Here's my sob story: I blew a head gasket a few months ago and had it replaced. Since right before the replacement, it had been idling rough. I thought it was the gasket, but the problem persisted after the repair. Then I started to get a code 71 (EGR). I had the shop check it out about 5 different times. They took out the EGR and cleaned it twice. Still idles funny and throws code 71. Then it occurred to me that the blown head gasket had been pressurizing the coolant and some was spewing out from the overflow reservoir right by my k&n filter...maybe the MAF was gunked up.

So, I unscrewed what I thought was the MAF (but was actually the connection for the AFM) and destroyed all 3 foil connection things inside. I tried to solder the 3 pins to the 3 squares, but still got one funny resistance reading (between pins 3 and 4). Put it all back on but the truck won't start.

Here's the strange part, the fuel pump also doesn't activate. I bent back the contact points inside the AFM and am 99% sure that they are functioning properly. Also, when I jump the B+ and FP terminals in the diagnostic box...still no fuel pump. Could I have messed something else up?

I am planning on just buying a new AFM for $100 on ebay, but the lack of fuel pump sounds worries me. The truck drove fine into the garage, just idled a bit rough. Any thoughts? Thanks!

 

You need to get a replacement AFM installed first, then see if the fuel pump will work. The bad AFM can also cause a ruff idle, so see what happens with the new AFM and go from there.

 

The AFM is completes the circuit for the fuel pump... meaning that if it is not connected or not functioning properly it shuts off the fuel pump because it breaks the circuit.

 

If you didn't already buy the AFM i have a stock one off my 86' 22RE (upgraded to the 82' Supra AFM) that i will ship to you for way less than $100. PM me if interested.

 

But bridging the Fp and B+ terminals on the diagnostic box should bypass the AFM part of the fuel pump circuit. I wonder if I could have blown a fuse or something. Let me check a few more things and I'll let you know Swimmerboy.

 

Sounds good.

 

Sure enough...blew the EFI fuse. Must have blown it when I tried to run the truck before fixing the AFM. Hopefully my repair job holds up...but for now it's running the same is it was before.

Next up is cleaning that nasty intake...