98 Cherokee Limited loss if power, wont start....

I just picked up a 98 Cherokee Limited last Friday, drove really well until last night. Driving at 35mph then it felt as though I was losing spark and the engine slowly faded until it stalled. The RPM were bouncing all over the place between 100 to 3000.

I was able to keep it runnning for half a minute by pumping the gas pedal but it sounded like it was back firing on the drivers side???

No Engine light showed up, 3/8 of a tank of fuel and has a new battery. Can I pull the codes of this year by the on off with the ignition or do I need to connect it to an OBDII scanner?

Any ideas??? Thank you for your help!

Z

OBDII to pull codes but since it died on you while driving it may have stored a code that will help you. If you get no RPM on the tach when cranking possible crank sensor died. Assuming it cranks but won't start.

I will plug it in after work and see what code shows up if any. It will crank over but not fire up.

I'll pick up a crank position sensor today at lunch and swap it out and see how that goes.

Is it common for CPS to fail on these Jeeps?

Thanks

Somewhat yes

So I changed the CPS and still no go???

I pluged it into a Snap On MT2500 scanner with the Jeep modules and it didn't pull any codes. I tested the relays and they all operate properly, I tested the fuel pump and it operates properly/

I am completely stumped? I bled the fuel rail from the schrader valve and there was some gas that came out. Not much pressure behind it though just a trickle came out. I don't have a fuel pressure tester should I go and buy one?

I performed the instrument cluster test and all the lights and gauges worked properly. My tank shows 3/8ths full, does the level gauge fail in Cherokees? could I be out of gas?

The battery is being charged overnight and will try to start it before I go to work in the morning. If the bat voltage is low could this pose an issue? The scanner read that it was at 12.7V; do I need 14.4V?

Coul dit be that I have an issue with my alternator, do you think this could be affecting it?

Any suggestions would be appreciated.

Thank you all for your help!!!

Z

Wow. Lots of questions!

Yes, if the voltage drops below 9 volts the electronics will either not work or give you screwy results. A fully charged battery, that has passed a load test, is essential. Next is good cables with clean connections--good cables as in tested with an ohm meter, should be at or near zero resistance. Clean and tight grounds, with special attention to the head-to-firewall POS braided strap.

Get a spare spark plug or pull one from the engine. Attach a spark plug wire to the plug and ground the body of the plug to the engine--a medium size jumper wire with clamps works well. You may not want to hold the spark plug against the engine with your hand--I wouldn't. Have a friend crank the engine and watch for the spark--bright blue and snapping is good. Yellow, not so good. Pick up a Bosch/Ford NOID light at any parts store, about $3 for a single. Unhook the harness from one injector, insert the NOID light in the harness. Crank the engine, you should see a flashing light indicating the the ECU/PCM is sending an injector pulse to fire the fuel injectors. If you haven't found the missing component by now then rent a fuel gauge, attatch it to the Schrader valve and crank it up to see how much pressure there is. Should be a healthy 49 psi, plus or minus 4 psi.

Post back your results.

XJZeee said:

I bled the fuel rail from the schrader valve and there was some gas that came out. Not much pressure behind it though just a trickle came out. I don't have a fuel pressure tester should I go and buy one?

My tank shows 3/8ths full, does the level gauge fail in Cherokees? could I be out of gas?

Click to expand...

You can always put some gas in. Have someone cycle the key on while you push the valve in and see if you get any pressure then. I think some auto parts stores may rent tools, I'd check that but if need be it can't hurt to have a fuel pressure gauge.

Even if you don't get fuel pressure you can jumper the fuel pump relay to see if it runs and/or you get pressure. If not you can check for power and ground at the pump connector under the Jeep back by the tank. You will only have power to the fuel pump for 2-3 seconds when the key is turned on. If the PCM sees the engine cranking over it will turn the pump back on and keep it on as long as the engine is turning (cranking or running).

16DG/WT FUEL PUMP FEED
Z1 16BK GROUND