My 1994 Ranger 4.0 starts then runs for a short time then stops. I have replaced IAC solenoid, fuel filter, fuel pump. The EEC Power relay and Fuel pump relay are both working. I am at a point whereas I do not want to continue spending money. I am asking if any fellow Ranger owners have experienced this problem?

 

Welcome to the forum

"Short time"
How long or does it vary?

Does it shut down while driving or only when coming to a stop, i.e. at idle

Does it restart after shutting down, or do you have to wait, if so about how long

Does the Battery light come on when engine shuts down, it should
Or do dash lights go out?

Manual or automatic trans?


At 24 years old the fuel pump was due so not a waste of money, filter should be changed every 5 years in any case
IAC valve would be a good guess if it was dying at idle and its 24 years old as well

 

I don't have to be driving for the shutdown to occur; the vehicle is sitting static when the engine shuts down. I started the truck this morning and it ran for eight minutes. The transmission is automatic. Thanks for your reply but those conditions mentioned don't appear applicable to my specific issue. Thanks for your reply

 

???not applicable???

So it only shuts off when idling never when at speed while driving, or when in Drive or Reverse, only shuts off in Park

If it shuts off in Drive then try shifting to Neutral before slowing down and see if it stays running, could be torque converter is not unlocking like it should.

I really need to know if it restarts right after shutting down, or if you have to wait before it will restart, very applicable

 

Third statement, will restart after about 10 minuets but will shutdown again.

 

Good news then, do the 50/50 test after it shuts down on its own
50/50 test
Spray gasoline or Quick Start(ether) into the engine then try to start it
If it starts and then dies you have Spark but no fuel
If it doesn't start then you have no spark
50/50 instant results

In your case after the shut down try to restart right then, to confirm a No Start, then do 50/50 test


If its no spark
Then two things come to mind
Coil pack, but.............there are 3 coils inside the coil pack so the problem would need to be on the 12volt side that charges all 3 coils
Pull off the 4 wire connector and have a look at the one RED wire's connector, see if it looks discolored

EDIS-6 module, this runs the Spark system in 1990-1994 on the 4.0l
On my 1994 its mount on the FRONT side of the rad support drivers side, have to look up under the bumper to see it
These almost never fail, almost, usual demise is front end collision
Again wiring connections should show signs of heat damage

Both of these run HOT normally, so either can get heat sensitive and fail, then start working after a cool down

Had a fellow use his air compressor to test these, after engine shut down on its own, he test if it would restart, it didn't, then he blew cold air on coil for a minute or so, then try to restart, then did same test on EDIS module, it restarted when coil was cooled down but not when EDIS was, so coil was the problem
Probably do the same test with a small bag of ice


I can't see this being fuel related, an electric motor, like the fuel pump, usually won't stop once it is started, it will fail to start when its going bad, but once started it will run all day long

It could still be electrical and fuel related, i.e. a connection that is heating up because of corrosion

 

Hay Ron, thanks for the info, please provide your input regarding the distributor-less coil.
Herb

 

??

Ford coil packs have 2 or 3 coils inside
The 4cyl and V8s used the 2 coil versions
The V6 engines used the 3 coil version
Each coil in the pack sparks 2 spark plugs at the same time

One 12 volt wire was used for all the primary coils, and one Ground wire for each primary coil, ground wires run to ICM(ignition control module) which was a separate device until 1995 when Rangers got the new EEC-V computers with ICM built-in.

They work the same as all previous spark ignition systems and coils, they get 12volts with key on, then Points or ICM grounds the Primary coil to build up Magnetic Field around secondary coil, then points or ICM cuts the Ground which collapses the magnetic field and cause the secondary coil to release its voltage.

Ford uses a Waste spark system because it easier to time using the Crank Sensor than cam sensor, Waste spark was the first spark system ever used on gasoline/alcohol engines, just to simple to have a spark for every Top Dead Center(TDC) of every piston
Called Waste spark because 3 sparks per RPM(V6) will be wasted, 3 pistons will be at TDC on each RPM and on exhaust stroke, so spark is not needed(its wasted), but dosen't hurt either, and NO its not for lower emissions, lol

Waste spark has 2 spark plugs firing at the same time so they are wired in Series, this means one spark plug fires from center to tip(normal spark) and the other fires from tip to center(reverse spark), this is why you should only use regular copper spark plugs or Double platinum, Signal platinum will wear out the same as regular copper on one bank so waste of money using those

In all multi-cylinder engines the moving parts must be balanced, in a V6 that means there are 3 matched Pairs of pistons, 1 of the 3 pairs will be a TDC every 120deg of crank rotation
3 x 120deg = 360deg or one full rotation, this is how a V6 is balanced, 4cyl has 2 pairs(180deg), V8 4 pairs(90deg)

This is why the V6 Coil pack spark plug wires are setup the way they are
3 4
2 6
1 5

3/4 are matched pairs, pistons at TDC at the same time, as are 2/6 and 1/5
So each pair shares the one coil in the coil pack and both spark plugs fire at the same time, one spark powers the engine the other is Wasted

 

Hello Ron, started the Ranger this AM and ran for about 5 min. then shut down. I tried tried the 50/50 and engine will fire and run when starting fluid is used, but will shutdown when fluid is depleted. I did a press to test on the Schrader valve and there was no fuel. If this is a fuel problem I am at a loss, I don't have test or analytical ability to further troubleshoot the fuel and electrical system.

Thanks for your assistance
Herb

 

Good info, you know where to look now, not a spark issue

Do you hear the fuel pump running when key is turned on, it only runs for 2 seconds, but can be heard in the cab, a HUMMMM from gas tank
Turn key off and on as much as needed to either confirm you hear it or confirm you don't hear it

On the 1994 you can ground the fuel pump Relay manually so bypass computers ground
Find the OBD/VIP connector in engine bay, it has the ground slot for the FP Relay
Look here for drawing of the VIP connector with fuel pump slot labelled: https://therangerstation.com/tech_library/OBD_I.shtml

Second drawing shows the slot that needs to be grounded with jumper wire
FP relay will close, with key on
You can test FP relay by leaving key on and removing this jumper, you should hear relay "click" open, and then ground it again and you should hear it "click" closed
This is a way to confirm you can hear the pump running as it will be on when key is.

If FP relay is working, "clicking", but fuel pump is not running, then check FP fuse, swap it or test it, visual does NOT work, trust me, lol

If Fuel Pump is working then leave it on(engine off) for the 5 to 10 minutes to see if it stops working, it doesn't hurt anything, fuel pump runs full time when driving so much longer than 10 minutes, you can also test fuel pressure at schrader valve at this time, just to confirm pressure, 30psi is a lot of pressure so becareful

If it stops then its probably a bad pump, new or not, 3rd party pumps often need to be replaced under warranty until you get a good one
Motorcraft(Ford) pumps are tested so less likely to get a bad one, but way more expensive because of that

Its possible that a connection between FP relay and fuel pump is corroded, as fuel pump draws its 8amps the connection heats up and resistance goes up so voltage to pump goes down, and at some point drops low enough so pump shuts off
Connection under the engine fuse box is most likely place for that

Its doubtful the fuel injectors are the issue because there would still be fuel pressure if they stopped working
Same for FPR, because if it was stuck open you would have no/low pressure all the time, not after 5-10 minutes

Computer could be ungrounding the fuel pump relay after 5-10min, never heard of that happening but certainly possible, using the jumper takes computer out of the picture, so if pump stays running after 10minutes then this is a possibilty

You can drive the vehicle with this ground jumper in place, just make sure it is well connected so engine doesn't stall on you while driving

 

Has anyone thought about the catalytic converter. Had an 85 ford it would do that also. But on top of that, it also would only get up to 45 - 50 mph, with no power, and slow acceleration. My truck had a bolt on cat so I unbolted it, shoved a 2" piece of fence post through it and truck didn't shut off and I could go faster than 50 mph. replaced the cat, problem solved.

 

Very good point, clogged exhaust, but OP didn't report lower power just the shut down and no restart

 

Hello all Ranger owners, appreciate all the help you have provided. Problem fixed, after the 50/50 test I checked the EEC Power Relay and the Fuel Pump relay (both the same) and they were still clicking when I turned the ignition switch on and off. I finally said the heck with it and purchased new relays at Autozone; the truck started and only shuts down when I turn the key off. Still don't feel bad about the other stuff I changed. Again Thanks!
Herb D

 

Good work

Thank for the update