I am stumped. Jeep died while driving and wont start.

[pgf001]

I own a 1997 Wrangler and had the 4.0L motor rebuilt about 4 years ago. Since then I have replaced the fuel pump (about 3 years ago) due to hard start issues and it has been running smooth ever since.

The other week I was driving home from work and my jeep died about a mile from the house. It will crank but not fire. Also there are no codes that were thrown.

I thought it was the fuel pump because I know the Delphi units usually dont last long. I use to hear the humming sound when it primed before start and I could no longer hear that sound. Before replacing the pump I verified the relay worked by swapping the fuel pump relay with the horn relay. I also checked all fuses. Luckily I held on to the original fuel pump assembly and decided to rebuild it. I put it in and thought it was not working because the jeep still wouldnt start and because I still couldnt hear it priming the line. However, I verified the new pump motor works by disconnecting a gas line and seeing gas come out during the priming stage.

I really thought it was fuel related so I checked my fuel lines for a leak or clog. I even put a dash of gas in the throttle body to try and get it to fire off. NOTHING!

Next I replaced the crankshaft positioner sensor but still have had no luck.

I have been reading through this forum but have not found a solution yet. Since my jeep was running fine for years and just randomly quits after driving a 30 mile round trip, I am stumped. What also gets me is this humming sound I would hear before fully turning the key over to crank. I always thought it was the fuel pump... could the absent sound be my problem? Only if I knew what it use to be.

I appreciate any advice that can be given!

 

[macleanflood]

You probably need to troubleshoot the ASD relay.

I'd start with spraying some starting fluid down the throttle body and see if it fires off.

And I'd get a fuel pressure gauge on that rail so you know what's going on.

I rebuilt my pump assembly on my 97 and the "new" Bosch pump from Brazil lasted a week. My plastic cage was pretty brittle and snapped during an accident...so I decided to buy the almost cheapest pump assembly on Rock Auto...a Brute Power. It's been perfect for 6 months and made it down the Rubicon.

-Mac

P.S. Clean grounds and battery terminals and verify starting voltage!

 

[pgf001]

You probably need to troubleshoot the ASD relay.

I'd start with spraying some starting fluid down the throttle body and see if it fires off.

And I'd get a fuel pressure gauge on that rail so you know what's going on.

I rebuilt my pump assembly on my 97 and the "new" Bosch pump from Brazil lasted a week. My plastic cage was pretty brittle and snapped during an accident...so I decided to buy the almost cheapest pump assembly on Rock Auto...a Brute Power. It's been perfect for 6 months and made it down the Rubicon.

-Mac

P.S. Clean grounds and battery terminals and verify starting voltage!

Mac, thanks for the reply.

Decided to test the ASD relay tonight since I was only focused on fuel pump relay before. Turns out it is not getting power on the always hot leg. It gets 12V to one leg when I power the Jeep on. The ASD fuse does have 12V on both sides.

So I would think it has to be a connection or wire between the fuse and relay. Maybe behind where the relay mates.

 

[B1Toad]

Are you saying there is power at the ASD relay coil when the ignition is switched on but no power at the relay from the 30 amp fuse #6?

 

[pgf001]

You probably need to troubleshoot the ASD relay.

I'd start with spraying some starting fluid down the throttle body and see if it fires off.

And I'd get a fuel pressure gauge on that rail so you know what's going on.

I rebuilt my pump assembly on my 97 and the "new" Bosch pump from Brazil lasted a week. My plastic cage was pretty brittle and snapped during an accident...so I decided to buy the almost cheapest pump assembly on Rock Auto...a Brute Power. It's been perfect for 6 months and made it down the Rubicon.

-Mac

P.S. Clean grounds and battery terminals and verify starting voltage!

Mac, I appreciate the reply.

I tried pouring some gas in the throttle body and that didnt work.

I swapped the ASD relay

Are you saying there is power at the ASD relay coil when the ignition is switched on but no power at the relay from the 30 amp fuse #6?

Exactly. If you look at the connection hole layout. There are three vertical holes on the left, one hole in the middle, and one hole on the right. I get power on the top left hole when the ignition gets turned on. But when the ignition is off I don’t get power on the single hole on right side. I verified power on both sides of the fuse. So I know the fuse is not blown.

 

[B1Toad]

Looking at the diagram power leaves fuse #6 (30A) in the PDC thru connector C100 (located at the PDC) on a Red/Wht wire where it goes to splice 100 near the battery (see pic) and from that splice one red/wht wire goes to the PCM and another to the ASD for constant power.

So I would check for power on that red/wht wire to see where the power got lost. If there is power to the splice S100 check the 2 wires leaving the splice. If no power at either side of the splice check at connector C100.

 

[pgf001]

Looking at the diagram power leaves fuse #6 (30A) in the PDC thru connector C100 (located at the PDC) on a Red/Wht wire where it goes to splice 100 near the battery (see pic) and from that splice one red/wht wire goes to the ECM and another to the ASD for constant power.

So I would check for power on that red/wht wire to see where the power got lost. If there is power to the splice S100 check the 2 wires leaving the splice. If no power at either side of the splice check at connector C100.

View attachment 558827View attachment 558828View attachment 558829

Thank you!!! I’ve been searching all over for a diagram. I will trace it out tomorrow.

 

[B1Toad]

Thank you!!! I’ve been searching all over for a diagram. I will trace it out tomorrow.

There is a free pdf of your factory service manual in our resources section.

https://wranglertjforum.com/attachments/1997-jeep-wrangler-service-manual-pdf.308365/

 

[AndyG]

Whatever happened to “fuel-fire-compression”.

Do you have fire? At the plugs.

 

[B1Toad]

If you are absolutely sure there is no power to one of the relay pins (with the key off) it's got to be in that section from C100 to S100. On the other hand, if there is power to the relay with the key off and you missed it (and the ASD is indeed not closing), it points to the ECM or the ECM connector. The ECM sends the ground signal to the ASD coil.

 

[pgf001]

If you are absolutely sure there is no power to one of the relay pins (with the key off) it's got to be in that section from C100 to S100. On the other hand, if there is power to the relay with the key off and you missed it (and the ASD is indeed not closing), it points to the ECM or the ECM connector. The ECM sends the ground signal to the ASD coil.

Thanks everyone for the help so far!

Update: I was able to start the Jeep by adding a jumper behind the connector box. I placed a jumper from the fuse to the normally hot relay leg.

However, I haven’t been able to find the cause yet. From the fuse the red wire with white stripe runs back towards the cab. I have not removed the corrugated tube that surrounds the harness yet. I do see the wire in two places. It is a part of a connector under the hood and a part of a connector that lands on a terminal under the left speaker on drivers side by

 

[pgf001]

Whatever happened to “fuel-fire-compression”.

Do you have fire? At the plugs.

I do after jumping the ASD relay. It seems to have prevented it from firing off

 

[B1Toad]

The red/wht wire splits into 2 at splice S100 near the battery so be sure to find that and check the splice. It comes from the fuse and hits the splice first, then one wire comes out of the splice and goes to the ASD and the other one goes to the ECM through connector C150. (The one from the 40 amp fuse comes out of the PDC, hits the splice, then a second one heads out of the splice back to the PDC to power up the ASD always hot terminal)

 

[pgf001]

The red/wht wire splits into 2 at splice S100 near the battery so be sure to find that and check the splice. It comes from the fuse and hits the splice first, then one wire comes out of the splice and goes to the ASD and the other one goes to the ECM through connector C150. (The one from the 40 amp fuse comes out of the PDC, hits the splice, then a second one heads out of the splice back to the PDC to power up the ASD always hot terminal)

Looks like the output fuse wire was nicked long ago just before the splice. The harness appeared to be in the original corrugated tubing with electrical tape underneath. Basically fell to dust as I took it apart.

 

[B1Toad]

Good job! I'd call that a smoking gun!