1996 XJS 4L, 107K miles.

It’s been a while since I last posted but I think I’m on the verge of having an issue with starting.


I have owned this Jag for over 10 yrs. and basically never had any issues.

The Cat always started on the 1st or 2nd revolution. It is maintained and looks as good as any new car considering it as all original.


About 2 hours ago I got in to start the Jag and it took over 10-15 revolutions (Fast revs) before firing up. I let it set for a while and tried to start it up and again the same thing happened. Let it set while and tried to fire it up and another 10-15 revolutions (rapid revs)
Each time it does start but Not as before!!

The first time it happened I was out picking up something and after starting I drove home (~2 miles) with no issues.

I haven’t checked anything out yet as I wanted to get your input on potential issue.

I do a lot of preventative maintenance and was thinking for a while that It might be time for a fuel pump??

As always thanks for your help

Softball60/Paul

 

clogged fuel filter? maybe just bad gas? try some fuel stabilzer in it. not sure how long between runs you do but if it sits for a month or so i would put fuel stablizer. maybe check battery voltage? how old is battery?

 

Hi Softball

(1) Crank Position Sensor

(2) Fuel Pump

(3) Fuel Pressure Regulator (FPR)

Fuel Pressure regulator, would be high on my list because She eventually Starts!

 

Replaced FPR with my original FPR and had the same issue. 10 to 15 revs then it fired up.

Very little leakage of fuel when taking apart to replace FPR.

Fuel filter, if plugged Would not normally be repetitive in trying to start.....??

Possibly fuel pump taking time to build up pressure??

Don’t have any experience with crank sensor. Why would it have changed from 1 or 2 revolutions then startup to 10-15 then startup/

Thanks

Softball60/Paul

 

I’ve had exactly this problem. One day, OK, then very long crank, albeit for me really only bad from cold start. Given what you’ve checked I’d suggest two options. Firstly battery... Even with a fast turnover if you’re not getting at least 12v at the coils it will struggle. Secondly as you’ve suggested, pump. The XJS has an internal non return valve and I’m suspicious of mine. Don’t buy a jaguar pump if you go that way... it’s a standard unit and can be picked up cheaply. Otherwise, it’s one or more of fuel, air or spark... have you tried priming a couple of times before starting?

 

It has electronic ignition. There are no coils

Thanks

Softball60/Paul

 

You have six coils, Paul. They're under the removable cover atop the cam cover.

A fuel pressure test would be good idea here.

To clarify, this extended cranking occurs every time you go to start the car? Or only if the car has been sitting a few hours?

Degraded readings from the crank sensor or cam sensor can cause hard starting. Sometimes the crank sensor just needs cleaning.

Cheers
DD

 

Doug,

Two (2) days ago the car would always start first or second revolution and the prior 10yrs.

As of two (2) days ago it now takes 10 to 15 revolutions.


You are correct, I forgot about the plug wires w/coils on each of the spark plugs. I was thinking back to my youth.

As I mentioned earlier in one of my replies that when I pulled the FPR and replaced it with another there was NO PRESSURE AND VERY LITTLE FUEL DRAINED.

DID YOU READ WHERE I THOUGHT THAT IT MIGHT BE THE FUEL PUMP AND IT IS STARTING TO GO BAD. POSSIBLY THE ADDITIONAL CRANKING THAT IT IS TAKING IS BECAUSE THE FUEL PUMP HAS TO BUILD ENOUGH PRESSURE TO MAKE IT’S WAY FORWARD TO THE INJECTORS??

I don’t have a pressure device to monitor the fuel. I can pull the FPR and have someone crank the starter to see if there is any fuel

 

Start the car. Wait just a few moments. Now try restarting. Same condition? or improved?

The fuel pressure in the rail shouldn't drop off in just a few moments. If the condition is improved it suggests you do have a fuel pressure problem as you suspect.

If the condition is not improved it suggests something other than a fuel pressure problem.

Also, does engine temp have any bearing on the condition? A cold engine uses different fuel metering than a warm engine; a 'cold start' mode.....like a choke on an old car with carburetors. If the computer doesn't know the engine is cold it would be harder to start. A coolant emp sensor would be worth checking in this scenario



From what you've said it does sound like a fuel pressure problem. Only a pressure test would confirm that, though.

You can replace the pump. As guesses go, it isn't unreasonable in this case, IMO

Cheers
DD

 

The prolonged turnover for firing up has stopped. It now fires up just like it used to....1 or 2 revolutions and bingo!!!!

Earlier today ordered new filter and pump.

Will let you know how things go.

This is confusing but either a clogged filter or pump? And now it broke loose.

Will let you all know how this goes.

Thanks

Softball60/Paul