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Old 04-07-2009, 10:25 PM   #1
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Hard to start

So recently my 97 Tj 6 cyl is getting harder to start
If i dont press the gas down first it takes a good 10-12 seconds to start with the key turned and sometimes takes tow or three attempts of ten seconds
I've found that if i turn the key and don't push the clutch then pump the gas twice, wait 5 seconds then turn her over it starts like normal, not sure what my problem is,
tomorrow im gonna try injector cleaner, any ideas would be great!
thanks!

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Old 04-07-2009, 10:51 PM   #2
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fuel pump?

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Old 04-07-2009, 11:29 PM   #3
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any way to check it besides pulling stuff and seeing how fast it fills up a jar?
and its weird cause once it starts i have no problems at all
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Old 04-08-2009, 03:31 AM   #4
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when was the last time it had a tune up?
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Old 04-08-2009, 06:22 AM   #5
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Sounds to me like you have a converted-to-diesel TJ and don't know it Just kidding. Have you changed the O2 sensor?
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Old 04-08-2009, 07:31 AM   #6
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umm i didn't realize fuel injected needed tune ups, I haven't really done anything

and second any idea I could test which O2 sensor or if it is one or do i need to take it in or just start replacing them

also i vaguely remember something to spray on them they were talking about to clean them any idea if that would help in this situation?
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Old 04-08-2009, 12:46 PM   #7
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Check the fuel rail for ample fuel pressure before you start it. Key in "on" position will charge the pump. You should hear it fire up. There's a bicycle tire valve (Schrader Valve) on the rail. Open the cap and use a small screw driver to push the pin in and gas should squirt out (be careful). If you are not getting a steady flow, then your pump could be the culprit.

I believe there is also a purge solenoid on the FI systems. If I'm not mistaken, this could also cause a similar problem. Cheaper and easier to replace than the fuel pump.
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Old 04-08-2009, 03:51 PM   #8
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First, stepping on the gas pedal does not pump gas into the engine or throttle body. All that stepping on the gas pedal does is open the butterfly valve on top of the throttle body. Pumping gas with the gas pedal is something you can only do with carbureted fuel systems. So if you stepped on the gas ten times vs. zero times on your TJ, it won't speed up or affect how fast it starts.

There's a 99.99% chance your slow start, if it only happens after the Jeep has been sitting a while, is nothing more than a leaky anti-drainback valve that is located inside the pressure regulator that sits on top of the fuel tank... it's part of the fuel pump assembly. When it leaks, it allows fuel that is supposed to stay put in the fuel rail next to the fuel injectors to instead drain out and back down into the fuel tank. The time it takes to start after that happens is the amount of time it takes the fuel pump to get the fuel back up from the tank to the fuel rail which attaches to the fuel injectors.

EBay often has fuel pressure regulators for the TJ for sale separately that contain the anti-drainback valve. That will save you $$$ over buying the entire fuel pump assembly which is the only way you can get the fuel pressure regulator from the dealership.
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Old 04-08-2009, 04:55 PM   #9
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well since I've bought it (year and a half) it has been slugging starting if i stall out but i assume that has to do with stalling out and not the drainback valve?
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Old 04-08-2009, 05:39 PM   #10
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I'm 100% confused now. "Slugging starting if I stall out"... what does that have to do with a slow start? You never mentioned stalling before, you just said it took a long time (10-12 seconds) to start.
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Old 04-08-2009, 11:05 PM   #11
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i mean; u asked if it only happens after sitting for a while. And it also does it after I stall, If i stall out i have to turn the key for about 8 seconds after i stall kind of like how i have to turn it for ten after it sits for a while. not sure if that has anything to do with the valve or if that is what usually happens after any stall.
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Old 04-09-2009, 03:29 AM   #12
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Hard to start, stalling then hard to start -- sounds like an ignition problem.
Plugs, coil wire, coil etc.

Yes, just because it has fuel injection it doesn't mean the usual things can be ignored.

Don't fall for advertising of "trick" or "performance" plugs, it's all hype. Use what the underhood label or the book says.

If it is the drainback valve - prove it by turning the key on 5 seconds but DON'T CRANK IT, then off, then on for 5 seconds, then off -- do it 3 or 4 times but DO NOT CRANK IT! Then next time turn it on and crank it - if it starts easy then, it's the drainback valve.

The pump only runs about 3 seconds when you turn the key to the on position. If the fuel has drained all the way bask to the tank it takes about 3 on/off cycles to get it back up.

But - that won't make it stall!

O2 sensors don't come into play until it's warmed up - they do not affect starting.

Wide gap or wrong plugs, loose or bad coil wire, or coil.
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Old 04-09-2009, 07:22 AM   #13
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Debruins: please explain how the engine is stalling. Does the engine stall at idel? Does it stall because of improper clutching? Does it stall at highway speeds? Any codes?

Need more info....you may have more than one problem. If it's stalling at idle, I would suggest cleaning out the IAC with some carb. cleaner.
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Old 04-09-2009, 07:29 AM   #14
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i mean if i stall it out by clutching/putting it in wrong gear

the only problems im having is just starting everything else is fine

ill try the turning the key several times this morning and see if it is that valve
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Old 04-09-2009, 07:42 AM   #15
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Quote:
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i mean if i stall it out by clutching/putting it in wrong gear

the only problems im having is just starting everything else is fine

ill try the turning the key several times this morning and see if it is that valve
OK, well at least the stalling problem isn't related (operator error)....that's a good thing

Check the fuel rail for pressure when you turn the key to "on" (not start) position. If you have pressure, then it's something else we need to look into. If you have to repeat the procedure until you get pressure then it's related to either the pump or drainback valve. How many miles do you have on your rig?
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Old 04-09-2009, 10:28 AM   #16
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It's easy to be misled by just pushing in the Schrader valve. Fuel may be still be present right in the rail by the valve, but the lines have drained back. You'll get a dribble, tricking you, but not enough pressure to start it.
The air in the line compresses slightly, forcing out the dribble, but not near enough pressure to start. Similar problem to a brake line with air in it.

The only real way to check it is with a pressure gauge.

Harbor Freight has pressure gauges for about $12.

It takes time for the fuel to run back to the tank - at least several minutes - stalling and trying to immediately restart isn't enough time.

But - if it still has the starting problem after it's been running, then stalled - it's something else, most likely ignition.

Pull a plug wire off at the plug - put a Phillips screwdriver in the end. Hold the screwdriver close to ground while someone cranks it so you can look at the spark.
The spark should be able to easily jump at least 1/4", and look like a thin crispy bright blue line. If it won't jump that far, or looks red, ignition is weak.
Then pull a plug - look at it - worn? Dirty etc? Not a stock type? Platinum? Call a parts house to verify what SHOULD be in it.


Vent -- I just had the experience last week - new plugs were in a 4.0 - carbon fouled, ran terrible. Owner got them from AutoChina, installed them himself - they were for a 4 cylinder! Bet when the guy looked it up the owner said 4.0 - parts slinger thought he meant 4.0 cylinders. That's what you get when they employ people that got fired from a burger place's drive thru.
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Old 04-09-2009, 11:43 AM   #17
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Vent -- I just had the experience last week - new plugs were in a 4.0 - carbon fouled, ran terrible. Owner got them from AutoChina, installed them himself - they were for a 4 cylinder! Bet when the guy looked it up the owner said 4.0 - parts slinger thought he meant 4.0 cylinders.
Rich that's pretty unusual because I'm pretty confident that the 2.5L and 4.0L engines use the exact same spark plugs. At least they are the same when I look at Autolite and Champion spark plug model number lists.
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Old 04-09-2009, 12:05 PM   #18
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It's easy to be misled by just pushing in the Schrader valve. Fuel may be still be present right in the rail by the valve, but the lines have drained back. You'll get a dribble, tricking you, but not enough pressure to start it.
The air in the line compresses slightly, forcing out the dribble, but not near enough pressure to start. Similar problem to a brake line with air in it.

The only real way to check it is with a pressure gauge.

Harbor Freight has pressure gauges for about $12.

It takes time for the fuel to run back to the tank - at least several minutes - stalling and trying to immediately restart isn't enough time.

But - if it still has the starting problem after it's been running, then stalled - it's something else, most likely ignition.

Pull a plug wire off at the plug - put a Phillips screwdriver in the end. Hold the screwdriver close to ground while someone cranks it so you can look at the spark.
The spark should be able to easily jump at least 1/4", and look like a thin crispy bright blue line. If it won't jump that far, or looks red, ignition is weak.
Then pull a plug - look at it - worn? Dirty etc? Not a stock type? Platinum? Call a parts house to verify what SHOULD be in it.


Vent -- I just had the experience last week - new plugs were in a 4.0 - carbon fouled, ran terrible. Owner got them from AutoChina, installed them himself - they were for a 4 cylinder! Bet when the guy looked it up the owner said 4.0 - parts slinger thought he meant 4.0 cylinders. That's what you get when they employ people that got fired from a burger place's drive thru.

The line test I suggested was meant to be subjective. No fuel (or a dribble) indicates a fuel related problem. If that line is pressurized under normal - working conditions, he's going to get a significant amount of fuel when he pops the valve open at pressurization.

low tech approach 1st, then get into the details
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Old 04-09-2009, 01:42 PM   #19
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low tech approach 1st, then get into the details
Me too, though I hate it when the low-tech 1st approach doesn't sort the problem out.
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Old 04-09-2009, 03:14 PM   #20
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Me too, though I hate it when the low-tech 1st approach doesn't sort the problem out.
I'm just trying to keep it low tech for Debruins. He needs something simple and easy to do in the driveway without tools. Perhaps we should send him a service manual for his birthday? (just fooling with you Debruins) Let us know already what's going on.
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Old 04-09-2009, 04:38 PM   #21
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i have a service manual for my 55 but it doesnt help doh

im gonna try all these tests tomorrow when i have school off and I'll see what it seems like
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Old 04-15-2009, 07:42 AM   #22
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i have a service manual for my 55 but it doesnt help doh

im gonna try all these tests tomorrow when i have school off and I'll see what it seems like
How did you resolve your issue? Inquiring minds want to know....
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Old 04-15-2009, 11:16 AM   #23
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i have a service manual for my 55 but it doesnt help doh
You got a 55 code? If so, that code isn't a problem code. It only signifies no more codes follow and that the diagnostic test procedure completed normally.
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Old 04-15-2009, 12:40 PM   #24
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You got a 55 code? If so, that code isn't a problem code. It only signifies no more codes follow and that the diagnostic test procedure completed normally.
Perhaps you misread...he's got a service manual for his 55, not code 55
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Old 04-15-2009, 06:01 PM   #25
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Jerry - it may be unusual - but the numbers I came up with for the '90 4.0 is RC9YC - CarQuest showed it in their computer AND it's printed on the underhood label.

CarQuest, and Champion's own web page shows the other plug RC12LYC as being for the 2.5 4 cylinder.

Here they are together, as you can see, they are very different.
The engine ran terrible with the wrong ones, the right one shown here only has about 5 minutes running on it. They were having trouble clearing out the carbon from the wrong ones, that's why it's black. A 2nd set of the right ones were installed, it ran even better - I put about 30 miles on it since. Runs great! Plugs are clean now.

You'd think it would be the opposite - the wrong ones look like they'd be hotter, but obviously aren't, go figure.

I think the confusion started because it's a '90 4.0 with a 2000 head, then the parts Yo Yo made it worse!
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Old 12-17-2013, 10:02 AM   #26
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Similar problem on my 2001 Sahara

Just a note to thank you guys in this thread for providing clues to a similar problem I had with my 2001 Sahara. Very hard starting but a determined it was a fuel pressure issue using the key-on key-off procedure mentioned above.
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Old 12-17-2013, 10:08 AM   #27
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Similar problem on my 2001 Sahara

We dropped the fuel tank and changed the fuel pump assembly but the problem persisted. Fuel pressure at the rail started high but then dropped. Turned out it was a leaky fuel injector. Jay at AutoCouture in Fair Lawn, NJ found it when he noticed that one of the spark plugs had a cracked ceramic insulator from getting hit with cold raw gas. He then pulled the injectors and saw the leak. Jeep starts instantly now runs much smoother. Shoutout to Jay. I should have had him troubleshoot the problem at the outset and saved the cost of the fuel pump.

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