First problem was misfiring P-0307. Changed Wires and Plugs. Same Code. Exchanged No.6 and No. 7 injectors. Code remains. Engine finally quit and then No Start. Checked PIP-good. ICM tests good in store. HEI coil and wire test good. Fuel pres. 50# with key On.
Key OFF, drops to 25-30 and holds for 1-2 hrs. New PCM. Cranks, No run. No pending codes.Cap and rotor visually OK. Mechanical timing good (no timing chain jump). Injectors getting pulses. What next?

 

302 or 351?

Test for spark:
Plug a spare wire with a plug into your cap, lay the wire/plug over your intake so it's visible from the drivers seat then try starting it. You should be able to see and likely hear the spark.
Otherwise I think a failing Throttle Position Sensor could stop you dead in your tracks just like this. I forget if it will give you a code or not. You could try tapping (lightly) with the heavy end of a screwdriver or a ratchet and it could start working for a short while again. I've seen this work more times than I care to admit. The TPS is the little black bowtie shaped part on top of your Throttle body.
2 spare parts to always keep with you is a spare fuel pump relay and a TPS.
FYI, my experience here is with 5.0's in mustangs, but the trucks are nearly identical.

 

96 is OBD-2, so a TPS should throw a code.

 

I am leaning towards a stopped up cat converter.

 

I don't think a cat converter would be plugged that tight. As a troubleshooting measure, I would spray some starting fluid in the intake to determine if you are lacking spark or fuel delivery.

 

Air, Spark, Fuel.
Air is always the least likely.
Spark - test at your plugs (as I described above) to be sure you have spark being delivered into the cylinder
Fuel - As masseyman said above you can shoot some starter fluid into the intake as you're cranking. Pull one of the big vacuum lines on your throttle body and give it squirt as you're cranking it. If it starts to sputter and try to start, you know it's a fuel problem.

 

Checked with a service tech at the local Ford dealership and said that the cat is a good possibility. The truck has 260K miles on it so it's a good possibility that the cat might be stopped up. I have spark at the plugs and have tried starting fluid into the intake chamber, but nothing happens.

 

To check for a stopped up cat conv., I am going to loosen the bolts from the exhaust pipe and the manifold to see if there is excessive back pressure. If the engine starts then the cat conv. is suspect.

 

My guess is it has nothing to do with a plugged cat. Keep us posted as to what you find. I wouldn't be surprised if timing chain has jumped time especially with 260K on it. A compression test is in order if you have fuel and spark.

 

As I stated in the first post, the mechanical mtiming is good, ie. when approaching TDC, the dist. rotor is approaching #1 position. If I loosen the bolts connecting the exhaust manifold and the exhaust pipes, that shouild tell me if the cat is plugged. Thanks.

 

Not to offend or cause you any negative vibes, but I got $10 that says it is not the cat. A plugged cat will in some cases severely affect performance , but will not prevent engine from starting.

You need fuel, spark and compression of air to make an internal combustion engine run. If you have fuel and properly timed spark then a compression test is advisable.

I do wish you best of luck with it.

Bob

 

^^^ That is 110% correct.

Doubts you say? Just try the simple potato test. Insert a 'tater into the (single out) exhaust tip on a normally healthy vehicle. Ah Garn'tee yall it WILL start even wif thet ol' buttplug. Axe me how ah knows ....

Glad yer here, Bob - yer battin' a thousand so fer!

Best of luck OP.