1992 F150 4.9 (starts but doesnt run)

Fuel psi at the rail 58psi, Key on eng off

Motor will run for about 3-5 seconds till the psi drops from 58 to 47 psi then dies,

PSI goes from 58psi to 50psi with key off in around 2 mins,


I have just flushed out rear tank with fresh gas and seems to sound better when its starts and trys to run,

Old gas was kinda brown and didnt look right,

I flushed the tank by disconnecting the filter and running the hose into a bucket with the key on, I noticed that the stream of gas wasnt very far for something that pressurizes to 58psi,
Is this normal??

Does this sound like my fuel pump??
Or do I need to adjust my fuel pressure regulator?

Thanks,

 

The fuel pressure regulator isn't adjustable. I'd probably change it.

 

the FPR is brand new,
it was the first thing I replaced

 

How does the pump sound? Is it noisy?

 

yes it is noisy, both of them are

they never shut off,

my 99 crown vic (289) pump is quiet and shuts off after 3 sec or so,

I have looked for the answer for the reason it never shuts off and some people think its ok and some its bad,

I have changed all 3 relays, (just to make sure)
When I changed them the pumps did get quieter but im still wondering,

 

also

Both pumps are pushing 58 psi at the rail, i just dont see why the pressure drops after I get her running with a shot of fluid, it drops to about 47psi then dies,

doesnt sputter, snap, crackle, pop, bogg down or up,
she just dies, almost like flipping a switch,

ive tried pushing the throttle also and it doesnt do anything

I replaced all injectors last week, and same problem, (but does sound smoother when she fires up)

Thanks for the help,

 

Are you getting any codes?

 

nope,

ive tried the old school way with the CEL and with a amtron scanner, I think its basicly the same idea,


I have takin my EEC out and inspected it, there are no burn marks that I could see, it looked pretty good for being 19 years old

 

Sounds like the computer is bad.

 

ive have been thinking that for awhile, thats why I checked it out,
nobody seems to know how to test it,