Help Me Diagnose Starting Issue - Pleaseee
03-20-2017, 06:12 PM
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Model: Cherokee
Help Me Diagnose Starting Issue - Pleaseee
Hello all,
New to the forum, but have relied on your guidance for keeping my ZJ running like a champ over the past five years. I've read and searched the forum high and low for troubleshooting this issue, to no avail and thought maybe I can get some help. I have a 98 ZJ with a 4.0 that completely stock aside for the repairs & tune-ups done over the past five years. It has started immediately ever since I've had it, until the other day. No warning signs, no symptoms and has been running great. Got off the train, hopped in the car, and she cranks strongly but won't start. Radio, lights, gauges, windows - everything works. Before doing any diagnostics, i purchased a new crankshaft position sensor. I was at the train station for an hour and half waiting for a tow truck, so i just walked across the street and bought it thinking it was the root of the problem. The next day, became a contortionist and changed CPS. Still not starting. Now time to check for air, fuel & spark. Removed intake and shot carb cleaner into the throttle body and she started, albeit for a second or two. Must be fuel. I don't have a fuel pressure gauge, but removed schrader cap, depressed button and nothing came out. Even had the wife attempt to start while keeping schrader depressed and still nothing came out. Listened for fuel pump and it didn't turn on/prime when turning the key. Switched some relays (fuel pump, ac/clutch and asd) and still nothing. I'm not sure how to test relays aside from putting my finger on them and feeling a click, the fuel pump and ASD both clicked. Time to change the pump. Finished changing the fuel pump last night around 10pm and now pump is working as I'm getting prime and fuel to the rail (ordering a fuel pressure gauge today to measure psi). Still not starting. Pending the fuel pressure is normal, I would have to assume it's the injectors. Can I assume that its highly unlikely that all six injectors would fail at the same time, therefore making it electrical? If so, what could cause injectors not to fire? PCM? Camshaft sensor? Being that I finished at 10pm last night, I didn't have time to play with it after trying to start it with the new fuel pump. Went to bed frustrated at the thought of taking Uber to and from the train station until this gets fixed....
Also, how much gas should be in the tank with the new pump to get is started. I only had about 4 gallons of fresh gas to put in.
Many thanks in advance for all of your help.
New to the forum, but have relied on your guidance for keeping my ZJ running like a champ over the past five years. I've read and searched the forum high and low for troubleshooting this issue, to no avail and thought maybe I can get some help. I have a 98 ZJ with a 4.0 that completely stock aside for the repairs & tune-ups done over the past five years. It has started immediately ever since I've had it, until the other day. No warning signs, no symptoms and has been running great. Got off the train, hopped in the car, and she cranks strongly but won't start. Radio, lights, gauges, windows - everything works. Before doing any diagnostics, i purchased a new crankshaft position sensor. I was at the train station for an hour and half waiting for a tow truck, so i just walked across the street and bought it thinking it was the root of the problem. The next day, became a contortionist and changed CPS. Still not starting. Now time to check for air, fuel & spark. Removed intake and shot carb cleaner into the throttle body and she started, albeit for a second or two. Must be fuel. I don't have a fuel pressure gauge, but removed schrader cap, depressed button and nothing came out. Even had the wife attempt to start while keeping schrader depressed and still nothing came out. Listened for fuel pump and it didn't turn on/prime when turning the key. Switched some relays (fuel pump, ac/clutch and asd) and still nothing. I'm not sure how to test relays aside from putting my finger on them and feeling a click, the fuel pump and ASD both clicked. Time to change the pump. Finished changing the fuel pump last night around 10pm and now pump is working as I'm getting prime and fuel to the rail (ordering a fuel pressure gauge today to measure psi). Still not starting. Pending the fuel pressure is normal, I would have to assume it's the injectors. Can I assume that its highly unlikely that all six injectors would fail at the same time, therefore making it electrical? If so, what could cause injectors not to fire? PCM? Camshaft sensor? Being that I finished at 10pm last night, I didn't have time to play with it after trying to start it with the new fuel pump. Went to bed frustrated at the thought of taking Uber to and from the train station until this gets fixed....
Also, how much gas should be in the tank with the new pump to get is started. I only had about 4 gallons of fresh gas to put in.
Many thanks in advance for all of your help.
