Hello, 2002 TJ Sahara 4.0. Starts good 1st thing in the morning (1st start of the day). After that suffering from hard starts after that. Checked fuel pressure and system pressurizes to 40 + on first key turn and then starts to drop slowly. I crimped off the fuel supply line going into the fuel rail and the pressure still drops very slowly (approx 2psi per minute). If I remove the clamp pressure does not appear to drop any faster. I noticed when I clamp the line that pressure in the rail rises a few psi and then drops off at the slow rate which makes me feel like I had the fuel supply fully clamped off removing the check valve and pump assembly out of the equation. This leads me to believe I have a leaking injector which may be dumping fuel into a cylinder after I turn off the Jeep and causing the hard start due to a rich condition in a cylinder next time I go to start it. Figuring when it sits overnight fuel evaporates in the cylinder and then it starts fine. I have gotten the cylinder 3 misfire a few times but not often maybe 3x in the last year and it clears and vehicle drives fine even with CEL on. I have the thermal wraps for the rail and injectors ready to go on. Not sure if the issue is the vapor lock however and figure if its the injectors I can swap them while I am doing the wraps. Does this sound like a proper diagnosis?
Leaky Injectors?
- Thread starter MCATDT
- Start date
Could also be a leaking fuel pressure regulator that sits outside the gas tank on top of the fuel pump. It too has a check valve in it. If you figure out it's the injectors leaking I'd try replacing their o-rings first which is a fast simple job.
Thanks Jerry. So even though I crimped off the fuel line the regulator could still be an issue?? Also I have read I can reconnect the injectors to the rail once I have pulled the rail to find the leaking injector. Will the injectors hold to the rail once I repressuriize the system?
Here's a simple test. I had several leaking injectors on a different vehicle once and it also gave hard starts when warm.
When you experience this, while cranking, hold the pedal to the floor. This will open the air intake and encourage the engine to clear out the excess fuel.
Also, pull the spark plugs and look for any darker plugs. Might not be extremely dark, just darker. If it's leaking, the guilty injector may show up as a darker plug on that cylinder.
When you experience this, while cranking, hold the pedal to the floor. This will open the air intake and encourage the engine to clear out the excess fuel.
Also, pull the spark plugs and look for any darker plugs. Might not be extremely dark, just darker. If it's leaking, the guilty injector may show up as a darker plug on that cylinder.
So I pulled the rail and injector #4 is leaking when under pressure. Its a small drip (1 every 30 seconds). I am the second owner and noticed cylinders 1,2 5, and 6 are mopar injectors and 3 and 4 appear to not be (no chrysler logo). So the original owner at some point had these changed and a non Mopar aftermarket part strikes again. I ordered a Mopar replacement for the leaker and number 3. Hopefully this was the cause of my warm start issue and this will take care of it.
But then the original Mopar injectors must have also failed at some point thus necessitating their replacement!!!
Thanks for the update! Lots of people ask for help diagnosing problems and then forget to update us to let us know what they figured out!
Mopar injector finally arrived and installed. Jeep fired right up as usual on cold start. Did several restarts after driving and letting it sit for a bit and each time she started right back up. Feeling like the leaky injector was the culprit and very glad I did not have to drop the tank to swap the fuel assembly. The engine feels smoother as well but its probably just the placebo effect of having the start issue tackled.
Good to know! Just for future reference, dropping the tank isn't hard as long as you get the gas level as low as possible and then empty it completely before you install it.
Bumping this.
I had the same issue where cold starts were great but hot starts were hard. I replaced all the injectors with eBay OEM Siemens remanufactured injectors 2 years ago. This fixed my issue up until last week when it all started again. I just did a fuel rail pressure test and as soon as I shut the engine off the gauge goes to zero in about 15 seconds.
I had the same issue where cold starts were great but hot starts were hard. I replaced all the injectors with eBay OEM Siemens remanufactured injectors 2 years ago. This fixed my issue up until last week when it all started again. I just did a fuel rail pressure test and as soon as I shut the engine off the gauge goes to zero in about 15 seconds.
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