MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - Upper fuel pressure limit.

Can anyone tell me what the upper limit is for fuel pressure in our T-cars? Thanks, Bud Krueger
Bud Krueger

About 1-1/2 to 3 PSI for firewall mounted pumps.
Lew Palmer

For TD through early TF, stock is 1.5 PSI from an L-Type AUA25 SU pump. Later TF used (I think) an HP pump at 3 PSI. I'm pretty sure a 3PSI pump would work fine on the earlier carbs, but the pump would want to be mounted down low rather than on the firewall.
Steve Simmons

Thanks, guys, but my issue isn't with the ability of the pump. It's a question of what the carburetor end of the fuel line can handle. In the latest TSO, Don Lawson indicates that a burst of higher than normal pressure could overcome a vapor lock condition. What do you think? Bud
Bud Krueger

The only difference I can think of that it could make would be in the lines between the pump and carburetor. The higher pressure would raise the boiling point of the fuel in the lines. But the difference would likely be very slight. I'm not a chemist but I suspect the difference would be less than that between one blend of fuel and another.

The pressure after the float valves is always atmospheric no matter how much pressure the fuel pump is capable of. Since vapor lock seems to happen mostly after that point, namely in the bridges between bowl and jet, I don't believe the higher pressure pump would make any difference. I would certainly welcome any evidence to the contrary.
Steve Simmons

This thread was discussed between 17/10/2023 and 19/10/2023

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.