My car wont start yet my RPMs are jumping?

Question

I have a 1993 Jeep Grand Cherokee and I use to have to wait 10 mins for my check engine light to go on before starting my vechile the colder it was the longer it would take to start. Now instead of the check engine light going on the RPM gauge jumps up to 2, then stops and I still cant start my Jeep. I change my fuel pump my fuel Relay automatic shut off relay and my fuel filter along with the crankshaft sensor. I am lost in what to do now after spending alot of money$ I got nowhere. IF anyone has ANY suggestions on to what it could be Please help

Answer 1

Don't throw parts at a problem, diagnose first. If possible put a code reader on it, it might point out the problem. If not, read on, I've included a number of possible issues.

The starter needs a lot of amperage to crank, dash lights & fuel pump do not, so a weak battery or dragging starter can cause a no-spark/no-start. But, before going to procedure below, lightly rap on all relays with a screwdriver handle, a sticking relay can cause all kinds of problems.
Here is the test procedure for determining battery or alternator problem after requiring a jump start. Note, requires a voltmeter [$3.50 at Harbor Freight]
1] Check battery voltage on non-start vehicle. Will probably be under 12V. Verify good clean connections, look for cracked corroded or loose terminals.
2] Jump start. Note, always have the the jumper vehicle running when performing a jump start, sounds basic but I actually had a friend who argued it should not, meaning he would be jumping with less voltage & could strand both vehicles.
3] With jumper cables removed, check voltage at battery. It should be 12.8V to 13.4V. If below 12.8V the alternator or voltage regulator are suspect. If in the range, the battery is either dead, low on water or in need of a full charge. If over 13.4V the voltage regulator is not functioning properly.
4] Failing those problems, with the vehicle shut off & the doors closed, disconnect the battery ground cable, put a 12V test light between the battery negative & a known good ground. If it lights, something, like an interior or glovebox lamp is staying on.

NO START but cranks
1st- check for good spark at the plugs. I use an old plug, clamp it to a good ground w/the plug wire attached.
2nd- if weak at step 1, try a jumper wire from coil output to a gap [such as the same test plug], if weak spark, verify full 12V at coil, if voltage present, replace coil. If not 12V, follow wiring diagram back, may have bad ballast resistor. If coil spark good, check cap/rotor for corrosion & check plug wires for less than 3,000 ohms of resistance per foot of wire. If this is a points ignition it may be due for points & condensor.
3rd- if spark appears okay then check for fuel &/or verify fuel pressure & volume. Check injector spray pattern. Check air filter. Dump a can of Dry-Gas in the tank, it may have moisture problems.
If possible check starter draw, it may be pulling too much current so there is not enough left for everything else.
Keep the battery charged while you work so you do not induce a phantom problem by running the battery low by too much cranking.

More NO-START
Possibly the battery in your keyless entry fob might be low, perhaps the weak signal is causing security system malfunction.
If still NG: Next, be absolutely certain that your battery connections, at both ends, are good. Buy a terminal cleaning tool. Replace any suspect connectors. Watch the battery terminal itself, if acid is leaking around it or it moves, replace the battery. Borrow a known good battery if possible.
If still NG: disconnect battery ground and then pull the large computer connector. If it is blade style use a pencil eraser to clean the contacts. The computer is usually near the glovebox, a Haynes or Clymer manual will help. Reconnect everything in reverse order.
Also, push all relays firmly into their sockets, if the problem is occurring, try tapping on each relay with a screwdriver handle, sometimes they stick. If tapping a particular relay resolves problem, replace.
Check the steering column switch, which is located at the bottom of the column, inside the car and operated by a rod coming from the key turn

RELAY TEST
Use a 12V test light or inexpensive volt/ohm meter [VOM] to see if both of the required input slots for the relay are live. Remember there is the blade for signal voltage & another for the pass through voltage, both12V. If either is dead, chase that circuit, if not, check to be sure the slot for ground is grounded [use ohm-meter or test light from +]. There should be a diagram on the side of the relay. A Haynes or Clymer manual might help.

Take your time, be methodical & good luck!
I was an ASE certified Technician & GNB Battery, customer service rep.

Answer 2

Battery should be good but still is it Swollen (Shorted) on the Sides "Signs of a Bad Cell" Have it Fully Charged then "Load Tested" at 50% of CCA for 15 Seconds not dropping below 9.6 Volts during the Test showing if the Battery can Take and Hold a Charge. Sounds like you could have a Bad Alternator that is Draining your Battery. Have the Alternator "Load Tested" to make sure it is Putting Out the Listed Amperage, Low Amps means Bad Diode(s) that Will Brain your Battery. Checks: Make sure All Ground Wires are Clean & Secure, Starter to Block, Alternator to Block and Block Strap to Firewall.

Answer 3

YOU SHOULD GET THE VEHICLES COMPUTER SCANNED AND CHECK FOR ANY PROBLEMS AS WELL AS CODES AND THEN YOU WILL HAVE A GOOD IDEA ON WHAT THE PROBLEM TRULY IS.

TRY FINDING AN INDEPENDENT SHOP INSTEAD OF THE DEALER OR A CHAIN STORE BECAUSE YOU WILL BE OVERALL MORE PLEASED WITH THE FINDINGS AND THE SERVICE.

LEAVE IT THERE WITH THEM SO THAT THEY CAN FIND THE PROBLEM FOR YOU, IT WILL BE A LOT BETTER THAN JUST REPLACING PART AFTER PART AND NOT DOING ANY GOOD.

Answer 4

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Answer 5

this seems to be a pure engine problem. The chek engine light appears to be related to a minor problem, but it usually results in a big one. You need to have your engine checked immediately.

Answer 6

the one thing you havent mentioned was that you have spark or even fuel. you need the basics, air, fuel and spark before it will even start. check for these and go from there