Hi new to this sight .just got a 83 xj6 barn find has not ben on road since 1996 .have Ben sorting it out and doing well. But have run into a problem ,car will not start after it starts to get warm.

 

Welcome to the forum Craig. Please post an intro in the new member area when you get a moment.

https://www.jaguarforums.com/forum/n...-intro-must-5/

Not a good idea to post your address in the location, Just a City/Suburb will do. You might get unwelcome visitors coming to relieve of your car.

 

Weird problem. More often we hear about no starting/hard starting when cold.

How does she run otherwise? is the no-start-when-warm the only symptom you are experiencing?

Fuel system problems are common after long storage. Rusty tanks, rusty gasoline, clogged filters.....but I'd expect other symptoms.

That it starts on ether certainly suggests a fueling problem, yes.

A cold engine benefits from a spurt of fuel from the cold start injector and fuel metering enrichment based off the coolant temp sensor readings. A warm engine lacks this.

You can try capping off the AAV but my gut feeling is that it isn't culprit. If stuck open you'd have a high idle at all times. If stuck closed, you would lack a high idle when cold. But I can't see how it would cause a fuel metering problem.

Still on my first cuppa coffee. I'll do some more mulling

Cheers
DD

 

Hi thanks for thoughts DD car runs ok when cold a little rough on idle tends to stall after running very short time .looking at vacuumed leaks or poor connections have set timing drained old fuel before trying to start.car has 80000 miles

 

I've sipped my one and only cup of Nestle's Classico. Self imposed limit.


I like to think in terms of starting issues as first, a healthy crank whether a cold engine or a hot engine. If the starter is dragging, it will consume all the volts and the engine will not fire.


Then think a bit more. Ether will fire an over fueled engine!!! The old tech way to clear a flooded engine, other than waiting a bit, is to crank it with the throttle butterfly wide open. Objective, being to add air, lots of it.


Another old tech diagnostic is to remove the spark plugs and read them. Not as clear as it was at one time as the fuels of today are different. But, sooty black still means the engine is over fueled. . f


Working theory: When cold, the engine will tolerate or even enjoy a fuel rich mixture. When the temperature rises, not so much, if at all.


My first places to examine would be a dirty intake filter. Thence, a bit more complicated, one or more leaking injectors.


Carl

 

Good points, Carl.

I'll admit that my first thoughts.....the one cuppa coffee type....went towards lack of fuel. But you're quite right.

Here's some reading material on over fueling.....


XJ6 Series - EFI Rich Mixture

XJ 6 Series III 4.2 - Cold Start EFI Overfuelling

Cheers
DD

 

I am having a similar issue on my '83 XJ6. Already replaced; fuel filter, all injectors and fuel pressure regulator, distro, coil plugs and wires... and still have my hot start issue. Starts well cold, AAV seems to be working properly as idle rpm decreases as engine warms up a but... but when trying to re-start the hot engine, I'm having to crank more than is customary. It ends up starting... but it's very annoying. When running, engine runs well. Idles, doesn't hesitate, doesn't miss, etc. For the life of me... I can't figure out why this is happening. Any thoughts?

 

How long must you crank, exactly? Three seconds? Five? (count one-thousand-one, one-thousand-two)

And how hot is "hot"? City traffic in Las Vegas in August?

I had a daily driver Series III XJ6 for years and have worked on many others. None have been "instant starters" when hot and I've never been able to isolate an actual repairable fault. Interestingly, I've found that if you crank for about 3 seconds, release the key, and then turn the key back to 'start' the engine fires instantly.

Personally, if yours will start in 2-4 seconds I wouldn't waste time time trying to locate a repairable fault.

On general principles you might want to clean the throttle body and make sure the throttle blade gap is at the correct 002". Make sure the ducting between the Air Flow Meter and the throttle body isn't loose of leaky.

If "hot" means something other than merely fully warmed up, you might want to check you fuel temperature switch...if you have one. This temp switch is mounted on the fuel rail and, if the fuel reached xxx-degrees, it dumps the vacuum signal to the pressure regulator. This increases fuel pressure to clear any vapor lock or percolation from the fuel rail. This switch was a retro-fit and early cars but later incorporated into all cars during production.

Cheers
DD

 

Hi Doug - thank you for the detailed note. I am nearly certain the scenario you describe is the same as mine, so I guess a bit calming as it sounds 'normal'. That said, I need to count it, and will report back if the time exceeds 4 seconds. 'Hot' is simply 'fully warmed up', and in March in Chicago, so I don's suspect it's fuel vaporization... but I've been wrong before. I will get some throttle body cleaner and check tolerance... but suspect this is also in an acceptable state, as is. Thanks again.

 

But, hold on...a difficult hot start, or no start when hot is the classic symptom of the failed GM module in the ignition amplifier....that is where I would go first unless the fault is proven to be fuel-related.

 

Thank you for sharing the thought... as it's likely a perfect place to look on most Series 3 jags. On mine, I have made this part redundant by installing a new pertronix distro (D171618) and complementary coil... so I don't think this is the culprit on my car. Thanks again.

 

To all,

Hi, I have a 96' XJS convertible. I think I am having a similar issue to this string, except, it's not just when the engine is hot, it's when the day is hot. In the morning when it's it's in the 60's or low seventies, it starts right up. But if it's been outside in the heat (80-90), even if the car has not been on for 8 hours, it starts, but then sputters to a stall in 2-3 seconds, unless I rev it for 4-5 seconds, then it's fine. I thought it was bad fuel, but it's been doing this for the last 2 months (around 4 tank refills). any suggestions would be appreciated.

 

Gregory,

Hi, if I was looking for this part you mention here for a 1996 Jaguar XJS, do you know the part number? I don't know the difference between the ignition amplifier module and the engine(ignition) control module. I am seeing varying prices out there between the two. thx

 

The amplifier module I refer to is Delco 1906 - these are generally easily available although Doug now reports that they are more scarce; the same module has a very long numerical part number under the GM brand - but they are identical. Aftermarket modules are NOT reliable in the V12.

However, your car (1996 V12) does not use the Lucas ignition amplifier used in the 5.3 XJS up to 1989 (?); your car has the Marelli ignition system, which is quite different, so it will not use the module I have mentioned.

 

what I have discovered in 30 years of owning, driving, and starting my 1984 XJ-6 is that after driving the car a while to fully warmed up. then shutting the engine off, the fuel system de-pressurizes, in other words, the gasoline goes "back" into the tanks and if the engine is hot. it will take a bit of cranking to pressurize the fuel system again. So I blame the problem on the Fuel Pressure Regulator not holding gasoline "in the ready". That is my theory and the probable reason an engine starts with Ether, because the ether is RIGHT THERE WHERE IT NEEDS TO BE.

To resolve this, I have learned to pressurize the fuel system BEFORE cranking the engine when cold AND after it is hot.

how I do this? I place the shifter in First Gear, turn the ignition switch to Start and hold it there for 4 seconds, then back to OFF. then I repeat this 3 more times.
The 5th time I place the shifter in Park and it fires up instantly. Fuel System pressurized.

I also own a 1965 Jaguar S type with twin tanks and two carburetors, it does the same thing when hot. I tried the same remedy and it fires inmediately.

So in my non-scientific non-expert conclusion, the problem is that the gasoline goes back away from either the injectors or the carburetors. and it takes more time and cranking to bring it back to pressure and combustion.

Is this genius or what? Maybe, maybe not.
I am not trying to compete with anybody's expertise, I only say this because of my experience with this issue. So if I am wrong, it's a good kind of wrong.

 

Jose: I am interested in what you say about starting your S Type when hot because my 1966 Mk 2 fires instantly when cold but when hot is reluctant to start - it takes a fair amount of cranking.
But I cannot figure out what your process would be, given that it is a button start; just turning the ignition on energises the fuel pump, clicking away until the system is, in theory, pressurized. So if the pump stops clicking but the (hot) engine does not fire, what do you do?
Do you put the transmission in D (because it will not start in D) and then, what? I have never been able to figure out a way to get a quick hot start in the Mk 2, and I'd love to learn what your trick is.

 

yes Gregory, exactly as you figured it but in the S type I step on the throttle pedal after placing the ignition switch in ON, not touching the START button at all, and pressing and releasing the throttle pedal rapidly a number of times and what results sometimes is that the pumps start clicking again, which to me translates to "more pressurizing was needed". Then I turn the ignition switch to OFF and do it again.

you might argue that this leads to flooding the carbs but it doesn't. The engine cranks and starts almost instantly when hot, something like "chug chug, vroom"

the S type has 2 fuel pumps and 2 tanks like the XJ, the MK-2 has 1 tank and 1 fuel pump. but it should not be any different, it's the same engine, carbs, etc.

 

Thanks for that tip regarding the Mk 2 and hot starts. I will try that.