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Old 07-27-2013, 08:30 PM   #1
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99 TJ Fuel Engine Issues

Did a search and got some good leads but nothing has worked so far.

99 TJ Sport, 4.0L Auto, 100k miles

Symptoms were hard starting and loss of power when under acceleration after starting. Jeep would run fine when on longer trips.

Read on forum that probably fuel pump but did a once over on Jeep and found a broken distributor cap. Off course I sheared off the other bolt in distributor housing trying to get it off. Had to leave town for work so dropped off at shop to remove the bolt, replace cap and fix hard starting.

They attribute it to the distributor and decide to replace the whole cap, rotor and distributor since they couldn't reach me. Lo and behold that doesn't work and then they check fuel line pressure and find it at 0 when not started. Quote me 900 to replace it so I do it myself.

Get the fuel pump out and replaced (I hate the plastic ring holding in pump more than anyone I can ever imagine). Jeep starts right up on first try. Shut off and try to start and it will turn over and stumble real bad like its running on 1-2 cylinders. Shut off jeep and try to start two more times, fires up perfectly again.
Same thing again, 3rd start and fires right up otherwise won't start or only two cylinders.

Thinking timing take back to shop that did distributor and they said it can't be anything they did since its an electronic ignition and if it starts distributor is installed correctly.

What does everyone think, I really can't keep dropping money into this thing right now. Thanks!

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Old 07-28-2013, 04:53 PM   #2
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Well today was plugs, wires and a camshaft position sensor replacement. Still no dice, runs way better with the new plugs but the damn thing won't start for three times. I can hear the fuel pump come on and there's pressure in the rail.

I'm at wits end, what could they have done to the distributor to cause these starting issues? Any help would be greatly appreciated.

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Old 07-28-2013, 05:04 PM   #3
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Possibly clogged injectors? Pull a few of them and see if there's a lot of dirt and debris around them if so clean them
That's all I can gather so far. I pulled my motor and when I took my injectors out they were terrible. Oil had seeped in there. Once I cleaned them out....perfect
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Old 07-28-2013, 05:34 PM   #4
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Quote:
Originally Posted by Milkman View Post
Well today was plugs, wires and a camshaft position sensor replacement. Still no dice, runs way better with the new plugs but the damn thing won't start for three times. I can hear the fuel pump come on and there's pressure in the rail.

I'm at wits end, what could they have done to the distributor to cause these starting issues? Any help would be greatly appreciated.
In addition to injectors, check wiring for shorts, grounds, corrosion, etc.

Good luck.

Chuck
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Old 07-28-2013, 06:06 PM   #5
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Start with the basics. An engine needs compression, spark, and fuel to run.
A compression problem doesn't sound like it's yours, so that leaves spark or fuel.

You need to find what you are loosing on those first couple of start attempts.

You may have pressure in the rail, but is it enough? Can't tell without a gage on it.
Could be your pump is not fully pumping up the pressure, and after three starting attempts it finally has enough pressure built up to run the engine. Also flow, is the pump flowing enough fuel. You can have pressure but little flow, if you have a restriction somewhere in the feed line, and/or pick up.

Spark? first are you getting the proper voltage to your coil? Did you check it?
A poor connection causes resistance, resistance causes heat. Heat can cause metal to swell/expand. If you have a bad wire somewhere to the coil, it could be taking the three start attempts for the wire to get hot enough to make a "decent" connection, and finally let the motor start.

Also I didn't see a crankshaft position sensor listed in your replacements. A bad crank sensor can cause all kinds of problems. Seen em crack get moisture in them and act up. Might be similar to what you are experiencing, takes three attempts before it starts working fully.
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Old 07-28-2013, 07:28 PM   #6
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Thanks for all the replies. I'll get a gauge on the rail tomorrow and borrow a multimeter from work.

I replaced the whole fuel pump with a OEM replacement and the crankshaft position sensor along with wires/plugs. Maybe I got a faulty fuel pump but this one doesn't exhibit any of the issues I had with the old one.

I'll chime in tomorrow with what I've found and see where we go next.
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Old 07-29-2013, 07:41 PM   #7
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Update: my buddy let me borrow his obd ii reader tonight before I went to autozone and get a pressure gauge.

Hook it up and there's just one code....P1391. Did some digging and looks like its it crankshaft or camshaft position sensor. Since this is the second crankshaft sensor I tried I'm leaning toward the camshaft sensor.

It looks like either an aftermarket sensor or possibly they did not adjust the timing with the programmer. Pulled apart distributor and everything's looks ok. Nice and tight but I have no idea on timing. I see some threads where people have set by hand with toothpicks and a mirror but since they replaced distributor I will probably just take it back and have them fix it.
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Old 08-06-2013, 07:36 AM   #8
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Just to update in case anyone ever searches for this thread....

Long story short first shop tried several times to reset the timing on the Jeep and failed. After 4 days they said it was the crankshaft sensor and the fuel pump causing all the issues even with the P1391 engine code.

We got into a heated conversation and I told them it was going to the local Jeep dealer and they would be covering the entire cost of the bill if it was the distributor.

4 long days later the dealer got the Jeep in. I get the call, fuel pump checks out perfect and pressure in rail within limits, crankshaft sensor is perfect (did you know it was new?) but the timing was completely off, I don't think they even tried to set it or didn't know how. Jeep is ready to go.

Pick it up and she's like a brand new Jeep again running even better with the new plugs and wires. Took my receipt to the first shop this morning where the dealer clearly stated that the issue was the timing and distributor and they refunded me the entire dealer repair bill.

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