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1994 4.0L will not run... need help please


jleas524

Member
ASE Certified Tech
Joined
Sep 3, 2022
Messages
24
City
South Carolina
Vehicle Year
1994
Transmission
Automatic
Okay, I have a 1994 Ext. cab splash.
4.0L, Auto, 198,000 miles.
It's been sitting for 5 years.
I have removed the gas tank and cleaned out.
I have replaced the fuel pump and sending unit.
New fuel filter.
The fuel lines have all been drained. I am getting fresh fuel to the fuel rail.
New plugs gapped and installed.
New plug wires.
Checked cylinder compression and all 6 are good.
New battery installed.
Checked all fuses, relays and the diode under the hood. All are good.
Checked codes and had 11 and 151, which I was expecting.
I replaced several bad vacuum lines.
All 6 plugs have fire when I removed and tested.

The issue I have is the motor will spin over, but not run.
I have started checking all the grounds and cleaning them.
Any thoughts?
How do I check to know if the fuel injectors are actually working? What provides the signal to the injectors to fire, the PCM?

Thanks for any help you can give me.
 
you can get a noid light to check signal at the injector or, the old-fashioned way is pull the injector and put it in a jar
 
50/50 test...starter fluid...
 
New plug wires.

Double check, then triple check, that the plug wires are in the correct order.

firing order.jpg
 
Double check, then triple check, that the plug wires are in the correct order.

View attachment 83962
RobbieD, thanks for that diagram. When I replaced the wires, I did them one at a time, but I remember the # 6 wire was in a different position on the coil pack then what your drawing indicates. If so, that would mean at least two of the wires are off. That may explain the backfire I had when I tried using starter fluid too.
 
Hope that gets you in a better place- good luck!
 
I'm betting it will fire up when you change the wires

FYI, I have the same set-up in case you haven't noticed, so I'm pulling for ya. 🤞
 
YES, on coil pack wiring, check it, then check it again

YES, 50/50 test
Spray fuel into the engine
If it doesn't start then NO SPARK, this is the ONLY test you can do for spark on this engine, testing spark plug wires doesn't tell you anything

If it start runs and dies you have a fuel delivery issue, injectors



You have a Waste Spark system
There are only 3 coils in the coil pack, NOT 6
[3 4]
[2 6]
[1 5]

These are the Match Pairs, 3 and 4 fire/spark at the same time, as do 2/6 and 1/5
That's why its wired that way
5 6 4 side often gets miswired
 
YES, on coil pack wiring, check it, then check it again

YES, 50/50 test
Spray fuel into the engine
If it doesn't start then NO SPARK, this is the ONLY test you can do for spark on this engine, testing spark plug wires doesn't tell you anything

If it start runs and dies you have a fuel delivery issue, injectors



You have a Waste Spark system
There are only 3 coils in the coil pack, NOT 6
[3 4]
[2 6]
[1 5]

These are the Match Pairs, 3 and 4 fire/spark at the same time, as do 2/6 and 1/5
That's why its wired that way
5 6 4 side often gets miswired
Thanks, RonD. If the wiring isn't wrong, I will do gas spray test. I'm sure I have a spray bottle around somewhere.
 
Quick Start is something good to have on the shelf, its Ether in a spray can, it can be used on small or large engines, gas or diesel

Spark can only ignite gasoline VAPOR, not liquid gasoline, yes the movie guys do take liberties with that FACT, lol

Its why engine compression is so important, compression heats up the liquid gasoline so some of it becomes a VAPOR and the spark plug can ignite it

Ether is a VAPOR at a much lower temp, room temp, than gasoline, so can easily be ignited by a spark
So excellent starting fluid even with ice cold outside temps
But spray bottle with gasoline is also OK if outside temp is not to cold

If you can "smell" the gasoline, that's the VAPOR, no smell no VAPOR
Ether SMELLS all the time, lol
 
Okay, we’ll thank you for everyone’s help. I picked up the noid lights. All the injects get signal. I did find the plug wires crossed at the coil pack. Explains why it would run. Put them to how they should be and she fired right up. Next problem is the water pump…
 
Good to hear; thanks for letting us know how it turned out.

Water pump shouldn't be too bad.

Fixing problems keeps getting easier as you go. That's the good part of having lots of problems . . . (y)
 

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