Can't keep up!

[dezwartj]

I installed a blower on my TC a while back. (mega fun).However, every time I do higher speed highway driving or climb a longer hill,
the engine will loose power and only returns to power after a couple of seconds.
It appears to me that the older original lucas petrol pump cannot keep up.
I plan to install another petrol pump to assist the flow to the carburetor.
What is the best way to go about that? Install a pump in series with the existing pump or do I have to install a parrallel fuel line from the tank to the carburetor? Get a cheap modern pump in the back or install a second Lucas pump on the bulk head (Same as the factory did with the TD MkII?)

[Rob Reilly]

I don't have any experience with superchargers, but your situation sounds similar to what SS Jaguar faced when they increased their engine size from 2-1/2 Liters to 3-1/2 Liters. One type AUA25 fuel pump was still fine for the 2-1/2 Liter, but couldn't keep up with the demand at high speed on the 3-1/2 Liter. So they put on two AUA25 pumps in parallel. Note there are 2 tees in the fuel pipes. All their 3-1/2 Liter models had this arrangement from 1938 to 1948.

Later on SU came up with a new pump called the LCS for Large Capacity Single, and Jaguar used this one on all models from 1949 on until about 1969 when the V12 came along.

SU fuel pump 009.jpg (128.74 KiB) Viewed 83 times

[Steve Simmons]

It does sound possible that the pump isn't keeping up, although I know a lot of people with supercharged TCs running a standard pump. I had a similar issue on my supercharged MGB and the problem turned out to be a mixture issue. It might be worth installing an O2 sensor in your exhaust to monitor air/fuel ratios throughout the range. One way to determine if fuel starvation is indeed the issue is by waiting for the problem to arise and then cutting the ignition, rolling to a safe spot to stop, and checking for fuel in the float bowls.

In addition to Rob's example above, there was also a double-ended SU pump used on some cars, as seen below.

Some pre-war MGs also used dual SU pumps. The photo below is my MG SA. The incoming fuel is split to the two inlets and the two outputs have a T into a single line to the carbs.

dual-su-pumps.jpg (68.56 KiB) Viewed 82 times