merc 454 magnum stalling

[netman555]

a friend has a 1999/98 454 magnum fuel injected motor,just had the head reconed,now he has refitted them,and found that the engine keeps stalling when throttle is put to idle position,if he keeps it just of idle it is ok,i was thinking it was the idle passage in the throttle body blocked,or air leak at inlet manifold,thinking a vacuum gauge may pick up a leak, also when at operating temp it is hard to start,have to hold full throttle and crank for a while to fire up,any help would be great,thanks john from new zealand.

 

[rodbolt]

Re: merc 454 magnum stalling

hello<br /> is this an MPI or TBI system. the TBI has 2 injectors in the body assy.<br /> the MPI has 8 injectors on the intake

 

[waterone1@aol.com]

Re: merc 454 magnum stalling

Has the IAC (idle air control) been properly re-installed and connected ?

 

[Don S]

Re: merc 454 magnum stalling

Is it a Mercruiser or Volvo?<br />Do a vacuum check. A leaky intake manifold gasket could cause the problem.

 

[newport dave]

Re: merc 454 magnum stalling

Opening the throttle to the wide open position would put the ECM in "clear flood" mode stopping the injectors from firing. Wouldn't that make a lean condition (vacuum leak) worse? I am thinking bad connection at the Idle Air Control (IAC)Motor or leaking injector. A scan tool would help find the problem if you can get access to one.<br />Dave