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Need some diagnosis help quick!

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N

Norton47

Jedi Warrior
Offline
Hello
Was driving the TR6 today and on the way home, as I pulled up to a red light and de-clutched the engine died. It restarted when I let the clutch out, but will not idle.
It will run fine with the foot feed depressed to get it over 1000 rpm or with the choke on to hold it at fast idle. It just dies straight away if you let the foot feed off or close the choke. It runs fine while driving. Seems to only have an issue at idle
Has been running fine for 15,000 miles.
Where should I start? I checked the vacuum hoses and no cracks or leaks. While at idle with the choke on, I sprayed down the intake manifold joints to check for vacuum leaks with cleaner fluid, no real change to the rpm.
These carbs were rebuilt by Joe Curto about 8,000 miles back.
There is fuel at the filter before the pump.
Any thoughts?

Thanks
 
Sounds like fuel to me. What pump ya got Mark?
 
What happens if you disconnect and plug the vacuum line to the brake booster?
 
Norton,

When was the last time you put gas in your 6 before it started to stall at idle?

Cheers,
M. Pied Lourd
 
Hi
Answers to the 3 inputs.
1. Don, rebuilt the pump and it is a engine driven with the manual pump handle. Seems to pump up but I still need to do the pump pressure test.

2. Randall. No change, and I seem to have 16 to 17 units of vacuum when the car is running with the choke on. I also check the vacuum line to the distributor and the anti run on valve. All lines checked by removing and connecting a plugged piece of hose.

3. M. Pied Lourd: I filled it 107 miles ago. Probably this last Tuesday, I drove to work on Tuesday and that was a 80 mile round trip with no issues. Went to the bookstore today about 7 miles and this happened on the way back. Don I confess I was working virtual.

Thanks for the help.
 
Was going to suggest the following....

1. Clogged Fuel Filter or clogged line from the tank with rust/debris etc.
2. Overfilled gas tank and got gas in the tank vent line. Created a vacuum.
3. Poorly seated/staked valve in the fuel pump.
4. Possible bad condensor.
5. Vacuum line disconected/collapsed
6. Problem with the vac advance on the dizzy

Cheers,
M. Pied Lourd
 
i doubt it is bad gas, it would have turned up before this, not suddenly. i bet it has to do with your pump, but sometimes the needles in the carbs stick so you can tap on the float bowls with a wrench or something to just be sure they are free. i would check the filter, maybe that is clogged. you may also have an ignition problem check the coil and plug wires, run it in the dark and see if you can see arcing along the outside of the wires. let us know what happens.
Randy
 
My next thought would be a split carb diaphragm.

But I'd also double-check the point gap; a closed-up gap can sometimes act that way. It would have closed gradually, of course, but there seems to be a magic boundary where the ignition quits working at low rpm.
 
To All
ok here's the really weird results.
I let every thing cool off while I had dinner.
Went back out and started the car. Still needed the foot feed depressed to maintain it running. Only ran it for a couple minutes < 5 to check this out.
Disconnected fuel line to carbs and installed fuel pressure gauge. Pumped up by hand using lever on pump, gauge went to 2 psi and then bled off per manual. Then tried starting engine,fuel line still disconnected, it started and ran at idle with no foot feed or choke and pump pressure indicated same 2 psi. Shut off engine, fuel pressure bled off. Reconnected fuel line to carb. Engine starts and runs at idle just fine. Straaaaange. Guess I will get a pump on hand just in case.
 
Probably Had some crud in one of the float valves. letting the fuel level in the carb drop allowed it to open up wide, dislodge, and clear itsself. It was flooding out before, now it's back to a proper level. Maybe time for a fuel filter.
watch for black smoke if it does it again.
 
Remember Mark. Most of the rebuilds for the Fuel Pumps are garbage. Contact Paul for the good rebuild kit
 
Couple of the "tricks of the trade", so to speak.....Mexic......errr....."quickie" card rebuild.....get it running, open it up to about 2K, air filter off, slam you palm over the venturi, just before it dies let go the palm, do it again.
Sucks small pieces of crud out of the jets.

The other is stuck open needle valve.
First off, a fuel filter won't do what you were experiencing.
It would idle and not rev (once the float chanbers emptied), nor, I don't think, a fuel pump.
Float bowls hold enough gas to keep it running for a bit, yours died right away.

Anyway, block off the fuel line (simply un-doing the inlet from the pump will do), run it until it quits.
Re-connect line, crank until it starts.

What this has done is drop the fuel level in the float bowls to about nothing, dropped the floats all the way down, and the needles off the seats.

When you re-connect and crank, fresh gas flushes anything stuck in the valve out, float comes up, problem solved.

However:
Something caused it.
Fuel filer, fuel line going bad, diaphram in pump going away.

Any or all of those can dislodge a small piece of rubber and plug a needle valve open.

Worst case is dropping down a freeway off ramp.
You've been doing 60, if the needle is partially open, you'll never notice it, come to the light at the bottom, stab the clutch and let off the foot-feed, and it dies.

How many cars you see stalled at an off ramp?

That's usually why.

I usually stab the clutch on the way down the ramp, let it idle, watch the tach or ammeter, if they drop, I know to pop the clutch to get it running, and heel-toe the gas and brake to keep it running at the light.

Dave
 
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