1995 5.7 Mercruiser no start, no fire.

vroom ZOOM

Chief Petty Officer
Joined
Aug 15, 2017
Messages
425
Hello

Ive been scratching my head over this one. 1995 5.7 with 4bbl carb and thunderbolt ignition. I am not too familiar with these things but I still am surprised why it won't run. The boat ran fine last week. This time it cranks and intermittently fires, but won't run. The accelerator pump shoots a good stream of gas into the primaries when the throttle is pumped. Tried putting gas into the carb manually, no change. Checked for spark with a timing light and nothing. Checked for power at the purple wire on the coil, also nothing. There was power at the ignition switch, so I bypassed the kill switch, and now I have power at the coil and spark. I thought I had nailed it now, but it still won't start, won't even fire. Tried adding gas to the carb again, no dice. Tried holding the throttle wide open to clear a flooded engine, it fired once and nothing again. Thinking that the flood was now clear, I gave the throttle a couple of pumps and tried again, still nothing. Checked for spark and it is still there. I need some ideas.
Thanks!
 

stresspoint

Lieutenant Junior Grade
Joined
Sep 19, 2022
Messages
1,048
also , make sure the motor is spinning over fast and the fuel pump is operating with your hot wire solution ,
on a side note , not knowing your procedure when it fired up , when a flooded engine fires it is good practice to keep @ WOT or close to for a second or 2 to burn off excess before pumping the throttle.
 

tank1949

Lieutenant Commander
Joined
Apr 4, 2013
Messages
1,911
Hello

Ive been scratching my head over this one. 1995 5.7 with 4bbl carb and thunderbolt ignition. I am not too familiar with these things but I still am surprised why it won't run. The boat ran fine last week. This time it cranks and intermittently fires, but won't run. The accelerator pump shoots a good stream of gas into the primaries when the throttle is pumped. Tried putting gas into the carb manually, no change. Checked for spark with a timing light and nothing. Checked for power at the purple wire on the coil, also nothing. There was power at the ignition switch, so I bypassed the kill switch, and now I have power at the coil and spark. I thought I had nailed it now, but it still won't start, won't even fire. Tried adding gas to the carb again, no dice. Tried holding the throttle wide open to clear a flooded engine, it fired once and nothing again. Thinking that the flood was now clear, I gave the throttle a couple of pumps and tried again, still nothing. Checked for spark and it is still there. I need some ideas.
Thanks!
bad coil????
 

vroom ZOOM

Chief Petty Officer
Joined
Aug 15, 2017
Messages
425
I pulled a plug and it is sooty and dry. I set the batteries to charge and will give it a try tomorrow.
 
Top