496 Mag HO died while cruising won't start.. Help!!
09-12-2017, 05:59 PM
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496 Mag HO died while cruising won't start.. Help!!
Went out for the day and it has been running great. Running back to the dock and at about 3,000 rpm for about 35 min, the engine just dies, i don't recall an alarm sounding. I tried to start it many times and it would fire, but barely run and it was running very rough and then die again. Got towed back and when I got to the shop the next day I hookup the scanner and it showed the same four faults as always, but when I looked at the history it is showing Cam sensor and crank position faults about 18 of them each. and ever time I try to start it, the faults on these two increase in the count number. There also was 4 fuel pump relays faults, which about I think happened at the first part of the season when the engine would start fine and then after it was up to temp I tried to accelerate and the ran very rough like it was missing and didnt have the power to get up on plane., stop the engine refired it and it ran great and this problem happened 4 times. As a precaution I replace the batteries ( 1 year old) and new plugs and it never happened again. So I'm at a lose and could use some help with this!!!
I had good oil pressure and temp, fuel was low about an 1/8 in each tank. I pulled the Cool3 filters and all looked good, ( I change them out every 20 hours) Fuel in the bottom was clean and no water. Fuel 1 week old and the two tanks ran great. Boat is highly maintained and is never run hard, usually about 3,000 rpm most of the time with 181 hours, 2006 model. Also I can hear an electric pump running when I turn the key to the run position and it never shuts of is that normal?
I had good oil pressure and temp, fuel was low about an 1/8 in each tank. I pulled the Cool3 filters and all looked good, ( I change them out every 20 hours) Fuel in the bottom was clean and no water. Fuel 1 week old and the two tanks ran great. Boat is highly maintained and is never run hard, usually about 3,000 rpm most of the time with 181 hours, 2006 model. Also I can hear an electric pump running when I turn the key to the run position and it never shuts of is that normal?
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09-13-2017, 08:45 AM
#5
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your Location is ?
With gen 3 cool fuel your engine must be a 2006 and up
engine serial number is ?
at all your fault codes what RPM does the cam and crank sensor show faults at ?
why because an PCM 555 controlled engine that dies on its own can and or will show these 2 faults. example if one runs out of fuel supply, or lost correct voltage and so on and so on.
Do you have a tach signal ? the crank sensor is the tach signal here.
I WOULD CHANGE the crank sensor especially if one has no tach signal and or your faults are the crank at normal rpms. meaning crank faults at 600 rpms and above. CHECK the connection to it also as there is reports of water that drips down in that area from engine hatch / wet swimmers and so on. - if applicable about the water entering in that area.
Fuel pressure is with key on and then while cranking the engine over and if it will run for a minute ? just because you can hear the fuel pump come on means nothing about its pressure. Yes it is normal to come on then shut off with just key no cranking. If you are cranking and it shuts off then you have an issue there. Just saying
Do you have spark and to check that PLEASE use inline sealed spark checkers
if one is going to work on their own app -
5 tools are must. QUALITY TOOLS needed as well.
1. A current scan tool with the latest software version(s) if applicable EFI, TPI, MPI engines.
2. A good fuel pressure gauge with the correct adaptors and fittings
3. SEALED inline spark checkers
4.. portable remote fuel tank like what small outboards use. with a fuel primer bulb and fuel line hooked to it. Very Fresh gas used as well. This is also a must for boat lay ups and winterizations.
5. Quality compression gauge
Voltage keep you eye on that while scanning and running - that also caused your relay faults. 12.7 is a fully charged battery but many think 12.0 is a fully charge battery, 12 volts only is a half charge battery.
Also on voltage issues as an FYI make sure your serpentine belt is at the correct tension.
With gen 3 cool fuel your engine must be a 2006 and up
engine serial number is ?
at all your fault codes what RPM does the cam and crank sensor show faults at ?
why because an PCM 555 controlled engine that dies on its own can and or will show these 2 faults. example if one runs out of fuel supply, or lost correct voltage and so on and so on.
Do you have a tach signal ? the crank sensor is the tach signal here.
I WOULD CHANGE the crank sensor especially if one has no tach signal and or your faults are the crank at normal rpms. meaning crank faults at 600 rpms and above. CHECK the connection to it also as there is reports of water that drips down in that area from engine hatch / wet swimmers and so on. - if applicable about the water entering in that area.
Fuel pressure is with key on and then while cranking the engine over and if it will run for a minute ? just because you can hear the fuel pump come on means nothing about its pressure. Yes it is normal to come on then shut off with just key no cranking. If you are cranking and it shuts off then you have an issue there. Just saying
Do you have spark and to check that PLEASE use inline sealed spark checkers
if one is going to work on their own app -
5 tools are must. QUALITY TOOLS needed as well.
1. A current scan tool with the latest software version(s) if applicable EFI, TPI, MPI engines.
2. A good fuel pressure gauge with the correct adaptors and fittings
3. SEALED inline spark checkers
4.. portable remote fuel tank like what small outboards use. with a fuel primer bulb and fuel line hooked to it. Very Fresh gas used as well. This is also a must for boat lay ups and winterizations.
5. Quality compression gauge
Voltage keep you eye on that while scanning and running - that also caused your relay faults. 12.7 is a fully charged battery but many think 12.0 is a fully charge battery, 12 volts only is a half charge battery.
Also on voltage issues as an FYI make sure your serpentine belt is at the correct tension.
Last edited by BUP; 09-13-2017 at 08:55 AM.
09-13-2017, 10:12 AM
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BUP I'm in Portland Oregon.
I hope you fared well from the storm??
Engine # OW618645
Both batteries are new and voltage is 12.5 at rest.
I will check the tech signal by watching the tach.
I have a new Techmate scanner for the engine.
I have all of the tools that so mention and they are good quality.
The scanner said faults happened at about 300 rpm which is what the rough idle seemed to be at just before it died.
I know how important it is to describe everything I saw so here goes...
Just before the engine stopped at 3,000rpm, both tanks had just under an 1/8 tanks, which I have been that low before, so I switched tanks and it still would not run but for more then a few seconds and rough, then die. I always switch tanks during the day to keep them balanced, I don't just use one at a time. I fuel both with the same amount of fuel at fill up time.
Before putting it on the scanner, I filled the tanks and then put it in the water for testing.
The next day in the shop after sitting over night, when I checked the fuel filter and disc, the amount of fuel in the in the bowl was just barely covering the white filter. When I pulled the white disc and the fuel looked clean but I noticed that there was a steady stream of really small bubbles coming from the fuel outlet or inlet port in the bottom of the bowl. I have never seen this happen before and the fuel level seemed to be much higher in the bowl? Is this normal.
The scanner says that the two faults happened at 300 rpm which is about what the engine was running at before it stops. So on restart the engine lites up and for a second it sounds like a normal start but after one second I can tell that it is going to die because of the low idle speed and rough running and sound.
I hear the fuel pump running but it will not shut off, it just keeps running. Should'nt the pump run for a short time then cut out when proper pressure is reached?
Thanks for helping me with this BUP
I hope you fared well from the storm??
Engine # OW618645
Both batteries are new and voltage is 12.5 at rest.
I will check the tech signal by watching the tach.
I have a new Techmate scanner for the engine.
I have all of the tools that so mention and they are good quality.
The scanner said faults happened at about 300 rpm which is what the rough idle seemed to be at just before it died.
I know how important it is to describe everything I saw so here goes...
Just before the engine stopped at 3,000rpm, both tanks had just under an 1/8 tanks, which I have been that low before, so I switched tanks and it still would not run but for more then a few seconds and rough, then die. I always switch tanks during the day to keep them balanced, I don't just use one at a time. I fuel both with the same amount of fuel at fill up time.
Before putting it on the scanner, I filled the tanks and then put it in the water for testing.
The next day in the shop after sitting over night, when I checked the fuel filter and disc, the amount of fuel in the in the bowl was just barely covering the white filter. When I pulled the white disc and the fuel looked clean but I noticed that there was a steady stream of really small bubbles coming from the fuel outlet or inlet port in the bottom of the bowl. I have never seen this happen before and the fuel level seemed to be much higher in the bowl? Is this normal.
The scanner says that the two faults happened at 300 rpm which is about what the engine was running at before it stops. So on restart the engine lites up and for a second it sounds like a normal start but after one second I can tell that it is going to die because of the low idle speed and rough running and sound.
I hear the fuel pump running but it will not shut off, it just keeps running. Should'nt the pump run for a short time then cut out when proper pressure is reached?
Thanks for helping me with this BUP
Last edited by zgoo; 09-13-2017 at 10:14 AM.
09-13-2017, 10:18 AM
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check your fuel pressure at the fuel rail ( shrader valve) and you are saying with just KEY ON ONLY the fuel pump never shuts off ???
I have to go to work now - I fooled around too much this mourning and I am overloaded with boats.
I ll look up here tonite late as usual
I have to go to work now - I fooled around too much this mourning and I am overloaded with boats.
I ll look up here tonite late as usual
09-13-2017, 10:22 AM
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Yes with key on engine off I hear the pump run. I will hookup a pressure gauge and get a reading for you, Thanks and have a Good Day!
Last edited by zgoo; 09-13-2017 at 10:41 AM.
09-13-2017, 11:58 AM
#9
When you have the fuel pressure gauge hooked up, use the bleed valve to see if you have a good (air bubble free) stream of gas.
Might want to swap out the fuel pump relay, when you turn the key on the pump should only run for about 30 seconds and then shut off until you cycle the key again or crank the engine.
Might want to swap out the fuel pump relay, when you turn the key on the pump should only run for about 30 seconds and then shut off until you cycle the key again or crank the engine.
09-13-2017, 05:04 PM
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Here is an update....
I hookup a fuel pressure gauge to the fuel rail and when I went to attach it air pressure came out of the fuel rail, but no fuel. I put the gauge on and and turn key on engine off and heard a gurgling sound coming from the fuel tank for 4 to 5 seconds then the fuel pump sounded like it was building pressure for about 5 sec then it stopped. Then I looked at the gauge and had about 45 psi. When I removed the gauge I release the fuel pressure and got a good flow of fuel. Looks like I might have been out of fuel even thou the gauges are at an 1/8+ in each tank. Going to water test it now and I will give an update a little latter.
I hookup a fuel pressure gauge to the fuel rail and when I went to attach it air pressure came out of the fuel rail, but no fuel. I put the gauge on and and turn key on engine off and heard a gurgling sound coming from the fuel tank for 4 to 5 seconds then the fuel pump sounded like it was building pressure for about 5 sec then it stopped. Then I looked at the gauge and had about 45 psi. When I removed the gauge I release the fuel pressure and got a good flow of fuel. Looks like I might have been out of fuel even thou the gauges are at an 1/8+ in each tank. Going to water test it now and I will give an update a little latter.
