Mercruiser 5.7 thunderbolt ignition running issues

[Rufdod]

So I fired the boat up today , fired up fine after sitting all winter , idled at 800rpm, the fuel pressure gauge was bouncing between 8.5 and 9.5 psi, and running ac Delco mr43t plugs .

 

[Rufdod]

I have a question about two black assuming ground wires on top of the motor near the intake , they aren't connected to anything and not sure if they should be , and other question is the 50a circuit breaker , it is somewhat cracked and rusty , could this be an issue ?

 

[alldodge]

I have a question about two black assuming ground wires on top of the motor near the intake , they aren't connected to anything and not sure if they should be , and other question is the 50a circuit breaker , it is somewhat cracked and rusty , could this be an issue ?

Yes, very much so, they should be connected to the engine block in a clean spot. Take a pic and post

As for rust on the bracket of the breaker, that should not be much of an issue so long as its not on the wires

 

[Rufdod]

I have pictures but it says they are too big , how do you guys get around that?

 

[Rufdod]

No Title

Nvm I got it to work

 

[alldodge]

I have pictures but it says they are too big , how do you guys get around that?

Either resize or use a third party photo service like google docs or the like.

Grounds are used among other things, for the three warning switches, which are lube bottle, over heat and loss of oil pressure. If the lube bottle goes empty, motor over heats, or loss of oil pressure, the switch closes and sounds an alarm with a ground.

The ring terminal may be the ground on the lube bottle switch. Check to see if one of the wires goes to a ground.

The spade terminal could go the ground side of the choke, but it does appear it has a ground wire on the bottom

 

[Rufdod]

That's the thing the wires aren't very long , there's a place maybe the ring terminal could mount to the intake but not sure because it's not bare metal or rusty like it was at one point, the choke has the ground connected

 

[Bondo]

That's the thing the wires aren't very long , there's a place maybe the ring terminal could mount to the intake but

Ayuh,..... The shift switch is right there,.... yer's uses a Ground, Right,..??

Distributors can sometimes have a screw hole up from the bottom for a ground wire,....

Sometimes it's just an unused wire,.... for a different app,....

The circuit breaker don't look bad, 'n is easy to test with a light or meter,...

Readin' the rest of yer thread, it sounds like to much fuel pressure for starters, 'n then possibly another trip through the carb,....

 

[Rufdod]

So had the boat on the river today , new mr43t plugs gapped to .035. And 10 gallons of fresh gas with 10oz of sea foam Boat fired up immeadtly and idled great . Got it up to 42mph no problem. (42 is the best I've ever seen) After a couple wot runs, when went back to idle it was rough sometimes sounding like it was going to stall. Eventually the idle smoothed out , but didn't restart quite as easily

 

[alldodge]

Still sounds like a carb issue. May need to recheck the float level

 

[Rufdod]

Does anyone know or have the correct carb specs for this motor? The serial number is 0F761999. I remember when I have the instructions from the rebuild kit it had a chart with several different motor specs , I thought I used the correct one, but have also since had a boat shop set the float so I do not know what it's set to currently

 

[alldodge]

Float level depends on which needle and seat you have

Spring loaded needle is 3/8 (10mm)
Solid 2 piece needle is 9/16 (14mm)

Here is bulletin View attachment mercarb 2brl carb bulletin.pdf

Float drop is 1 3/32 (27mm)

Here is your motor
http://www.mercruiserparts.com/5-7l-2-bbl-gm-350-v-8-1996-0f601000