It's curious... What is the relation between the fuel pump and the VAFM? I have a fuel pump that is dropping pressure when accelerating... But if I play around with the VAFM (forcing it closed) I can get it to accelerate just fine...I saw a random post awhile back can't remember if it was here or else where but it mentioned that when accelerating the VAFM draws the power down on the fuel pump..... Did I read that wrong or did I misunderstand what it was meaning... I had the VAFM tested and was told that it tested out of specs... I'm assuming it tested bad... I'm replacing it and at the moment with it in I'm getting codes 24 and code 31 which are both air flow... Well 24 is cold air injector.

 

Cold air injector? What is that?

Here are the codes; no need to guess: http://personal.utulsa.edu/~nathan-b...85diagnosi.pdf

Code 24 tells you the ecm is not getting a valid reading from the intake air temp sensor. Code 31 tells you the ecm is getting a short or open from the air flow sensor. Both of these can be due to something as simple as unplugging the VAF (yes, people do that).

In addition to the temp sensor and the potentiometer connected to the vane, the VAF has a reed switch that closes when the vane opens "at all." This reed switch powers the second winding in the COR, to allow the fuel pump to keep running with key-on (not key-start) and air flowing.

The VAF does not "draw the power down on the fuel pump." But if the reed switch is messed up enough I suppose it could intermittently open when the vane is moving. This is easy to check; put your voltmeter on FC to ground http://personal.utulsa.edu/~nathan-b...92volumeai.pdf With the key-on, engine-off you should read 12v (through the COR, not grounded). When the engine starts (or you move the vane with your finger) it should drop to ground (powering the COR, powering the Fuel pump.)

 

Sorry was having a conversation while I was typing and the error for code 24 is air flow temp not cold air injectors... Sorry for that confusion.. As for the rest it makes sense I'll check those tonight.

 

This maybe a dumb question... When you say unplug the AFM... Are you referring to the vacuum line going into it? If I unplug the plug it won't start

 

No, I meant the electrical plug. And if it is unplugged, it won't start (for the reasons given above).

The cluster of problems you have (bad temp signal, bad potentiometer signal, possibly bad FC signal) have the electrical connection to the VAF in common.