V8 Cutting Out

[Spike2450]

Hi, this is my first post on this forum so please be gentle!!!

I have just purchased a 1998 Bayliner with the same year 5.0 V8 with thunderbolt 5 ignition. At the moment it is on stands and out of the water. My problem is that the engine starts and runs fine and after about 10 secs she will cut out and die no spluttering etc, she does this whatever the revs are set at, again cuts out around 10 secs. She doesn't always start straight back up, but will after a short time. There is also black smoke from the exhaust but i don't think it is related. The boat had been sat for about nine months waiting to be sold. Any ideas would be great.

 

[WillyBWright]

Re: V8 Cutting Out

Welcome to iboats.

I'm going to guess that the carburetor float valve is stuck nearly closed. Fuel pressure eventually allows enough gas in to start, but quickly runs dry once the motor is running. Then refills enough gas from residual fuel pressure and does it all over again the next time it's started. The black smoke would be from a rich condition which could be flooding from the carb overflowing, again from a stuck float valve not closing once the carb is full. But with such a short run time, I wouldn't pay too much attention to that quite yet. It takes more than 10 seconds to burn all the excess gas out from all the places gas can collect.

 

[Don S]

Re: V8 Cutting Out

You have an electric fuel pump. The oil pressure switch that gives power to the pump when it's running may be bad, or the connections are loose or corroded. The switch is located above the engine mounted oil filter boss.
You can jump the 2 wires together with a jumper and see if the pump runs when the ign. switch is in the run position.

 

[Spike2450]

Re: V8 Problem sorted

Re: V8 Problem sorted

Hi
Thank you very much for your input, it was the oil pressure switch, i bridged the two wires and she is now purring like a kitten, i don't know why but it has also sorted the black smoke from the exhaust!!

When i change the pressure switch will i get a gush of oil from the block?

 

[Haut Medoc]

Re: V8 Problem sorted

Re: V8 Problem sorted

Hi
Thank you very much for your input, it was the oil pressure switch, i bridged the two wires and she is now purring like a kitten, i don't know why but it has also sorted the black smoke from the exhaust!!

When i change the pressure switch will i get a gush of oil from the block?

No......

 

[Don S]

Re: V8 Problem sorted

Re: V8 Problem sorted

The reason the black smoke stopped is the choke is also run off the same circuit as the pump. No power and it won't open the choke.

 

[Spike2450]

Re: V8 Cutting Out

I don't know what i would do without this forum, thanks again. When i replace the Oil pressure switch i presume that will also solve the black smoke problem?

 

[superpop]

Re: V8 Cutting Out

If it was me I would give it a complete tune up and check the Manifolds and Risers. I would also check all lubrication points on both the motor and drive. also do a complete oil change. This will give you a good baseline point to start from.

 

[big_hoovie]

Re: V8 Cutting Out

just a quick question - were you running your engine with the boat out of the water?? just a word of caution - it doesn't take much to ruin an impeller, and as such, I would at least make sure you had muffs on the outdrive with a water source hooked up(like a garden hose).

Apologies if I sound paranoid, but I would hate to find out that after diagnosing and fixing your first problem, that you lose an engine to overheating the first time back on the water.

gl

 

[Spike2450]

Re: V8 Cutting Out

Hi
Thank you for your concern, yes i have a hose to the mufflers on the leg with lots of water, mind you i nearly had an idiot park on the hose the other day!!!!! :-(

 

[Bondo]

Re: V8 Cutting Out

The reason the black smoke stopped is the choke is also run off the same circuit as the pump. No power and it won't open the choke.

Ayuh,...........
Thank you Don, That is a Great little tidbit of Knowledge I didn't know or think of,..........
Thank you for My Lesson for today.....

The "Black Smoke" lead Me to think Willy was headed down the Wrong trail.......