I replaced my failed Walbro fuel pump with another Walbro pump. After that, I have noticed a intermittent surging whenever I am in gear and off the throttle. My wideband will read lean, but every couple seconds it will register like 12:1 for a moment, then go back to lean, and then repeats.

I was thinking maybe TPS, but its weird that this started after replacing the fuel pump, thoughts?

 

Do you have some form of fuel control?

 

Yea, I am running an SAFC, but I have been using the same settings on it for months. It has gone unchanged since the fuel pump replacement.

 

Well, the new fuel pump more then likely changed your tune.

 

Thats what I was thinking. But, unless I am mistaken, fuel is supposed to be cut when you're in gear but off the throttle. What would cause my engine to be periodically supplied with gas? Its worth looking at, but I dont see how it could be an SAFC issue.

 

how is your fuel pressure?

 

The TPS/Boost sensor input to the ECU, cuts the fuel injectors off completly when you fully let off the throttle while DRIVING. On some occasions it will just cut the front rotors fuel injector if you just lightly let off the pedal.

Fully letting off results in a very lean reading. Letting off just a touch, for some unknown reason, on my cars, results in a bit richer condition. See FSM or training manual to confirm what I just wrote.

None of the above explains why you didn't see this with the prior pump.

 

So... What was the fix?

 

Might be a difficult question as the OP hasn't posted for over 3 years.

 

its was probably a clogged/dirty line or he drives on empty all the time