Sounds like a problem I had for a while until I relined the gas tank. Lots
of the same symptoms. If a needle valve isn't closing it might be clogged
with some debris and you could be getting some flooding which would cause
the symptoms you described. And also would explain why it runs good cold
(cold engines LIKE lots of fuel) and bad when warm (warm engines don't do
well with excess fuel).
Easiest and fastest thing to try is pull the float chambers off with the
carbs still on the engine and work the needle valve up and down and blow a
little canned air up around it. Dump the gas from bottom of the fuel
chambers into a white or yellow bowl..if you have black specs grind one up
between your fingers..if it turns to gold dust it's most likely varnish...if
it's red then it's rust. Both are bad news. Put a fuel filter between the
fuel pump and the carbs or if it's a continual problem reline your gas tank
and clean/replace the fuel lines throughout. Oh and clean your fuel pump
out too (from the top).
Fuel contamination would explain why cleaning the carbs would make it run
good and then after awhile revert to running bad. Even with added fuel
filters (3 in a line together) I couldn't keep the gas clean enough to not
foul the needle valve. The ultimate and long term solution was
cleaning/relining the fuel tank...wish I'd done it a couple years prior.
You might want to try bypassing the gas tank again like you did before once
you've cleaned out the float chambers...maybe even clean them out a couple
times to make sure the junk has flushed through the lines and the fuel pump.
Then you'd know if it's indeed the gas tank contaminating your gas.
Pull the plugs to read their color. Black is too rich, white is too lean,
light milk chocolate is perfect. A flooding problem will cause a rich
mixture which will be evident by a "sooty" black plug, and usually the
worst is a front plug because the front carb usually gets gunked up first
(don't know why exactly but maybe because it's first to catch junk). So try
a plug fed by the front carb first...but check them all. You can tell which
carb is rich or richer than the other by reading the plugs it feeds its
mixture into.
Oh and one more test for flooding. Run your hands on the underside of the
loat chambers...if you feel gas then it's definitely the float needle valve
sticking open and letting gas overflow the float chamber. Same solution
though....cleaner gas.
Bud Rolofson
71TR6 CC57365 (Good 6)
66TR4A CTC57806 (The Wreck-Almost Parts)
66TR4A CTC57529 (The Project)
----- Original Message -----
From: <dstauffa@csc.com>
To: <triumphs@autox.team.net>; <6pack@autox.team.net>
Sent: Monday, January 07, 2002 1:12 PM
Subject: Trouble with Spitfire
> Listers,
>
> I friend of mine who owns both a TR6 and Spitfire sent me this message
> about the trouble he is having with his Spitfire. I thought I would pass
> it along to the collective wisdom of this list to see if anyone has ideas.
> I know there is a Spitfire list but I'm not a subscriber. TIA, Dave
>
> ive got a great 79 spitfire Ive had since 1980. It only has 43,000
> miles on it. Its always run great although I dont drive it much, but I do
> keep it running every few weeks to keep things oiled up. Ive never had a
> dilema like my current one. Heres my problem I hope you can advise me. The
> car suddenly started running poorly. Missing when hot, particularly over
> 2500 rpm, even in neutral. So I started on the voyage to see what was
> wrong,
> thinking its probably something simple.
>
> I started with the electrical. I switched the wires, new plugs, cap,
rotor.
> Then I replaced the older Crane electronic ignition with a new one. I
> swapped the coil with my TR6 and also the battery. I cleaned all the
> grounds, checked all other wiring and cleaned. No luck, so I started on
the
> fuel system. Bypassed the fuel filter, and even bypassed the tank itself
if
> there was a clog or bad gas etc. No luck.
>
> So I pulled the carb, cleaned it, put in new diaphragm and metering jet,
> cleaned choke. It started up nice but once warm running poorly again. no
> backfiring or anything like that. I replaced the fuel pump thinking
> pressure
> might be too low. No luck. It runs as though its starving for fuel. If I
> rev
> it up it recovers briefly, then starts to run rough again and will die if
I
> let it idle. Still, whats weird is when I get it started from cold it runs
> well. Once warm is when it all starts going downhill.
>
> Here's only thing I can think of thats left>> could it be the EGR valve on
> the manifold? that thing is original and Ive never done anything with it.
> Its pretty old looking and it plugs right into the intake manifold, so it
> the diphargm (does it have one?) was leaking maybe air is getting in. The
> only other thing I can think of is the carb itself. Maybe I should replace
> it?
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