Yes it does, but it is all a mid-brown:dirty transluscent colour. At full throttle (zero vac) I believe it adjusts/earths/something the TPS signal so the TPS effectively gives the ECU a full enrichment signal. If anyone can confirm ths, I would be very grateful and generally enlightened.

re: your last post, Doug, that seems to clear it all up.

To Grant: is Doug's link to the vac switch the blue and white thing you were mentioning?

Final question: I wonder what the difference is between the two sorts of switches, if any! The part (on my car) is listed by Jaguar Classic spares as EAC4371 and is not available any more, I think.

Greg

 

Very enlightening. Thank you. For info, mine is an '86 UK car, which later went to Hong Kong,then to Aus.
I think mine has the blue vacuum switch at the rear of the right intake manifold.

 

Bizarre I have both switches the idle switch on the end of the B bank rod and a switch on the throttle capstan.

BTW my car is Australian delivered and April 89 build??

God Jaguar made things difficult

 

Doug, ALWAYS listening, but watching the women's swimming at the Olympics at the moment, and I am getting DISTRACTED slightly.

My '85 has BOTH switches, always did, NO cats ever.

Made 7 phone calls to XJ-S guys I know of that were home, and ALL have both switches, and that is 1983(1), 1985(1), 1986(3), 1988(2), and always have had, and NO cats on any but the 2 '88 cars. Then found 2 S3 V12 guys home with a 1987(cats), and a 1984(no cats), and BOTH have the 2 switches.

My coffee has a dash of JD for medicinal purposes hahaha.

Jaguar info with errors, NEVER, HAHA.

 

Greg, and others, YES that is the Blue/White I talk about regularly. They fail, and they are also adjustable, mmmm.

They earth Pin #3 (corrected 29/7/12) of the ECU, as does the micro switch, and that I reckon gives the enrichment required.

I worry a tad about the vac only enrichment, due to the fact that when you stand on it, YES, the vac drops, the contacts close, the ECU does what it does, and the engine roars off, but as the revs increase, and load decreases, the vac returns, and the contacts open, then the ECU goes back to Closed Loop lean fuel. At least with the micro switch the gas pedal still being "down", that switch is mechanically earthing pin #22, so the engine gets more fuel, as I think HE definately requires.

Just my basic thoughts.

 

NOW THAT CLEARS A LOT UP.

This only confirms to us all, that the info on/about the car being asked about is SOOOOO important, the markets (as Doug has pointed out) dictates some very different items, and then the people that have shipped these cars all over the world by now, is making life a tad more stressful. LUV IT.

 

Thanks for all that info.

Shoot, I really thought I was onto something with my grand theory ! :-)

Long ago I earned how difficult it can be sorting out all the build variations and the rationale behind them. I should have known better this time....the conclusion seemed too easy!



It seems almost comical at times....but it really isn't. And I've seen 2nd-3rd-4th editions of manuals and catalogs that contained the very same errors as the 1st edition.

I've long maintained that the poor quality of the tech information played a role in the lousy repair/reliability reputation of these old Jags

Cheers
DD

 

I take Grant's point about the 'belt and braces' effect of having both micro and vac switche, seems a sensible mod. To sum up the situation so far, is this correct?

The Vac switch earths pin 22. I take it that the vac switch itself is then normally open, and when the vac drops, the switch makes contact and earths?

The microswitch on the capstan (were it there) is also then normally open, and makes contact on full throttle and thus earths pin 22?

These two I assume are wired in parallel, so that either one closing will earth pin 22?

Anyone got a wiring diagram, as I have no spare wires hanging around my capstan?

Greg

 

I agree Doug.

The Australian market cars as written are not what we actually got, mostly, and a lot of that was our illustrious Federal Govt/s of the day/s, constantly altering the emission requirements for all sorts of cars, and the introduction of "unleaded fuel" in Jan 1986, and the HOO-HA associated with that.

We saw "cats" in late '86, and the Lambda came about '89, and fuel tank venting just got lost in the fine print until about '94ish.

The classic from our Jag point, is the vac advance plumbing for the mid '80's HE. We got some of the USA/UK spec, and then some of our own added just to make it interesting.

Biggest issue came a few years later when service was needed, and as you said, the info was sooooo wrong, the parts were listed as "no longer available", and so on, so back to basics (per emissions) was the order, and many are still at that point today.

Where I abode, no emission testing has ever been part of on road activity, and many other areas are the same, so maintenence as built/designed is not a priority to anyone.

 

Greg,

That is SPOT ON.

I have a wiring drawing somewhere, and will PM to you as soon as I find it.

BUT, I have done the same as Doug, and misread my wiring schematics, or its wrong???, but PIN #22 is NOT part of the enrichment , I got confused following the lines on the print, so I will dig out the manual in the shed library tomorrrow, and sort out just what goes on and post back here.

My apologies to anyone I may have confused/upset/mislead with that pin #22 comment. I will sort it and do so quickly.

 

Thanks Grant. No worries about the pin. Could you also please pm me a pic of the microswitch installation at closed and at WOT? So I can get an idea of how it is activated. It looks from the pic you posted that the microswitch is the same as that used for the kickdown (ie normally open). I hope so as I have a spare in stock!

Greg

 

Here's Rod's latest. Attended the Milton Ulladulla Vintage & Classic Car club ULLADULLA HARBOUR CLASSIC.
Fantastic weekend. Thanks to all. Here's what I found out. My mate's '85 (Australian delivered) has this setup:


Where can I get this bracket and switch (which I can then use for my kickdown)

ALSO.
I'm having probs with (pretty sure it a fuel pump problem - as per start of this thread). Whilst down there after about 30mins driving, I could hear the fuel pump making noises and when loading up the throttle, the engine hesitated again. No loud coughing and spluttering.
So, I put back the original fuel pump (yes, all on the side of the road) and headed off again. Great, until again after some 30min, hesitation under load. I noted when changing the fuel pumps that both the pump and filter were quite warm. Also leave the car off for 30mins or so, then restart and all ok until the dreaded 30 or so mins into the drive.
As we had a 3 hr drive home this arvo, I thought, ah ha, it must be overheating. SO, took battery cover off, moved a lot of bags around and propped the boot lid open about 3" and guess what, NO hesitation whatsoever on way home.
So to conclude, I can only presume that both of my pumps are prone to overheating. Is this common and what's the fix it? Ram air tube?

 

OK ALL SORTED. NEW SEEING EYE DOG.

The Blue/White vac valve and the micro on the capstan simply EARTH pin #3 of the ECU.

NOW, read on, the cars that Doug mentioned the markets for WILL NOT have a wire in that pin position in the ECU plug, so the ECU (as smart as it is) has NO signal, no wire, so does NOTHING, simple me thinks.

That is also why my "no cat" car works sweet with a 16CU "cat car" unit installed, coz my ECU plug has NO wires in those termimals, so the ECU has no idea what to do with nothing, so does nothing, hope that makes sense, it does to me haha.

I cant scan the wiring diagram and post it, as it simply is tooooooo messy to follow, thats how I got it wrong in the first place.

Greg, I will PM you what you asked.

 

I have not read all the earlier posts to remind myself; but have you cleaned out the sump fuel tank under the battery and changed the sock filter that goes round the output tube from this tank to the pump?

Your symptoms are classic 'sump filter blocked' ones. Noise because the sock filter is blocked, heat because the pump is straining, gets better after a stop because the grunge drops off a bit. Also, change the cannister filter as well, as these even new can be semi-blocked if you get a duff one.

As well as this, not a bad idea to then get some compressed air and blow through all the fuel lines, (undo in the engine bay before the rail) especially the main feed from the tank to the sump tank. Finally, if you leave the fuel cap a bit loose, does this aleviate the symptoms? If so, there is a vent problem so the pump is effectively trying to evacuate the fuel tank.

Apologies if you ahve already done these things, but the problem must be one of them!
Greg

 

The bracket should be available at any Jag wrecker type mob, I dont have one, but could easily be made I suppose, or better yet, NICK your mates when he not looking, mmm.

The fuel pump noise, I have experienced, and ALL I have had noise from are NON Bosch brand pumps.

The fuel is getting hot in the tank, and that is maybe causing the pump to "cavitate", and make noise, and not pump fuel as required.

As a temporary "test", remove the fuel cap, and go for a "test drive" and see if the issue returns. It may be the tank not breathing properly.

I dont run a fuel cooler on mine, and have no issues with noise or performance, even in 40+c temps.

The luggage in the boot has me confused as to the "fix" when moved around, not disputing it worked, coz it seems to have. On both round Australia trips in ours, the boot/back seat/under seats areas were CRAMMED with "stuff", and no problems at all, YES the boot got hot, for sure, but no pump noises to speak of.

Are the smallish vents in the boot floor open???. Not sure of the airing efficiency of those vents, as I reckon they are there to drain fuel out when things leak.

Something I found on mine a very long time ago, was the hi-pressure hose coming out of the pump does a very sharp right angle bend before travelling under the sump tank area to the outside world, and maybe yours is crimping over as was mine??.

 

Thanks Greg and Grant. Will follow up on your leads and report back.
Regards, Rod.

 

Took surge tank pickup and filter out, clean as.
Decided to follow tank venting lead as this is quite a possibility. Took off a tank hose and put compressed air in and tank PRESSURISED. Undid fuel tank filler lid and NO pressurisation. Did this a few times to confirm. I therefore conclude that the fuel filler lid is not allowing venting. Could I be right?

 

Yep.

The filler lid (cap) should NOT vent to atmosphere, as designed.

There is a valve somewhere (and I do really forget its exact location), but it is in the line going to the charcoal cannister up the front, called a Rochester valve, that controls the vac and pressure in the tank. There was a recall to replace this valve waaaaay back, as they stick??, duh, and tanks imploded.

My tank is vented to atmosphere, and that was one of the best things I ever did to this car. I used the line going to the cannister (under LH headlamp) and plugged it with a metal bung with a "TINY" hole in it, just enough to allow venting. I have NO odours ever. HOWEVER, if you are in an area where emission testing is done, DO NOT DO THIS PLEASE.

Since your in OZ, get a fuel cap from an early Holden (HQ or similar), it fits, and drill a small hole in it, VENTED.

 

Good chance it will be vented in about 5 :-)

 

This link has a good discussion regarding the fuel venting system, with an associated diagram. Note that while it is specifically discussing the '87 and '88 H&E convertibles in the US, the venting system is common (main difference the H&E Jags have is the secondary fuel tank & pump and as well the fuel cooler is hardwired to always run).

Jaguar Fuel Problems

Cheers,

Will