So my buddy just installed a fuel pressure gauge in his 97. The pressures are pretty erratic. I'll attach a short video. The video is of a full load acceleration and some highway driving after warming up. On occasion the pressure will drop to 15psi under hard acceleration. The pressures will at normal operation jump between 40-60 psi. His truck still runs the normal mechanical fuel pump.

What would cause the erratic pressure during normal operation? FPR going bad was my thought but wanted a second opinion. The high load dropout will likely only be solved through efuel im sure...

 

Mechanical pump pulsates and usually won't keep steady pressure on a gauge.

 

Get a liquid filled gauge. Yes, E fuel will solve the big drop in fuel pressure.

 

What he said!

 

My factory pump produces 45 to 50 psi no matter what the throttle position. If it were to fall to 15 under heavy throttle, I'd suspect the pump is beginning to fail. Or, perhaps a restriction in the fuel system such as a clogged fuel filter.

 

under 40 psi and you will starve the injectors which can make them knock


I tried bb mod and ended up using a new stiffer spring since the old spring bent under pressure


could have trash in tank, broken shower head in tank, pinched line, bad pump, filter not changed in 10k or clogged, algae in tank, fuel selector not switching all the way, clogged FPR screen