Crank but no start

[lu_cas]

Hello guys , this is my first post in the forum. I have a 98 tj sport with the 5-speed manual. A couple weeks ago i started having issues were the jeep will suddenly stall and later crank with no start. We first changed the coil , the jeep started and ran for a couple days and then back again to no starting. Today i changed the CPS , it ran for 5 minutes then stalled again and have no start again.
i´m clueless on what to do now. I´m from Argentina , so parts availability is a little tricky.

 

[Chris]

Hello guys , this is my first post in the forum. I have a 98 tj sport with the 5-speed manual. A couple weeks ago i started having issues were the jeep will suddenly stall and later crank with no start. We first changed the coil , the jeep started and ran for a couple days and then back again to no starting. Today i changed the CPS , it ran for 5 minutes then stalled again and have no start again.
i´m clueless on what to do now. I´m from Argentina , so parts availability is a little tricky.

Since you've already replaced the coil and the crankshaft position sensor (CPS), here are a few more things to check:

• Use an OBDII scanner to figure out if it's throwing any codes. This could provide more insight into what might be causing the problem. This is where you should start.
• Ensure that your fuel pump is functioning properly and that there is adequate fuel pressure. A failing fuel pump or clogged fuel filter could cause stalling and no start conditions.
• Check the spark plugs and wires. Worn out spark plugs can lead to performance issues. Also, confirm that you're getting a strong spark when cranking.
• Ensure that your battery is fully charged and inspect the connections for any corrosion or loose wires. A weak battery can crank but not provide enough power to start the engine.
• Make sure all ground connections are clean and secure. Bad grounds can cause erratic electrical issues.
• Look into the possibility of a faulty PCM or blown fuses related to the ignition and fuel systems.

Good luck, and let us know how it goes!

 

[macleanflood]

Check your fuel pressure on the rail and listen for the fuel pump to kick on when you turn the key to run but not start.

-Mac

 

[CharlesHS]

Do you have access to a digital multi meter to do some testing ?
When this problem occurs turn the ignition to ON; do you hear the fuel pump run for approximately 3-5 seconds ?
IF the fuel pump does not run; does the Fuel Pump relay engage (feel for a snap on the relay body) when ignition is placed to ON ?
IF not... test to see if 12V power is available to relay (relay terminal 30).
IF 12V power is available when ignition is placed to ON and the relay still does not engage; the problem is the relays magnetic coil or internal contacts.
With relay removed from the PCM; test the coils magnetic windings by measuring continuity (Ohms) across the relay windings (relay terminals 85 & 86). This should be around 70 Ohms.
IF not; replace the relay.
Test Automatic Shut Down relay with the same procedure used to test the Fuel Pump relay.

 

[Rosco1216]

I just started having an issue for the first time and mine won’t start. Never had any issue starting before but after a month of sitting it wouldn’t start. Would crank and crank forever but not fire.

Mechanic friend came and tried every trick to get it started or find the issue but couldn’t get it started. Wasn’t getting spark and Checked signals and found there wasn’t a signal or current to the distributor cap.

Apart from towing and having a full diagnostic ran. Any suggestions?

 

[macleanflood]

Clean battery terminals and grounds. Check fuses. Check ASD relay...swap it with the horn.

Can you hear the fuel pump running?

-Mac

 

[Rosco1216]

I just started having an issue for the first time and mine won’t start. Never had any issue starting before but after a month of sitting it wouldn’t start. Would crank and crank forever but not fire.

Mechanic friend came and tried every trick to get it started or find the issue but couldn’t get it started. Wasn’t getting spark and Checked signals and found there wasn’t a signal or current to the distributor cap.

Apart from towing and having a full diagnostic ran. Any suggestions?

He thought it was probably the ecm but couldn’t be certain and I don’t want to buy a new one and that not fix the issue.

 

[JKP]

Spark requires the crank sensor signal to the PCM, PCM grounds coil to fire. Coil should have 12V on one wire and pulsed ground from PCM on the other.

The cam sensor is in the distributor, and if there's no cam sensor signal to the PCM, it won't run either.

 

[CharlesHS]

I just started having an issue for the first time and mine won’t start. Never had any issue starting before but after a month of sitting it wouldn’t start. Would crank and crank forever but not fire.

Mechanic friend came and tried every trick to get it started or find the issue but couldn’t get it started. Wasn’t getting spark and Checked signals and found there wasn’t a signal or current to the distributor cap.

Apart from towing and having a full diagnostic ran. Any suggestions?

Please read my response #4 above; this may assist your with your problem ....

Do you have access to a digital multi meter to do some testing ?
When this problem occurs turn the ignition to ON; do you hear the fuel pump run for approximately 3-5 seconds ?
IF the fuel pump does not run; does the Fuel Pump relay engage (feel for a snap on the relay body) when ignition is placed to ON ?
IF not... test to see if 12V power is available to relay (relay terminal 30).
IF 12V power is available when ignition is placed to ON and the relay still does not engage; the problem is the relays magnetic coil or internal contacts.
With relay removed from the PCM; test the coils magnetic windings by measuring continuity (Ohms) across the relay windings (relay terminals 85 & 86). This should be around 70 Ohms.
IF not; replace the relay.
Test Automatic Shut Down relay with the same procedure used to test the Fuel Pump relay.