Hello fellow jagmads, I have a 3L S type V6 automatic, 2005 reg. very fond of it but for 14 months it has had an intermittent but persisten starting problem.

Ignition key into lock, car either starts immediately or does not. The engine turns over but then needs repeated attempts before it fires up and runs normally. When turning over there is no misfiring or spluttering.

It has had 5 diagnostic checks but no firm indication of problem has emerged. New battery and crank shaft sensor fitted (12 months ago), no improvement. New key obtained and programmed, no improvement, staff at 3 garages stumped.

I have recorded all starts over 14 months as 'good' 'poor' and 'bad'. Poor/bad accounted for 14%, or 1 in 7 of starts. The record shows that frequency/severity of problem fell in warm weather. Currently running at approx 30% (Jan)

Don't know what to do, can anyone please suggest what the problem might be, I'm becoming desperate, look forward to responses, desperate Geordie

 

Geordie,

I've moved your thread from General Tech Help section to the S-Type section.

This will get views by more members with the same vehicle. I hope the combined knowledge and brainpower can come up with a solution for you.

Graham

 

Geordie - Look into your fuel system. When was the last time your fuel filter was changed? If the answer is "I don't know" - I would get that changed straight away. Additionally, after getting your fuel filter changed - get the fuel pressure tested at cold start up (hook up fuel pressure gauge at rail, turn ignition key on but don't start the engine and record fuel pressure.

Sounds like a fuel delivery problem to me. (fuel pump, partially blocked fuel filter or even possibly dirty injectors) Good Luck!

 

There are some previous threads with a LOT of detailed help on here and there's a detailed jag troubleshooting guide too. Next time it fails, watch the PATS light (top centre front of dash, blinks red) very carefully as you crank. It may flash a code. If it doesn't then at least you can rule out PATS.

Non-start is usually something easy but not always so be prepared...

BTW, see below (both items):

 

Good afternoon gentlemen and thanks for your responses, been delayed getting back due to finger trouble on my part.

To Graham, thanks for the relocation.

To Abonano and JagV8, your replies are helping me build a picture of what might be wrong, please may I draw further on your expertise:-

1. I'll have a look at the fuel filter/fuel pump but does the diagnostic system not register such things.

2. Any thoughts on why higher ambient temperature reduces the problem?

3. Can you give me some directions to the trouble shooting guide, that sounds very interesting.

4. Has it ever been suggested that the starter motor, on turning over, generates a pulse which affects the starting/ignition circuitry?

Again, many thanks for your replies, nice to be in touch, regards,

Geordie

 

Georgie, low fuel pressure issues (thats what it sounds like to me) won't register in a "diagnostic mode" - The only way to rule out fuel pressure is to test at "cold start up" and at idle.

Fuel pressure should be at least 40 psi at cold start up and should be slightly higher at idle. You should have no loss of fuel pressure.

Any fuel pressure variations would dictate an issue.

Typically, when you have hard starting from time to time - it points to an intermitient or "failing" fuel pump. The cheapest option would be to change the fuel filter - it could be partially blocked causing the issues you describe above.

A $20 fuel filter change may save your $700+ fuel pump.

Just my $0.02

 

The later cars (like mine) and I think also the earlier ones can report the fuel pressure via OBD so if you have a tool with live data you could just monitor it.