug installed) - no sputter.

Took out the plug and left it unplugged / ungrounded - sputter!!

My two theories were a bad ground (that I somehow corrected by grounding out the plug on the block) or some sort of exhaust blockage that opening up the combustion chamber fixed (which doesn't REALLY make sense to me either). Does anyone have any theories on this that actually DO make sense?

 

[Lil-Pony]

Earlier you said you heard a light backfire sound like air was escaping after cranking. This supports your exhaust blockage theory.

 

[martin]

To check for blocked exhaust, just remove o2 sensor closest to motor. See if anything changes.

 

[Insanejughead]

An engines needs 4 things to run: fuel,air, spark and timing. It always puzzles me why everyone says it just needs 3 things.

I've always heard it needs four things, too. Fuel, air, spark, and compression.

I guess it needs five things.... Fuel, air, spark, compression, and timing.

 

[tmcalavy]

Well you can check the blocked exhaust by disconnecting the pipe from the cat, or the manifolds from the exhaust pipe. My 93 with 3.0 v6 actually has a distributor cap and a rotor underneath it so I'm guessing your 4.0 does, too, but not sure. If it does, see if you can find the firing order for that 4.0, then pull the spark plug on the No. 1 cylinder and turn the motor over by hand (socket on crank pulley nut) until the No. 1 piston is at top dead center (at top of its stroke). Then pull the distributor cap off and see if the rotor is pointing to the No. 1 plug tower/wire on the dist. cap. It should be with No. 1 cylinder at top dead center. If not, your timing is off...maybe your future bro-in-law played with it...or maybe the timing chain/belt has jumped and is off...don't know which one (chain/belt) your truck has. If the timing is off, it can have fuel, air, fire, compression and not start...just backfire as you mentioned. Sometimes us old farts forget that you younger guys have never dealt with adjustable timing, carbs, and other assorted dinosaur-era features.

 

[TheBobmanNH]

To check for blocked exhaust, just remove o2 sensor closest to motor. See if anything changes.

Will that just open up another path for the exhaust to get out? Or is there another reason?