This is a 2003 XK8. I can go out to the car and sometimes, actually most times, it starts right up. Other times it cranks over fine on the starter but it acts as if there is no spark or fuel. It just cranks and cranks and no matter how many times you turn it off and back on, same result. This happens even if the car is warmed up or cold. Maybe one out of twenty times.
If you walk away and come back in a few minutes, it will usually start right up like nothing went wrong. No codes of any kind.
Checked the battery at NAPA and it passed the test fine.
Anyone else seen this?
Thanks

 

I guess no one has any ideas?

 

Well you only need fuel and a spark ..easyest to check is the fuel ..schrader valve on RHS to rear ... when it does not start get someone to open the valve with a small screwdriver and see if fuel spurts out ( watch your eyes)
Remember the fuel pump is a brushed motor and the commutator etc can go intermittant.

 

Intermittent, especially situations like this, can be the worst.

I think the next thing to do when this starts happening is digging in. Hope for a reoccurrence, actually.

The checking for fueling (and spark) when this happens next time are dead on. There is no problem running these cars with those flat plastic covers off the coils. And there is no problem leaving one of the coil packs with the two 7 or 8mm bolts undone. Like PistonB said, next time check schrader for fuel pressure and, pull a coil to see if you can visually see spark at the plug when turning over.
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If these things aren't happening it might be time to start digging into the whole "ok to crank, ok to fuel" series of events between the key, KTM, BPM and ECU... Great fun! Or just some good old fuel pump stuff..

I would LOVE know what folks think of this...
https://www.ebay.com/itm/18448152478...is&media=EMAIL

 

There sure is a lot of this intermittent hard starting going on. Ive had it on a 2001 XK8 and now on a 2004 XKR. Different fuel systems...I've checked everything nothing seems to make it fire off instantly as I'm use to. I've noticed on this XKR it seems the more I drive it consistently the easier it starts consistently. At this point that's all I can share.

 

Yep, driving these cars on a consistent basis indeed keeps them happier and healthier in the long run....

 

Agreed, problem is its completely rust free inside and out, akways garaged and i dont drive it on wet roads or in rain so sometimes there are long spells of both I don't take it out. Plus I'm no longer as joyous to wash and dry and...as I use to be. Lol. I did the same with my last Corvette and never had any issues except the battery wouod go dead. I can say this one never does.

 

Could also be the Neutral Safety Switch on the side of the transmission going bad, though it will eventually throw a code.

Don't know why they call it a Neutral Safety Switch...maybe my terminology is wrong...Its the electrical widget that plugs into the side of the ZF transmission and changes gears. When it went bad - twice on my '97 - the car first starts only intermittently, then not at all. Don't know if they changed things by 2003.

 

I think on the 2003 XK8 and the 6hp trans, in place of the neutral switch on the side of the trans, is something called a linear selector switch that is found on the side of the gear selector. In it, I believe, is an electrical component that will inhibit cranking if the trans is not in Park and Neutral,,, and then other functions, to do with gear selection and relaying info to the trans and BPM...

On closer look (electrical diagram) it may also be that this switch plays a part in signalling to fuel and spark, but I don't have the ED in front of me and can't remember.

 

Well, it is doing it again. Would not start yesterday and would not start this morning. This evening, it started immediately. Therefore I know there was no loss of fuel pressure as it did not crank over long enough to build up pressure but not sure about spark. I tried locking and unlocking. Tried moving the shifter back and forth but it just cranked like no spark or fuel.

Ideas?
Thanks

 

If you are turning the key and it IS cranking it IS long enough to build pressure. Turning the key to the last position in the turn, not engaging starter, will even prime the pump which will repressure-ize the rail, which SHOULD already have fuel in it. Of course, this is assuming that "things" are working as they should.

Also, if cranking, with help, you are able to check for spark. Are you, or are you just sitting in the driver's seat and turning the key? It's time to (when it's NOT starting) to get under the hood and start investigating...

Now, ahead of time, remove one of the coil covers and loosen coil bolt(s) (leave it this way, cover on the shelf, bolt undone) and have it so next time you can quickly pull a coil and test for spark. Have a spark plug tool around.... Also, go to the rail and press in the schrader valve and see if fuel shoots out. Have ya tried these things? Can you hear the pump prime with key turn (not cranking) when it's not starting?

 

I never here the pump running but I have stuck a pin in the schrader valve and gotten sprayed with gas.
I have yet to try a coil over for firing.

These cars don't have anything in the keys that the computer could know about like a chip do they? I can see nothing of the sort. THey look simplistic

 

Hi,
Yes, the key has a transponder chip, but the car won't crank if it isn't recognised.

Surprised it's not throwing any codes. A check for spark would be logical given that you have fuel pressure

 

No codes.
It was a lot easier to check for a spark before these coil over plugs. Not quite sure how I will do it

 

If various OBD monitors can't or haven't set, codes are unable to flag.

I thought these cars would crank even with an unrecognised key, but not start (because the injectors are not enabled).

You usually get either a flash code (via PATS) or actual codes (DTCs).

 

No codes unfortunately. I have another set of keys and am taking them with me to see if another key will start it when the one I normally use won't

 

Remove the coil cover plate, remove ONE bolt (or 2) from ONE the coil hold downs, when the car refuses to start but does crank, have a friend turn the key while you push your finger over the coil boot hole. You will get a definitive, lol...or use a spare spark plug or ONE that you remove from the head

Usually you can hear the electrical CRACKING as soon as you start to lift the coil and boot away from the plug down in the well.

I don't think the BPM gives the "OK TO CRANK" (see electrical diagram) if the key is not recognized. I don't think

 

No No No ..to check for a spark remove one coil pack from its plug and fit a loose plug to it ( any variety of plug will do ) and then use some jump leads to join the plug threads to the engine earth . When it cranks you will /should see a spark at the plug.
Operating the coil without an earthed plug attached can induce voltages which may damage the coil pack.

 

When it's cranking but not starting try fully depressing the accelerator pedal to tell it to cut off the flow of gas. It could be that you have TOO MUCH gas in the cylinders.

I had a similar issue with my '97. For years I noticed it was worse in the summer and eventually found that some of the tank vent valves were bad, allowing fuel vapor from the tank into the cylinders while the car was parked. In the heat there would be more vapor so it happened more often.

I wonder if you can see any other pattern to your issue. Is it more likely to happen the first start of the day? When it's hot/cold? Full moon?
Such correlations could be helpful.

 

I can try that.
Usually happens on the first start but it did it the other day after I parked it for about 30 minutes. I waited another 39 and it started right up like nothing was ever wrong.
I think it usually happens in the 3rd quarter of a waning moon.