i have a 91 f-150 4x4 with the 5.8 motor. my question is if i hooked up a fuel pressure gauge what reading should i get at idle and how do i check it under load and what should it read.Do i leave it in park and just rev it up or what? thank you

 

Ehh, I've always done it at idle - looking for 30-35 psi.

If the pressure falls under load or revving, would look toward a plugged filter, a fouled pick-up screen in the tank, or a fuel pump that just ain't cutting it.

 

Should actually be between 35 and 40 PSI at the rail....to check for a bad regulator watch the gauge and unhook the vacuum line.....if it jumps up to 45 or more PSI it's fine. If it doesn't, it's broke.

 

it stays rite around 30 at idle but when i rev it up [or try to] it goes down below 20psi.it has a brand new regulator on it.

 

What do you mean or try to?what's the problem you're having?

 

it will start and idle just fine but when you give it gas it'll just die

 

Do you have a HP pump on the frame or just 1 per tank? how many tanks? And your filter is new?

 

91 should be in tank pumps.....

 

Check for codes.

 

its got in tank pumps. i finally just put it in the shop.they called today and said they think its the fuel pump.aint it kinda funny for both pumps to go out at the same time tho.it does have a new filter also(someone ask that)