usafjamie

Not sure who else to turn to and someone suggested here is the best to ask.

I just bought this 1999 Jeep Cherekee a few weeks ago. 4.0 V6 with all the options. Its been a good car so far and a good deal... 1,700.00 out the door. Runs good and most everything works but I have a few major issues and not sure if any are related to the other...

First, runs out of gas reliably at just over half a tank. I get it to the gas station and can only put in 8 gallons in it... I figured it sat a while and maybe bad gas so put some aditive in it to clean it out and has done it again consistantly 4 more times.

Second, Overdrive wont work. It seems to shift pretty evenly just not into high gear. At 65 mph I am running close to 3000 rpms. Transmition fluid is new, no particles in the fluids, and has 3 codes for selinoid, tcc, and speed sensor.

Third, and this is randome... when you start it alot wont work electrically... left turn signal, heating and air, speedometer, some lights inside the car, etc... but when you play with the key it all starts to work again. Messing with the key gets all that to work again but not sure if that could be causing my other problems.

Help guys... which should I concentrate on first and what should I do.
Limited on my knowledge and tools here.

Xj88

First..you posted in GC tech, but said its a Cherokee...which is it?

dave1123

You also stated it was a 4.0 V6. If it's a 4.0 it's a straight 6. There is an overdrive lockout switch in the shifter. Make sure it's not engaged. You need a new key switch also. I haven't a clue about the 1/2 gas tank problem, unless it got caved in.

PAFirefighter11

For the fuel tank issue it may be something with the filler or vent hose. I have seen some issues with this from customers and on the forums.

dave1123

My thought was the tank got punched and bent the pump mount or intake, not allowing it to draw off the bottom. There could be a suction leak on the pump intake when the fuel level drops below it. If it has been replaced, was it installed properly or even the right one? When it runs out of gas, is the pump still running?

Remote diagnosis is difficult at best. Especially if you don't have all the data.

If it was a filler or vent problem, it should be throwing an evap code.

usafjamie

Yes its a Cherokee... my bad I wasnt sure where to put it... I'm new here.

As for the gas, I havent had anything changed as of yet and dont have the tools to really get to it... has a house fire recently and still not moved back in yet. It is pretty consistant as to where it runs out, just over half a tank. I can only put back in 8 gallons at best so the indicator should be good. No codes for that at all. And no venting problem or back pressure in the tank. Not sure about dents or such but no visible damage anywhere.

For the Overdrive your right, straight 6. And there is a button on the shifter but does nothing. Not sure if thats an idication issue or just not working. I have 3 codes for the transmission yet no Engine light... strange right. Anyhow checked again today and there for Shift solenoid, TCC solenoid, and Speed Sensor. However this morning it seemed to work for the first time... for about 10 miles. Then it downshifted and went back to the 2800 rpms at 65 mph or so... all the other gears seem to shift normally.

still not sure if the electrical issue with the key could somehow be related to the Overdrive issue. Having 3 big problems like this makes it harder to figure out and I just dont want to give it to the dealership so they can change everything possible and charge me an arm and a leg. I have some tools but limited and about as good of knowledge to do it...

fletchFL

You will likely have to pull the tank and check the fuel pump/sender assembly. I agree with dave. In-tank, there is most likely a suction problem with the pump; fuel level drops to a certain point, pump won't suck anything but air.

First thing to check is all wiring connections on the transmission, and at the ECU; also look for corrosion and any pinched wires. Check battery voltage and alternator output, and verify the battery terminals are clean.

Dave said it here, too. I do particularly remember Jeep using GM ignition switches(among other things) on the Cherokees, not sure if they were still there by 99, but if it's the one I'm thinking of, it will be mounted on top of the steering column, under the dash, slightly behind the position of the gauge cluster. Even if it's a different style, it's pretty likely that's the cause for your electrical issue.

dave1123

I read something somewhere and I'm not sure where, something about if the Overdrive switch is activated for too long, it makes the TCM think something is wrong with the transmission. Maybe I'm smoking something or have delusions. If your indicator light is out, you really don't know if it's activated or not.

Chime in here, Blue. You must know something.

usafjamie

I will check those things this weekend for sure...

However, again this morning for the 3rd time now... the Overdrive works great for about 5 miles when cold... seems when cold everything shifts so smooth and works fine and then right at 5 miles once its good and warmed up it downshifts and back to no Overdrive... is this a symptom that helps narrow it down any. Again the fluid looks new and redish but there is alot of it and from what I can tell maybe even overfull.

dave1123

One of the things the TCM reads is engine temp. I'll bet your issue is with whatever sensor is involved with this input. As soon as the temp comes up, the overdrive cuts out. It's supposed to do that when overheating from heavy load.

usafjamie

thats kinda what I was leaning towards. But which sensor, relay, fuse, or whatever would have anything to do with that I just cant figure out.