Hello,

New member here. Our Jag is taking more and more cranking before it will start. Sometimes I have to try 2 or 3 times before it starts. What can I check?

Thanks!

MountainMan

 

The fuel pump may be on it's way out, or the fuel injectors may be leaking, among other things. Turn the ignition on and off several times without engaging the starter. The turn to the starter. If it fires up immediately it indicates a lack of pressure in the fuel rail was the problem.

 

Hi MountainMan,

Welcome to the forum!

There are a number of things known to cause hard starting. The first one to rule out is the Crankshaft Position Sensor (CKPS). If the tachometer reads 200-250 rpm while cranking, the CKPS may be OK. If the tach reads 0 rpm while cranking, suspect the CKPS is failing.

Low battery voltage is a common cause of poor starting or non-starting, because the Engine Control Module (ECM) will not trigger the ignition if the battery voltage sags below 11V or so while cranking. If you have a Volt-Ohm Meter (VOM) you can check this yourself, although some meters do not react quickly enough to give you an accurate representation of the actual cranking voltage. Most chain auto parts stores will do a basic check of the electrical system for free.

Other likely contributors to hard starting include the Fuel Pressure Regulator (FPR) and Check Valve or Non-Return Valve, which work together to maintain 32-44psi in the fuel rail, and when one or both fails, it can take a while for the fuel pump to refill the rail at startup, and as RJ237 has already mentioned, the fuel pump itself doesn't last forever (it's mounted in the fuel tank).

I'm sure others will offer other possibilities - the list is long, but the CPS and battery voltage are the ones I'd check first for any obvious malfunctions.

Cheers,

Don

 

OK, Don, you have done what you (correctly) chided the rest of us for! I think you meant the CKPS, not the CPS, right? And the Cam Position Sensor can cause a hard start, also!

 

Ross!

You got me! And I was doing so well until that last sentence!

I don't recall chiding you or anyone else about mixing CKPS and CPS, only offering Jaguar's own usage of CKPS, beginning with the X300, as a standard to which all of us should aspire to conform! :-)

Good point about the CMP or CMPS, since the ECM uses its signal to establish initial ignition timing. I've read that the CMP can drift out of spec over time, its electrical connector can accumulate gunk or corrosion, and the drive teeth have been known to break, so MountainMan could check for those issues too.

I was trying to avoid my typical laundry list, but while I'm on a roll, basic tuneup items are always worth checking when diagnosing hard-starting: air filter, fuel filter, spark plugs, coil power relay...

Cheers,

Don

 

Thanks guys! I'll check things out tomorrow and let you know!