Hi All
I have a Series 3 1983 XJ6, the engine has just been rebuilt, and now it is hard to start if left overnight, the mechanic that rebuilt the engine has told me that the battery I have in the car is not up to starting it, it is a new battery and has 12.55volts, he is telling me that the starter motor ( original ) is drawing to much power and that there is not enough left to efficiently operate the fuel pump etc. the car will turn over but takes 5-10 min to start once started it will run fine and restart straight away, he has checked the fuel pressure and is OK, he had the same issue with it and used a battery booster and it would start on the first crank.
his suggestion is to
1) get a better battery
2) fit a reduction starter motor that uses less power


Has anyone come across this ?
Thanks Gary

 

well the XJ-6 Series 3 likes a lot of electrical juice, so if the battery is not up to Cranking Amps.

are you "priming" the fuel system before trying to start the engine?

here's what I do in my '84 when it sits for a while:

1) place the shifter in 1st Gear,

2) turn the ignition switch to START and hold it for three seconds, then back to OFF.
> you should hear the fuel fump whinning in the trunk as you hold the switch in the START position; (the starter will not crank with the shifter in 1st gear).

3) repeat another 3-4 seconds,

4) repeat another 3-4 seconds,

5) place the shifter in Park, and try to start the engine.

Did it start?

If yes, the system needed "priming" or "charging" or "pressurizing", whatever you call it.
If no start, there is another issue preventing it from starting.

possible problem: The Cold Start Injector ?

My '84 still has the original starter, it has been reliable since I bought the car in 1989. I have heard negative things about those gear-reduction starters, but have never tried one, so I have no clue.

 

Hi Jose

The mechanic "hot wired" the fuel pump so it kicks in when you turn the switch on I can hear it clicking, the cold start injector is fine, the fuel system and electrical are off my old motor and were working fine, but he did run out of fuel on a test run , don't know if that may have caused issues but I do have fuel filters between the tanks and the changeover solenoid
Gary

 

I agree with Jose's advice about priming the system. If the starting behavior changes then you might indeed have a fuel pressure problem.

And, yes, the battery has to be 100%. One idea is to to get a jump from another car next time you start, thus ensuring you have plenty of volts and amps. If the starting improves then you know you're on the right track. Ill add that poor connections and/or poor main ground can mimick a weak battery.

The fuel pump should hum, not click. If yours is actually clicking....that might be a clue.

What the the ambient temps where you are?

Cheers
DD

 

Hi Again
Just went out and tried to start, no go just keeps cranking, attached a battery charger, and it started first time, so assume that even though the battery is only 6 months old and is showing 12.55 volts either it is not up to the task or faulty ?
I did check the voltage the first time and it drops to 10v when cranking
Gary

 

My previous battery eventually couldn't cope and gave up cranking even though it showed around 12v static. I was recommended to get a HD battery of at least 650cca, and it performs just great. I also keep it on regular charge with a smart charger. I assume it's the XK engine you had rebuilt? If so, it's a heavy old beast to turn over and power the ancillaries.

However, yours is still cranking but not firing?? In which case there may indeed be other things at play than the weak battery.

 

Have been doing a bit of reading re batteries, from what I can ascertain a battery needs to read 12.7v to be "fully" charged, mine is reading 12.55 which is approx. 80-85% charged, when I run the car it comes up to 12.64 ( the alternator is charging at 14v ) but then goes back to 12.55 overnight.
when I attached the charger it reads 13.1 and starts straight up, I would have to assume then that the battery is at fault, I will leave the battery on charge overnight and see if it comes up to fully charge, fingers crossed.

 

Sounds like you're on the right track, Gary.

Remember to ensure the connections are the battery are clean and tight and the main ground is clean. The main ground is under the car, RH side, about where the engine and transmission join together. It's a heavy braided strap

A million years ago I was experiencing a "extended cranking, hard start" problem with my 1987 Series III XJ6. I was a Jaguar newbie then and got way off the beaten path. Anyhow.....long story short...a new battery solved the problem. Oddly, the starter cranked well....there was no outward sign that the battery was weak.

Cheers
DD

 

Have a look at the positive lead that goes to the starter...

It is the thickest cable in the whole car. Ergo, the starter is the one thing that draws the most power. That is why on pick-ups trucks an winch is connected to this wire...

When you are cranking the starter with a weak battery, the starter will drain it and leave no juice left for the ignition system to trigger....
That is why you can crank but it won't fire...

A good battery doesn't drop under 12V at starting. Should be around 13V when fully charged (6 cells of 2.2V each). Do yourself a favor and buy a recreational battery for your Jag. They have thicker plates inside that can cope with the huge instant power drain a lot better...

 

Connections, absolutely.


A bit ago, my up to now utterly dependable old Jeep came home on a flat bed. I had loaned it to my daughter. A long tale since told.


The battery was very low. no crank. OK, I can fix that. I attached the cables of my Schumacher "smart' charger. After hours, it wasn't getting anywhere!!!


So, I removed both cables ands attached the charger cables to the bare posts. Charge effort resumed. This time, after a while, volts coming up.


Hours later, 100%.


But, me a more than a bit perplexed. I'm close to **** on clean and tight electrical connections. These looked good ???


But, I got out my tools and cleaned the cables and posts. Connected. The Jeep cranked just fine. But, the no run issue remained. That ultimately resolved. that other tale.


Carl

 

Doug, why would the mechanic "hot wire" the fuel pump?? I mean, once you turn the switch to ON, the fuel pump kicks in anyway.

 

I'm not sure. I suspect to eliminate the control circuit A) for diagnostic purposes or B) to supply as much available voltage to the pump

On a Series III XJ6 that should not happen.

The pump should run wen A) the starter circuit is engaged and B) when the micro-switch in the AFM closes.....which happens just as the engine begins to fire.

Cheers
DD

 

Hi All
I put my charger on overnight yesterday, and the battery was fully charged at 13.01v the car started first go, checked the battery that afternoon after 8 hours and it was showing 12.98v car started first go, after 12 hours overnight battery is showing 12.91v and car again started first go.
I can only assume that the battery has to be at 100% ( 12.7v) to start a series 3, mine was 12.55v and would crank the engine but has been said did not have anything left for the ignition system. I think the battery is fine, it just dropped charge because it was sitting idle for 2 months at the mechanics while the engine was being rebuilt, and the test drives and the drive home was not enough to fully recharge the battery. looking at the drop in charge over 1 day, I can assume that the battery will be below 100% ( 12.7v ) in 4 days if not started and driven, the car is only used for club runs approx. 3 times a month so I will need to have the battery kept on charge.
Gary

 

I only use mine around once a week, sometimes only for a short distance, which is why I keep it topped up on the smart charger. When you replace the battery, eventually, you'll find a high cca rating a little more forgiving.

 

A couple of points:


1. Alternators are good at sustaining charge, but much less so at bringing up a low battery to full charge.


2. You may have a low amp drain. Other than the memory stuff if any in the computer, but, definitely in the radio.


3. At times, a drain just comes on for a never discovered reason. Usually not an issue in a frequently driven car.


4. Battery storage capacity. The best are really heavy!!! The "economy" grade much lighter.


5. A poor ignition circuit. Extra resistance overcome by lottsa volts. Starter gets first grab. Test in one way. Jump in 12v from an independent source to coil +. I suspect it will fire, in the main battery low volt stage.


Carl


Carl

 

Final update


its been a week know since I recharged the battery and all is still OK car starts first time every time, battery is now at 12.7v so it may need to be recharged again soon


Gary

 

Curious thought:


Hardware stores have 6 v dry cells usually used in lanterns. But, at times on old one lung engines. Pair up two in series to get 12v.


When the Jaguar battery is a bit low and can crank, but not fire, jump in the "jump battery pack" directly to coil +.


I have a feeling, that the reluctant cat will then fire right up.


Like Doug, cranking well but not firing is a bit perplexing.


Side bar: In my starter travails, the Fire wall post to starter battery "melted" off at the starter solenoid. I replaced it with a generic cable.
Much better ends and thicker. So far, my lump fires right up.


But, I gotta say that a battery or two back, it cranked and just when is seemed it was going to quit cranking, the engine fired!!!


Why? perhaps more robust power to the coil. I use a switch triggered relay for the coil.


Carl

 

How well is the starter motor turning over the engine ? I had a lot of trouble in the early 2000s with starting a Series 3 that a replacement starter motor cured. I also had to replace a fuel pressure regulator. This is mounted on the fuel rail and lets excess pressure blow off back to the fuel tank.

 

More;


The more I think about it, the more I like the idea of a relay to provide more volts to the + post of the coil. Enough in the crank cycle, but best in both crank and run.


Carl

 

Gary, I just noticed this thread and it appears you haven't introduced yourself in the intro section.....when time permits that would be great. I have also added you to our NSW Roll, just follow the link below...WELCOME