My '96 VDP is a gem of a car, and always starts instantly with the briefest turn of the key, but about once a year, if I allow it to stumble by releasing the key a hair too soon, it will thereafter refuse to start - cranking vigorously but without the slightest hint of any ignition occurring. In years past this has typically occurred on cold winter days, and has resolved itself over a period of days, eventually firing erratically, then finally catching and smoothing out. I replaced the Crank Position Sensor, but this did not seem to correct or prevent the problem. This year, the "no-start" incident occurred on a warm summer day. As before, the dashlights all come on normally, and the starter cranks perfectly, but the engine does not fire. I mean not at all, and very suddenly, as if fuel or spark has been disabled. I do hear what I take to be the fuel pump cycling for a few seconds in the rear of the car when the key is turned. I have not yet pulled plugs or checked injectors. We did have a cam position sensor light on earlier this spring, and the engine sometimes misfired above 2,000 rpm. The OBD computer recorded P0340 (cam position sensor) and P1315 (peristent misfire). I cleared these and they have not returned in several weeks of driving or during this episode, nor have other codes have appeared. I would be grateful for any suggestions.

 

The V8s did have a starting problem on the lines you describe, even failing to re-start if only run for a few seconds, yet from your model year, you should have a 6 not a V8. The trick with the V8 was to press the throttle pedal to the floor and crank away to clear the combustion chambers, until it started firing, then keep cranking until the engine would finally run on its own. You need a good battery, though.

It does sound like you have flooded the engine, I have to say. Other thing is this is normally a cool weather/winter problem, not summer.

Other thing is ECUs are very shy of low battery voltages, and starting lowers it even more. Is your battery up to scratch ?

 

The six-cylinder has the same problem.

 

Is the tach registering while cranking?

 

Thanks to all for your thoughtful suggestions.

re: Fraser Mitchell, yes this is the six. I did crank for a very long time, which the battery sustained magnificently, however with pedal depressed, probably defeating the purpose of "clearing the combustion chambers". Sounds like I should try this again without gas. Having said that, I have let the car stand for a day and would have thought this enough time for any fuel in the c.c. to evaporate on a hot summer day. As you note, cold weather seemed to be a factor in the few prior instances of this problem, though not this one.

re: Keesh, thanks for confirming that the six has the same re-start issue as the eight.

re: Sparkenzap, I don't recall if the tach was reading during cranking, but will check tomorrow AM.

I appreciate your insights and suggestions and will follow up.

 

Ross,

In response to your query about whether the tach is registering while cranking. The needle twitches slightly but does not indicate revs. I don't recall seeing revs indicated during cranking at other times, but the cranking is usually so brief there would hardly be time before the engine springs to life.

 

The "foot hard to the floor" method of clearing the engine flood problem is a known well documented way of fixing the no start problem of x300. This commonly happens when an engine is started and then turned off too soon before it has warmed up. The known way to clear this is to hold the accelerator hard to the floor then turn engine over. It should then kick into life. I believe this may have something to do with re-setting or fooling the computer.

 

Regarding the suggestion to floor the accelerator pedal as a way of "clearing" the computer during a restart, this is actually what I did, for a good 60 seconds, alas without success. I appreciate suggestion and am reassured that the procedure, while ineffective, was at least not inappropriate.

 

can anyone tell me where my crank sensor is located 99VDP?

 

99 VDP
Schematic says sensor is located engine/rear of bed plate.
I know where the engine is, but....

 

I can report that replacing the CPS resolved this problem. I had hestitated to replace this since it had been done within 25K miles and hence seemed unlikely to have failed, but this turned out to be the culprit. Car is back to starting instantly and running beautifully. Given the relatively low cost of the CPS and its easy accessibility on the XJ6 (front of timing cover) this is a pretty easy fix.