Hey guys, I posted about this awhile ago, thought the problem was corrected but in fact was just masked over. 96 f150 6cyl 2wd 4speed with od. So every so often it'll start missfireing and stumbling, sometimes it's not so bad, sometimes it gets so bad that it'll stall out and you won't be able to re start it for the rest of the day. First I thought it was an ignition problem. Changed out the whole ignition system, it was still doing it. Then I adjusts the timing and this is where I masked it over, itd still do it but it was close to unnoticeable. I'd drive it around no problem, then get into stop and go traffic and itd start stumbling and missfireing again... So I'm back to square one because last night it almost stalled out. Today I began thinking that maybe it could be a head gasket that only leaks when it gets heated up. So I let it run for what seemed like an hour and all i could get was a slight miss. My next step was to do a compression test. I turned it off, yanked the fuel pump fuse started it up to let it run out of fuel and it behaved EXACTLY as it usually does when it wants to stall out and die. Now I have dual tanks so my question is, is there a fuel pump in each tank or is it an inline fuel pump? And could there be something else making it look like the fuel pump going bad? I've also noticed that when using my rear tank it doesn't return gas to the rear tank, instead it returns gas to the front tank and I'm getting pretty bad gas mileage considering it should be around 17 or 18 and it's at 11mpg. Complicated problem and I'll accept any suggestions y'all got! Thanks everyone

 

I tried to get a fuel pressure reading but couldn't get anything... the thing wouldn't run at all with 0 psi right?

 

You have a fuel pump in each tank. If you're filling your front tank when using the rear tank, then the fuel pump module in the front tank is bad.

 

ok thanks, but that wouldn't cause it to stall out would it? It'll missfire and stall no matter which tank it is

 

It could possible. First step would be to pull the codes. The second step will be to check fuel pressure when it starts acting up. Try a different gauge, you should get something.

 

ok, I'll rent a better gauge from advance auto, I did run codes before when it was acting up, all I had was a cylinder 1 missfire and some egr code, I'll get a pressure reading and come back

 

Alright I got a lot of codes...
1)evaporative emission system control valve circuit
2) cylinder 1 missfire
3) bank 1 system too lean​​
​​​​​​4) bank2 system too lean
5)idle air control underspeed malfunction
6)oxygen sensor bank 1 sensor 2
7) lack of heated oxygen sensor bank 1sensor 1 indicates lean
8)Heated oxygen sensor bank 2 sensor 1 switch point indicates lean
9)fuel pump circuit voltage low

 

Please post the actual code numbers.

However, from what it sounds like, it appears that your engine is starving for fuel.

 

P0443,p0301,p0171,p0174,p1507,p0136,p1131,p1151,p0 231

The guy at the parts store said there's a vacuum leak but that doesn't sound right to me...

 

Any ideas? If I don't get it figured out soon I'm taking it to the scrap yard....

 

As previously suggested by Ian, verify the fuel pressure with a known good pressure gauge.

Once that is validated then you need to look for vacuum leaks.

 

Still waiting for that fuel pressure reading.

 

Fuel pressure seams fine. 20 psi with key on engine off, 45 psi engine running...

 

What happens to the fuel pressure if you snap the throttle.

 

It drops about 2 or 3 psi when I hit the gas if that makes any difference