454 efi hesitates and has been running warm
 

I have a 22 scarab with a 454 tbi in it, since I have owned it I have been trying to track Down a hesitation problem, no matter where the rpms are if I nail it it will hesitate also seems to not have full power on the top end,I have replaced cap rotor fuel filter. Also I'm not sure if this is related but seems to run warm like 210-220 replaced the water pump t stat and checked for clogs. Any help would be appreciated

If its really running 210-220* water temp, the alarm would be going off. Have you replaced the sea pump impeller???

No Merc 454's used a TBI that I know of. They were carb'd or EFI/MPI.

Merc did use tbi in 96-97 only it was the 7.4 lx efi not mpi and yes I replaced the seawater pump and housing

Is it a bravo drive? If so, the plastic water pipe fitting in the gimbal housing could be collapsed.

But i don't think that would have anything to do with the hesitation issue. Might want to get a 20.00 coil from Napa and see if that helps. Also just check timing to be sure it's good. Plugs and wires maybe?

Wellcraft used Volvo as well so once again we need make of engine, model, year model and engine serial # to even come close of a fix. if not we can play darts and keep on throwing them for years.

just saying so lets start off is this app Mercruiser or Volvo or something else ? Is it a stock app and does your ECM have a stock tune ?


next when Genmar owned Wellcraft , Glastron, Larson and so on, In 75% for their apps of boats 25 feet and down they had Volvo Penta's installed The reason for this was Mercruiser / brunswick who is Sea ray, Bayliner, Maxum are the competition so the feeling was WHY put money into Brunswick pockets to make them stronger being a competitor for the same business and market share of boat brands.. Hence a lot of Volvo Penta's out on the market. . FYI

Ok I see your post # 3 is I take it Mercruiser - My bad and sorry - still will need year model and serial # of engine/

POST # 1 has not enough info to even know what make or model or year and no engine serial # just saying.

He is right and I was never good at darts:D

It's a 96 mercruiser 7.4 lx efi with a bravo one drive I done know the serial number right off hand the boat is in storage still. It starts up great runs smooth if you nail it it will hesitate for a second and feels like it falls on its face on the top end. Only getting 4200 rpm at wot with a 21p prop

I said I was sorry but only after post 3. Sorry its a pet peeve thing. No offense