Fuel rail pressure bleed down
 

I'm trying to figure out why I need to crank the engine over for about 5 seconds before the truck finally starts. I hooked up a pressure gauge to the fuel rail and it showed 0psi. Turned the key to run and it shot up to about 35 on both tanks. Started it up for a few mins then shut it down. Pressure returned to 0 in about 5-10 seconds.

Is this an issue or normal operation?

That is not normal and suggests it has one of a couple possible issues, either a leaking injector which can be confirmed buy reading the spark plugs and looking for the wet or really sooty one, or you have a bad check or shuttle valve in one or both gas tanks.

Thank you for the reply. I'm hoping this will help me figure out the idle surge issue also.

The check valve is in the HP (High Pressure) fuel pump that is mounted on the frame. You do not have any valves inside the fuel tanks.
You will need to replace the the HP fuel pump if the injectors and the FPR (Fuel Pressure Regulator) are OK.

Hi, I have a question plz tell me how to bleed air from my 1987 ford bronco full size!???

Is it EFI or carb?

EfI and is a 302 motor.

If you are talking about the fuel system you just turn the key on and off a few times.

When I purge it air sprays out. I can purge until gas comes out and the air comes out again o the fuel line??

I have checked for fuel leaking out of a hose and can't seem to see any. I do run it low on gas often simply because it uses the cap out of gas. There is definitely air in the lines though and I have no idea as to how to get it out.

The fuel system on this truck is a bit more complicated with the frame mounted resovoir/switching valve and also the dual stage fuel pumps. I suspect either you have a dead in-tank pump or there is something wrong with the "switching valve" which is officially known as a single function resovoir or dual function resovoir depending if the truck has 1 or 2 tanks.
Normally if both pumps are working then this system moves a lot more fuel than the engine can use so most of the time it's just dumped right back in the tank and there is simply no way air can get in the lines.

Conanski, I just changed the pump in the tank, and it didn't change anything. Where is the switching valve at? This one only has 1 tank and I changed the pump on the frame about 8 months ago so I would hope to think they both are still working. Lol.... thank you for trying to help me because I'm at my wits end with it and it happens to be my only vehicle at the moment.

You have no switching valve on a 1987 ford Bronco full size with one tank and with EFI and a 302 motor.

But you should have a fuel reservoir mounted on the frame. It could be broken or missing the big "O" ring for the cup.
OR a bad fuel line connection to the between the high pressure pump and the single tank Reservoir.

The single tank Reservoir:
http://i54.photobucket.com/albums/g9...kReservoir.jpg

http://i54.photobucket.com/albums/g9...psd8474cd6.jpg

/

It's actually an 1987 but thy changed the motor that was originally on it to a 1996 one.

Also, aside from when I purge it and air coming out, when we are driving it and have to give it gas to go up a hill for instance it cuts in and out. It's gotten to where it even does it by just pressing the gas period unlike at first it only happened when we had to really press the gas. Also I told y'all wrong I thought we had changed the pump in the tank but we actually didn't because when we pulled it out and checked it, it was working. Is it possible for a pump to stop working properly on and off???