Fuel issue or something else?

DropTopDon

DropTopDon

TJ Enthusiast
Joined
Nov 7, 2019
Messages
642
Location
VA
My jeep has been sitting in the garage immobile for roughly a month. It will crank like a champ but it won't actually turn on. So far I have replaced the ignition coil bar, the spark plugs, and the camshaft position sensor (mopar). When I click the key to on, I do hear the fuel pump prime. I am still thinking it is a fuel issue because if I put my pedal to the floor when I try to turn the engine on, it will come on for a second and rev. Whenever I do this though smoke begins to come out of the exhaust along with a smell. I do not have a schraeder valve so I am not sure if it is my fuel pressure. I have checked all of my fuses and relays.
 
Air, fuel, spark. That is what a basic Functioning engine requires. These engines are the next level up from basic. Look to the electronics on the fuel end if you have good spark and air.

My check would be the IAC. Cleaning and/or replacing unit.
Clean up the throttle body and air flow sensor in the air intake tube while your at it.

Report back on your results. Make sure you actually have fuel in the tank.
 
To confirm spark; remove the intake tube from the top of the throttle body and spray some starter fluid or carb cleaner into the throttle body throat. Attempt to start the Jeep; IF the engine starts and shuts down or coughs briefly; you have spark and the problem is with the fuel system or control circuits.
 
Kid Mechanic said:
Air, fuel, spark. That is what a basic Functioning engine requires. These engines are the next level up from basic. Look to the electronics on the fuel end if you have good spark and air.

My check would be the IAC. Cleaning and/or replacing unit.
Clean up the throttle body and air flow sensor in the air intake tube while your at it.

Report back on your results. Make sure you actually have fuel in the tank.
Click to expand...
I have half a tank, and I did remove the throttle body and clean it with throttle body cleaner along with the IAC.
 
CharlesHS said:
To confirm spark; remove the intake tube from the top of the throttle body and spray some starter fluid or carb cleaner into the throttle body throat. Attempt to start the Jeep; IF the engine starts and shuts down or coughs briefly; you have spark and the problem is with the fuel system or control circuits.
Click to expand...
I tried conducting a spark test with my old spark plugs and coil rail to which I did not get any spark. I will try this since I have now put in new spark plugs and a coil rail.
 
Like CharlesHS said, spray some carb cleaner or starting fluid down the throat of the throttlebody and see if it starts and idles for a few seconds.

Did you pull the plugs back out after numerous attempted restarts to see if the are wet?

Also putting the pedal to the floor enables the fuel cut off. It tricks the pcm into thinking the vehicle is flooded. So it going to cut your fuel.
 
williambmac said:
Like CharlesHS said, spray some carb cleaner or starting fluid down the throat of the throttlebody and see if it starts and idles for a few seconds.

Did you pull the plugs back out after numerous attempted restarts to see if the are wet?

Also putting the pedal to the floor enables the fuel cut off. It tricks the pcm into thinking the vehicle is flooded. So it going to cut your fuel.
Click to expand...
I just tried spraying some starter fluid down the the throttle body and It did not idle or start for a few seconds. My old spark plugs smelled like gasoline but I have not checked if the new ones are wet after attempting to start it.
 
Haaris Khan said:
I tried conducting a spark test with my old spark plugs and coil rail to which I did not get any spark. I will try this since I have now put in new spark plugs and a coil rail.
Click to expand...
When conducting your spark test, you made sure the spark plug was grounded correct? Just sticking a plug into the rail is not going to give you a correct diagnosis.
 
Double check and make sure you have spark with the new coil pack and plugs.

The engine harness connector behind your coil rail is a known problem also. Check and make sure there is no corrosion at the terminals and that the harness is not pinched and grounding out.
 
  • Like
Reactions: CharlesHS
Update: I confirmed that all 6 spark plugs have spark. I attempted to turn the key to the on and off position 5 times in order to prime the fuel pump and tried to start the jeep and it turned on for about 30 seconds. In those 30 seconds the idle would sometimes be at 900 rpm and then it would fluctuate down a little bit every 2 seconds or so. The idle however sounded soft and not how it usually sounds when my jeep is running. After those 30 seconds my engine stopped and turned off by itself. I have already cleaned my IAC and throttle body prior to this. Is it safe to say this is a fuel pump issue?
 
Haaris Khan said:
Update: I confirmed that all 6 spark plugs have spark. I attempted to turn the key to the on and off position 5 times in order to prime the fuel pump and tried to start the jeep and it turned on for about 30 seconds. In those 30 seconds the idle would sometimes be at 900 rpm and then it would fluctuate down a little bit every 2 seconds or so. The idle however sounded soft and not how it usually sounds when my jeep is running. After those 30 seconds my engine stopped and turned off by itself. I have already cleaned my IAC and throttle body prior to this. Is it safe to say this is a fuel pump issue?
Click to expand...
I should add, I do still hear my fuel pump prime for 2 seconds before I try to turn it on.
 
you need to get a fuel pressure gauge on your jeep. I think most Autozones loan tools. see if they have a fuel pressure gauge and fuel line disconnects. You need to verify that you have fuel pressure.
 
Another update: For some reason now it starts up just fine on first crank but there is hesitation. I had to keep the rpms up but when the engine got warm it would idle fine. I put it in reverse and it began to die but I quicky put it in neutral and kept the rpms up to keep it alive. I gave it a quick spin around the block and it seemed to drive fine and idle fine when I returned. I am thinking it is a TPS issue now maybe but not gonna rule out low fuel pressure just yet unless you guys tell me otherwise. Gonna test the fuel pressure tomorrow.
 
Update: It was the goddamn crankshaft position sensor 😕 Unless it shits out on me in a few days again. Hopefully not.
 
Update: Just died on the side of the road and I am stranded. It was running fine but all of a sudden while i was driving my engine would hesitate and turn off. I would put it in neutral and it started. This happened twice. The third time it didn’t start and it just died.
 
Haaris Khan said:
Update: Just died on the side of the road and I am stranded. It was running fine but all of a sudden while i was driving my engine would hesitate and turn off. I would put it in neutral and it started. This happened twice. The third time it didn’t start and it just died.
Click to expand...
New codes: p0351 and p0353. Gonna go back and inspect my ignition coil rail wiring clip. Replaced the coil rail with OEM about 3 weeks ago. Will try putting the old rail back in and seeing what happens.
 
Top Bottom
Back