Daughter has a 2006 F150 2 x 4 with 4.6 motor. Has about 110K miles on it now. Just started to have long crank times prior to starting in the last month. I told her to turn key on - off a couple times to buildup fuel pressure and see if that helps. Seems that might be working. She stopped by today and I was going to check fuel pressure and leak down.. I did not see a Schrader valve on the rail, and I don't see the pressure regulator that leaks back to the tank........... not like my 2001- 2002 .. any ideas ?

 

just a few questions...

has it had its 100k tune up? spark plugs might be on their last legs.

last time the fuel filter /air filter has been replaced?

last time the battery was replaced? I know that with mine I can count on a battery lasting about 2.5-3.5 years due to the heat here in Texas.

 

well, its been 3-4 days and she has been turning the key on- off - 3 times prior to cranking and the truck then starts on the first revolution. It is definitely loosing fuel pressure over night. Either the fuel pump has a check valve and leaks backward or there is a regulator under the hood that leaks off overnight.... any ideas ?

 

Truck seem to gradually get worse. Will not start in the morning unless you turn the key on 3-4 times to build up pump pressure.. I bit the bullet sunday and pulled the bed off the truck, then removed the fuel pump unit. Put it in a bucket of water and I can blow backward down the discharge line and get a few very small air bubbles. I guess the check valve is bad. Since the pump was 8 years old I decided to buy the entire unit with pump, check valve, float, etc.. $299. Installed it tonight, turned key on once to fill empty lines that had been removed, then fired right up. Will let it set overnight and test startup again tomorrow night. If all is well, then I will put the bed back on the truck. Looks like its fixed at this time. Sure started up fast with the new pump. I bet the old one was low on pressure in addition to the check valve leak back.

 

Sounds like that truck uses an Electronic Returnless Fuel System. The PCM sends info to the FPDM (located above the spare tire), and the FPDM actually controls the fuel pump speed to maintain the pressure requested by the PCM.

Best way to monitor the fuel pressure is to use a scan tool and see what the PCM is seeing.

Do a forum search for FPDM (Fuel Pump Driver Module) and you will see how they rot out where they are bolted to the frame.

 

Yea, the module was my first inspection last week. Took it off and looked o.k. Cleaned and spray painted cover, then reinstalled with spacers onto the frame. Problem persisted so I though I would try the pump..... Second day in a row and it starts on the first revolution... I think I got it !
I have a scan tool that does the static test when you get a CEL light. It says you can start the motor and monitor "other problems"... I have not tried that yet. I need to learn more about the ability to read fuel pressure and other items. Is that scanner called something special ?