Fuel delivery issue, 3fe idles(somewhat rough) no go. (1 Viewer)

[masong]

This is not supposed to happen. With the AFM disconnected there is no ground path for the fuel pump logic once the starter motor stops cranking.
Without the AFM, the engine should fire while cranking and die once the key is released from the start position.

Hmm, predictably, the other airflow meter did not make a difference.

I'm wondering if a short somewhere could cause this? Perhaps in the AFM pigtail?

 

[tacosupreme]

Just because the fuel pump runs when you jump it doesn't mean fuel is getting to the injectors. This crap ethanol fuel we get is hygroscopic and absorbs water, which then freezes into an interesting slushy mixture that sinks to the bottom of the tank and is perfectly suited to clogging fuel filters.

A) Is it getting enough fuel?

B) Are the spark plugs igniting that fuel?

C) Is it getting the right amount of air to burn that fuel?

Fuel, fire, and air. I bet it is something simple.

 

[masong]

Hmm, predictably, the other airflow meter did not make a difference.

I'm wondering if a short somewhere could cause this? Perhaps in the AFM pigtail?

Or, perhaps a Circuit opening relay that tested fine on the bench but works poorly in operation?

 

[jonheld]

Hmm, predictably, the other airflow meter did not make a difference.

I'm wondering if a short somewhere could cause this? Perhaps in the AFM pigtail?

Pins 1 and 2 of the AFM harness are the ground path for the fuel pump logic. Solid brown and red with a white stripe respectively. This is the air flap switch in the AFM that closes and fires the second coil in the circuit opening relay that provides power to the fuel pump when the engine is running.

 

[masong]

I

Just because the fuel pump runs when you jump it doesn't mean fuel is getting to the injectors. This crap ethanol fuel we get is hygroscopic and absorbs water, which then freezes into an interesting slushy mixture that sinks to the bottom of the tank and is perfectly suited to clogging fuel filters.

A) Is it getting enough fuel?

B) Are the spark plugs igniting that fuel?

C) Is it getting the right amount of air to burn that fuel?

Fuel, fire, and air. I bet it is something simple.

I try to keep non-ethanol fuel in my truck, it isn't easy though. It certainly seems like I have some issue with the fuel pump circuit as it will run with the AFM disconnected, which Jonheld says should not be the case.[/QUOTE]

 

[Camino]

Did you check all vacume hoses? Post some pics of engine compartment. Did you check the hose for holes/cracks when you switched AFM's? Did you bypass fuel tank and run temp line from new gas source?

 

[masong]

Did you check all vacume hoses? Post some pics of engine compartment. Did you check the hose for holes/cracks when you switched AFM's? Did you bypass fuel tank and run temp line from new gas source?

All vacuum lines are intact, intake tube is solid. I have not bypassed the tank because it will run(idle only) if I disconnect the AFM harness. Won't run/start if it AFM harness is connected.

 

[masong]

Also, just swapped the Circuit opening relay out of my 22re 4runner and no different results.