Good afternoon, Team,
My XJ-S V12 HE is now back on the road after much restoration and repair: refurbished rear cage with all new moving parts; EFI harness rebuilt; injectors tested; new fuel hoses; new fuel regulator; new ignition module; refurbished Teves brakes; brake pads; brake hoses; and a general clean-up of the engine bay hoses, wiring, as per my very good friend Grant Francis.
All good, drove around the small town of Raymond Terrace, NSW, and a bit of highway driving on the M1: smooth acceleration, plenty of power, temperature was good, oil pressure as per the usual!
Stopped off for a coffee 45 minutes or so: car was very difficult to start. Cranked over OK and eventually caught but it took a while.
This is compared to my Series 1 Double Six (carburetor) which starts immediately once warm.
Tried a few start methods, the one which seems to kick the car over almost immediately is:
a. Turn ignition on, wait until pumps stop running:
b. Depress accelerator once to the floor;
c. Start engine!
Just thought I'd post this to gain any similar experiences or to assist those finding it difficult to get the V12 EFI started.
Cheers, Chris

 

This is caused by evaporation in the injector feed tubes. Push your accelerator pedal right to the floor while cranking and it will start in about 4 secs of cranking. If you can pop open the bonnet (assuming you are parked in a safe private place) the car will strat more easily as the fuel will not evaporate.

 

Would insulating it with something like a fire-sleeve help?

 

You can always do what the previous owner of my car did. (sarcasm).

I am not sure what the center vents are from, but i found out the side vents are 1998 Honda Civic grills.

Doug

 

Thanks Doug, could we get a wider angle shot of the car with louvres? I have thought about making this modification but didn't want to stuff up the aesthetics.

 

IMVHO, you will!

Cheers!

Paul

 

Here is pic after i got rid of the Honda Civic grills and replaced them with something a bit sportier, as i do not have a spare unmolested hood close, and wanted something that didn't look as dorky as Civic grills.

The new vents are something i found online, made for a more recent Mustang, that were large enough to cover the cutouts of the civic grill, I had to remove more hood sheet metal, of course for the new louvers. If you want some other ideas, google "camaro hood vents"

Doug

 

My 88 starts fine even after sitting for 5 or 10 minutes. Any longer and it takes a couple of seconds to fire. I dont think my case is vapor lock as i have parked it with the hood open for 15 minutes and still have the iisue. Went so far as to rig a switch to the fuel pump so i could run the pump for a minute or two to cool all the fuel lines, no help. Would appreciate any other ideas

 

"...a couple seconds..." is better than typical. I have some doubt that this can be improved upon.

Harder starting when warm has been a common complaint with these engines since day one. Jaguar themselves were aware of the situation and tried correcting it with only limited success. Over the decades some guys have made it their life's mission to solve the problem, trying every trick and modification they can dream up. I don't recall anyone who was 100% happy in the end.

I have best luck with warm starts by pressing the throttle about half way while cranking....which is exactly what's mentioned in the owner's manual. It helps a bit but, still, longer cranking is required than when the engine is dead cold......which requires little more than me looking at the ignition key to start the engine!

Cheers
DD

 

Thanks for info. Ill keep hacking away.

 

Thanks Greg, I have tried this several times since your post, and it works exceptionally well. Any thoughts on MooseOHJ idea, and insulating the fuel rail/injector tubes

 

A bunch of guys on the Jag Lovers forum have tried insulating the rail with no improvement in hot starting. The rail temp vacuum switch needs to operate correctly to increase fuel pressure via the presssure regulator bwhen the rail is hot, and the fuel cooler in the A/C system also helps by cooling the fuel returning to the fuel tank.
When Jaguar went to the 6 liter, they increased the normal fuel pressure to around 3 bar specifically to help with hot start problems. They deleted the
fuel cooler and the rail temp switch at the same time with no ill effect.
Jon

 

My beasts:

The 77 PreHE always started, cold or hot. Very different rail system of course. Fuel cooler deleted when 134A retro done. Ove run valves deleted.
The 85 HE, MONGREL, like a damn clock winding up. That was when I first got it. During my "Doug" ad\ventures, the fuel cooler went AWOL, the pressure switch (remains of) followed. RH FPR, gone. Over run valves gone. None really made a smiling face difference.
Inertia switch got the hissies, so a rocker switch upside down (to fool the thieves) replaced it. YEH I know the fuel cut off etc. That had the pump runnongwhever the key was in the ON position. That helped.
I got in the habit of throttle to the floor, once, with key ON, prior to start, as Chris has mentioned. That helped a lot.
I eventually lowered the fuel rail, the hoses being a "bees;s apendage" longer than the 2 spigots mated up, and that allowed me to lower the throttle capstan accordingly. The capstan drop was the goal, as I hated it being so close to the bonnet, a V12 jammed at full throttle sounds thrilling, it is NOT.
That made a difference, NO idea why, maybe the car got sick of me messing, but it fired up every time withing ONE rotation of the crankshaft.

As we know, these cars are trying at best, and what works for one, will not for the other, fact.

 

Greg's post re: full accelerator pedal has worked for me extremely well, and I'm in Australia in summer. If your car only takes a few seconds to fire up I don't think you really have a problem? As an aside I'm about to put an Ole Mobek EFI/ECU distributor less kit into my car, which will be another post, comparing to another Forum member who is mid installation now. I'll assess start and performance pre and post changes when I have finished. I'm positive it will be better just don't know how much better. Cheers, Chris

 

I forgot, dont laugh, your turn is creeping up.

I fitted a Relay in the White wire TO the coil Pos terminal. Thus ensuring a GOOD solid 12V during cranking, as the Ign Switch electrical sections are getting flaky these days.

I use NGK BP6EF spark plugs. The "P" is for Projected nose, putting the Spark out into the incoming Bang Juice mixture. The Standard Spec spark are what we call "flat nose", and the spark is almost up inside the cone of the sparker.

NOTE: NGK is MY choice, and they no longer make BP6EF, so BPR6EF is the Resistor spec equal.
0.025" gap is needed.

I use Magnecor HT leads. OK, old school, and still available, BUT, Bosch, NTK/NGK, etc are all using Stainless Spiral Wound style now.

My AB14 Ignition Amp is located OUTSIDE the engine bay, on the RH side of the panel in front of the radiator, nice and COOL out here.

 

I believe insulating the tubes down from the rail to the injectors would be a mistake, as once they are hot the insulation will be hot and so that will be even worse than standard.
My view (as yet untested but it chimes with Grant's post just above) is that shortening the rubber tubes between the rail and the injectors will help considerably, as then cool fuel on cranking has a far smaller volume of hot/vapourised fuel to get rid of before proper cool fuel arrives and the engine fires. I have just rebuilt my injector set with shortened tubes and am in the process of making a new silicone-insulated-wire injector loom which will be impervious to heat and thus should permanently cure the injector loom failure mode on the engine.

Showing the difference between OEM length and shortended length.

The entire A bank row of shortened injector tubes.

 

Whilst at the All British day in Newcastle NSW, I mentioned the hot start issue to one of the engineers in the Hunter Jaguar Driver's Club. He mentioned that this is a fault and after looking at my car noted that I was missing the Thermal Valve on the fuel rail. This valve apparently allows for an increase in fuel pressure (bypassing the fuel regulators) if it detects a hot fuel rail until such time as the rail cools: probably fairly quickly with fuel running through it. Does anybody else have this valve in their XJ-S? Maybe the panacea to my problem? It is part number 13 on the spare parts manual diagram.

 

My take on that thing, back then, and now.
There is NO Vac until the engine starts, so the FPR is at Max pressure, just sitting there.

One I was dealing with recently by remote, had issues like this. It took me ages to convince him that this 12.5:1 engine needs a Fat Blue Cracker spark to even fart. He had the rail down, better, and then he finally fitted a relay to the coil Pos wire, and all sorted. The Ignition switch refurb was done after that.

ALSO

My Fossil brain forgets ***** at times.
I moved the Ign Amp out the front, RH side of that valance, and simply ran wires to suit, and NO shielded wire until the bulkhead connector. Those wires ran up the underside of the drain channel. Heated AB14 is not a happy AB14. Also removed that condensor thing inside the AB14, not needed, and they leak to earth and upset spark.