around town my 2002 tj runs ok but on the road after driving about 125 miles it acts as if its running out of gas. after coming to a stop the motor will never die completely , let it set for about 30 seconds it will run fine for about a mile then does the same thing again. any suggestions as to what the problem might be. its a 4.0 engine with 325000 miles.
Fuel Problem
- Thread starter Robert McCool
- Start date
It could be a sticky EGR valve or one of the engine sensors, O2, air temp, MAP, but they will usually throw a check engine light.
Fuel filter.
A weak or bad coil.
Injector problem.
How long has it been since you put spark plugs in it?
fuel pump going bad.
fuel pressure regulator.
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Fuel filter.
A weak or bad coil.
Injector problem.
How long has it been since you put spark plugs in it?
fuel pump going bad.
fuel pressure regulator.
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I'd suspect the fuel pump at this point. There is no EGR valve in the TJ. The fuel pressure regulator wouldn't cause it either since all that does is limit excessive pressure, it can't keep fuel pressure up where it needs to be if the fuel pump isn't putting out enough pressure.
If you end up replacing the fuel pump, make sure to only go with a Bosch like the factory installed. Store brands or online brands like from Airtex or Spectre don't last long enough. This is the one I'd go for, it also includes a new fuel filter and fuel pressure regulator as part of the assembly. https://www.amazon.com/dp/B000BZJDK2/?tag=wranglerorg-20
It could also be a bad ignition coil but the symptom just gives me a gut feel that it's the fuel pump. Especially with 325,000 miles on the engine.
The first thing I'd do is rent/borrow a fuel pressure tester (gauge) from your local auto parts store. Autozone has a good fuel pressure tester kit with the adapters you should need to connect it to your fuel rail since your 2002 doesn't have the pressure test port present on older TJs.
If you end up replacing the fuel pump, make sure to only go with a Bosch like the factory installed. Store brands or online brands like from Airtex or Spectre don't last long enough. This is the one I'd go for, it also includes a new fuel filter and fuel pressure regulator as part of the assembly. https://www.amazon.com/dp/B000BZJDK2/?tag=wranglerorg-20
It could also be a bad ignition coil but the symptom just gives me a gut feel that it's the fuel pump. Especially with 325,000 miles on the engine.
The first thing I'd do is rent/borrow a fuel pressure tester (gauge) from your local auto parts store. Autozone has a good fuel pressure tester kit with the adapters you should need to connect it to your fuel rail since your 2002 doesn't have the pressure test port present on older TJs.
WOW! I learned something new today.
I never realized that the Jeep TJ didn't have an EGR valve. Of course I never looked for it either. I just thought all Vehicles had one since OBD1 started.
I found this on line;
I searched the internet to find out where the EGR valve is located on my Jeep and discovered where it is for '95 Wranglers (I6 and I4) as well as '04, 05, '07, '10 and '11 Wranglers, Grand Cherokees, Hondas, Fords, and Chevy's. Not one mention about my TJ or any other TJ with the I6 4.0L. I also couldn't find anything about it or what the heck replaced it in my Haynes manual. It took a call to the parts counter at the local Jeep dealer to find out that that particular model ('97 to '04 Wranglers) didn't have EGR valves. What that model has is a system that captures fumes from the fuel tank and stores them in a canister until the engine gets warm enough and then injects those fumes into the intake manifold.
If you follow the tubes they go into the intake on the driver's side.
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Jerry I am having the hard start issue on my 04 and suspect the fuel pressure regulator also. Can you tell me where the fuel pressure guage would plug into the fuel rail without me cutting the line? Thank you
That's not being caused by the fuel pressure regulator which only prevents the pressure from being too high.
On newer TJs, you have to use an adapter that goes between the gas line and fuel rail where they connect together to attach a fuel pressure gauge.
However, the usual source of the problem is a bad check valve in the fuel pump assembly allowing fuel to drain down out of the fuel rail and back down into the gas tank. The extra-lengthy time required to start is how long it takes the fuel pump to get fuel back up from the tank to the fuel rail.
But you can avoid the need to verify the pressure tomorrow morning after it has sat all night. Before trying to start the engine, and make sure not to try starting it yet, cycle the ignition switch on-off-on (not to Start) a dozen times. Pause a second each time it's in the On position. This will prime the fuel rail by giving the fuel more time to get gas up next to the fuel injectors.
If the engine starts right away after doing that, that will confirm the problem is being caused by the fuel pump assembly. This is the Bosch fuel pump I'd install if the above test confirms what is suspected. https://www.amazon.com/dp/B001C64PWU/?tag=wranglerorg-20
Make sure to avoid store brands like from Autozone or online brands like Airtex or Spectra which don't last long enough to make them worth installing.
Don't mean to hijack the thread @Jerry Bransford The jeep was not started this morning so I went out as suggested and turned the switch on for three or four seconds twelve consecutive times. Then started the jeep after turning over a couple of times. Normally I turn the key on for ten to fifteen seconds and then crank. The jeep turns over around seven or eight times but doesnt start. I turn the jeep off and crank again and it starts right up. Looks like you may be right regarding the bad check valve on the fuel pump. I will get the Bosch ordered this evening. Thanks again for the help.
Good plan. Keep in mind that the pump automatically shuts off 1.8 seconds after each time it turns on so leaving the key on longer than 1.8 seconds won't help. It only pumps during its initial 1.5 seconds then it shuts off and stays off if the engine doesn't start. That's why I suggested only leaving the key on one second after each it is turned on before you turn the key off and back on again to cycle the fuel pump again.
If you'll cycle the fuel pump on-off-on in 1 to 2 second intervals at least 3-6 times it should start much faster every cold start when that problem exists.
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Thanks. I think I could hear it click in when I turned the key on.Good plan. Keep in mind that the pump automatically shuts off 1.5 seconds after each time it turns on so leaving the key on longer than 1.5 seconds won't help. It only pumps during its initial 1.5 seconds then it shuts off and stays off if the engine doesn't start. That's why I suggested only leaving the key on one second after each it is turned on before you turn the key off and back on again to cycle the fuel pump again.
If you'll cycle the fuel pump on-off-on in 1 to 1.5 second intervals at least 3-6 times it should start much faster every cold start.
You should hear the pump actually running in the rear of the Jeep for that 1.8 seconds, not just a clicking.
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Kiwi TJ
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I'm thinking we should have a forum heading call 'Ask Jerry' hehe Your a wealth of knowledge and helpful advice Jerry:campeon: Thanks for all you help.
2004 four cyl having the same problem. Been to dealer three times they do not believe me because they cannot duplicate the problem. They insist there should be a code, I told them only time you get a code thrown is when the engine is running, you can read the code engine off but they argued that point as well.
They have not charged $ but annoying to drop it off and rent a car. I have a new back flow check valve.
They have not charged $ but annoying to drop it off and rent a car. I have a new back flow check valve.
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You installed a new back flow check valve? How did you do that and where did you install it?
have not installed it yet. It sits on top of the fuel pump in the tank looking at the pictures.
drive up on blocks, drop the tank and replace the check valve.
drive up on blocks, drop the tank and replace the check valve.
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I’m trying to bring this thread back to life in hopes of reaching Jerry. My Jeep is 1999 4.0 with 92,000 Miles. I have similar problems to the initial problem described in the thread. I have scoured the internet for the plethora of possibilities found with loss of power and have changed out almost all of them. The ignition coil I changed out, the fuel pump assembly I changed out six months ago. Now I also get first turn starts on cold start up and rough starts after driving and restarting. I believe I’ve changed out everything that functions with starting. I’ve also noticed that after I fill my tank I get anywhere from 3.5-4.5 gallons I’m able to hold 80 and have wonderful power. After the loss of power my TJ runs like s*** until I find a gas station and fill up. Basically like my Jeep has a 4 gallon tank. On my last two long distance drives I threw up a code for cylinder 3 misfire and another moment where the check engine light flashed for a few minutes before turning off but no code. Previously the O2 sensor code came up and I replaced both sensors. I should also mention that I recieved a “no bu5” error code and swapped my computer as well. Please any advice would help. The shops around here gouge you for money and have told me hundreds for diagnostic. DIY all day. I’m praying for help.
It's really hard to say but quick starts just means the check valve inside the fuel pump is ok. It doesn't necessary mean the fuel pump is maintaining its 49 psi fuel pressure as it should. At this point I'd rent/borrow a fuel pressure test gauge from your local auto parts store and see if the fuel pump is able to maintain at or very close to 49 psi while the engine is running and being revved hard. Did you install a Bosch fuel pump or an aftermarket?
And it is normal for the 'whoosh' sound when removing the gas cap as you asked about in your message.
And it is normal for the 'whoosh' sound when removing the gas cap as you asked about in your message.
That is not the check valve, it's the fuel pressure regulator which only limits the upper-end of fuel pressure... as in if the fuel pressure gets above 49 psi it will dump the excess pressure/fuel back down into the gas tank. Also contained inside is the primary fuel filter.
The fuel pump I purchased was aftermarket... sort of rushed into the purchase as soon as I knew what was wrong. It does have lifetime warranty. If there is a drop in fuel pressure that means the fuel pump has already gone bad? Also with the starting, it goes from quick start to very very rough starts after running. Also with my gas cap, the pressure buildup can be so bad my gas cap shoots off.
John Scoggins
TJ Enthusiast
If you are building pressure in your fuel tank, make sure the EVAP system is operating correctly. You could have a plugged charcoal canister and/or a plugged vent line from the charcoal canister. A quick way to check is to remove the rubber section of line that goes from the EVAP purge valve (by the frame just under the drivers feet) from the engine side and see if you can blow thru the system toward the fuel tank with the engine off. You should be able to easily blow thru the system with the air coming out of the charcoal canister vent (located at the rear passenger side behind the rear tire under the inner fender).
By the sound of things this might be the problem and is why on the highway after a while it is acting like it is running out of gas, because it just might be.