ok I have spark I have 40+ lbs at the fuel rail jeep tries to start sputtters but wont start.changed cps and same thing.Havent changed any of the other sensors .Is there a map sensor and a tps .I just need to get into your heads and give me a jump start on where to start.do you check the sensors like I do on my 87 renix I dont find any info on how to test the map or the tps please send lawyers guns and money

 

as someone who has been through the ringer this past year with my 97 GC, i can offer you what i've learned. first, your fuel pressure should fall between 44 - 54. if your at 44 or below, you definitely got a fuel pump or fuel accessory part problem. did your jeep just start having this problem out of the blue? have you had cranking or stalling issues leading up to this? you have a ASD relay fuse in your PDC fuse box behind your battery. swap it with your a/c clutch relay. there the same size and rating. just to see if it's that simple. before you blow money on sensors, have your ignition system checked out. you have a condenser, a module ( like a mini - computer ), an external ignition switch box, and a free neutral pin something. sometimes one of these is your culprit. especially if you are not getting any MIL or check engine light codes. they have sneaky symptoms like alot of the sensor symptoms. a short in or a going bad ignition part will drive you crazy. usually, you have some over- heating issues with a bad condenser or module. if you don't, focus on your external ignition switch box. my jeep would run great all day. turn it off and on multiple times a day. if it sat more than an hour and a half, it would turn over but, not fire up. 3 or 4 crank attempts later, it would start right up and stall after about 5 seconds or less. i changed all kinds of sensors and parts. still did not work right. before i go on for an hour typing, type in on your search engine ( like google ) symptoms of a bad throttle position sensor for example. scroll down for one that is by ehow.com if you don't have a repair manual by Haynes or Chilton, they are the most thorough of most sites. they list all kinds of symptoms / signs to match up to your problem. while your on that page, scroll down and look for other part problem listings on the bottom right side of page. if you don't see what you're looking for, go to top of page an type in on the search box another type of sensor or part. for example, symptoms of a bad map sensor. do this for every part you think it could be. idle air control valve, speed sensor, throttle position sensor, map sensor, maf ( if you have an V8 ) sensor, knock sensor, O2 sensor, camshaft position sensor, EGR ( engine gas relief ) sensor, EVAP canister, purge control solenoid. just to get a feel for narrowing down possible culprits. this will save you time and money. if the problem just came out of nowhere, 99% chance it's electrical related. have you worked on anything recently? removed an connector? an hose? anything you touch / pull apart, even something without an electrical connector to it, will store a code in your computer that will cause performance problems. some codes do not reveal themselves with an MIL or check engine light. just something to consider. make sure no hoses are loose or torn ( vacuum leak ). the map sensor has a tiny hose on the bottom of it connecting to the throttle body. have you recently cleaned your throttle body? let me know what you remember specifically when it started. see what seems close as possible to your symptoms on e-how.com maybe i can save you some headaches. if you have an 4.0L motor, your map sensor, throttle position sensor, and your idle air control valve sensor are all on your throttle body. map sensor is on driver side by itself. TPS and IAC are on the back side of throttle body facing firewall. if you hook up a meter to the TPS or MAP sensors, put it on OHMS and check the resistance. i'll have to look for where i put my notes for the acceptable resistance range. on volts ( DC of course ) you should read 5 volts with ignition switch in the on position ( not cranking position ). like turning your radio on with motor off for example.

 

as someone who has been through the ringer this past year with my 97 GC, i can offer you what i've learned. first, your fuel pressure should fall between 44 - 54. if your at 44 or below, you definitely got a fuel pump or fuel accessory part problem. did your jeep just start having this problem out of the blue? have you had cranking or stalling issues leading up to this? you have a ASD relay fuse in your PDC fuse box behind your battery. swap it with your a/c clutch relay. there the same size and rating. just to see if it's that simple. before you blow money on sensors, have your ignition system checked out. you have a condenser, a module ( like a mini - computer ), an external ignition switch box, and a free neutral pin something. sometimes one of these is your culprit. especially if you are not getting any MIL or check engine light codes. they have sneaky symptoms like alot of the sensor symptoms. a short in or a going bad ignition part will drive you crazy. usually, you have some over- heating issues with a bad condenser or module. if you don't, focus on your external ignition switch box. my jeep would run great all day. turn it off and on multiple times a day. if it sat more than an hour and a half, it would turn over but, not fire up. 3 or 4 crank attempts later, it would start right up and stall after about 5 seconds or less. i changed all kinds of sensors and parts. still did not work right. before i go on for an hour typing, type in on your search engine ( like google ) symptoms of a bad throttle position sensor for example. scroll down for one that is by ehow.com if you don't have a repair manual by Haynes or Chilton, they are the most thorough of most sites. they list all kinds of symptoms / signs to match up to your problem. while your on that page, scroll down and look for other part problem listings on the bottom right side of page. if you don't see what you're looking for, go to top of page an type in on the search box another type of sensor or part. for example, symptoms of a bad map sensor. do this for every part you think it could be. idle air control valve, speed sensor, throttle position sensor, map sensor, maf ( if you have an V8 ) sensor, knock sensor, O2 sensor, camshaft position sensor, EGR ( engine gas relief ) sensor, EVAP canister, purge control solenoid. just to get a feel for narrowing down possible culprits. this will save you time and money. if the problem just came out of nowhere, 99% chance it's electrical related. have you worked on anything recently? removed an connector? an hose? anything you touch / pull apart, even something without an electrical connector to it, will store a code in your computer that will cause performance problems. some codes do not reveal themselves with an MIL or check engine light. just something to consider. make sure no hoses are loose or torn ( vacuum leak ). the map sensor has a tiny hose on the bottom of it connecting to the throttle body. have you recently cleaned your throttle body? let me know what you remember specifically when it started. see what seems close as possible to your symptoms on e-how.com maybe i can save you some headaches.

 

on 2 occasions, i lost all fuel pressure and spark. changed the crankshaft position sensor again, and still just turned over without starting. had to clear some hard stored codes from my computer as a result. turned out to be an ignition problem ( not the switch itself ).

 

I put a new fuel pump assyblie on today 50 lb pressure stilll same thing acts like it wants to start but wont even run.

 

I bought the jeep this way so its like starting new with trouble shooting the po said he changed the cps and that didnt do it

 

By the way, Vandergator. Jeeps don't have EGR (Exhaust gas recirculation) valves unless they're California emission equipted. Check and clean your throttle position sensor and your idle air control valve. As far as I know, the only way to test the MAP sensor is to replace it.

If it sputters, you've probably got power to the injectors. Check the spark plugs and see if they're wet with fuel.

 

Only the V8 in a ZJ had a EGR valve, but not all years. The 4.0 has not had an EGR valve since 91, even in The Peoples Republic of California.

 

Hello Busted! I was waiting for you to chime in. Mogood, you're in good hands now.

Actually, he never said which engine he had, now that I think about it.

 

you can check your tps and map sensors. this will cause a check engine light and trouble code stored to your pcm that you will have to clear with your obd-2 scanner tool. this will work the same way for both sensor tests except, you will not start the motor for the tps sensor tests. you will start the motor for one of the map sensor tests. now, for EVERY engine but a 4.7L V8, you will disconnect the wiring harness electrical connector from the map sensor and connect your red (+) lead of your multimeter to terminal # 3 and the black lead (-) to terminal #1. that's the metal prongs inside your connector ( just in case ). if you HAVE a 4.7L V8 engine, the connections are the reverse. turn the key to the on position ( not crank ) and you should read 5.0 volts. reconnect the connector and insert a tiny nail or straight pin in the middle terminal. gently push & wiggle the pin until it makes contact with the metal terminal inside the connector. connect the red (+) lead to the metal pin you just inserted. connect the black lead to a good engine ground point. turn the key to on position again. you should read 4.0 - 5.0 volts. start the engine ( only for the map sensor test ) and let the motor idle. the voltage should decrease to 1.5 - 2.0 volts. if your nubers don't match this, you need a new map sensor. now for the tps sensor. same exact hook ups for leads. turn key to on position. you should read 5.0 volts. reconnect your connector. insert metal pin into middle terminal like before. connect leads like before ( red to pin and black to ground point. turn key to on position. you should read between 0.20 - 0.90 volts. slowly open your throttle by hand and you should see a smooth increase of voltage to 4.5 at wide open throttle. if your #'s don't match, time for a new tps sensor.

 

will the map and tps cause it not to run at all?

 

its a 4.0 by the way

 

check the round cam sensor with 3 wires located under dis cap and button these things go bad causing a no start cherokee and grand cherokee 4.0 have this issue