Driving home the other the day the car starts ‘‘stumbling’’ and won’t
respond to accelerator…but ‘‘chugs’’ along at no more than about
30mph. This goes on for about 5 miles and then everything is back
to normal. Thinking it might be fuel starvation I change the fuel
filter (which was past due) and, while unrelated to fuel, put in 6
new plugs. Take the car for a ride and it now seems to be running
extra smooth and powerful (imagination might be playing role).
Drive about 3o miles with some aggressive bursts of acceleration
and marvel at both the cars performance and my great mechanical
skills. Bubble is quickly burst as I come up my driveway and
the ‘‘troubles’’ are back.
Started it up again this morning, instant start, warmed up nicely,
responded well to rev-ing…and then after about 5 minutes
reverted to the bad behaviour.
I have an electronic fuel pump from Barratt that I installed about
10 years and 22000 miles ago. It clicks when the key is turned. Can
you tell if the fuel pum is the problem by looking at the glass
fuel filter bowl…which appears to stay full of gas while car is
running?
Advice apprecaited.
Sandy
65 OTS–
sandy eisnitz
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from sandy eisnitz sent Mon 11 Jun 2012:
I am eager to hear the replies. This sounds a lot like what my car
is doing and I can’t seem to get it fixed. It acts like fuel
starvation but I can’t seem to find the fix.–
PTC
Bonner Springs, KS, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from PTC sent Mon 11 Jun 2012:
Try switching out the coil, bad coils act like that when they get
hot. They sometimes work ok when cold.–
The original message included these comments:
is doing and I can’t seem to get it fixed. It acts like fuel
starvation but I can’t seem to find the fix.
–
Dan Myers 69 2+2
prospect connecticut, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from sandy eisnitz sent Mon 11 Jun 2012:
My 66 OTS does the same thing only all the time. I’m working on it
and hope to find that the distributor is not advancing the timing
correctly and that it needs freeing up with a little lube. The
coil sounds like a suspect if it happns only when the ignition is
on for a while. I would like to hear comments. Bill–
Capt Bill
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from sandy eisnitz sent Mon 11 Jun 2012:
Sandy,
I had this happen in the past, and the problem was that after hard
acceleration the piston caught and stuck at the top of its travel.
The cap has a recess to take the top of the shaft at its maximum
rise, and if it’s distorted or marred – or perhaps in the wrong
chamber – it can catch.
To see whether this is your problem, stop the car immediately and
open each of the dashpots. The stuck piston will fall with a
clunk. If that’s the problem, you can probably fix it by filling
the dashpot (to the top of the inner rod) with SAE 20 oil or ATF,
because unless you are a mad dragster the oil will slow the piston
so much that it won’t get up tht high. I opened the cap out a
little with a Dremel, and that’s a more permanent fix.
Hope that’s it. That’s much too sudden a symptom to be fuel
filters or pump problems since you’d experience a slow
deterioration as the float bowl emptied out.
Jerry–
Jerry Mouton '64 FHC 889791 ‘MIK Jaguar’
Palo Alto, California, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
Driving home the other the day the car starts ‘‘stumbling’’ and won’t
respond to accelerator…but ‘‘chugs’’ along at no more than about 30mph.
This goes on for about 5 miles and then everything is back to normal.
Thinking it might be fuel starvation I change the fuel filter (which was
past due) and, while unrelated to fuel, put in 6 new plugs. Take the car
for a ride and it now seems to be running extra smooth and powerful
(imagination might be playing role).
Drive about 3o miles with some aggressive bursts of acceleration and marvel
at both the cars performance and my great mechanical skills. Bubble is
quickly burst as I come up my driveway and the ‘‘troubles’’ are back.
Started it up again this morning, instant start, warmed up nicely, responded
well to rev-ing…and then after about 5 minutes reverted to the bad
behaviour.
I have an electronic fuel pump from Barratt that I installed about
10 years and 22000 miles ago. It clicks when the key is turned. Can you tell
if the fuel pum is the problem by looking at the glass fuel filter
bowl…which appears to stay full of gas while car is running?
In reply to a message from Michael Goodwin sent Tue 12 Jun 2012:
Yup, and not just the fuel tank. The original filters passed fuel
into the glass BEFORE filtering so junk was visible. Many repro
filters hold junk out of sight inside the pleated element so a
clean-appearing bowl does not mean a free-flowing filter. Don’t
know which type the OP has.
Then there is a filter in each carb top and the likeliest culprit
perhaps, the pump pick-up filter in the tank sump. So five filters
minimum to check on a triple SU car.
I doubt it is a coil if the car ran/runs well for 30 miles, though
if it is only just starting to break down it could be the start I
guess. Easy swap anyhow if you have a spare hndy but I wouldn’t buy
one until I had ruled out feul.
It doesn’t sound like anything to do with timing and Jerry’s
dashpot experience is definitely out of left field. But you never
know with California/Texas/Louisiana people like him, so if it
happened it happened and you can’t argue with a real datapoint.
Probably something simple anyhow, just a case of being methodical
and thinkinbg/checking before spending on new parts.
Pete–
The original message included these comments:
Maybe junk in the fuel tank, when was it drained and inspected. I do mine
annually.
–
1E75339 66 D, 1E33100 66 FHC, 1R7977 69 OTS, 1R9720 69OTS
Cambridge, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from PeterCrespin sent Wed 13 Jun 2012:
I have the pleated filter and replaced it. Also had cleaned the 3
carb top filters. How do you access the in-tank filter (tank is
full)?
Checked Jerry’s suggestion, pistons move freely up and down via
lifting pins.
Just tried again; instant start w/choke, idles for a few minutes,
rpm’s drop, starts stumbling, stalls out. Instant restart, brng
rev’s up to 1500rpm, runs strong for a few minutes, then begins
stumbling, will not respond to accelerator, then ‘‘catches’’ and
rev’s strong. Repeat above.–
The original message included these comments:
Then there is a filter in each carb top and the likeliest culprit
perhaps, the pump pick-up filter in the tank sump. So five filters
minimum to check on a triple SU car.
In reply to a message from sandy eisnitz sent Wed 13 Jun 2012:
You need to run the tank low and then have more than
enough containers the right shape to drain the tank either
directly or by siphon. Beware. This is a very dangerous
job if you underestimate the volumes and risks involved.
Grip the sump near the end to unscrew if the hex rounds
off. It will distort if you squeeze it hard in the
unsupported mid section.
Pete–
1E75339 66 D, 1E33100 66 FHC, 1R7977 69 OTS, 1R9720 69OTS
Cambridge, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from PeterCrespin sent Wed 13 Jun 2012:
Now you’ve scared me. I think next step for me is to seek
professional help (automotive). Just started it again and now it
seems to be running fine…let it idle and rev-ed for about 10
minutes w/no problems. WTF?–
The original message included these comments:
directly or by siphon. Beware. This is a very dangerous
job if you underestimate the volumes and risks involved.
In reply to a message from sandy eisnitz sent Wed 13 Jun 2012:
Drive it and see how you get on. Didn’t mean to scare you unduly,
but just putzing around until the tank is showing, say, a quarter
full or whatever, could leave you with gallons of flammable liquid
squirting out as you try to stem the flow by putting the sump back
into a gushing awkward hole…
The gauges aren’t that accurate and you could wind up in trouble
because what you thought was an easy gallon or two into a two
gallon tray turned out to be 3.5 gallons and you find you started
the job in a garage which also houses your heating furnace, which
runs a permanent pilot light or spark ignition - you get my drift.
If you take care and use sensible precautions you’ll come out OK
but petroleum flash fires take no prisoners. The late cars had a
small drain plug in the sump and yours may have one of those, which
makes it easier to control tank emptying. I’d still get it as low
as possible though, and your pro - should you go to one - will
appreciate a low fuel level too for this job.
Pete–
The original message included these comments:
Now you’ve scared me. I think next step for me is to seek
professional help (automotive). Just started it again and now it
seems to be running fine…let it idle and rev-ed for about 10
minutes w/no problems. WTF?
–
1E75339 66 D, 1E33100 66 FHC, 1R7977 69 OTS, 1R9720 69OTS
Cambridge, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from sandy eisnitz sent Wed 13 Jun 2012:
Given how suddenly the problem occurs I would suspect an electrical
issue, although the immediate restart seems a bit contraindicative.
My list of suspects would be:
Coil/condensor/points/flex wire to points.
Ignition switch/fuse/wiring.
Try hotwiring it first, that will tell you if it is the ignition
switch or not.
Andrew–
The original message included these comments:
Just tried again; instant start w/choke, idles for a few minutes,
rpm’s drop, starts stumbling, stalls out. Instant restart, brng
rev’s up to 1500rpm, runs strong for a few minutes, then begins
–
1968 3.8S
Zurich, Switzerland
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–