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Spitfire Spitfire Stalling Problems

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Flatlander

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I purchased my 77 Spitfire last fall and drove it for a short time. It seemed to run good except for needing usual maintenance caused from neglect. Since completing this work I have been chasing a stalling problem. Typically it would run for a short period of time then die. After a period of time (10-15 minutes) it would restart then do another distance and die again. The distances and temperature variances at the time of failure lead me to believe that the problem isn't temperature related. I believe it isn't ignition related as I wired in a timing light and at the time of failure was still getting spark. So this to me leaves the fuel system as the problem. I have done all of the following in the last few months prior to and after this problem manifested itself:

Replaced coil
Replaced plugs, points, condenser and ignition wires
Replaced fuel pump
Replaced and/or blew out all fuel lines and filters from tank
Rebuilt carburator

I am now at the tank. Earlier this summer I had removed the tank to drain all of the old gas and replace the fuel sending unit. A visual inspection of the old gas and what I could see through the only openings in the tank led me to believe that the tank was pretty clean (Arizona car). I have noticed that blowing air back through the supply line from the tank is restricted if the gas cap closed but clear if it is closed. (This is using my own air power as I was concerned about blowing compressed air possibly making the matter worse.) The vent line from the small black canister on the vent line from the tank to the engine compartment is clear. My question is:

What is that black cannister on the vent line at the tank?
Shouldn't there be free flow of air through it?

Side note; At the time of my car dying I have tried opening the gas cap but still was not able to restart though if the car had rune out of gas then maybe I didn't try long enough to refill the fuel line.

Any help would be appreciated. Also has anyone seem a web site that dealt with the calibration of fuel gauges? Seem s like I have seen one but can't find it again.

Thanks,

Gary
 
The black can is called a carbon canister; it's function is to absorb and hold gas fumes from the tank & carb until they can be sucked into the engine. Although it can be somewhat restrictive, you should be able to blow air through it. Sounds like yours is plugged up, which does happen when they get old. The earlier ones could be disassembled and serviced (there is a screen and mesh filter in the bottom that can be cleaned and/or replaced), but the later ones were supposed to be replaced as a unit every 48,000 miles.

The only "Fuel gauge" webs site that I know of is for the earlier style "balanced" gauges; don't know of any for your later "hot wire" type gauge. I've been meaning to write one, but haven't tripped over that particular round tuit yet.

But the first thing to check would be that the "voltage stabilizer" is working properly. If it has failed, both the fuel and temperature gauges will read too high. Easiest test is to pull off the wire from the temperature sender on the engine, turn on the key and check the voltage from the wire to ground. If you have a working original VS, you'll see full battery voltage alternating with no voltage (flashing kind of like a turn signal). Or if you have one of the popular electronic replacements, you'll see a constant 10 volts. If you get 12v and it doesn't flash, then probably the VS is bad or not grounded.
 
If that "black cannister" is at the gas tank you might be talking about the "separator canister" It's sort of an evaporative loss device.If it is, then there will be an inlet from the tank and an outlet hose leading to the carbon canister up in the engine bay
You should be able to blow air into the hose,once disconnected from the Carbon Canister, all the way back thru the separator and into the tank. Any blockage will limit the gas reaching the fuel pump and cause the engine to stall within a few miles.
 
I removed the fuel tank and blew out the "separator" canister. There was also an inline brass fitting just downstream of this canister which restricts the diameter of the pipe from 0.25 inches to about 0.03 inches. This was somewhat blocked so blew that out also. My next step, while I have the tank out, is to clean and line the tank so I can eliminate the fuel system and hopefully solve my problem.

Has anyone successfully cleaned your tank in the past?

Thanks,

Gary
 
Eliminate the fuel system?
Flux capacitor time!
 
I cleaned and lined probably the worst tank possible. It took seven gallons of white vinegar and the prep that came with the POR 15 kit. In addition to that I had to put chain in the tank and keep flipping it around. I used the chain that is used to hang light fixtures. For two reasons, one it is lighter weight than most chain and also I am an electrical contractor and had a whole bunch of it. Do not use rocks there are a lot of places for things to hide in a Spitfire tank and you will go nuts trying to get them out.
I have heard horror stories about using lining. If you take your time and follow the directions to the letter you should have no problems. I haven't in over two years.
 
I'm not a Spitfire expert but I had a similar problem on my 6 and ended up having to recreate the fuel tank venting system. I doing so I had everything apart and did not find anything remotely like a brass inline restrictor as you have described. I would eliminate this or drill it out to get the maximum venting to the fuel tank.
 
I don't really know what purpose it served, Roman, but from 72 to 76 there was a restrictor. It was fitted between the 2 flexible sections of the vent line hose, just a few inches before the line attached to the Carbon Canister.
If they had an Anti Run-on Valve in 72, I would surmise that the restrictor may have been there to prevent the manifold vacuum from being diverted to the gas tank, instead of to the carb's float chamber's to discourage engine run-on
Maybe it was late 72 in anticipation of the ARV, which appeared in 73. Who knows ?
 
The brass fitting occurs a couple of inches after the "separator" canister and is located above the fuel tank on the pasenger side. My thought ( and it was the only thing that I could come up with ) was that they didn't want a siphon set up between the tank and the carbon canister in the front engine bay in case of fuel expanding past the capacity of the separator" canister.
 
Well the plot thickens.In the interim I cleaned and sealed the gas tank and blew out all the fuel lines. I took it out for its test drive and the problem still occurs. At sporadic intervals (haven't been able to identify what precipitates it other that higher rpms therefore greater fuel demand). the car would just lose power and if I let it it will die. I am able to now recognize when it occurs, push in the clutch, pump the gas a number of times and it will refire and go normally for about another half to three quarter mile.

I had replaced to carburator on it last fall with a manual choke Stromberg that I rebuilt. I am now wondering if there is something in the carburator which is not working properly. Any ideas?

Thanks,

Gary

P.S. Looking at getting dual SUs to replace the current Stromberg.
 
I question the effectiveness of pumping the gas when it's beginning to die. I don't believe these carbs have accelerator pump circuits so you are actually pumping "nothing". Since you ARE changing the position of the butterfly that may have some effect on whether it will run or not. Bob
 
I fought that for a year on my Midget and it was a faulty non vented cap from VB. Yours has to vent. Run it w/ a rag in it and see if it happens again.


If it does.......light the rag on fire and run. :jester:
 
Some good points. I did try driving with the cap not "snapped" shut also thinking that this might be the cause but did not make a difference. I will try your suggestion of running with a rag in it to see if this helps. If not then I might light it!

Another good point about pumping the gas I wonder what opening/closing the butterfly is doing to the carburetor as far as gas supply. Will read the Stromberg manual and see if I can find some correlation.

Thanks,

Gary
 
Another point is that last fall before I started all this work the car did not have this problem. The only thing that changed from that setup was adding the manual choke carburetor. Could it have the wrong metering needle? If so then why would it run well at times and die out other times.
 
Well success, I think. Just got back from a 30 mile test drive with no problems. When I initially rebuilt the carburetor it had a Grosse Jet (which I like) so I didn't replace the float valve. The other day after replacing everything else I remembered that the only thing left was the Grosse Jet. I removed the carburetor, replaced the old Grosse Jet with the float valve included in the rebuild kit and set the float height. I don't know what in the Grosse Jet could have been malfunctioning but the problem went away when it was removed.

Thanks for everyone's help!!!

Gary
 
kellysguy said:
I fought that for a year on my Midget and it was a faulty non vented cap from VB. Yours has to vent. Run it w/ a rag in it and see if it happens again.


If it does.......light the rag on fire and run. :jester:
Click to expand...
\

Ha! After weeks chasing down a fuel problem, I enjoyed that more than I should have! :laugh:
 
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