Engine Problems NEED HELP

"I have a 93 crownline with a

"I have a 93 crownline with a 350 mag. I brought it to the shop because I was having some minor cold start issues. They made some adjustments to the air/fuel ratio. The next time out on the lake it ran great.The following week we took it out, it started a little hard, and ran it up the lake. It appeared to be fine. When we turned around and started off all was well then while at a high speed the engine started to slow down. The rpm's were dying off. So I slowed down and the engine quit. After this it wouldn't start. I thought for sure it was a fuel filter. The marina towed me back. Now they say I have major engines problems. 4 of the eight cyl's have very low compression and one of them is at 0. I never had a overheating issue, no signs of leaks. Tommorow I'm going to go up to pull the dipstick out. They say it could be valves, rings, head gasket. Your thoughts? I don't want to get screwed! I want to add too.. that it will start cold but once it warms up is dies and won't start again until its cold
thanks"

Do your own compression test f

Do your own compression test first and see what happens. Sounds more like ignition issues to me but can't be sure with out testing.

I think I'll go with the r

I think I'll go with the rep on this one.
How does the engine sound when it does start? Rough smooth running on all eight ETC.
If it sounds ok then I doubt you need any major work. How is the oil pressure? Water in the oil?
If it starts cold time how long it will run and at what temp it shuts down.
Just my opinion but I'd keep my hands in my pockets around this mechanic until you find out a little more about how this engine is running.
Are the low compression cylinders on the same side? What # cylinders have the problem?

"just a thought, but I had a v

"just a thought, but I had a very similar problem with my boat. 5 miles from shore I spent an hour trying everything I could think of. finally I pulled the fuel line from the tank, and found it plugged in the tank! as long as the boat bounced around for a while, it would start and run at low rpm, but once I pushed the throttle, that's all she wrote. I now run from an extermal tank since the previous owner forever sealed the tank beneath the floor!!
If that mechanic is the one who told you about the compression, I would run a test myself, or get a 2nd opinion!"

"The tank can be cleaned at ho

"The tank can be cleaned at home if it is plastic. If you can access the fuel vent and fill connectors at the tank, cleaning it is easier. If not, remove the fuel level sending unit. Drain or siphon out all the fuel and buy a small package of TSP powder at a paint store--it will not make suds. Mix half of it in a quart of very hot water to completly disolve it and pour it in the tank (remove fuel siphon hose and pipe from tank). Fill with very hot water to half to three-quarters full. Close the tank openings and drive it around in a parking lot, stop and go for 10 min. to agitate the scum. Use a shop vac to siphon it out. Repeat if the fluid coming out is dirty. I have used a pressure washer inside the tank with hot water TSP solution on the detergent siphon bottle with good results. Rinse thoroughly with hot water several times and then attach the exhaust side of a high volume shop vac or yard debris blower to the fill hose and blow air in it until it is dry. Moist air will come out of the vent and sending hole. A hot day improves drying along with a few bottles of 90% rubbing alcohol poured in the tank to evaporate the water residue. Park on a hill to facilitate draining and drying the tank. If it is an aluminum tank, contact a truck tank cleaning firm for their advice.

Use a telescoping mirror and flash light to look inside the tank thru the sending unit hole."

thanks for all your replies. I

thanks for all your replies. I have found the problem. I've got 6 valves that are bad. I have also learned that the engine is a rebuild. Pistons are bored 60 over. Anyways it would start cold but when it warmed up would just quit and not start again until cold. We have pulled the engine.. since I've got it out I'm installing thru hull exhaust. It didn't have it before. So what the hell. Thanks again guys