502 MPI Starting issues
#1
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502 MPI Starting issues
Got a buddy with a 28 Sunsation. It has a mid to late 90's 502 MPI that has been bored to a 509 @ 550 HP. The engine runs great except he is having starting issues. The VST tank has been removed and he has 2 electric fuel pumps. Has a return line to the gas tank. After long runs he can shut it off and it will start right back up. If he shuts it off and waits 15 minutes it won't start. Just cranks and cranks. We checked the spark while it was in that condition and it's good. Has plenty of fuel pressure. If he waits another 15 to 20 minutes it will start right up. He just put on a new distributor cap, ignition module and Map sensor. Still has the same problem.
What should we be looking at next?
Thanks,
Steve
What should we be looking at next?
Thanks,
Steve
#2
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Got a buddy with a 28 Sunsation. It has a mid to late 90's 502 MPI that has been bored to a 509 @ 550 HP. The engine runs great except he is having starting issues. The VST tank has been removed and he has 2 electric fuel pumps. Has a return line to the gas tank. After long runs he can shut it off and it will start right back up. If he shuts it off and waits 15 minutes it won't start. Just cranks and cranks. We checked the spark while it was in that condition and it's good. Has plenty of fuel pressure. If he waits another 15 to 20 minutes it will start right up. He just put on a new distributor cap, ignition module and Map sensor. Still has the same problem.
What should we be looking at next?
Thanks,
Steve
What should we be looking at next?
Thanks,
Steve
#3
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Yes it is normally wired and the pumps start with the key. We believe the pressure in the rails is up. There is a little port on the front of the engine just below the plenum. I believe it is for checking pressure. When you push in on it fuel sprays out under pressure. That is why we think have fuel rail pressure.
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Yes it is normally wired and the pumps start with the key. We believe the pressure in the rails is up. There is a little port on the front of the engine just below the plenum. I believe it is for checking pressure. When you push in on it fuel sprays out under pressure. That is why we think have fuel rail pressure.
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I will have to get a guage to check it. What pressure should it be?
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Mine used to do that, vapor lock. Check fuel separator when happens, mine was half empty during vapor lock and sitting for a while and rolling motor over eventually cranked in 20 minutes or so.
#8
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My buddy is trying to find a pressure guage, but is finding it hard to find . None of the auto parts stores have one. I think he will get it checked at a local marine repair shop next week.
#9
there is a million blogs on here about this and sounds like Vapor lock,, Mercruiser has a service bulliten on this. We Formula guys suffer from this because they insulate the engine area so well..., Go to the Formula section on here,, and someone is having the same issue and that bulliten is in that string of messages.
Can bet you thats the problem.... Best thing is Mercruiser tells ya whats arong and OOHH WELL. tuff titty's.. but there are fixes...just search on here.. I bet I have read 100's of articles in this on this site.. Good luck
Can bet you thats the problem.... Best thing is Mercruiser tells ya whats arong and OOHH WELL. tuff titty's.. but there are fixes...just search on here.. I bet I have read 100's of articles in this on this site.. Good luck