Help me diagnose Ford 302/5.0 EFI

Ladies and gents, I'm about to pull my hair out trying to get a 1991 F250 5.0 running right. Any help or advice is appreciated!

Project background: I bought the truck partially restored after the family experienced some medical issues and had to ditch the project. The PO did a bunch off odds and ends, like brakes, leaking diffs and tearing down the engine for a reseal. When I got the truck the engine was a short block and the PO had installed a new timing chain which I believed based on the new timing cover gasket and all the parts included in the sale. I went ahead and removed a few broken studs in the heads and got the engine together, back in the truck and running. That's where the problems started...

Once running the engine ran very rough and I figured out it's only running on 2 cylinders (1 & 6). Firing order was set to the firing order shown on the sticker under the hood. I went ahead and tried the newer HO firing order thinking he might have done a cam swap (although I don't believe he did) and the truck ran better, picking up an additional 2 cylinders, running on 1, 4, 6, 7. I replaced the spark plugs and wires, no difference. When I unplug the spark plug wires from the dead cylinders and hold them close to the plugs I can see the spark jumping the gap. It looks just as strong as the spark on the "good" cylinders. 

Unplug the injector plug from #5 (dead cylinder) and nothing changes. Unplug the injector plug from #6 and the engine stumbles. I switched injectors between 5 and 6 and the problem stays on 5. So I don't believe it's an injector issue. 

I also unplugged the ECM plug and grounded pins 58 and 59 (fuel injector pins) and I can hear the injectors clicking. 

Any idea what to check next or how to determine if the injectors are actually firing? 

Edit: timing set at 10 degrees

Plugs are gapped to .44

Compression as follows:

1. 127

2. 129

3. 116

4. 130

5. 125

6. 120

7. 124

8. Not checked

This is a free, high mileage truck so I didn't bother lapping the valves or anything. 

Do we know that the cam and the crank are clocked right?  Possible that the PO botched the timing chain install?

In reply to wae :

That's about the only thing on this engine I really don't know. I did the compression test go make sure its at least got some compression, but it could definitely be off. Pulling the timing cover is hopefully a last resort option. 

In reply to WillG80 :

Is the distributor in the correct orientation? It's pretty easy to be off a tooth or even 180 out and still have it run badly.  Does it have a hydraulic roller cam? If not, then the likely hood of the HO-351 firing order is pretty low.  Have you put a timing light on it? That would tell the tale on the dizzy.    

In reply to tester (Forum Supporter) :

Yup, timing checked with a timing light. Got it lined up with the white paint mark at 10 degrees 

If you want to be sure that the injectors are spraying, you could:
get a spare dizzy
remove plugs on one side
plug spare dizzy in in place of one installed
turn the truck on, spin the spare dizzy.

Rotate engine by hand as needed to open valves and check for spray in each cylinder.

However, if you hear them clicking, I doubt the above is needed

I second the concern about the cam timing.  Might also be worth checking that they didn't get the wrong cam for the engine, ie when the #1 is at TDC both valves are closed, also could check that the dizzy rotor is turning as the engine spins.

I remember doing head gaskets on my 302, and trying to get it to run again when I had forgotten which direction the distributor rotated. Obviously, all the plug wires were wrong, but it still ran, sort of. 

In reply to Floating Doc (Forum Supporter) :

Ugh, I'm so happy and embarrassed at the same time. I think this might be the issue... I assumed the distributor spins clockwise but a google search quickly proved me wrong. I can't believe I spent so much time chasing this. Thank you so much for the idea Doc!

In reply to Mr_Asa :

Thanks - If Doc's idea below doesn't solve the problem I'll move on to this. But I think it'll be fixed.

Case closed... I had the distributor direction wrong. Turns out it spins counter-clockwise...

In reply to WillG80 :

Damn Fords and their backwards ways.

Fords often rotate diametrically. 
 

In reply to WillG80 :

Well, glad to help, especially since I had to pay someone $50 to figure this out.

Stampie said:

In reply to WillG80 :

Damn Fords and their backwards ways.

The best Fords rotate the proper way.