496 Mag starts great cold, slow hot
06-07-2015, 10:28 PM
#11
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I have a 496 as well with the Gen III cool fuel.
The tach gets it rpm signal from the crank sensor. With that said a delay in tach reading or no tach reading can mean crank sensor problem. The worst is no tach and no start - bad crank sensor.
Also seen many of times boat running fine and just stalls out of no were and lost its tach readings just before the engine completely quits running. Its like somone pulled the kill lanyard while trucking down the lake. . Problem is Bad crank sensor, just saying
You can have lost rpms with no codes and that can even be a bad crank sensor. The crank & cam sensor in a combine reading back to the PCM persay is very important for engine starting the 496 as well.
Also do have DTS = digital throttle & shift ?
A scan would or could pin point an issue for the delayed starting in which might just have to the option soon. .
The tach gets it rpm signal from the crank sensor. With that said a delay in tach reading or no tach reading can mean crank sensor problem. The worst is no tach and no start - bad crank sensor.
Also seen many of times boat running fine and just stalls out of no were and lost its tach readings just before the engine completely quits running. Its like somone pulled the kill lanyard while trucking down the lake. . Problem is Bad crank sensor, just saying
You can have lost rpms with no codes and that can even be a bad crank sensor. The crank & cam sensor in a combine reading back to the PCM persay is very important for engine starting the 496 as well.
Also do have DTS = digital throttle & shift ?
A scan would or could pin point an issue for the delayed starting in which might just have to the option soon. .
Last edited by BUP; 06-07-2015 at 10:31 PM.
06-08-2015, 11:08 PM
#12
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BUP, it sounds like the scan is the next step. I'll post the results once we get back.
I deeply appreciate your willingness to share your knowledge, advice and troubleshooting tips. It is a huge help to me, and likely other boaters with a similar setup. For those who enjoy having and taking care of nice toys, part of the thrill keeping it running at its best. The security of knowing that your boat is reliable enough to enjoy it with family and friends is highly satisfying. The only thing worse than not going out at all is to enjoy a good day on the water and have to be towed back to the marina.
Happy boating!
I deeply appreciate your willingness to share your knowledge, advice and troubleshooting tips. It is a huge help to me, and likely other boaters with a similar setup. For those who enjoy having and taking care of nice toys, part of the thrill keeping it running at its best. The security of knowing that your boat is reliable enough to enjoy it with family and friends is highly satisfying. The only thing worse than not going out at all is to enjoy a good day on the water and have to be towed back to the marina.
Happy boating!
06-22-2015, 10:08 PM
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Finally have the problem solved! Two issues, really.
One is that the ECM provided no useable codes. At least nothing to indicate the symptoms that I was seeing. They said that the boat mfr enclosed the engine bay too well, without enough ventilation to cool the engine while sitting. Suggested raising the hatch while sitting to see if that helps. Cheap and easy fix it it works. If it does, I may install a second fan blowing air into the engine bay and put it on a timer.
Second issue turned out to be a water pressure sensor. Launched after the ECM read and couldn't get on plane. No alarm, buts lots of sputtering and no power at all. It apparently went into Guardian Mode. Sensor only read about 1.2 (psi?). Replaced it and relaunched.The boat ran like new, WOT no problem.
Big thanks to the guys at Lake Mojave Marine @ Katherine's Landing. They got us back on the water as quickly as possible.
One is that the ECM provided no useable codes. At least nothing to indicate the symptoms that I was seeing. They said that the boat mfr enclosed the engine bay too well, without enough ventilation to cool the engine while sitting. Suggested raising the hatch while sitting to see if that helps. Cheap and easy fix it it works. If it does, I may install a second fan blowing air into the engine bay and put it on a timer.
Second issue turned out to be a water pressure sensor. Launched after the ECM read and couldn't get on plane. No alarm, buts lots of sputtering and no power at all. It apparently went into Guardian Mode. Sensor only read about 1.2 (psi?). Replaced it and relaunched.The boat ran like new, WOT no problem.
Big thanks to the guys at Lake Mojave Marine @ Katherine's Landing. They got us back on the water as quickly as possible.
Last edited by PDQH2O; 06-22-2015 at 10:16 PM.
06-22-2015, 11:24 PM
#14
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That would be a form of vapor lock after engine shut down - heat soak boils some fuel away especially at the fuel pumps without enough ventilation in and around the engine compartment. .
Did you have a second problem as I do not recall you posting not able to get on plane nor a 2 nd problem just asking ?
Also thanks for the follow up and reporting what was done to get you running again correctly.
Did you have a second problem as I do not recall you posting not able to get on plane nor a 2 nd problem just asking ?
Also thanks for the follow up and reporting what was done to get you running again correctly.
06-24-2015, 10:31 AM
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That would be a form of vapor lock after engine shut down - heat soak boils some fuel away especially at the fuel pumps without enough ventilation in and around the engine compartment. .
Did you have a second problem as I do not recall you posting not able to get on plane nor a 2 nd problem just asking ?
Also thanks for the follow up and reporting what was done to get you running again correctly.
Did you have a second problem as I do not recall you posting not able to get on plane nor a 2 nd problem just asking ?
Also thanks for the follow up and reporting what was done to get you running again correctly.
That would be a form of vapor lock after engine shut down - heat soak boils some fuel away especially at the fuel pumps without enough ventilation in and around the engine compartment. .
Did you have a second problem as I do not recall you posting not able to get on plane nor a 2 nd problem just asking ?
Also thanks for the follow up and reporting what was done to get you running again correctly.
Did you have a second problem as I do not recall you posting not able to get on plane nor a 2 nd problem just asking ?
Also thanks for the follow up and reporting what was done to get you running again correctly.
I've not heard of heat soak before, but it makes sense. Tried the suggested method of raising the hatch today and it seemed to be the ticket.
The secondary problem is new and surfaced only after the first code reading that showed nothing. When we went back to the shop, they were very interested in my prior testing and results. I'm confident that it helped in diagnosing the water pressure sensor problem. I talked to both the service desk guy and the mechanic. Both great guys that really knew their stuff. We ran the boat all over yesterday and it performed flawlessly.
Now I also get to replace the 5 pin connector on my trailer. The #5 pin that disengages the brakes when backing up finally gave out as I picked up the boat from the shop and connected the trailer to my Yukon. But that's probably another forum. Jimmy rigged it for now. Planning to install one of those coiled 5 pin to 7 blade connectors to keep everything neat and out of the way.
BUP, I deeply appreciate your willingness to share your expertise with me and fellow boaters. It is an invaluable resource for do-it-yourselfers. Thank You!
