Possible fuel issue? Injectors?

[Ants93]

Hey everyone. I was hoping to get some diagnostic help with my 1993 xlt 4x4 5 speed manual. Ive been having issues for a while now with what I feel is fuel. Ive replaced the Fuel pump (first a junk yard find and then a brand new delphi). The fuel filter has been replaced. The throttle position sensor. The MAF. As well as the pressure regulator (new one from store and off junk yard x) the IAC
and the engine coolant temp sensor. Spark plugs and cables where done last year when I did the ignition coil. I have since swapped out spark plugs and cables that had excessive wear on the driver's side of the engine.

When you turn the key to on in order to prime the rail. My fuel pressure hits about 32 and then drops off rather quickly to zero. When you start the vehicle it will idle at 32 psi and run for a while. Until it starts to warm up some and then it will start to stumble and drop rpms like it is trying to stall but the fuel pressure will jump up to about 40ish psi. After a little but the engine will indeed stall out and die unless I give it some gas.

When driving it will run fine for a few miles. Sometimes more sometimes less. And then it will start to bog down. Even with the accelerator mashed to the floor it will struggle and then suddenly surge up in rpms. Sometimes this doesn't work at all but after pushing in the clutch and turning the car off. I can restart it on the move and it will run fine for a while longer. Rinse and repeat. I tried to upload some videos of the issue but can't get the files small enough... any help would be greatly appreciated. This is my daily driver and I'm at my whits end

 

[410Fortune]

42 psi plus or minus is spec for your fuel rail

You said three plugs on drivers side were worn out quickly?

Any loss of coolant?
Any check engine light? Trouble codes?

Can try cleaning the mass air flow sensor
Also check for a plugged cat converter, the catalyst can break loose inside the converter and actually plug your exhaust

The 91-94 is notorious for getting a large
Hole in the air filter intake tube, remove it and inspect it carefully… no leaks allowed

How Many miles on the 93?
I’m suspecting a bad head gasket maybe bad intake gaskets

A bad crank sensor can lead to a no spark situation, but I agree with you initial reaction is sounds like fuel pressure / running out of gas

Yes injectors from 1993 are old now and could likely need replacing along with all the intake gaskets

 

[Ants93]

42 psi plus or minus is spec for your fuel rail

You said three plugs on drivers side were worn out quickly?

Any loss of coolant?
Any check engine light? Trouble codes?

Can try cleaning the mass air flow sensor
Also check for a plugged cat converter, the catalyst can break loose inside the converter and actually plug your exhaust

The 91-94 is notorious for getting a large
Hole in the air filter intake tube, remove it and inspect it carefully… no leaks allowed

How Many miles on the 93?
I’m suspecting a bad head gasket maybe bad intake gaskets

A bad crank sensor can lead to a no spark situation, but I agree with you initial reaction is sounds like fuel pressure / running out of gas

Yes injectors from 1993 are old now and could likely need replacing along with all the intake gaskets

Thanks for the response! 58000 on the odometer. Though I'm sure it's rolled over at least once.
I have no loss of coolant and no oil in my coolant either.
The problem has definitely gotten worse with time. The maf is new but I could have gotten a bad part. The vehicle has no cat or exhaust side oxygen sensors. They where removed by the previous owner and welded up. And as far as plugs go. The driver's side plug and cable at the back of the engine where toasted at the joint for the cable and plug. Looked like the plug wore through the cable and grounded out somehow. I just replaced all three on that side since they where easy to get to.

 

[410Fortune]

How does the other side look?

Your 93 only had two oxygen sensors, one in each side of the down pipe, none after the cat converter

The passenger side plugs you can access from above the tire, almost a straight shot. Very helpful to remove tire if needed

 

[Ants93]

How does the other side look?

Your 93 only had two oxygen sensors, one in each side of the down pipe, none after the cat converter

The passenger side you can access from above the

I have the other sides plugs and cables so I'm going to throw those on tomorrow and see if it helps any.
I can't get it to throw any codes other than the ac being on and the clutch not being depressed. (I have an obd1 scanner tool). No check engine light but it may be burned out.
Is there a recommended intake gasket? I found a ton of different ones online that look drastically different

 

[410Fortune]

The check engine light should come on when you first turn truck on and go off when engine starts to rotate

This indicates the pcm is getting power and seeing a signal from the crank sensor

A Lack of power or missing with good fuel pressure and no codes is often in the ignition… plugs wires or coil
The coil pack can be inspected for cracks on the bottom
Or any signs of deterioration

 

[410Fortune]

Victor reinz or felpro or mahle gasket sets all very good engine tech also seems decent

The 4.0 ohv had 2-3 different lower intake gaskets over the years, your 93 uses the one piece
It looks like this:

 

[Ants93]

Victor reinz or felpro or mahle gasket sets all very good engine tech also seems decent

The 4.0 ohv had 2-3 different lower intake gaskets over the years, your 93 uses the one piece
It looks like this:

View attachment 465444

So my gaskets seem to be good. Got her to idle (rough) and sprayed starting fluid all around the air box/intake tube/throttle body/intake manifold with zero change to my rpms. I drove her to work the other night and it bogged down over and over the whole way there. I unplugged the battery while I was in work and then 10 hours later reattached it. The car started immediately and then died immediately. I restarted it and it idled with a little throttle. Drove it home and it didn't bog down at all. Just a slower acceleration and near constant backfiring while pressing the gas. I was worried for a second my transmission was making the noise but it was definitely the engine and exhaust.

 

[410Fortune]

Backfiring not good likely lean if it’s backfiring in intake

The carb cleaner trick doesn’t really work well on these engines I have never had good luck with it…

A smoke test will find the leaks

A visual inspection with flashlight it a better idea… look for soot around the intake where the upper plenum meets the fuel rail… soot will gather where the air has been leaking in

Can do a simple test to your coolant / radiator see if combustion gasses are mixing with coolant (head gasket or lower intake issues)

https://www.amazon.com/Combustion-Leak-Head-Gasket-Test/dp/B0D4JGMZ85

 

[Ants93]

Victor reinz or felpro or mahle gasket sets all very good engine tech also seems decent

The 4.0 ohv had 2-3 different lower intake gaskets over the years, your 93 uses the one piece
It looks like this:

View attachment 465444

Backfiring not good likely lean if it’s backfiring in intake

The carb cleaner trick doesn’t really work well on these engines I have never had good luck with it…

A smoke test will find the leaks

A visual inspection with flashlight it a better idea… look for soot around the intake where the upper plenum meets the fuel rail… soot will gather where the air has been leaking in

Can do a simple test to your coolant / radiator see if combustion gasses are mixing with coolant (head gasket or lower intake issues)

https://www.amazon.com/Combustion-Leak-Head-Gasket-Test/dp/B0D4JGMZ85?tag=seriouexplor-20

Ill definitely pick that kit up. Tomorrow I'm off of work so I was going to pull the intake manifold off to check the resistance of the injectors with a multimeter. Just to make sure they are functioning. Also. Is it possible the computer is trying to relearn the parts and sensors I replaced all at once combined with having mixed up two of the spark plug cables. (Got them right now. And that's part of what improved things I think) going to do the filter as well.

 

[410Fortune]

If you access the fuel rail you could just pull the injectors and bench test/ clean them and then re ring with new o rings and re install

Many of us have built simple injector testing setups using a battery and can of
Carb cleaner I can activate and spray each injector to check their performance

 

[410Fortune]

Like this
An old tire stem fits the injector inlet perfectly