2000 Sahara cranks but does not start

[mashenden]

It seems the issue is either fuel or ignition related. After a fair amount of research, I feel like I have some things to check.

The plan is to listen for the whirring of the fuel pump after switching on the ignition.

Also, we hope to check for a worn wire behind the valve cover and confirm if the plugs have a spark.

We also have not ruled out the ECM.

A couple of questions:

1. If there is a spark, is the ASD relay or the crankshaft position sensor more notorious for going bad?
2. If the fuel pump is bad will fuel squirt out of the schrader valve (its a no start problem)? Looking for an easy buttton to narrow down if its the fuel pump

 

[Daryl]

Remove the air intake tube from the throttle body. Spray a small amount of starting fluid into throttle body while a second person is cranking the engine over. If it runs you have a fuel supply issue.

 

[GregBelleville]

It seems the issue is either fuel or ignition related. After a fair amount of research, I feel like I have some things to check.

The plan is to listen for the whirring of the fuel pump after switching on the ignition.

Also, we hope to check for a worn wire behind the valve cover and confirm if the plugs have a spark.

We also have not ruled out the ECM.

A couple of questions:

1. If there is a spark, is the ASD relay or the crankshaft position sensor more notorious for going bad?
2. If the fuel pump is bad will fuel squirt out of the schrader valve (its a no start problem)? Looking for an easy buttton to narrow down if its the fuel pump

If you have spark then the ASD relay and CPS should be fine, as either of those malfunctioning should cause a no spark condition.

To confirm fuel pressure you should get a loaner fuel pressure gauge from your local auto parts store to confirm the fuel pressure is within spec, which I believe is around 50 PSI. Just pressing the Schroeder valve isn't enough as the pressure may still be to low even if fuel comes out.

I went through this recently with my 99, and fwiw my problem ended up being the connection to the ignition coil was not good. All I did was disconnect and reconnect it and she started right up.

I'd recommend confirming if it's fuel or spark first. If it's spark, then try what I did and disconnect and reconnect the following to see if it's just a bad connection:
1. Crank position sensor
2. Camshaft position sensor
3. Ignition coil
4. Swap ASD relay with the horn relay

Do you have any check engine light codes by the way?

 

[mashenden]

Remove the air intake tube from the throttle body. Spray a small amount of starting fluid into throttle body while a second person is cranking the engine over. If it runs you have a fuel supply issue.

Good idea. We purchased starting fluid for exactly that. Thank you.

 

[mashenden]

If you have spark then the ASD relay and CPS should be fine, as either of those malfunctioning should cause a no spark condition.

To confirm fuel pressure you should get a loaner fuel pressure gauge from your local auto parts store to confirm the fuel pressure is within spec, which I believe is around 50 PSI. Just pressing the Schroeder valve isn't enough as the pressure may still be to low even if fuel comes out.

I went through this recently with my 99, and fwiw my problem ended up being the connection to the ignition coil was not good. All I did was disconnect and reconnect it and she started right up.

I'd recommend confirming if it's fuel or spark first. If it's spark, then try what I did and disconnect and reconnect the following to see if it's just a bad connection:
1. Crank position sensor
2. Camshaft position sensor
3. Ignition coil
4. Swap ASD relay with the horn relay

Do you have any check engine light codes by the way?

 

[mashenden]

Good to know that if there is a spark then it's not the relay or crankshaft position sensor. Thank you!!

Unfortunately getting a loaner pressure gauge is not an option as the jeep is in the Keys and I am helping troubleshoot remotely. All options need to be something that is fairly easy and no more than a bike ride away to try.

With that in mind, is it safe to say that if fuel does not come out when pressing the Schroeder valve, then something is causing the fuel pump to not run (possibly a bad pump, bad relay, or bad cps)? Put another way, when the fuel pump is working correctly does the fuel rail always have pressure even when the engine is not running?

Also, does the 2000 Sahara have an ignition coil? I had it in my mind, maybe incorrectly, that it has coil packs.

 

[mashenden]

Arrg!! Can anyone confirm the MOPAR part number for a crankshaft position sensor on a 2000 Jeep Wrangler Sahara with the 4.0 L (6 cyl) and a manual transmission? After an exhaustive Google search, it seems there are many part numbers (4897321-AB, 4897321-AA, 4897321-AC, 68407888AA, etc), some with 1 bolt hole and others with 2 bolt holes, some for an automatic transmission, others for a manual, but nothing that shows the right one for a 2000. Apparently even the dealerships have been known to get this wrong!! Or maybe its not as critical as it once was... dunno.

So first off, is it supposed to be a one or two hole sensor on this year/model? Unfortuatnly I am not at the vehicle to get under it

I think the part number is 68407888AA, but not yet sure enough to order one. Can anyone confirm?

While I am not yet convinced that this is the problem, conventional wisdom seems to be that its a good idea to carry one that is OEM (not after market - been down that rabbit hole before) so buying one does not seem like money wasted even if its not the immediate problem. Oh, and it has recently had the tranny rebuilt so checking the Crankshaft Position Sensor connection is high on the list of things to look at.

 

[mashenden]

Current plan:

1. Listen for fuel pump whirring when ignition is first turned on.
2. Press Schroeder valve just to see if there is any pressure at all in the fuel rail.
3. Look for wire chafing on vertical threaded stud behind the valve cover
4. Check if ASD relay is clicking - maybe swap with horn relay
5. Squirt starting fluid into air intake to see if it tries to start
6. Inspect Crankshaft Position Sensor connection etc - the tranny was recently rebuilt.
7. If 1 thru 6 do not determine a direction (ignition vs fuel), then check for a spark by removing coil pack and putting a grounded spark plug in one. Maybe replace the coil pack. Not overly expensive.
8. Buy crankshaft position sensor so that the local shop will have it if it needs to be replaced.
9. Consider buying an ECM - Easy install but a bit hard to swallow given the price, particularly without testing 1-7 first.
10. Consider taking to shop to see if fuel pump is the problem

This is likely to change as I get more answers to questions, but its a start.

 

[mashenden]

Current plan:

1. Listen for fuel pump whirring when ignition is first turned on.
2. Press Schroeder valve just to see if there is any pressure at all in the fuel rail.
3. Look for wire chafing on vertical threaded stud behind the valve cover
4. Check if ASD relay is clicking - maybe swap with horn relay
5. Squirt starting fluid into air intake to see if it tries to start
6. Inspect Crankshaft Position Sensor connection etc - the tranny was recently rebuilt.
7. If 1 thru 6 do not determine a direction (ignition vs fuel), then check for a spark by removing coil pack and putting a grounded spark plug in one. Maybe replace the coil pack. Not overly expensive.
8. Buy crankshaft position sensor so that the local shop will have it if it needs to be replaced.
9. Consider buying an ECM - Easy install but a bit hard to swallow given the price, particularly without testing 1-7 first.
10. Consider taking to shop to see if fuel pump is the problem

This is likely to change as I get more answers to questions, but its a start.

UPDATE - Sorry for the slow update - this was resolved back in April.

This should make everyone's day

The problem was... (drum roll) ... a loose starter. Please keep in mind that I was trying to troubleshoot over the phone and posted this in an effort to have as much of a plan as possible so I could hit the ground running once I got to the Keys. All that was for nought though as the problem became apparent very quickly!!

Apparently when the transmission was repaired, they forgot to fully tighten the starter. One bolt was missing and the other barely hanging on.

This was the cheapest Jeep repair of my life