454 cuts out on restart

[Dave K]

Good morning. I have a 1998 7.4 MPI 454 mercruiser. It will start and run fine. Once I shut it down I have problems on restart. It will start, idle in gear but when I give it throttle it spits sputters and dies. It may take as long as 3 or 4 minutes to restart. It will then run fine all the way home. Engine has 660 hours on it. New batteries this year. I replaced the fuel filter once this issue started. Didn’t help the issue. Has anyone had this issue before? Boat is a fresh water boat.

[Turtle Blues]

You replaced filter after problem started. It is possible you may have trash accumulated in the injectors and fuel rail.

It starts when cold - pressure has dropped and fuel makes it through the injectors.

Warm restart - rail is at full pressure and partially clogged injectors will have very poor spray pattern.
Are you comfortable bleeding the fuel rail? Removing and pulsing injectors to visually check spray pattern?
Maybe try off the shelf injector cleaner in the fuel before going to that extreme but the problem with fuel additives is getting enough through the system to make a difference due to the larger volume of fuel a boat carries compared to a car.

[rslifkin]

Could also be a heat related problem. Ignition or fuel issue when heat soaked after shutdown that clears up once it's running for a few minutes.

[Lepke]

Gas engines in hot weather, when shut down, can over heat the fuel or rail lines. It can expand the fuel and force fuel back to the tank or boil off fuel leaving a void. The solution may be to vent the engine area after shutdown. If the engine uses a mechanical fuel pump, a fix can be to replace it with an electric.

[NPCampbell]

I had a bad check valve in my fuel pump. When I stopped the engine, the pressurized fuel in the rails would back flow into the tank leaving air in the rails.
My fuel pump would start pressurizing as soon as the ignition was set to "on" but there would still be trapped air in the rails. I'd have to turn the engine over a number of times just to get fuel back to the injectors. I was able to confirm a fuel rail pressure problem by hooking a fuel pressure gauge to the Schrader valve on my fuel rails.

[Manateeman]

Remove Heat, clean out the dirt, buy a pressure gauge....excellent advice above.
Excellent. Nothing more to add.

[Boatyarddog]

Originally Posted by Dave K

Good morning. I have a 1998 7.4 MPI 454 mercruiser. It will start and run fine. Once I shut it down I have problems on restart. It will start, idle in gear but when I give it throttle it spits sputters and dies. It may take as long as 3 or 4 minutes to restart. It will then run fine all the way home. Engine has 660 hours on it. New batteries this year. I replaced the fuel filter once this issue started. Didn’t help the issue. Has anyone had this issue before? Boat is a fresh water boat.

Check the secondary ignition system, cap and rotor if it has one.
Maybe weak spark issue.
Boatyarddog