Engine cuts off
 

I'm having a problem with the 5.7, carburetored Mercruiser engine in my boat. I was winterizing the boat today, warmed the engine for about 20 minutes (ran fine) and changed the oil and filter. When I refired the engine, it kept stalling out. It starts normal, runs for about 10-15 seconds then cuts off. It will restart fine and do the same thing. I let the engine cool, while I changed the lower unit oil, to see if it was temp. related, no change. I'm pretty sure it's losing spark, here's what I have observed: No abnormal smoke from exhaust, engine speeds up a couple hundred rpm for a couple seconds just before it stalls, carb has gas in it after it stalls and pumping throttle as it's cutting out makes no difference. Engine runs fine and will rev up until it cuts out. It was getting dark (and cold) so I couldn't check much except to make sure I didn't knock something lose. I plan on working on it tomorrow so any advice anyone has would be helpful. TIA

Andrew

Re: Engine cuts off
 

You have to determine whether it is spark or fuel related. After it stalls out, with the engine off and not cranking, have someone pump the throttle while you look into the carb to see if fuel is being squirted in from the accelerator pump. If there is fuel present, then most likely the problem is spark related.

Re: Engine cuts off
 

Gas sqiurts out of the accel pump after the engine stalls so I am pretty sure I'm losing spark. I just don't have a spark tester at home to be 100% sure that is the problem.

Re: Engine cuts off
 

Sounds like it is running out of fuel. An engine always speeds up as fuel runs out. This is because the a/f mix begins to lean. Did you change the fuel sepertor and fill with fuel before reinstall? Maybe pinched a fuel line when changing the oil? Also, if for some reason you got water into the carb, the water would be displacing the fuel in the bowl and not allowing the float to drop and let in more fuel.

BT :cool:

Re: Engine cuts off
 

I had a similar problem...one tiny wire in the wiring harness had chafed through. The engines vibrations would cause it to short out on the block. It would restart just fine until the harness shifted again. One day, a friend and I both heard the arc...can you say fire hazard?..After lots of fresh air, and some close observation...and a piece of electrical tape, problem solved.

Re: Engine cuts off
 

The shift interrupt located on the stbd side of the engine, assuming it's an alpha, is probably shot. I've seen it before, especially during winterizing, for it is a clumsy task. Possible you knocked into it or something.

Re: Engine cuts off
 

Mercruiserparts.com has the whole new shifter bracket with a revised cut out micro switch. also has the spring loaded assist built in. $84 to save you guys alot of headaches. Original switches are not availiable Also if not done yet, put a new ss shift spool in the lower unit. the old brass ones wear creating excessive play. My 2 cents BBB

Re: Engine cuts off
 

Might be the carb flooding.
If it sat winterized for a period of time, could be spunk in the needle & seat.

Re: Engine cuts off
 

Your winterizing your boat already? :eek: where do you live?

Re: Engine cuts off
 

Racer,

this thread was started back on 11-13-04! Hence he was winterizing!

Big block billy was just suggesting a new part for this guy.

Re: Engine cuts off
 

Sorry I didn't see the date, The only person I know that has winterized his boat this early is tomtbone1993 :D

Mercruiser Mercury 5.7 engine doesn't stay running
 

Hi, My engine didn’t run for more then 10 – 15 seconds on any RPM. It started easily every time, but just didn’t stay running. It was making me crazy as everything seemed to be in order. I thought that the fuel was contaminated and changed Fuel Filter/Water Separator. I added stabilizer as well as some fresh fuel to the tank. It didn’t help. I was googling the problem and couldn’t find an answer. The fuel pump seemed to be working, but the engine didn’t stay running. Oil pressure was good. I finally spoke to the mechanic at the marina, who suggested disconnecting the wires from the actual fuel pump and cleaning it up thoroughly. I sure did take a look on the wires and it needed to be cleaned with some send paper to restore the connections. It took me 15 minutes and the engine was running again with no problem. The mechanic told me that it was a common problem. The fuel pump works for a few seconds on the initial ignition start and then dies after the power is taken from the engine or so. As I understood the fuel pump is powered from both locations. The engine wires had bad connections. I hope it could help someone. CLEAN FUEL PUMP WIRES FIRST )