Its like every other day something goes bad on my 94 f150 4.9. I replaced all the gaskets that I could see were leaking (valve cover, intake, lifter and trans gaskets). I cleaned the intake, throttle body, and iac valve (atleast half an inch of buildup throughout), checked vacuum on all lines replaced what was bad and brittle. I then redid vacuum test on fuel pressure regulator pulled it down to 20in let it sit after 5 minutes or so it bled back down to 10in replaced defective regulator. Took it for a test drive and now noticed that it has the tank bleed issue from front to rear, and another oil leak after cleaning all oil from engine the distributor is leaking and the sensor in front of it looks like an oil pressure sending unit. I have two questions when replacing the fuel pump do I need or should I even install check valves if they aren't there already? I tried to pull vacuum on egr and was unable to pull it down not even a little movement on vacuum gauge. I don't have a fuel pressure gauge yet. You can smell how rich the truck is running.

 

I wouldn't necessarily worry about the tank bleed issue my truck did it for years and it was actually a recall. Contact ford and give them your vin and they will tell you if it's under recall and they would fix it if it is. Mine got fixed but started doin it again so I got one of the tanks deleted and it's all good now.

 

My tanks have done that the entire time I have owned my truck too. Ive just learned to live with it and it doesnt even bother me. As far as the oil pressure switch leaking, it is just threaded into the block so try snugging it down a bit, it may just be loose.

 

Is that the oil pressure switch or something else? I thought the oil switch was on the back driver side of the block not the front driver side.

 

Oil pressure sending unit is right next to or above the oil filter.

 

When you say the tanks are bleeding into one another, what are the symptoms? (wondering because I believe I have the same problem)

 

You run on one tank and when its empty you have more fuel in the other tank then before. It also makes it seem your fuel mileage is terrible when its simply just returning the fuel to the other tank.

It has the potential to overfill a tank if it flows into an already full tank.

For example for every full tank on my front, it will fill 1/4 tank in the rear meaning my rear fuel pump check valve is bad.

 

okay, that isn't my problem lol. I have to cycle my key 2-4 times sometimes to get the truck to start. it will turn over every time but not always start. sometimes it starts right up. sometimes, i'm not so lucky. also happens in my dad's 99 f250 7.3 gas. any input?

 

Possible weak fuel pump or pressure regulator. You would need to test for fuel pressure and try pulling the vacuum line on the regulator.

 

I already replaced the fuel pressure regulator and redid the vacuum test it held after replacement