Originally Posted by
EagleMark
For a comparison a stock LT1 fuel pump feed wire is 18 gauge and when upgrading the fuel pump it needs a 12 gauge wire. So a wire size increase should fix the voltage drop but if the Howell harness is only 16 gauge to feed fuel pump relay I'm not sure it will help having bigger from relay to pump. Longer the run of wire to pump would be where voltage is lost.
There's always a ground issue with fuel pumps. More pump and more fuel = more ground issues. Unless the engine is a stock low HP, when I do a conversion the fuel pump ground comes back to block. Issues are fuel pump ground to frame, is frame grounded to block? Or worse grounded to body? Corrosion?
But like JP mentioned the fuel feed line from pump to TBI unit... it has to be 3/8ths or bigger for TBI and TPI which is the pump you have. Smaller would put a big strain on pumps output = load straining pump. Since your voltage drop is double when running? Did you use the Jeep 4 cylinder fuel feed line? What size? Although pressure was MPFI 43 for the 4 cylinder jeep the volume was much less needed.
I'm down to 2 pumps, GM or Carter. Carter is vane drive and noisier but a better pump. Even if airtex pumps are not the best I doubt you could go through 4? You've got wiring or fuel feed issues causing a load on pump.