7.4/Bravo - no hot start

[tango13]

Hi all,

Earlier this summer, my 95' Cougar was starting to refuse starting when warm. Its got a carbed 454/Bravo 1 drive. The block and bottom end are almost new, 25'ish hows (0.30 over with an upgraded cam, built and installed by reliable people). Anyways, it would fire right up every morning as it should and run fabulous.. until it was shut off. After about 5-10 minutes, when I would go to start it, it would just crank and crank and crank.... no start. I tried WOT and everything else when cranking, but it just wouldnt catch. After sitting at the dock for 45-1hr later, I could get it running again but it definitely put up a fight. Once I got it running, it would puff out a bit of black smoke and run a little hard, acting like it was flooded but eventually smoothing out.

I did not check for spark when it would only crank over with no fire. The carb is a Carter AFB. I thought the ignition was a TB4, but I see a knock sensor so I'm guessing its the TB5?

My current thoughts are: Carb is dumping gas after shutdown, vapor locking bad, or some sort of ignition issue when its warm (though I'm skeptical on this as it runs like a dream even when hot). The motor is completely factory other than the bottom end.

Anyone ever encounter this?

 

[Rick Stephens]

First thing is take a spark gap tester out with you and test to see if you have spark or if some component is hot and stops working.

Personally, I would automatically purchase a high quality carb kit and do a thorough clean and replace needle valve (where quality really shows in a kit). Make for sure and for certain I have float height right. Rule the carb out now. It very well can be dumping fuel in and flooding, based on your description.

added note: Carter/Weber/Edelbrock carbs are somewhat notorious for dribbling when shutdown hot.

 

[dubs283]

Definitely ignition and carb inspections needed. Check for the fuel dribble upon shut down, like Rick says it's common on webers

For ignition definitely need a spark check upon no start, especially when hot. Yeah, thing runs great for a long time but the engine gets hotter upon shutdown, heat soak in the engine compartment and such. Electrical components, especially older thunderbolt stuff suffers from excess heat.

Best bet is to just do a full tune up with latest ignition sensor and carb rebuild. Super easy stuff to do and for and older boat necessary

 

[QBhoy]

I’d be checking the position and function of the silly auto choke, at the moment when she plays up like this.