7.4 stalls and no start

[rick36]

I just got a 1988 Wellcraft Antigua with the 7.4, bravo 1, thunderbolt ignition.....
It stalls in the no wake on the river I'm on and then it cranks and no start ,a shot of starting fluid wouldn't make it sputter.
So I get boat us to tow me back. I change fuel and water filter the next morning it starts nice i took it to state marina pump out to pump the waste tank ran great I go up the river a mile and a half i hit the bay and proceed to plane out choke .... puke... bla no start...cranking no start get towed again so now Im throwing a full tune up at it. So i see the pick up module under the rotor of the distributor its rusty and looks bad .
So before I start troubleshooting this thunderbolt ignition set up can I just through in a HEI distributor and be done with it the old set up ....Thoughts?

 

[dubs283]

Re: 7.4 stalls and no start

don't know why you'd want to get rid of the thunderbolt ignition - its one of the best systems out there, a lot of people knock them cuz they dont understand them and yes, they can get expensive if you have to replace the module but merc had them designed specifically for use on their motors and they do work well

9 times out of 10 a no spark issue with a tbolt ignition is an old rusty sensor - not a bad idea to do a full tune up too

 

[grewvin1]

Re: 7.4 stalls and no start

Agree thunderbolt Ign. good system keep it. This is now a chase and find issue, could be dis. cap has crack and opens up when hot and when cool works. Coils are weird items they work great when good but can go funky fast and some new ones right out of the box are bad good item to check with meter to be sure in spec. look for leaking oil in tower hole. Tune up yes best place to start but rusty pick-up under rotor will still work fine they work or don't.

 

[dubs283]

Re: 7.4 stalls and no start

rusty pick-up under rotor will still work fine they work or don't.

i have seen sensors that work intermittently, 99% of the time, yes, when they fail they're toast but occasionally they act up

if its rusty, replace it - period

 

[rick36]

Re: 7.4 stalls and no start

Ok so Ill keep the ignition ...I thought an HEI distributor would be the smart thing to do since there 250 bucks and the thunderbolt modules are 400 . I ordered a new sensor and a coil the 2 cost me 75 bucks.The new sensor is potted looks like a better design.
I will update if it fixes the issue. Thanks guys!!!