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5.7 MerCruiser Alpha 1 issues

S

Seabiscuit

New member
Folks,

Just bought a 1993 Thompson with a 5.7 Merc. Very low hours!!!! Test drove the boat----no issues! Towed it home, launched it no issues. Tied it up for 45 minutes and after that it had no power, would not plain off and strong smell of fuel. Removed the Weber carb and took to dealer where he cleaned it and installed a kit. This did not resolve the problem! It seems like it will work okay if the boat sits for awhile (not always) and then use it.

Replaced the fuel filter/seperator, ran methly hydrate through system, ran carb cleaner through system

Now looking for Distributor cap, button, wires etc. Hard to find marine aftermarket in Canada!!!!

Last trip out the boat is running hot on gauge--------normally around 125 degrees but now shooting up to 200 degrees in minutes

Any RELEVANT advice welcome and appreciated!!!!!!
 
New impellor in outdrive may be needed or you picked something up clogging intake.

Also pull the oil dip stick and make sure you only have oil on it nad it is at the appropriate level.

Also when warn remove the flame arrestor and see if the choke is wide open or close to wide open.
 
Thanks for the tip on the impeller!!!!!!

The oil looked fine to me--------a little dirty but nothing major! Can low oil cause power loss????????????

The choke is opening fine----------carb and heating element just serviced

Any chance the T-Stat is causing the issue with heating???????????
 
Not to be smart, but low hours doesn't necessarily mean no troubles. jmho Could be alot of things but you gotta start somewhere. Boat may have sat for a few years and initial water test may have come up ok but doesn't rule anything out. Was any maintenance items changed before you bought the boat? For an Alpha One:
1)maybe raw water impellar as kghost suggested
2)maybe check in exaust manifolds for broken exaust flappers possibly partially blocking exaust flow or maybe stuck in lower outdrive exaust
3) maybe thermostat for cooling system is stuck closed
3) take raw water supply hose off of heat exchanger and see if you have any flow from raw water pump. (that may help you rule out problems with raw water pump and restriction of water hose at gimble housing
4)check all of the plugs and see what they look like (all black with carbon if you say you smell alot of unburned fuel vapor) That could be a problem with ignition,wires,cap,rotor etc. How many volts is your alternator putting out? How are your battery connections and batteries? Do you see white smoke coming out the back that smells strong of fuel? Reason being is that I had a problem like that because my charging system was not working correctly. Maybe nothing to do with it but just wanted to throw it in to narrow it down.
5)could be antisyphon in tank that is stuck. Is the tank all rotten with crap? (lack of power but doesn't answer strong fuel smell)
6) Are you burning the fuel that you bought the boat with and is there a possibility of phase seperation? (rotten tank of fuel?)
7) Did the guy check the screen on the inlet side of carb where there should be a screen for any blockage? He probably did but just being cautious.
8) I guess you probably have electronic ignition. If so and that is a problem I can't help you with but someone else will if indeed that is an issue.
9) It sounds like engine is getting either flooded out with fuel or you have weak spark.
10) Is the fuel pump original to the boat or was it just changed? Fuel pressure to high into carb? stuck float, accelerator pump working correctly?
11) I could go on and on and on so basically it will be a process of elimination for you to determine what is happening but you gotta start somewhere that doesn't cost you anything but a little time rather than a bucket full of money. That is if everything is well and good internally in your engine system. jmho. all the best, Tom
 
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