Missing under load...

[NavyRanger1994]

Been racking my head on this one for a while. Got my BII 4.0 swap done and everything runs great, till I hit 3rd gear and if I give it too much gas she starts to miss and sputter. I back out of it and it goes away. And only happens after its warmed up. Was thinking vacuum leaks but I cant find any. Also looked for an EGR valve but cant find one. Engine came from a 93 Ranger. Any help would be much appreciated.

 

[JerryC]

Have you checked the fuel pressure?
Have checked for codes?
Checked the plugs, wires, etc...

 

[SenorNoob]

In a '93 you probably don't have EGR...

It definitely sounds like a loss of fuel. I don't understand why it'd only happen when warm though unless the fuel pump is getting flakey.

 

[trail B2]

When you hooked up the fuel pumps electrically did you make sure that the booster pump in the tank was working?If it doesn't work it can put air in the system by building a vacuum between the two pumps but not in all situations.It only happens when its warm makes me wonder.

That's my combination as well 86 B2 93 Ranger 4.0 about 4 years ago now have been very happy with it.

 

[NavyRanger1994]

I did a full tune up on it less than 500 miles ago. I have not checked codes on it yet. Both pumps were working fine but I have not dropped the tank yet to replace the sending unit. I'm almost wondering if it could be something as simple as a clogged screen in the tank that is keeping enough fuel from getting to the engine under acceleration. Still cant understand why it would only do it after it gets warm but I've seen stranger things.

 

[Mickey Bitsko]

fuel filter

 

[NavyRanger1994]

Fuel filter is brand new. That was my first thought but made no difference with the new one. Is there a screen or anything in the tank that could get clogged up that could be causing this?

 

[JerryC]

There is a screen in the tank at the bottom of the sending unit/pump mount.