MAF questions and fuel pump relay

[DirtyEars]

Sorry, if this has been answered but maybe fresh thoughts can help us all. I have a 94 4.0 Ranger xlt. I am having issues finding a good part number for the MAF as this is the original I would like to replace it, the part number on the unit is F07F-12B579-A1C AFH55-05. I can find some that say they fit but are off by 1 number and that is the number between the a_c. Also, could someone tell me if this would be normal, if I disconnect the MAF it will kill the engine. If I plug it back it runs (I can see if it had a rough idle but it kills the engine). Caps have been replaced on the ECU, fuel pump about 4500 miles with an idle pressure of 30psi. Any new number for the fuel pump relay, the number listed is FOAB 14B192-AA.

 

[Curious Hound]

The fuel pump relay is a common 5 pin relay (might only have 4 pins, but still common). There is nothing special about it. You can get 4 pin and 5 pin relays at any auto parts store. If you have fuel pressure, the relay is obviously working. You haven’t stated anything here that would indicate that it needs to be replaced.

Regarding the MAF, I believe the “A1C” portion is just a revision code. Not normally critical.

The F07F means 1990 Ranger general part.

The 12B579 is the part number

 

[SenorNoob]

30 PSI idle seems a little low. What happens if you unplug the vacuum line to the fuel pressure regulator? Should be 42 psi.

What makes you think you have a MAF problem? I'd expect it to die if you unplug it while running. The computer sees the voltage go to 0 and probably thinks the air flow through the engine just stopped...

Clear codes (unhook the battery for 10 minutes or so) and try to drive a few miles then report back what you have.

 

[DirtyEars]

30 PSI idle seems a little low. What happens if you unplug the vacuum line to the fuel pressure regulator? Should be 42 psi.

What makes you think you have a MAF problem? I'd expect it to die if you unplug it while running. The computer sees the voltage go to 0 and probably thinks the air flow through the engine just stopped...

Clear codes (unhook the battery for 10 minutes or so) and try to drive a few miles then report back what you have.

I did a small bit today but did not drive anywhere, that will get done. I did want to tell about the fuel pressures. At idle it shows 29 to 30 psi. at idle with regulator vacuum line off pressure will increase to about 38psi. I do not have a CEL light on at this minute but will pull the cable and clear any possible ones there. One thing I did notice on the exhaust I can sometimes make out a stronger puff occasionally. Almost like a miss but a stronger random puff. Engine has about 180000. It does have a newish coil about 10000 miles ago.

 

[SenorNoob]

38 without regulator vacuum is probably fine.

IDK about the rest of it.

 

[Curious Hound]

Sounds a little bit low. I'd replace the fuel filter.