Hey all!

Noticed that my 88 xjs will start just about instantaneously on the first start of the day. All starts after that get the slow dying cat sound for about two seconds then it starts. Will start nicely on same day if car has sat and cooled, alot. New alternator (115 amps)that is providing proper current. Battery fully charged always. Seems to be related to engine being at normal operating temp.

I rather prefer the instantaneous start up. Any ideas?

Thanks!
Michael

 

I do not quite understand what you mean. When hot does the car crank normally but fail to start or is it cranking slowly???

 

Possible small crack in distributor cap, letting in moisture? Try new dizzy cap...
My friend's dad's 3 year old XJ12 series III suffered this in the 80's, took many expensive trips to the dealers until the (relatively) inexpensive new distributor cap cured the beautiful beast.

 

Warrjon - Car starts instantly first start of day. After that it cranks quite a bit for about two or three seconds then starts.

Al - Thanks! I'll check out the cap. No moisture non start issues. Just every start except the first.

 

Ok that's what I thought but didn't want to make assumptions.

There are a few things it could be
Fuel Vaporisation - yours is an 88 model so will have the larger fuel rails.
Too rich this will cause any engine to be difficult to start when hot
Ignition amplifier located on the B bank manifold - this is where I would start, although I have no experience with these. A can of spray freeze is a great tool for chasing these types of issues, you will get it from an electronics store.

Grant might me lurking here and give you his words of wisdom.

 

What about injector leakage. After being pressurized, could they be leaking leading to a rich situation. Can you test for fuel rail pressure test and if it reduces while you wait due to leak?

 

Lots of possibilities, as mentioned.

Are you slightly opening the throttle on warm starts? Although entirely contrary to conventional wisdom on fuel injected engines the owners manual specifically instructs that this be done. Might wanna try it and see if anything changes.

Or......

With the key "on", but before engaging the starter, give the throttle a stab. Then crank the engine. On the HE engines this will pulse the injectors....sorta like an accelerator pump on old carburettors. See if anything changes.

That said.....

I'm not at all convinced that 2 or 3 seconds of cranking is excessive. Go ahead and count off "thousand one, thousand two, thousand three". That's not very long. If there's an actual fault at play here it's probably minute. That is, it will probably be hard to find.

FWIW I have an '88 V12 in my driveway that behaves as you describe and the '88 V12 I owned for several years was also the same.

Cheers
DD

 

When you put the key in the ignition don't turn it 'start' straight away; turn it to fire up the fuel pump and when the pump stops (meaning that the system is pressurised) then turn to the 'start' position.
If you are losing fuel pressure for whatever reason after stopping then this should cut down on the number of cranks that you need to do before it fires up.

 

warrjon, dsetter, doug, SteveM:
Thank you for all of the great advice! It certainly isn't a long period, maybe "1 thousand two". Just prefer the instant start. I will certainly check up on the diagnostics prescribed by all here. I will report back if I am able to clear it up to my satisfaction.
Thanks!
Michael