alright... ive been having this problem for a while on my 87 with a 5.0... the fuel pressure will just randomly drop for no known reason

i changed the fuel pump in the tank.. external fuel pump and the fuel filter.. i also did a complete tune up when i bought the truck not to long ago..

its the EFI model with dual tanks...

any advice on what could be the issue here??

thanks alot!!

-Glen

 

Just curious - how did you determine the fuel pressure dropped?

Assuming you have fuel injection - I get confused on what model year the change was made from carbs. If so, there is a fuel pressure regulator on the fuel rail, along with a related control vacuum solenoid. Don't hear of a lot of trouble from these, but it's there, so it could be a problem.

Also, can you tell if the pumps remain running? Thinking about the possibility of the relay dropping out intermittently. Then there's always the possibility of a wiring problem somewheres in between.

And - welcome to the site!

 

i have a fuel pressure guage hanging out of my hood lol... i also replaced the fuel pressure regulator as well..


i can hear both pumps working properly when im not moving but i have no idea whats going on when im moving


thanks!