Scag turf tiger surge kawa 29hp dfi
Hello everyone. First time posting here, long time reader. I have been able to fix many machines off these threads and im hoping someone can help me with my issue.
07 Scag Turf Tiger 1000hr
FD791D Kaw 29hp DFI
all maint, fluids, tune up done once a year no matter what
My customer brought this machine to me after his regular mechanic was stumped. I do not work on mowers for a living. I do however run an automotive repair shop and very versed in fuel injection vehicles, that is why he brought it to me. I'm working on this thing at home and helping a friend.
Issue: surges warm off idle up to wide open with no load. intermittent surge at idle when warm. runs great cold and any time deck is on up to wide open
when surging governor is moving catching idle/changing rpm
Before it was brought to me:
fresh full tank of fuel
Things I have done in this order:
sprayed intake,throttle body with parts cleaner cold/warm for vacuum leaks
volt olm check sensors using repair manual specs, IAT, coolant temp, map, ohm injectors
removed throttle body/intake and cleaned
check and adjusted governor when intake was off.
adjusted "idle screw" at throttle body
last night i put mower back together completely to test if cleaning intake/throttle body helped. Idled great surged off idle to wot. ran great with deck on.
everything has checked out good and no change to anything that has been replaced or cleaned.
my thought process points me to checking fuel pressure while surging to see if it fluctuates, and vent fuel cap when surging to see if gas tank is under vacuum.
My customer is wanting to replace the fuel injection control module as a guess but nothing im finding is suggesting that to be the problem.
also in the manual one section mentions an engine speed sensor. I cant find any parts diagrams or writing on such part....
any help would be appreciated Thanks JD