new engine stalls out when decelerating

[stang32]

[FONT=Verdana, Arial, Helvetica][FONT=Verdana, Arial, Helvetica][FONT=Verdana, Arial, Helvetica]i just installed a new 4.3 vortec engine with thunderbolt V ignition system. set the timing to spec 10 deg BTDC by grounding the purple wire according to the manual.
the engine runs smooth, idles nicely & gets up with ease.
the main issue is when slowing down to or near idle, the engine stalls. when restarting it, the engine cranks as if the timing is off, cr,cr,crank,cr, cr, crank, etc...but does restart.

i thought the stalling issue was bad gas, I drained it this weekend & installed fresh gas but the problem remains.. I know that bad gas will not make it crank like this so I think the issue is something else. the powerplant is a mercruiser alpha 1 gen II set up

I am lost on this one guys & could use some help[/FONT][/FONT][/FONT]

 

[alldodge]

i just installed a new 4.3 vortec engine with thunderbolt V ignition system. set the timing to spec 10 deg BTDC by grounding the purple wire according to the manual.
the engine runs smooth, idles nicely & gets up with ease.
the main issue is when slowing down to or near idle, the engine stalls. when restarting it, the engine cranks as if the timing is off, cr,cr,crank,cr, cr, crank, etc...but does restart.

i thought the stalling issue was bad gas, I drained it this weekend & installed fresh gas but the problem remains.. I know that bad gas will not make it crank like this so I think the issue is something else. the powerplant is a mercruiser alpha 1 gen II set up

I am lost on this one guys & could use some help

Did a whole bunch of font and color changing here

Was the carb rebuilt?
During the restarts look down the carb and see if you see fuel dripping.
Can you put a vacuum gauge on it and see what the reading shows?

 

[MikDee]

Wait, I thought I read you were supposed to power up the purple wire, not ground it? With the Thunderbolt 5

 

[alldodge]

Wait, I thought I read you were supposed to power up the purple wire, not ground it? With the Thunderbolt 5

Have both manuals in front of me (18 and 25) and both say ground

 

[MikDee]

Have both manuals in front of me (18 and 25) and both say ground

Oops! Sorry :embarassed: You're right I must have been thinking about a different ignition system.