BlazinOR

Guy on another board I belong to believes a TBI pump will work fine for a TPI car.............I don't fully understand how but what is the word here? Figure TBI is less than 15 psi, TPI is 43.5 ish..........he says the regulator regulates the pressure.

Ed Maher

I believe TPI pumps work for TBI, but not vv. I *think* the stock TBI pump just isn't designed to run at that high of a pressure. But your friend was right, the regulator regulates the pressure. The pumps are positive displacement. They just move a certain amount of fuel as they move. The pressure comes from the restriction on the fuel line from the regulator. Just like when you hold your finger on a hose and it sprays out.
And where lack of design for high pressure comes in is this. At very high pressures, the pump has to work very hard to push through the regulator. This slows the pump down (thus less volume, another fact of high volume since the pump only moves a certain amount per revolution), and when you slow an electric motor down it makes more heat because more current passes through it. And heat kills electric motors. Which is also why you should keep your gas tank close to full so it;s always submerged and cooled.

mrr23

TBI pumps max out at 20 psi.

Swapmaster

Yep, dead head pressure.
Block the return line and a TBI pump will "dead head" at about 20
and a TPI pump will "dead head" at about 60

Jay

iTrader: (2)

I can verify from actual experience that a TBI pump will make a TPI car run. However, it doesn't really go anywhere
I learned the hard way, long before TGO was ever around and I even had a clue what the internet was, I swapped a TBI for a TPI. Car started right up. I was happy. Went to drive the car, it wanted to stall every time I let out the clutch.. the mroe gas I gave ( via the gas pedal ) the more it stalled out. I was not happy anymore.

Swapped to a TPI pump, and everything was good. Until 15 minutes later and the pump burned out and I had to swap in another.