Looking for advice - no start situation

mots

mots

Goldilocks Jeep Enthusiast
Supporting Member
Joined
May 11, 2018
Messages
1,351
Location
OH, USA
Hi All, I am looking for advice to see if you think I am on track.

05 Wrangler 4.0L, 106k

Symptoms: TJ was running fine yesterday. Woke up today, started Jeep and moved into the driveway so wife could leave. No issues. I then came out 40 minutes later and it wouldn't start. Just got home a bit ago and did some quick troubleshooting:
  • No CEL, no codes reported - I am using a known working scanner that has worked on this vehicle before.
  • Battery good - starter turns engine over nice and strong
  • Both gauges and idiot lights are working on the dash when turning key to ON position
  • Fuel Pump fuse and relay OK in under hood fuse box (I swapped the relay with the relay for horn, same issue and horn still works).
  • When turning key on, you can hear the click/buzz of the fuel pump in the tank, so it is getting power.
  • No fuel smell or leaks detected.
  • Sprayed in some starter fluid without the air filter hooked up, Jeep starts, runs and stops. Seems to be getting spark and air. but no fuel.
  • If I turn the key on, let it prime the fuel pressure, turn it off, let it prime, turn it on, let it prime...then try to start. Still nothing, won't start. Fuel pressure must not be building at all in the rail.
  • No schrader valve on these newer TJ's, so I would have to rig something to test pressure, but it's clear I'm not getting fuel.
First suspicion is fuel pump assembly since it is original and has over 100k. I ordered Bosch 67756 from Amazon and I will receive it Saturday. If I can figure out something else before then, I won't have to install it, haha! Every once in a while I would get a light stumble on low gear acceleration from a stop under load that I thought could be fuel pressure related. But, other than that, the TJ has been running great and consistent, even on the hot days here.

But...could it be a crank sensor or cam sensor without any codes/CEL, and the symptoms above (no fuel)? I also see some stuff about PCM connectivity issues etc., but that is usually accompanied with other issues that I don't have (like guages not working, only idiot lights etc.).

Let me hear if you have any other ideas besides the fuel pump? I need to go find the factory manual I downloaded somewhere and see what I can find for troubleshooting in there.

Thanks!
 
Does the engine actually turn over though when you attempt to start it?

Have you checked the fuel level? I'm serious about this too. Mine wouldn't start for the life of me, and the fuel gauge was showing it had fuel. However, I filled it with gas and it started right up. Come to find my fuel level sending unit was bad. Go figure, right? Ockham's Razor man... seriously. ALWAYS rule out the simplest, most stupid things first.

Have you load tested the battery? That's another one I would be sure of as well.
 
  • Like
Reactions: mots
Thanks Chris. Right! I have a half tank of fuel and have driven the number of expected miles up to this point, BUT I’ll definitely double check the tank to see if this is accurate. I do recall that post of yours!

As per my list, battery is fine. The engine is turning over strong as usual, and it will start and run briefly if I provide starter fluid in the throttle body.
 
Definitely a fuel issue. Just because you hear the pump doesnt mean its working properly. Any Leaks anywhere? Have you done a fuel pressure test at the schrader valve. Use a pressure gauge, don't just push in the needle and say gas came out. With the gauge you should be getting around 50 psi with key on engine off. also it should hold there for 5 to 10 minutes after turning key off. Good luck. Smart people here, you'll be running again shortly
 
  • Like
Reactions: mots
Oldguy said:
Definitely a fuel issue. Just because you hear the pump doesnt mean its working properly. Any Leaks anywhere? Have you done a fuel pressure test at the schrader valve. Use a pressure gauge, don't just push in the needle and say gas came out. With the gauge you should be getting around 50 psi with key on engine off. also it should hold there for 5 to 10 minutes after turning key off. Good luck. Smart people here, you'll be running again shortly
Click to expand...
Thanks for the reply @Oldguy . That is what I am thinking as well. Noise doesn't mean supplying the proper fuel pressure by any means. I also figure, if the pumps not dead yet at 106k, it will be soon! I would also love to get an OEM replacement in there and also fix my 05-06 Fuel tank filler hose\plunger issue (you can sand down the nubs from what I've read on here) so it slides like it is supposed to.

No obvious leaks or smells detected yet as stated, but like you said, I'll really need to pressurize the system to check pressure buildup if it gets to that level of troubleshooting (i.e. pump or something else recommended before that doesn't fix it). Unfortunately, as per my first post, sadly there isn't a schrader valve on the newer TJ fuel rails like the older ones had.
 
Well, my suspicion in the original post was correct, it was indeed the fuel pump. The TJ is back on the road and is running strong! I went with the Bosch pump mentioned.

Not a hard job for the most part, but I had a brief unwelcome shortcut. 3 carriage bolts that hold the fuel tank skid plate had failed and were spinning even if I tried to keep them in place. I had to cut the bolts with with the dremel, dremel extension, and a heavy duty cutting wheel. Despite the crappy oem hardware that had mostly disintegrated, the fuel tank, frame mounts, and skid plate were in great condition. Very pleased since you never know what you might find! I went and got some new grade 5 carriage bolts and matching 1/2” nut replacements at Fastenal (carriage bolts where 5/16”, 18 thread, 3/4” long). The clearance to install the new bolts is a joke, it is next to nothing without a body lift. So, I dropped them in with a piece of thread and picked them into place with a tiny screwdriver and a magnet. Whew!

Dropping the tank by myself was no fun either with half tank of fuel. I used a board over the the jack tip to balance the tank and it worked well. I dropped it halfway, disconnected the fuel hard line and fuel pump electrical connector, and then let ease all the way down. I siphoned most of the fuel out before the reinstall of the tank to make it easier so I could also manage to jack the tank back up in the same manner by myself. I also took my time to clean real good and then I hit the area hard with a bottle of fluid film since I’ll likely not see it for quite some time again, at least I hope!
 
Last edited:
  • Like
Reactions: BlueRidge304, Jerry Bransford and Chris
I had a feeling it was fuel related, glad you figured it out!

Having dropped the fuel tank more times than I care to count, I can tell you first hand that I encountered every single issue you explained above, including the carriage bolts. Thankfully ACE Hardware had all that stuff in stock, so I was able to get new hardware without an issue.

The second time I dropped my tank I bought an ATV lift and had another forum member help out. That made it so much easier than the first time when I did the entire thing by myself.
 
  • Like
Reactions: mots
Top Bottom
Back