TC fuel flow problem, or what?

[Fotog]

Thanks, Mark.  I'll replace the fuel line and filter as part of this process.  Good idea about blowing it back too.  I've got some things going on such that I haven't gotten back to it, but I hope to shortly.

Vince 

[Fotog]

Here's where this stands:  I replaced the fuel filter, located near the pass. side tank, just before the run up to the carbs.

I've driven the car about 15 additional miles, with no problems.  I did fill the starboard tank (passenger side, that is) with fuel.  I'm accustomed to it taking 5-10 minutes or something like that for the two tanks to equalize and the additional fuel to show on the fuel gauge.  This time it was much longer, though I can't give a figure.  I have not, but will replace the fuel lines.  Maybe when it 'ran out of gas', I used all in the passenger side tank, and the crossover line wasn't able to supply the additional needed to keep running due to a partial block. 

I have acquired a new coil, but haven't installed it yet.  Will soon, but it seems that wasn't the problem.

One question:  Will a supposedly higher-performance coil make for a better spark and thus less carbon fouling of the plugs?  Not too long ago I changed from NGK BP7ES to BP6ES and they're still quite carbon-fouled. 

Vince

[jbcollier]

Changes to the ignition system to increase voltage output just increases the amount of voltage “headroom” you have.  The plug will fire at the same voltage regardless.  You can take advantage of the higher voltage potential by increasing the gap.  That will raise the voltage at the plug.  It will also cause the plug to wear more.  This you can offset by fitting plugs with precious metal electrodes.

If you are still using points, then this is a bad idea.  Larger voltage at the plug means more current through the points, wearing them quicker.

Rocking Pertronix?  Fit a 3 ohm coil and open the plug gaps to 30 thou.

None of this will change your plug colour.  It may help fire a heavily carboned plug.

I’m always leery of changing plugs away from the recommended heat range.  Yes there are times you should do so but that is when your engine has been modified or is plain worn out.  If it is stock then fix the issue.  Don’t apply a bandaid heat range change.

[Fotog]

Thanks.  I'll do some further investigation.

-Vince

[Fotog]

Back to the original issue-  In conclusion, I ran the car out of gas.  Farther below I’ll tell you why it didn’t run right after adding fuel.  The gauge has little resolution below ¼ tank and I didn’t view it correctly: there is a parallax problem since it’s viewed from the driver’s position at a significant angle and there is about 1/8 inch between the needle and the scale behind it, so you really can’t read it very well until you move over to be directly in front of it… which is difficult if possible.  Another problem is that the fuel outlet pipes in the tanks are located at the front of the tanks.  If you start to go up a hill, fuel level will be lower in the front than the back of the tank and it will ‘run out’ when it’s low.

I replaced the fuel lines and filter, measured fuel level in the tanks with about a gallon of gas, and then again after all had dripped from the disconnected outlet hoses.  I documented voltages and resistances from the level sending unit at different levels and generally got familiar with it all. But I didn’t find anything to be out of order.  Fuel level in the tank with the level transmitter (left) went from about 3.5 inches to 1.325 inches, with a dip stick.  Level shown on the gauge changed, but very difficult to discern the difference.  I put that fuel back in, and drove about a mile and a half before I ran out again going up a hill.  I thought the gallon or so that I put back in would take me farther, but not so.  Now I know that once the gauge is clearly below ¼ full, I’m in danger of running out.

Regarding intermittent running after fueling:
My thinking was that the fuel comes from the right side tank, which communicates via a hose or pipe to the other (left, driver) side tank.  Not exactly!  The two are teed together near the right side tank with the outlet of the tee going up to the fuel pump, so at all times the fuel is supplied by both tanks to the fuel pump.  Therefore, once you run out and you’re sucking air, it’s important to put fuel in both tanks to cure your problem.  I initially had added fuel to the right tank only.  Some fuel flowed to the other tank.  I started the car and drove it a short distance before the left tank was again empty and I was trying to run on a mix of fuel and air again.  If the car sat for a minute, it would re-start and go again for a few hundred yards before the same thing happened again.  Dumb, but I got it now!

After my examination of the system, when I ran out the second time, I added fuel to both tanks.  Once it made it to the carburetors, the car ran fine with no anomalies.

[GavinT]

Glad you got it sorted and yes, running low on fuel with twin tanks can be problematic because you don't precisely know where the fuel is.
I recall parking on a heavily cambered road and when I came out and started the car again, I had more fuel than when I parked.

Here's the Greta approved solution...

[4129R]

Cars with twin tanks have problems when fuel level is low, and they are parked on a slope.

I parked my GT40 outside my local pub on a slope. It would not re-start after standing for an hour as the fuel had drained from the tank where the fuel was sucked by a powerful electric fuel pump.

Fuel gauges on old cars are very inaccurate from full to 3/4 full, and from 1/4 full to empty. They will not even register anything until you have about 4" of fuel in the left tank.

[Fotog]

I reported back in case my experience getting it to run without problems after refilling would be enlightening. It was a result of my habit of only putting fuel in one tank (right side) for the relatively modest amount of driving I do with it.  It just didn't occur to me that I'd be sucking air from the other tank in short order if I followed my usual habit after running out.  I hope some others learn from my experience.

4129, I wish I could say it had happened to me with my GT40 🙂.

And Gavin, I should follow the Greta approved solution, yes.

Vince

[4129R]

Whenever I fill up, I fill up both sides to the top, as we have to put Super Unleaded into the car in the UK, and not all petrol stations sell Super Unleaded.

[GavinT]

4129, I wish I could say it had happened to me with my GT40 🙂.

Me too.
I'm not sure there's a more dangerous mental image than a GT40 parked outside the local pub and half a dozen tiinnies under the belt.
Thus I picture 4129R saying this – "Driver, bring the car around to the front." 

One side benefit to an electric fuel pump is the somewhat furious ticking sound as it fills up the carbs. I wait the three seconds till it calms down prior to starting the engine. It'll do the same manic antics if sucking air, too.

[4129R]

 "Driver, bring the car around to the front." 

I have not let anyone else drive it yet. The clutch pedal is difficult, you have to bend your knee rather than your ankle to operate it, or you stall it.

As with the Europa, side and rear vision are limited, and you cannot see over even slight brows on a road so overtaking is difficult on normal roads. Plus at night, you are so low you get blinded by even dipped beams.