Ok so I'm new to the island, I've just bought a 97 tj (my first jeep), I consider myself pretty handy with cars and engines, I just don't have the budget to be replacing things that ain't broke, ok so lately the heep is turning over quite a few times before firing. I have done the plugs and the problem persists,Is this because of blocked or faulty injectors? Is the check valve in the fuel rail allowing fuel to return to tank? I've noticed a slight fuel smell while walking around it. I've read online that the fuel filter is in tank and has a huge surface area and will last awhile before needing to be replaced. I was thinking about pulling the injectors out to see if any are leaking? Any advice would be great!!
i drive and work on diesel trucks for the most part and am not a jeep guy so dont know how much this will help but i know i had a hell of a time with my truck for a bit when my injector return lines were leaking. my truck would have to crank over for a few min to get the fuel back in it and some times i would have to crack an injector or two so i could get some air out when it got really bad. $40 and i got all new o-rings, copper washers and return lines and with in the hour it was starting before i even turn the key all the way down. this was on my 91 and 93 fords just a few years ago so your getting around the same time line. look at the injectors after a bit of a drive and see if its wet around them. let me kow how it goes and i'll talk to a few buddies and see if they think of anything else
Hey thanks for the info! I'm thinking somehow the fuel is running back into the tank, if I switch the key on and hold for a second then off again, then turn it over it starts a lot better for some reason
I wouldnt rule out a plugged fuel filter. If your still suspecting fuel to be the issue. Tjs arent supposed to have a return line to the tank. Do you have 2 fuel lines running to the rail? Have you tried turning it over without it firing and pulling a plug to see if its wet with fuel?
Haven't tried that yet, Iv started stripping down the entire jeep today, and removing the body tub to replace it, il have a good look at all the lines and the pump etc hoping to have it off tomorrow or the next day depending on weather
My 05 TJ seems to take more cranking than I'm used to from my Fords but haven't bothered to look into it yet.
If yours starts better if you turn key on than off and on and then start, I would look at fuel as well. If you have an electric pump it should come on and pressurize your system when you turn the key to on. The 2nd time you turn the key on, the system is still pressurized and starts.....just a thought.
HD
Yah all jeeps with the I6 need to turn to tdc on no1 cyl to start the sequencial injection fireing system. Least thats how the odb1 logic module works, probably the same program functions were carried over.
would a vacuum leak cause these problems?
I suppose potencially it could if it was large enough, immight look at the air idle actuator possibly stuck? If when it does start and it has a high idle? Or runs like crap? Low idle?
If you suspect a vacuum leak, go buy yourself a can of start aid, (You should have some anyways incase you ever blow a bead on the trail) while the jeep is running spray all your vacuum lines, if you have a leak your idle should go up on its own when you spray the area that leaking.
thats some great info, thanks guys! so wife and i go out to sooke yesterday...on the way back to victoria jeep starts cutting in and out in a bad way ,really bunny hopping.
Jeep was revving high when i held the clutch in, a few taps on the gas in neutral kinda helped, so i pull over and pop the hood (meanwhile its idling like shit!). So i just got in and drove home, it started cutting out just as i got home. i was thinking it has to be the throttle position sensor! so i got one from napa for $95,i pulled the whole throttle body off to give it a clean up, along with the idle air controller, turns out chrysler used extremely good thread locker to bolt there TPS's on!! damn near sheered my torque drive bit in half and it was a small bolt!
Had to use a hack saw blade to remove old sensor. I put it all back together hooked up the battery and took her for a drive, and wow did it make a huge difference!!! smooth acceleration with no hesitation and idling like a dream, it seemed to start better, guess i will know in a few days if its helped with the slow starting. could a bad TPS cause slow starting?
I'm not real familiar with the TJ but I know a common problem is the "Anti drain back valve" and it's a pain in the ass to replace, it's in the fuel tank.
After it's been sitting for awhile (like overnight) before starting it, depress the pin inside the Schrader valve on the fuel rail. If it squirts out, there's plenty of fuel and fuel pressure at the fuel rail. If there's no fuel pressure at the rail (If there's no fuel that comes out or it just sorta leaks out) it's likely the anti drain back valve is leaking. The Schrader valve is like an oversize tire valve, it's underneath a black screw-off cap on the front part of the fuel rail
You could also try turning the key to on without starting it and let the fuel pump prime, turn the key to off and then back to on again letting the fuel pump prime again and then see how quickly it starts, if it starts right away it means there was not enough fuel pressure there on first prime, which would again point to the ant drain back valve
Never heard of an anti drain back valve in a jeep larry.... i know they switched the pressure regulator into the tank in the tj's insted of on the fuel rail. Could that anti drain back valve be part of this system? I have nefer ripped into a tj yet so am un familiar with the stuff on them.
As for the TPS sensor causing a long start issue... did it go away with the swap of a new one? I had a bad tps in my yj and it caused some shitty stuff to happen. If this fixed the drivability issues you were having i wouldnt doubt it was contributing to prior issues at all cause potenciohmeters dont fail overnight...
It's an internal part of the fuel pump and not serviceable.
Typically a person would just deal with the issue, but the fix would be to replace the fuel pump.
My Cherokee also has this and cranks 5-6 times before firing, or I can cycle my key twice to build the right pressure as I'm not dropping $200+ on a new fuel pump when mine works.
I just seen that you had mentioned pulling plugs....this Drain back valve I believe is only for injection systems, which would make all my previous posts non relevant to the situation.
The slow starting seems to have improved with the replacement of the tps, but not fixed it completely, I will check the valve on the injection rail for pressure this morning before start up. I guess il need a few days of start ups before I will really know. It's great to be able to bounce ideas off you guys thanks for the input!
As i stated before. These 4.0ls are know to turn over a little before flashing.....
Any updates Kiwi?
It's starting a bit better but still cranking a while, it's the check valve in the tank, This morning I checked for pressure at the rail by pushing the valve in, and nothing, not even a drop!
The tps has helped with the idle and acceleration a bit better, even crawling is better no bunny hopping at really slow speed
Ya that fuel rail should be holding pressure, Glad to hear your other issues have been solved.
yea slowly getting her fixed up, the previous owner completely neglected the poor jeep, so now its up to me to deal with all the issues.
i think it sat for a while because when i started driving it ,after a little while all the rust in the front fenders and the body mounts started falling out! changed the tub which sorted the body mounts, now it looks crappy with its big rust holes in the front, and its blue,red and black paint job. but hey its all good fun!
I like our enthusiasm! Keep on it Mike, your getting there.