I have a 1996 Jeep Cherokee Country 4.0 runs good cold except wont take gas when u kick it down to pass. Slowly picks it up to catch up but when motor hot not temp hot normal hot and then you cut it off and restart then starts right back but it sputters and dies then after 3 or 4 restarting attempts then it dies then wont start back. It cranks but no start untill after it sits for about 30 min.s then will start right up and run good till it does the same as above. im thinking fuel pump getting hot except you can add gas to throttle body as i crank it and pump gas pedal and it will finely start back after adding about a inch or so of gas to the throttle body from gas in a pop bottle. I have had codes run and it does show me po108 MAP SENSOR ,po118 ENGINE COOLANT TEMP SENSOR ,po171 02 SENSOR running lean. Will these codes cause it to do what its doing? I have replaced fuel filter,air filter,plugs,, cleaned all grounds. Cleaned throttle body, cleaned TPS and IAC.

 

Not sure what your issue is.

 

Follow the codes, always. And use a testing based strategy to determine root cause. Get yourself a good manual if you don't already have one; essential to any XJ owner.

1. Failing MAP sensor can screw with fuel/air ratio. They can be tested with a meter and a manual. Be sure that the vacuum line leading to that sensor is in good shape and pulling good vacuum.

2. Coolant temp sensor can also be tested for resistance changes. Instead of removing it, I can generally get a good enough idea if it is working properly by testing it cold, then when hot. Compare your resistances to the chart in your manual.

3. Test fuel pressure. Must be done with a gauge. 96 was a year of change for fuel systems on the XJ but if yours has a fuel filter along the fuel rail, you have the old system where fuel pressure is 31 psi. Then remove the vacuum line leading to the fuel pressure regulator and the pressure should jump to approximately 39 psi. Be sure that the vacuum line leading to the FPR is good and if there is raw fuel in that vacuum line, then replace the regulator as the diaphragm is faulty.

Performing testing on the above three things is a good start to figuring out what your problem is. Good luck and keep us updated!

 

OldTires -

If I read correctly
- Motor runs fine when cold (pre-operating temp).
- When motor is at operating temp, engine bogs down, (not sure if it dies).
- Crank no-start when engine is hot - starts fine when cold.
- 3 codes P0108, P0118, P0171

Original Poster -

If you suspect a fuel pump issue - you can (and should) check your fuel pressure with a test gauge. You can buy one relatively inexpensively at Harbor Freight or go to your local parts retailer (Autozone, Advance, Napa, etc) and get one as a loaner tool. Free, but you have to leave a deposit until returned.

I would start by doing diagnostics on the MAP sensor and Coolant Temp sensor (the Map sensor is on the firewall and the CTS is on the t-stat housing. There are a wide array of videos on YouTube that will guide you through this process. As the first step of each, however, you need to check that the wires and connectors are in good condition - you don't want to be replacing perfectly good sensors because of a bad connection and on a 20+ year old vehicle, it's common to find bad wires and corroded connections.

I personally don't have a lot of experience with testing these components, but since you have codes, that's where I would start unless someone more knowledgeable than I has a better suggestion.

 

Ah I see now. Then what TJ and Pat wrote about are good places to start.