View Full Version : Well that was a waste of $200

09-01-2007, 04:44 PM
Well I just spent most of my Saturday of the long weekend replacing my fuel pump just to find out that it WASN'T the culprit of my trouble starting. [16]

Really it wasn't a waste of $200 because it has 130k on it and it saves me from leaving me stranded if the old one did eventually die.

So here's my plea to those out there that know 4.0L really good.

If I leave my truck sitting for more than an hour and go to try to start it, the first try it wont start, no matter how long I crank it for, second time I try to start it it does the same thing but some times sputters, third time, starts no problem :confused: :confused: :confused:

09-01-2007, 05:34 PM
At least ya have a spare pump now:dontknow:

09-01-2007, 06:44 PM
It could be anything. Fouled plugs, cracked or broken plug wires, bad dist cap and or rotor, :confused0006: coil could be fubared... the list goes on my friend.

09-01-2007, 08:07 PM
I had that problem with a vw , it was the fuel accumulator , it kept pressure to the injectors or something along that line .

didnt affect it cold as the coldstart valve would add extra fuel to start it .

it seems to prevent something like vapour lock

BUT maybe the heep dosnt have something like that .

09-01-2007, 09:16 PM
have you changed your fuel filter recently? cleaned your injectors? first two thoughts for me.

09-02-2007, 10:27 AM
fuel filter is internal in the tank, no external pump,

09-02-2007, 02:15 PM
fuel filter is internal in the tank, no external pump,

what year? My 90 xj has the fuel filter is beside the tank. easy to access!

Mr Vic
09-02-2007, 03:25 PM
fuel filter should be on on the frame in front of the tank was on my 88 a nd my 93 cherokee. could possibly be plugs, cap, rotor or CPS sensor?

09-02-2007, 07:44 PM
Isn't there a flow-back valve or something? My swift does the same thing if I leave the key in the ON position without starting it, the fuel pump primes up and then sits - if I wait about ten minutes and try to start it it wont start. I turn the key off, then on again, the fuel pump kicks up and it starts with no problems.

09-02-2007, 08:01 PM
Check your CPS...crank position sensor. When it goes the engine won't start, or will only start sometimes. It's located on the bellhousing of the tranny, at the back of the engine.

09-03-2007, 10:15 AM
I got a 90 xj and i got home from work the other day, fired it up first try parked it in my drive way. went to start it again, it started then it got worse,sputtered, then stalled and wouldnt start, i guess i ran it out of gas then vapour locked it. i put some gas down the throttle body and it fired right up. still fires up everytime now. i guess i should fix my gas gauge lol. i dunno about urs though.

09-03-2007, 11:38 AM
I have the same problem, it always starts but sometimes its pain in the ass. Hot-starts after it's been sitting for a bit seem to be the worst.

Scanner shows open loop, and all sensors show within specs, everything looks fine.

I did my fuel pump and filter, injector o-rings, cleaned the injectors, TPS, and 02 sensor. Battery and alt are new cranks fast. I am thinking of doing cap/rotor/wires/plugs next or maybe it could be a stuck injector because it smells rich and runs a little rough at first. Sometimes it hesitates a bit too when cold.

09-03-2007, 12:12 PM
Check your CPS...crank position sensor. When it goes the engine won't start, or will only start sometimes. It's located on the bellhousing of the tranny, at the back of the engine.

ding ding ding ... [stupid] ... see this alot pull it off and clean it ... if it need's internal part's we rebuild them all the time ;) ...


09-04-2007, 07:04 AM
[stupid] [iagree] crank sensore dude! happened to me.

09-04-2007, 09:57 AM
Sweet thanks guys, so you think if I just clean it off it should be fine? I'm thinkin I might buy a new one anyway....

09-04-2007, 10:27 AM
Sweet thanks guys, so you think if I just clean it off it should be fine? I'm thinkin I might buy a new one anyway....

why spend more ? ...


09-04-2007, 04:07 PM
well tried cleaning it off, and re-installed it... didn't take longer than about 45 mins to do, tried starting it again, and same problem. Even tried moving the relays around to see if might be that. I think I'm in for a new CKPS

09-04-2007, 10:36 PM
why spend more ? ...


Never heard of cleaning the CPS? Shouldn't cause a no start as the dirt doesn't interfere with the hall effect signal, and they don't ground through the case as far as I know. I've seen wheel speed sensors with rust built up under them cause unnecessary abs activation though, but the bell housing on a Jeep is aluminum.

I'd just spend the $70 or so and buy a new one. Gotta do it to mine so I don't get stranded some day, no idea how old mine is! :D

09-05-2007, 04:30 PM
NAPA quoted me $197 for the damn sensor...

09-05-2007, 07:12 PM
As someone who works as a mechanic.....and has to rely on NAPA....I can say without a shadow of a doubt, RIP OFF ! call Lordco.......failing that, call the dealer......Mopar isn't so bad lately for prices......even ack GM dealers are sellin parts for reasonable costs lately

09-05-2007, 07:39 PM
The TDC sensor (crank pos sens) won't cause hard start situations it will cause intermitent NO start no spark problems, but the cam pos sensor can cause hard start situations it is located in the distributor this sensor has nothing to do with ignition it is there for timing the injectors as it is a sequential fire injection when the sensor goes the computer can go into a limp mode and still time the injectors but it takes a while of cranking to start.

Or the other thing which will be easier to diagnose is a possible leaky injector or some other fuel leak. Get the truck hot and attach a fuel pressure gauge to the shrader valve on the fuel rail and shut the truck off see how long it takes for the fuel pressure to drop off. An passable system should hold good pressure for a couple of hours no substantial drop 5 to 10 psi max (that will be the bleed through on the check valve on the pump) a great system will actually build a bit of pressure when hot, the fuel expanding in the fuel rail with nowhere to go, but if the pressure drops off to almost 0 in a few minutes then you have a leak somewhere.

09-06-2007, 08:26 AM
Slightly different vehicle, but we have a caravan at work, same problem as you. A couple tries to start it, but once it was started purred like a kitten, ran perfect. All sensors seemed good, took it into Dodge, apperently the temp sensor was screwed, would prevent starting thinking that the motor was overheated.

09-08-2007, 10:57 PM
fuel pressure regulator?

09-19-2007, 03:40 PM
I have the same problem.

thanks for all the advice.

Ill giv'r a look too.

09-19-2007, 08:31 PM
well I'm startin to think I've got fuel leaking back into the tank and not holding pressure, because when I prime the fuel pump 3 times, the sound the fuel pump makes changes quite a bit, by the 3rd time it sounds normal. Gonna run the codes first (once I find someone with a OBD2 reader), then maybe go pick up a fuel injection pressure tester kit

09-25-2007, 10:40 PM
if u clean it and it still doesn't work then just go to the auto wreckers and get a used one i think there only $20 or u can get a new one there $120

09-26-2007, 10:57 AM
I'm starting to think its fuel leaking back to the tank. I should go spend the $60 for the fuel injection pressure tester kit, and if its that then I'm thinkin about using that $15 BMW in-line check valve, because if this is a regular problem with the cherokee's, I don't want to be ripping my tank down every couple years to do the damn check valve.

10-03-2007, 09:36 PM
Well I do believe that I've figured out what was going wrong with my truck.

It started throwing a code a couple weeks ago, got it scanned at a friends place and it came up with P1493 which is 'P1493....Battery Temperature Sensor Voltage Too Low'. I tested my battery shortly after and sure enough the battery was toast. So $150 later and a red-top battery from costco and now she starts on the first turn even after sitting for 8+ hours! Next step is to replace the battery cables.

10-05-2007, 11:46 PM
dont just clean it replace it and pack the old one in stirofoam for trail repairs.