[v12-engine] my stalling problem update (was Allways Starts, Stalls when warmed up?)

V12-Engine
1

Hi Folks!

The other day, I wrote…

The next day, while at speed (about 130 kph) it all of
a sudden started to miss, and buck. It went away, and I got off the highway.
As soon as I was going slower, it started again. She stalled. I started her
right back up, and kept going. Several hours later, the same thing happened.
I was driving along, and the tach started to dip repeatedly, and she soon
stalled. started back up no problem.

That evening, I tried again, and once she began to stall, the length of time
I could keep her running began to diminish. I headed back home, and she
stalled 15+ times before I got her back (less than 8 blocks!) I noticed that
it does not happen only under a load, she’ll stall at idle too.

OK UPDATE.

She seems to run OK for a while after she’s been sitting. I’m almost sure
it’s not the ignition amp, because when I drove her the 5 or 6 blocks to
Canadian Tire to get a HEI module, she stalled out just as I got into the
parking lot. I popped the hood, and the amp was still quite cool to the
clutch. (I didn’t bother with the module)

I popped the trunk, and the 2 relays near the ecu were pretty warm to the
touch (not really hot, just warm) is that normal?

I gave her a 15 or 20 minute rest while I wandered around the store,
wondering whether I should buy anything, then drove home, She stalled 3
times before I got to my parking lot, then 4 or five times as I tried to
park.

I think I’ll check the surge tank this afternoon, because it’s sounding more
and more like a fuel delivery problem?

I did indeed clean it all out several months ago, while trying to nail down
my 4500RPM “brick wall”, which ended up cured by a plug and wire change (and
cap, rotor, 2 coils changed before the plugs seemed to solve it) but it was
already pretty pristine to begin with even after 12+ years of neglect. I
suppose it’s possible I got some lousy gas?

What do you folks think?

Just before she stalls, the revs drop quite a bit, and she gets REAL ROUGH
and lopey, like a chev with a 1/4" cam.

barRUmphF barRUmphF barRUmphF…

Shift to neutral, restart, and back to drive, OK for a few moments, then all
over again. Once this behavior begins, the episodes get closer and closer
together, until it starts, and dies within a couple of seconds. (talk about
a LOUSY way to limp home, 20-30 yards at a time!)

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2

At 13:40 2000-09-30 -0400, James Robinson wrote:

She seems to run OK for a while after she’s been sitting. I’m almost sure
it’s not the ignition amp, because when I drove her the 5 or 6 blocks to
Canadian Tire to get a HEI module, she stalled out just as I got into the
parking lot. I popped the hood, and the amp was still quite cool to the
clutch. (I didn’t bother with the module)

Let me reiterate what I said earlier:

It is not necessarily the AMP itself, but the WIRING to it, which may cause
these symptoms.

You might sit there and follow the amp wires and jigggle them a bit here
and there and see if the engine doesn’t start jerking about.

I popped the trunk, and the 2 relays near the ecu were pretty warm to the
touch (not really hot, just warm) is that normal?

I couldn’t comment - I haven’t gone out to measure the temp of my relays
when driving around.

I think I’ll check the surge tank this afternoon, because it’s sounding more
and more like a fuel delivery problem?

Since fuel delivery is performed by an electric pump, you should be able to
disconnect the feed side hose (suggestion: remove the pump relay, then run
the car till it peters out – then you won’t have pressure in the line when
you remove the hose), and put it in a large container (a CLEAN gallon cider
jug might be good - small opening, large capacity), reconnect the pump
relay, and turn the ignition to RUN (don’t even try to start it). I’d
expect a little burble at the beginning while the line is refilled (tho not
much), then you should have a reasonable stream. when the jug reaches 3/4
full, turn the ignition off, wiggle the hose to get any petrol just waiting
to dribble out, then return the fuel to the tank. Repeat the procedure a
few times if you want to be sure.

Since you indicated that there is a problem even at low RPMs, if the pump
or sump is at fault, the fuel stream should really fall off noticeably.

If it doesn’t, time to investigate other causes. Fuel pressure regulators
shouldn’t work then not work - so I wouldn’t suspect them (while you’re
looking, may as well check that you don’t have fuel in the vacuum line
connections to them, but that wouldn’t cause the problem you’re describing).

Just before she stalls, the revs drop quite a bit, and she gets REAL ROUGH
and lopey, like a chev with a 1/4" cam.

Does your tach go wild?

— http://jaguar.professional.org/
Sean Straw '88 Jaguar XJSC 5.3L V12 (LHD) ‘Black Cat’ 63K
Marin County, California '85 Jaguar XJS 5.3L V12 (LHD) ‘Bad Kitty’ 210K
'69 Buick GranSport 455 V8 324K

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3

Hi Sean,

Re: below, (I posted another update, but I’m in “digest mode”, so I just saw
this one now. I would guess that in removing the amp, and replacing the HEI
module, I got the connections OK. What’s driving me nuts now, is that it
seems to run fine for about the first 10-15 minutes. Regardless of how often
it stalls, (and the interval drops off DRAMATICALLY after the first one) it
ALWAYS restarts before it even turns halfway over. It just won’t KEEP
running.

I’m not too sure where to look next?

The relay in the trunk (the one with NO red stripe on it) gets warmer than I
would expect a relay to get.

Oh yeah, YES the tach drops, and jumps back up when it gets “lumpy”.

James RobinsonDate: Sat, 30 Sep 2000 12:10:19 -0700
From: sean.straw+Jaguar@mail.professional.org (Sean Straw)
Subject: Re: [v12-engine] my stalling problem update (was Always Starts,
Stalls when warmed up?)

At 13:40 2000-09-30 -0400, James Robinson wrote:

She seems to run OK for a while after she’s been sitting. I’m almost sure
it’s not the ignition amp, because when I drove her the 5 or 6 blocks to
Canadian Tire to get a HEI module, she stalled out just as I got into the
parking lot. I popped the hood, and the amp was still quite cool to the
clutch. (I didn’t bother with the module)

Let me reiterate what I said earlier:

It is not necessarily the AMP itself, but the WIRING to it, which may cause
these symptoms.

You might sit there and follow the amp wires and jigggle them a bit here
and there and see if the engine doesn’t start jerking about.

I popped the trunk, and the 2 relays near the ecu were pretty warm to the
touch (not really hot, just warm) is that normal?

I couldn’t comment - I haven’t gone out to measure the temp of my relays
when driving around.

I think I’ll check the surge tank this afternoon, because it’s sounding
more
and more like a fuel delivery problem?

Since fuel delivery is performed by an electric pump, you should be able to
disconnect the feed side hose (suggestion: remove the pump relay, then run
the car till it peters out – then you won’t have pressure in the line when
you remove the hose), and put it in a large container (a CLEAN gallon cider
jug might be good - small opening, large capacity), reconnect the pump
relay, and turn the ignition to RUN (don’t even try to start it). I’d
expect a little burble at the beginning while the line is refilled (tho not
much), then you should have a reasonable stream. when the jug reaches 3/4
full, turn the ignition off, wiggle the hose to get any petrol just waiting
to dribble out, then return the fuel to the tank. Repeat the procedure a
few times if you want to be sure.

Since you indicated that there is a problem even at low RPMs, if the pump
or sump is at fault, the fuel stream should really fall off noticeably.

If it doesn’t, time to investigate other causes. Fuel pressure regulators
shouldn’t work then not work - so I wouldn’t suspect them (while you’re
looking, may as well check that you don’t have fuel in the vacuum line
connections to them, but that wouldn’t cause the problem you’re describing).

Just before she stalls, the revs drop quite a bit, and she gets REAL ROUGH
and lopey, like a chev with a 1/4" cam.

Does your tach go wild?

  • — http://jaguar.professional.org/
    Sean Straw '88 Jaguar XJSC 5.3L V12 (LHD) ‘Black Cat’ 63K
    Marin County, California '85 Jaguar XJS 5.3L V12 (LHD) ‘Bad Kitty’ 210K
    '69 Buick GranSport 455 V8 324K

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