General Tech Fuel Flooding; Float Adjustments and Fuel Pressure

[KVH]

I installed my fuel pump pressure regulator. See pic. Nothing I could do would make my floats operate properly and I was continually flooding.

A few days ago, I tried adjusting the floats way up, then way down, and nothing made any difference.

I had near 4 PSI from the pump, and the recommended maximum is 2.5.

I’m not ready to declare victory yet, but I finally have floats that are operating the way the Triumph Manuel suggests. My fuel pressure is now set at near 2.2 psi.

I’m not seeing any flooding, and using the “lift the piston method“ I’m finally able to make some sense of the mixture adjustments. We’ll see.

I’m still not convinced I won’t be towed back home again soon.

 

[mctriumph]

This is what electric pumps get you into. I have always tried to stay with the factory mech pump
for this reason.IMHO a nice rebuilt original is the ticket to happy motoring.
The race car we drove for years had THREE electric pumps.Two primary pumps into the swirl pot
and one to the fuel injection from the pot. You could never go anywhere without a spare one of each.
If for some reason you are heck bent on an electric pump NEVER buy a cheap one!! The regulator too!!
Mad dog

 

[Sarastro]

That Holley regulator is a good unit. I have also had the problem with mechanical pumps forcing fuel past the float valve, so all my older cars have electric pumps and that regulator. I keep it set around 2 PSI; you don't need more.

 

[KVH]

All good to know. Thanks. BTW, why do so many people match an electric pump with a regulator? Why not mechanical with regulator?

Are the electric ones superior?

Also, I always fret over my weak generator. If I had an electric fuel pump would I want to switch to an alternator?

 

[CJD]

Electric usually puts out too much pressure. Try to find a 2.5psi electric...?

For true performance, the electric with regulator was the way to go prior to fuel injection. You could place the electric pump at (or in to keep it cool) the tank and pressurize to 14 psi or more. Then regulate it at the carb down to 6psi American, or 2.5 psi British. The extra pressure prevented vapor lock. We used to launch cars at 1 G force, so the 15 feet from the tank to the carb was like pumping fuel 15 feet straight up! You would loose 10 psi on the launch alone.

And, "yes", if you add anything to a TR, you will need to upgrade the charging system. The TR3 puts out 21 amps. Ignition is 2amp, Headlights are 10amp, and running lights about 4amps. Drive at night in the rain with the wipers at 6 amps and you are already overloading the dynamo! If you add an electric fan, electric fuel pump, or a radio, it would be a good idea to upgrade the charging system. Or, you could switch the lights to LED and perhaps delay the upgrade.

 

[Sarastro]

That was my thinking when I switched to an electric pump. My TR4A has a nice Carter pump mounted near the fuel tank and putting out about 6-7 PSI. I regulate it down to 2-2.5 PSI at the carbs. You can find lower-pressure pumps, but the specified output pressure range can still leave you with too much pressure. I went to the higher-pressure pump, figuring that it might provide some resistance to vapor lock, and the pressure regulator keeps it pinned at the desired pressure, with virtually no variation.

My only objection is that the Carter pump is noisy, enough to be annoying. I may replace it only for that reason.

 

[KVH]

Yet another technical SU carb question:

Assume the engine is at operating temperature and the engine has just been turned off. If I immediately pull the carburetor, piston and needle from the housing and jet in carburetor no. 1 what should I witness about the fuel in the jet?

I believe it is accurate to say that, in my case, the fuel level in the jet was at first stable, but that when I pulled the piston and needle gas spurted up and spilled into the intake manifold.

I suppose the void created by removing the needle would naturally cause more fuel from the bowl to enter the jet, but I don’t know why some fuel (maybe an ounce) would spill up over the bridge and into the intake manifold.

Is this some anomaly from the fuel pump pressure regulator having reserved pressure, and being “relaxed” with the engine turned off, or is it normal, or does this reflect an issue?

Thanks as usual.

 

[charleyf]

I will give it a try.
Once the fuel pump is stopped, you should be able to lift the piston/ needle and have the fuel level go down momentarily and the move up slightly to nearly approach the top of the jet.
Normally if fuel comes over the top of the jet you would have either a bad float valve, an incorrect setting for the float or a bad float.
One method of adjusting the float level is to remove the piston and needle and adjust the float until the fuel is at the top of the jet but not over.
Last question.
Again it is the float and float valve that stops the fuel flow under normal pressure.
Charley

 

[CJD]

Have you checked the carburetor vents?

 

[charleyf]

Have you checked the carburetor vents?

While trying to finish installation of new HS6 carbs on a TR6, I found out the hard way. If the carb float bowls are not vented the car will not run. You get no fuel through to the float chamber.
Charley