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[Darrenmcd1]

2003 tj manual 4.0. 19k miles.

Began having this problem with starting the engine around a fortnight ago. Gave it a basic service including spark plugs but no difference made.

When I turn the key, the jeep starts cranking but wont fire up.

I'll crank the ignition for a while and it will not start. I'll then turn it off before cranking it again immediately after and it fires up perfectly.

This doesn't happen every time, sometimes it starts on first attempt (never more than 2 tries). Outside temperature doesn't seem to play any part. Same goes for time between turning engine off and attempting to start again. It's worked fine first time after two days of sitting on the drive and it's needed a couple of attempts after being left for 5 minutes while I've nipped into the supermarket (and vice versa).

Runs great besides the starting issue.

Anyone else had similar problems? Resolutions?

[georgen]

Ive only had mine a few weeks, but the last week noticed its taking longer to start, like you have changed plugs and just picked up new cap and rotor today, not fitted it yet.

[Darrenmcd1]

Hmm.... Let me know if it makes any difference bud

[daggie]

we've just had this prob on 1 of our xjs
it was the battery
 

[Darrenmcd1]

The lights, radio, etc all seem to function normally though. In saying that, you can never be sure so I'll give the battery a check!

[Brynjaminjones]

Could it be the fuel pump? I've read before that if the fuel pump needs replacing it won't start first time, as the fuel doesn't get there quickly enough. Try keeping the key at "on" for a few seconds before starting it - this gives the fuel pump some time to get the fuel through and if it's the problem it may well start first time when doing this. 


Edit: I've just read some more into this, it appears it can actually be caused by the anti-drain-back valve failing. This causes the fuel lines to de-pressurise after shutting the engine off, meaning that it has to pump for a while to get fuel through. Apparently the fuel pump has to be replaced to replace this part, which is how I got to what I wrote above!

[mark]

A car not firing on first turn of the key isn't always a bad think and personally I don't mind if mine does this as it circulates some oil around the engine before the engine fires and runs which means the engine is well lubricated before it fires up and the revs go up. just my humble opinion 

[Darrenmcd1]

You are probably right mark but it's bringing out my OCD so I need to get it sorted haha!

Good shout on the pump. Again, definitely worth checking.

[georgen]

Well cap and  hasn't made any difference apart from a little crisper when started, I say Brynjaminnjones is on the money and when I serviced mine was surprised to find no filter, as its in the tank with everything else it seems. Ill do some more digging when I have more time or I am forced to as in getting worse. 

[JamesH]

Turn it to 'on'  and then off, to 'on' again and then try and start. This will prime the fuel pump twice , increasing pressure. If it fires straight up doing this I think it will be fuel pump related and whatever the problem is it will require a new fuel pump.

[Dave69]

you should ear the fuel pump priming when you turn the ignition on even before you get to the start position, if the car repeatedly turns over with no issue and no flattening of the battery the it most likely isnt the battery.
 If the fuel pump cant be heard running then dive underneath and clean the power contacts and try again

irratic starting could be down to a poor responding immobilisers, these allow the engine to turn over but not fire, repeated on offs could electrically jog the system into working. Stateside have ecu which dont have the security electrikery and are a popular retro fit.

[mark]

With an electric fuel pump the pump should fill the float chamber within seconds of turning the key and then stop pumping when the chamber is full and pressure is detected by the pump , could it be dirt in the carb , dirty fuel filter restricting flow ?, choke setting? A low battery causing a weak spark , ? process of elimination really

[charlie jeep]

I'd replace the relays ..... Relatively cheap and easy. I guess there's an ignition relay and a fuel pump relay? Probably only one?

Just a suggestion