FIXED!!! EFI stopped running - low fuel pressure?

[Randrew]

I was driving and my bronco all of a sudden started barely running. It would idle, but it would stumble whenever I gave it gas. Limped it home and checked it out the next day.

Codes:
81, 82, 84, 85 (no emissions), 29 (no VSS), and 32 (no EGR), 95 (Fuel pump: open, bad ground or always on)

I noticed that the TPS was loose, so recalibrated that (reads 1.1v at closed throttle).

Cleared the codes and tried to start the truck. Won't start. Only codes I get now are 81, 82, 84, 85.

I can hear the fuel pump priming, and it runs constantly and sounds normal if I ground the fuel pump test connector. The truck will idle (albeit poorly) if I disconnect the MAF and the IAC. This led me away from a fuel issue, so I threw a known good MAF and TPS at it. That didn't work.

Got a fuel pressure gauge and noticed that there was very little pressure at the fuel rail (5psi that would drop instantly when the pump turned off). I'm not sure I trust that reading, so I pushed on the schrader valve immediately after running the pump and no fuel came out. I changed the regulator and fuel filter and have the same problems. Also put 2 more gals of gas in it. Tanks is 1/3 full.

My question is... is this a fuel pump issue? The pump is an 8 month old BC Broncos in tank pump in their 23 gal tank. Is there anything else I can check before I have to drop the gas tank? Could this be stuck and leaky injectors?

I'm going to run a new ground directly from the battery to the fuel pump today and see if that affects anything.

FYI: I have an A9L with stock MAF and 19lb injectors, BC 23 gal in tank pump.

Thanks,
Randy

 

[ren71]

possibly a clogged filter, I've read those new tanks need a thorough cleaning before use.

 

[Randrew]

I tried a new filter already. No luck.

 

[76Broncofromhell]

My guess is a bad pump, clogged inlet screen, leaking hose from the pump to sending unit or a bad fuel filter.

Stock rail pressure should be at 40 psi (39 technically). What I did to test for fuel leaks was ground the Fuel Pump Relay terminal (check out FordFuelInjection.com for the proceedure) and let the pump run with the engine off and check for leaks and rail pressure.

Dropping the tank may be in your future, unfortunately.

 

[Randrew]

UPDATE:

I took the fuel inlet hose off of the fuel rail and ran the pump. There is a steady stream of fuel after the pump runs for about 1 second. Then I reconnected that and checked pressure. This time I get no pressure at all. Then I checked for fuel coming back to the tank... nothing, even after running for 20 seconds or so.

Is this a sign of a weak pump? Is it possible that all that fuel could be dumping out of a leaky injector? If I had to drop the tank, how would I test the pump. As it is right now, it seems like the pump may be fine. Or is there a way to test how a pump will build pressure?

 

[Broncobowsher]

If the flex hose in the tank splits, it will do exactly what you are experiencing.

 

[ransil]

The flex hose in the tank need to be rated for submersion, can't just use regular EFI hose or fuel line.

http://www.gates.com/europe/brochure.cfm?brochure=2486&location_id=2958

http://www.gates.com/europe/brochure.cfm?brochure=3014&location_id=5165

 

[Randrew]

FIXED:

Well, I fixed it a while ago. Forgot to come back here and tell you all what it was. Broncobowsher was almost right. I pulled the tank and the fuel pump hose had partially slipped off of the inlet tube going thru the tank. Unfortunately, when I went to put it back on the hose was very gooey and started disintegrating in my hand. So I installed a new piece of Gates submersible fuel hose and everything runs great now. Fuel pressure builds to 40psi.

Thanks for all the help.