nkdski

I have a 502 mpI stock engine when I first start it it works fine I run out to the beach about 10-15 minutes at wot 70 mph I park for hours. All the gauges read normal operatng conditions. But when I go to start the engine to leave hours later it cranks over then stops about 4 or five time then I open the throttle and crank till it turns over and revsup a little then it is good to go can it be the water pumpis going out and the heat censor is not allowing it to start agian? or give me something else to look at/Direction to follow

MOBILEMERCMAN

When you say stops. Does it stop like you released the key or like the starter motor is weak? If the later you should pull spark plugs and make sure water is not entering motor. A leaking exhaust can show up as a starter problem.

nkdski

i did take off the rubber baffles would this case water to get in It fire then when i release the key it dies sometimes it spuders for a little bit then stops

MOBILEMERCMAN

If when it starts it misses until you rev it up to say 2500 for a few moments and you notice the miss going away, that is classic water in the motor symptom when combined with starter having trouble turning over. The rubber baffles are there to prevent water from entering exhaust. Its possible that is the whole problem. Depends partly on how low your outlets are.

nkdski

I have a baja 272 i love the way it sounds without the rubber baffles I will put them backon and see if it is the problem I see other people running the pipes stright with no rubber flaps but there exhaust looks a little higher than mine mine is in the watter just a little theres may be a little above. another question i would like to run some new exhaust the kind i see on high dollar boats they look like car headers they do not have the iron manafolds can i do this with a 1999 502 mpi stock motor

Jerry B

If this happens during hot weather after a heat soak it coud be vapor locking. I have this problem with my 502's only when it's very hot and after a heat soak. It will start and die a few times and then will be fine untill next time. Usually it,s only on the starboard side engine.

t500hps

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Yes there are a few headers that fit your motor and can esily be swapped. These are not all standard so make sure you find one that fit your application.....Stainless Steel headers will be $3,500.00 or more for your motor.
If your parked on a beach several hours without the rubber baffles on the end of your tailpipes and then have trouble starting your motor and the tailpipes are just touching the water then I would bet your getting water in the motor....very bad!!!! Get that corrected ASAP and see if the problem goes away...then hope nothing is damaged in the engine.

nkdski

I checked the oil thereis nothing in there but i was looking at the path the water would have to take and it would have to travel up hill to get in. Someone suggested it could be the pump needing to be rebuilt. the pump may be getting hot on the way to the beach and the controll system is preventing the boat from starting. I dont know but I have not had the pump rebuilt yet 360 hours and they say every other season so i will try that.

DMOORE

When you say "pump" do you mean water pump? If so, I do not think that's your problem. If the motor is running at the desired temp and not running hot on the way to the cove, your water pump is fine. Like others have said, my guess would be water from waves, being pushed in the exhaust and into the motor, or vapor lock. I have had friends 496's vaporlock out here during the summer after not ventilating them during a stop..This has happened more than once. On the colorado river it's normally over 100 degrees, and after a long run, most of us open the hatches for a bit to cool the engine compartments while were at the sandbar.


Darrell.

Alex

Damned! You need to verify that it is not water, don't gamble because that's going to be expensive.
The starter is powerful enough to bend the rods if engine is hydrolocked. When done