My poor truck is acting up again. Rough morning idle and will stall out unless I hold the idle at 1000 til it warms up. After that the idle surges between 500 and 600.
Also in an earlier thread I researched a code 542 and found a bad breaker that appeared to fix the problem. Two weeks agao the fuel pump would not activate when the key was turned. I hit the tank 4-5 times with a 3 lb rubber hammer and it has ran since then. What does this indicate?
Here are the codes that were present.


KOEO

122 (O,M) TP low (possibly grounded or open circuit)

128(M)MAP vacuum has not been changing - check vacuum lines

334(O,R,M)EVP sensor is/was high

542 (O,M) Fuel pump open, bad ground or always on –

KOER

312 (R) AIR not diverting

I cannot find a vacuum leak nor can I hear one. I do not understand the other codes.

Any help/advice would be appreciated. Thank you

 

You could check the wiring to the fuel pump, but if banging the tank with a hammer brought it to life the pump is bad.

As far as vacuum lines, whenever I have to replace one, I just do them all, buy like 20 foot of vacuum line, and just make them one at a time.