I finally got my 94 3.0 running. ran great for a while, but ever since my head gasket repair (i got the heads machined and cleaned up) it had this hesitation when cold. like it would lose power (not shut down) when accelerating and sputter, but that would go away when it got warmed up.

also, i noticed an oil leak coming from the head gasket.

I replaced the water pump when it sprang a leak.

I replaced the radiator which was so gummed up it wouldn't cool the coolant enough.

so besides for the above issues, it ran great.

Until... I took it apart to retighten the head bolts to get rid of the oil leak (i heard that the heads sometimes need retightening after a head gasket repair) and to clean the fuel injectors (i thought that might be causing the hesitation when cold). the passenger side was indeed quite loose, the driver said was pretty tight. i tightened everything and put it all back together, but now, try as i may, it wont start.

I have tried spraying starting fluid, doesn't help (so i think its not fuel)

I have tried testing the sparks with a light, they flash, so i think its not spark (i even cleaned all the spark plugs)

I have tried adjusting the distributor, doesn't help.

I have not tried testing compression but that seems the most far fetched to me (and my compression testing kit is full of oil which is a story for another day).

I have the battery on a tender and its full, so its not that.

Any ideas out there of what to try next?

 

Welcome to the forum

If you sprayed fuel into the engine manually and it didn't start then its for sure a spark or compression issue
Yes, on a 3.0l especially, compression issue is unlikely unless you have been working on timing chain

So spark
1994 3.0l has a distributor with TFI module and a coil, last year for this setup
First thing to check is basic but best to look and take it off the table, lift distributor cap up so you can see the rotor, remember where its facing, give engine a short crank, make sure rotor moved, lol
I know I am sure its moving but if its not then a lot of tail chasing will follow if you don't check
While cap is up give rotor a quick look

If you have a tachometer on the dash is should move when cranking engine, 200rpm is cranking speed, if not then no signal from coil/TFI module

Also CEL(check engine light) should come on with key on, means computer has powered up
CEL should go OFF as soon as engine is being cranked, that means computer is getting a timing signal from TFI module
If CEL stays on then no signal and no spark

Coil terminal or its red/green wire should have 12v with key on, no fuse for this just comes from ignition switch, so if lights on the dash come on Coil should be getting 12volts

TFI module(ICU) and Distributor also get 12volts on this same red/green wire
One of these connectors could be unplugged, so no spark

The sensor inside the distributor is what starts the ball rolling for spark, it has a 12v on/off signal that goes to TFI module and the TFI module then grounds and ungrounds the Coil to get it to spark based on the distributor's 12v on/off pulse
TFI module grounding and ungrounding of the coil is the tachometer signal

If you have or can get a timing light it would make troubleshooting easier, and if you have moved the distributor then its required to reset spark timing

 

Thank you for taking the time to write this up.
I do have a timing light, but not sure how to use it besides for advancing or retarding timing when engine is running.

How do i use it when engine is not running?

I have no tachometer.

Just recently replaced the distributor (the gears were completely worn down (that was when i did the head gasket repair), the TFI module, and the coil as well. all new

 

Connect timing light to battery and to #1 spark plug wire, cap back in place

If you have a helper that can crank engine over while you hold the trigger on timing light have them crank the engine and timing light will flash each time #1 wire has spark
If you are alone then tape trigger down and point light at cab so you can see it under the hood, watch the wires and fan, lol
Crank engine and light should flash at each spark

If no flash then move timing light's spark plug wire connector to coil to distributor wire and try again

If coil is flashing but not distributor #1 wire then there is a problem with cap and/or rotor

If no flashing with either then no timing pulse to coil from TFI and or distributor

If you do get flashing on #1 then you will need a helper or a "remote crank switch"
You need to point the timing light at the crank pulley to see if distributor is timed to 10-15degF BTDC just like if it was running

 

Here’s the update. No spark with the timing light at spark #1 and neither at coil to rotor. Checked the voltage at coil (not sure if I’m doing this part right), as per the picture, only getting 0.16 volt? Battery is 12.93

 

Ground the black probe to the to engine metal
Red probe on red/green terminal
Key on

But if key was on in the way you have it picture you should have seen 12.x volts

The other wire on the connector runs to TFI module, and it will ground that wire with key on to power up the coil, key off its not grounded

Do the lights on the dash come on with key on?
If not check 60amp fuse in engine bay fuse box, unplug it and check it

 

2nd update.
done for the night, but:

I had the distributor unbolted and the rotor cap unscrewed, and the coil unbolted from the upper air intake manifold, then I noticed that my wire connecting coil to the rotor is different at either end. I flipped the wire and then checked and got a flash at both the coil to rotor and the #1 spark.

I quickly put everything back together and got in the truck, no dice. Cranks but doesn’t start.

went back to check for spark with everything still assembled, no spark at #1 spark nor at the coil to rotor…

im at a loss

 

Replying to your just now reply:

check engine light comes on with key in ignition.
then turns off on crank.

 

When key is turned on the Coil is power up
If you unplug it it WILL spark one time, nothing to do with anything else in the system just how ignition coils work


Ignition coils
They have a coil of wire around a metal tube with say 100 coils/wraps, this is called the Primary Coil and is for the 12volts, terminals + and -

Inside the metal tube is another coil of wire, with say 100,000 coils/wraps, this is called the Secondary coil

When Primary has 12v and a ground it creates a magnetic field and "charge" around and in the Secondary coil, and in this case at 1,000 times the volts of Primary, so 12,000volts, but no amps
The 12,000volts is held on the Secondary by the magnetic field
If you remove the 12volts or the ground on the Primary the magnetic field collapses and the 12,000volts is released in this case to the spark wire that goes to the distributor

So once the coil is "charged up" unplugging it will release one spark

In the "olden days", lol, points in a distributor(or magneto) where used to make the coil spark, by powering it up and then cutting the power
Because its safer to have ground wiring around metal parts the - side of Primary coil is what is cut not the 12volt "+" terminal
As we went to electronic and "pointless" spark systems it was just easier to stick with cutting the ground "-" connection to spark the coil
The fewer 12v wires running around the engine bay the better, lol

 

Turns out it was the timing of the distributor.
took another swing at finding TDC and lining it all up and it started right up.

I am hearing a massively loud backfire?

 

Re-check firing order then...................................do it again

 

Is it possible that all the cranking I did over the past few days has fouled the spark plugs and now they need to be replaced?

 

I doubt it but free to have a look and clean them