drove fine..parked..now wont start. please help!

Heres the situation:

I drove around and everything was running just fine. I parked my jeep in my driveway. I had to replace the radiator fan switch because I noticed my fan wasn't kicking on, so I did just that. After that was done I started the car, well tried to start the car and it would only crank. I thought that was weird.

I listened for the fuel pump and couldn't hear anything so i went to the store and replaced fuel pump relay. Nothing. Then I thought it was the fuel pump itself so i dropped the tank, replaced the pump and still NOTHING. It just cranks and doesnt turn over.

I read that the crank position sensor is the culprit in situations like this...but another mystery to me is that the gas guage is reading E. I know for a fact there is gasoline in the tank because i refilled it after doing the fuel pump. If the crank sensor was bad would the gas gauge not read?

Any help with anything at all in regards to these problems would be hugely appreciated. Cheers!

throwing parts at it just because you thought it would fix it is not the way to go. so far you spent good money on hunches and now you're going to spend more because people on these forums love to guess parts to see if their guess will fix your problem. did you even check for spark or fuel pressure?

radiator fan switch? this sounds bad already? what radiator fan switch? and who installed it? I would take some time to figure out what else dont work maybe you have blown a fuze or a link? does your dash lights come on when you turn the key on particullarly the check engine light? if thoes work crank it and see if the rpm gauge moves. let me know what happens. also what is this vehicule? year make model?

no shit. same thing just happened to me. check the four wires going to the pump. Mine had a small slit in it, and the inside of the wire was so coroded it fell apart. Mine happened to be the green wire, give it a look. Its free to check this out, and you wont be throwing money at it. But like MrJCrod said, go through the diagnostic steps. Before you check that wire, Id check the two fuses that control the fuel pump relay. If there good, I'd check that wire out. But deffinitly check fuel pressure if you have fuel pressure then id start looking elsewhere. I take it your not spitting any codes. Your sending unit works of ohms, not power. So that wire may be corroded to, Check out the plug that fuel pump plugs into the wiring harness, your looking for green shit.

PS your CPS has nothing to do with your fuel pump reading empty. Dont go changing that yet. its only 30 bucks, but it cost more than that in your time to change it. Furthermore, with a good multimeter you can run tests on almost any sensor to see if its doing its job.

maybe you broke the sender replacing the pump, maybe the wires are shorted

good advice above, start with the basics and check fuel pressure

If the fuel pump is not energizing when the key is turned to the ON position and you already replaced the pump, you could have either a control problem (fuse/relay) or a wiring problem as mentioned.

It would also be very helpful to know if you have spark or not. Takes all of 10 minutes to pull a plug, ground the electrode, have a buddy crank the engine while you watch. You're looking for a strong, blue, snapping spark.

If the pump isn't running at all, we know that you're missing the fuel component of the starting equation, but if you are missing both fuel AND spark, that will shorten the suspect list....

Good luck and let us know what you find!

I see you are a newbie, so you broke the first rule already. Model year, engine, tranny, etc. are helpfull to get you good info.

Pump will only pump with key ON for about 3 seconds unless engine is running. It should pump all the time with key in START position.

Reason to test for spark is that if you have spark, that means that your CKP crank positon sensor is working.

Did you unhook the negative terminal on the battery when you installed the fan switch?

If so, take it off and clean the connection good. Make sure you have a good connection.

winterbeater said:

I see you are a newbie, so you broke the first rule already. Model year, engine, tranny, etc. are helpfull to get you good info.

Pump will only pump with key ON for about 3 seconds unless engine is running. It should pump all the time with key in START position.

Reason to test for spark is that if you have spark, that means that your CKP crank positon sensor is working.

Click to expand...

X2 on everything he said. un plug the conection at the fuel pump, and have a freind turn on the ignition, using a 12v curcuit tester (just a little probe with a light and a ground clip) check all four of those wires in the plug. Remember you only have 3 seconds. you should get power from at least one, maybe two...check the haynes or chilton to verify. Unless someone on here can accomadate for my shortcoming. *sorry!* if you have no power, then its either a short....or a bad fuse/relay (there is two fuses for the fuel pump)

Check your battery voltage while cranking with a meter on the battery, not the dash gauge... if it reads below 9.5 the ECU probably won't let the engine start, engine electronics won't work without at least 9 volts to the whole system.

It cranks, so it's not the NSS. Assuming it's a RENIX year since you have a radiator fan switch, so the gas gauge works independently of the ECU, thus you can draw no conclusions from that. Make sure all your fuses are good also.

yea sorry folks. Its a 1997 4.0 5 speed Cherokee. I appreciate all the responses i will try all those this weekend and will reply with my findings.

Since the gas gauge is not working has this problem affected any of the other instrument gauges?

Here is a list of fuses for the '97 that may aid in your troubleshooting.

Power distribution center (under the hood)
Looking at the PDC from the front of the vehicle, the bottom right mini fuse is #16, the one above it is #17, the top one in the column is #18.
Fuse #19 is to the left (of #16)

Fuse #16 underhood lamp, transmission control module, radio & interior lights
Fuse #17 O2 downstream relay
fuse #18 coil rail & injectors
Fuse #19 headlamp switch & data connector
Fuse #20 combination flasher
Fuse #22 fuel pump relay
Fuse #23 brakelamp switch
Fuse #25 fog lamp relay
Fuse #26 power amplifier

Junction/fuse block (inside kick panel)
Fuse #1 is the large 25A on the top of the left column
Fuse #15 is the large 25A on the top of the right column

Fuse #1 power outlet
Fuse #2 cigar lighter
Fuse #3 left headlamp
Fuse #4 left headlamp
Fuse #5 right headlamp
Fuse #6 Dash lights (switches, controls, gauge cluster)
Fuse #7 license light & the left side turn, parking, marker and tail lamp
Fuse #8 Spare
Fuse #9 compass, sentry key, headlamp delay module, instrument cluster
Fuse #10 transmission range sensor, duty cycle evap/purge solenoid, radiator fan relay, a/c clutch relay, o2 sensor up/downstream relays, back up lamp switch
Fuse #11 transmission control module, powertrain control module, automatic shutdown relay, fuel pump relay
Fuse #12 instrument cluster, combination flasher
Fuse #13 Spare
Fuse #14 power mirrors, rear defogger & switch
Fuse #15 passenger power lock/window switch
Fuse #16 cargo lamp/switch, courtesy lamps, radio, instrument cluster, underhood lamp, transmission control module
Fuse #17 radio
Fuse #18 power mirror switch, driver power window/lock switch, heated seats
Fuse #19 starter motor relay
Fuse #20 trailer tow harness & trailer turn relays
Fuse #21 horn(s)
Fuse #22 rear wiper switch & motor
Fuse #23 right side marker, turn, parking and tail lights
Fuse #24 Spare
Fuse #25 shift lock solenoid, a/c heater control, abs controller, abs controller relay, blower motor relay, blend door actuator
Fuse #26 airbag control module
Fuse #27 airbag control module

alright so i tried everything this weekend. I went through all the fuses and relays and they are all good. I sprayed starter fluid into the throttle body and tried to fire it up and it was a no go. I pulled a plug and checked for spark and none. How can i park it and then try to start it and poof no spark? Any suggestions would be hugely appreciated. TIA.

Causes of NO SPARK:

Bad CKP/CPS crank sensor--without its signal the ECU/PCM will not trigger the coil.

Bad ASD/B Latch relay--this provides 12 volts input to the coil and the 12 volt signal to prime the fuel pump for 3 seconds.

Bad coil.

Bad coil-to-distributor wire.

Bad rotor.

Bad distributor/cam/timing chain and rotor is not turning.

Bad PCM/ECU.

Bad grounds/connections of the listed parts.

There is your list. Start with the easy stuff--is the rotor turning? Does the coil-to-distributor wire have continuity? Is there 12 volts input to the coil? Does the CKP/CPS crank sensor (91~01) have infinite resistance?

You just need to identify the missing piece.

I have a freind with a simalar problem.

what is the ASD/B Latch relay?

ASD, auto shutdown.

B Latch, well, that is what the Renix FSM calls the ASD relay.

so after some figuring around i figured out what happened.

when i had first checked to see if my radiator fan was working i used to wires to jump the switch off the battery. I didnt realize that there were "two" switches that control the fan and i jumped the brass one by the thermostat. I guess that sensor can only hand 5v and obviously the batter voltage was too much.

I figured out i fried my computer...yea i know...wtf! Called the dealer found out what i needed in a computer (serial numbers) and found one on ebay thats an exact match to what the guy said at the dealership. I out it in and now still DOESNT START.

The fuel pump turns on, all the gauges work and everything seems to be working just wont turn over.

Any answers on why im not getting spark and its still not starting?? thanks folks.

This is where a scan tool would come in handy. It's newer than 96 so you can use any OBD-2 scanner. Hook it up, does it communicate with the pcm, read codes and get into live data? Yes, pcm's ok. No, pcm may be bad or power/ ground issue.

If you can get into live data, take a look at the rpm reading. No rpm shown during cranking and the computer doesn't know the engine's trying to start, so no fuel/ spark etc.

This may be one of those times where it's cheaper for a pro diag than a parts chucking contest.