hi everyone,
having a new problem on my 1988 4.9. EFI
i seem to get no fuel pressure on the engine, the front pump runs but it keeps running without pressurizing the system. it started yesterday, i took it for a drive, came back home, wanted to start it to go to work and just kept cranking, i checked spark plugs and everything, when using starter fluid and selecting the cng i can start it, normally i need to put on the pump by a button to start on gas,
if i select petrol, wheter its for starting or during the drive there's nothing, just keeps cranking, i added petrol to be sure its not on the lower limit, didn't help.
can only test on front tank because the previous owner disconnected the rear tank.

 

I'm not familiar with dual-fuel systems but I would strongly suspect your fuel pressure regulator is not working.

Pull the vacuum hose off the regulator and see if there is petrol present in the vacuum line. If so you must replace the regulator

 

where can the regulator be found?
i also hear something blowing, can't find out where. (i think the left side of the engine (passenger side)

 

The regulator is near the front end of the fuel rail.
The fuel rail is on top of the engine on the passenger side and connects to the fuel injectors.

 

no petrol in vacuum hose of regulator, but it is blowing when fuel pump is on. there is no leak of fuel (fuel passing straight to tank?)
regards


ps haven't been active much on the forum because loads nd loads of work (renovating+baby on the way

 

What is blowing and where?

 

if you have the regulator underneath where it goes wider. if i can remember i don't think it was before my problems started but im not sure.

 

So it's blowing petrol out from underneath the regulator?

 

no:it blows air from the ring keeping the two parts of the regulator together, when i shut down fuel pump (for cng driving) it stops blowing. (even without engine running)

http://autorepair.about.com/library/a/1f/bl961f.htm

if you scroll on the link and you see the picture its where the regulator has a bigger diameter.

 

Well the regulator is dead for sure but it may not be the only issue.

 

changed regulator today (had to ship from us) still no fuel pressure, nor there is when i removed the old one and started up the fuel pump, my second gues is the in tank pump isn't running so i checked the tank selector switch, it has melted plastic and when i use the ohm-meter there is one side not responding, high pressure pump is running...


update: have only changed regulator; after few tries when driving and putting it to petrol it worked. (still don't know the real cause but i'm happy it works)

 

check fuel pump relay. should fix prob.