GreanBeastXJ

Working on my '88 4.0 aw4 4x4.Two weeks ago I went to a store and when I came out, the heep would crank but nothing else.

Fast forward to now, I have replaced or adjusted:

Distributor/cap/rotor/wires are new, the tab was removed and the dizzy has been indexed to TDC (confirmed compression stroke by removing valve cover and checking rockers) and the rotor is at the 5 o'clock position with the dizzy adjusted to be at the trailing edge of the rotor tip.

CPS was replaced (low voltage reading while cranking spurred the replacement)

TPS was adjusted a few days before it stopped working, should I recheck it?

Grounds at dipstick have been cleaned and the head to firewall ground replaced.

Coil was replaced with junkyard unit because mine had a crack.

ICM contacts were cleaned

C103 eliminated, wires joined with non-insulated crimp connectors and heat shrink.

Fuel pump and filter are brand new but I had to reuse the old fuel strainer as the replacement wouldn't fit in my tank.

TB and IAC were cleaned when the TPS was adjusted.

Vacuum lines are all intact but the TB to map line was replaced by the PO with clear tubing.

I have spark to the plugs.

I have fuel in the rail.

What am I missing? She cranks strong but won't fire, only rarely will it grumble a little bit. I'm pulling my hair out at this point. Please help.

Idunno

Reconfirm compression stroke by removing all plugs and putting your finger on #1 plug port to actually feel compression while rolling engine by hand. Once there, where is the distributor button pointing? If you have spark and fuel pressure on the rail then the only problem I can see is an incorrectly indexed distributor.

tjwalker

Even with some new fuel pump components, gotta verify fuel delivery with a fuel pressure gauge. For your vintage, you need 31 psi to fire the engine. Or introduce a little bit of raw fuel into the intake. If it starts and runs for a few seconds this "old school" way, you have identified a fuel delivery problem.

Test the cam sensor (synch sensor) located inside your distributor.

cruiser54

As stated above, fuel PRESSURE needs to be verified.

GreanBeastXJ

When I located TDC I was under the vehicle turning the crank and I had a buddy of mine who's a novice mechanic stand up top with his finger over the plug hole and the valve cover off. I'm very sure I'm on the money now. With #1 at TDC the rotor is pointing to 5 o'clock.

If I spray ether into the TB the jeep will rumble and fire like it wants to start but won't.

When I say I have fuel at the rail, I mean there is fuel there when I press the valve on the rail. It only dribbles out though, it doesn't seem like 31PSI. I bought a cheap harbor freight fuel pressure gauge but it was garbage and leaked out of the box. I currently don't have the funds to rent one from Oreillys for $135.

I know it's a fuel system issue now.
Fuel pump relay is clicking.
fuel pump pressurises with the key on.

I've read that these pumps often are victims of crib death. Could that be the case even though I can hear it start?
Fuel lines all seemed intact when I replaced the pump and filter.
Ballast resistor contacts are clean, what should the resistance be?

At this point I am inclined to put the old pump (Bosch, was working but was suspect) back in and see what happens. I think I will tackle tip #29 while I am down there.

Also in post #1 I meant the c101, not the c103.

Thanks for the input guys and thanks Cruiser for the Renix site. It's a life saver.

cruiser54

Good plan.

GreanBeastXJ

Old pump went in today but I lost the fuel strainer in the tank while installing it. oops! Any way she REALLY want to run now. It will fire like it's gonna take off on it's own but it just won't stay running. My best guess is the timing is slightly off.

Thoughts?

cruiser54

Check it.CRUISER'S MOSTLY RENIX TIPS

DISTRIBUTOR INDEXING

OCTOBER 30, 2015 SALAD 27 COMMENTS EDIT

1. Remove the distributor cap and cut a “window” into the side of the distributor cap at the #1 spark plug wire post . The “window” should be large enough to allow easy visual inspection of the position of the distributor rotor at the #1 spark plug wire post. Reinstall the distributor cap.
2. Use Tip 12 first to guarantee you’re on #1 TDC.
3. Install a ¾” wrench or socket onto the vibration damper retaining bolt. Rotate the engine in a clockwise direction until the #1 cylinder is at top dead center. Align the timing mark on the vibration damper with the “0” degree mark on the front cover timing scale. The tip of the distributor rotor should be near the #1 spark plug wire post.
4. Disconnect the distributor electrical connection. Remove the distributor holddown clamp, holddown bolt and distributor. Remove the distributor cap and rotor.
5. Place the distributor housing upside down in a soft jaw vise. Scribe a line 1/2 inch from the end of the distributor locating tab. Cut the distributor locating tab at the scribed line with a saw.
6. Remove any burrs and metal filings from the distributor. Reinstall rotor.
7. If necessary, using a flat blade screwdriver, turn the oil pump gear drive shaft until the slot is slightly past the 11 o’clock position. The oil pump gear drive shaft is accessible through the distributor mounting bore in the engine block. A little tip here. Rather than use a dizzy gasket, use an o ring instead. NAPA #727-2024.
8. Visually align the modified locating tab area of the distributor housing with the holddown clamp bolt hole.
9. Turn the rotor to the 4 o’clock position.
10. Lower the distributor into the engine block until it seats. The rotor should now be very close to the 5 o’clock position.
11. Reinstall the distributor cap with the cutout “window”. Rotate the distributor housing until the trailing edge of the distributor rotor tip is just departing from the #1 spark plug wire post terminal .
12. Reinstall the distributor holddown clamp and bolt.. Reinspect the position of the rotor to the #1 spark plug wire post to insure that it has not moved.
13. Install the new distributor cap, reconnect the distributor electrical connections.

Here’s WHY distributor indexing is so important:

Distributor indexing explained
For clarification though, that’s not a cam sensor inside the Renix dizzy. It’s there to fire the injectors sequentially with the firing order. You’ll never notice if it went bad because the ECU will try to “guess” where it is and does a heck of a job at it.

As for the “timing”, it is controlled by the ECU. Ever notice how wide the tip of the rotor is? Try and wrap your head around this:

When the ECU yells “Fire” to the ignition control module, where is the rotor in relationship to the dizzy terminal? Not to the terminal yet? Past the terminal too far?

What happens to the spark/secondary ignition strength when it has to jump the Grand Canyon in comparison to shooting from a rotor tip?

Use Tip 12 first to guarantee you’re on #1 TDC.

Revised 11-19-16

cruiser54

Also, make sure your fuel pump ballast resistor if it's starting, and then dying in a few seconds.

GreanBeastXJ

Indexing was off. Heep running now. Thanks for the help!

cruiser54

Cool!!!!!

DFlintstone

Ditto! In the link in my sig there is a pic of the inside if the tank BTW.