7.4 V-8 Eng will not start

[medakarobin]

For some reason my Mercruiser 7.4 V8 will not start. I just replaced the coil due to it was the original and it was getting water in it causing it to ground out and stall the engine. I also replaced all of the spark plugs for good measures. When I checked to see if spark was getting to everything it was, but it seemed like a weak spark. My batteries are fully charged and 1 is new and 1 a year old. I have fuel in the carbs....Im clueless as to what it is. Any suggestions?

 

[Scott Danforth]

Re: 7.4 V-8 Eng will not start

which motor? there have been many variations of the 7.4 liter over the years.

specific year and model along with a serial number for starters?

did you also replace the wires? cap and rotor? what is the voltage to the coil?

 

[medakarobin]

Re: 7.4 V-8 Eng will not start

Sorry about that. Its a 1995 7.4 V8 with the Thunderbolt ignition system. Quick story, I replaced the manifolds, risers, and spacers. After completing the task at hand I went to start the engine to test it all out. It ran great before I replaced the manifolds, risers, and spacers. But it would not start after. I have not replaced the wires, cap and rotor yet, and did not check the voltage yet.

 

[Bondo]

Re: 7.4 V-8 Eng will not start

Sorry about that. Its a 1995 7.4 V8 with the Thunderbolt ignition system. Quick story, I replaced the manifolds, risers, and spacers. After completing the task at hand I went to start the engine to test it all out. It ran great before I replaced the manifolds, risers, and spacers. But it would not start after. I have not replaced the wires, cap and rotor yet, and did not check the voltage yet.

Ayuh,.... Quit throwin' parts at it,.....

Go back, 'n go through the Basics to see where ya screwed up, puttin' it back together.....

 

[medakarobin]

Re: 7.4 V-8 Eng will not start

I did nothing that would cause the eng not to start. the only thing i did was loosen 3 nuts and disconnect the throttle from the riaser, 16 bolts to the manifolds, and 8 bolts from the risers to the manifolds. nothing was disconnected electrically.

 

[Bt Doctur]

Re: 7.4 V-8 Eng will not start

i did was loosen 3 nuts and disconnect the throttle from the riaser, 16 bolts to the manifolds, and 8 bolts from the risers to the manifolds. nothing was disconnected electrically.

throttle is not mounted to the riser, can you explaing the "water getting into the coil"?

 

[medakarobin]

Re: 7.4 V-8 Eng will not start

sorry, shifter cable. the coil would get wet when water would come in via rain, hosing off after coming in from the saltwater, etc... the way the 250 ccr crownline hatch was designed is poor. if a lot of water got in, it drip on the coil, causing it to rust eventually, letting more water in shorting it out.

 

[Scott Danforth]

Re: 7.4 V-8 Eng will not start

did you hook up the coil correctly?