496 Mag hesitation issues...
09-04-2015, 04:31 PM
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496 Mag hesitation issues...
Hi all. I'm brand new to this site and hoping to get some help with a frustrating issue. I bought a Crownline 260LS with the Mercruiser 496 Mag over the winter(157 hours on the meter). Ever since we put it in the water in early June, we've been chasing a few issues with no luck in resolving.
Issues:
1 - Motor stumbles/hesitates when I go from neutral and give it more than 25% throttle. Pulling skiiers and tubes, I have to roll into the throttle and it does fine. Basically, it falls on its face for a second or two and then builds power.
2 - Temperature gauge never gets over 145 degrees. I can let it idle for 15 minutes in Texas 100 degree heat and it gets to 140 and holds.
3 - When running at the lake trying to diagnose the stumble, I could hit the gas in neutral and hear a single beep/alarm. No idea what this beep is supposed to indicate
I reluctantly took the boat to a local shop. It was an awful experience full of delays, escuses, and odd conversations leading me to believe they were not competent. Being out of the country, the boat was with them for 3 weeks. Upon my return I told them I was picking it up regardless of what they had or had not done. Suddenly, they told me they had fixed the issues. Upon putting the boat in the water, it runs almost the exact same as it did before they worked on it. Here is what they did:
Raylar wires - I provided in advance
AC Delco plugs - I provided in advance
Cleaned/adjusted the IAC
Scanned engine and only got old codes. There were no misfire codes.
Checked the fuel pressure and said it was within spec
Scanned the engine for temperature and said it was cycling at 158-161 degrees
Based on my experience with the shop, I have no idea if they ever scanned the PCM or checked the fuel pressure. I have confirmed they swapped the plugs and wires. I'm wondering if all my issues are based around the motor never getting up to operating temperature? This assumes the gauge is correct and the shop didn't scan the PCM and I likely have a thermostat stuck open. I'm guessing if the motor is always cold then it is in a closed loop PCM program and it is running pig rich for protection. Does that seem logical? It might also explain the stumble/hesitation. One other issue might be the fuel/water seperator. It was changed in February by the previous owner but, the boat sat from February to June with 0 gas in the tank. I'm wondering if it might have accumulated some moisture and that led to the filter getting instantly clogged or some way not letting fuel to flow properly?
This week, I crawled all over the motor looking for any sensors not connected or any leaks. I found none. I did pull the IAC and make sure it was clean and installed properly. In addition, I cheaned the spark arrestor and checked all the wires to ensure they were tight on the coils and plugs. We're putting it in the water tomorrow and hoping for better results but, think I'm grasping at straws with these small changes. I'd just like to rule out any of the simple fixes before I ultimately get another shop to scan the engine for the issue.
I'm planning to drop the boat off in Fort Worth with a large, reputable Mercruiser shop in 2 weeks but, hoping you folks can lend some advice for anything I haven't checked yet.
Thanks,
Todd
Issues:
1 - Motor stumbles/hesitates when I go from neutral and give it more than 25% throttle. Pulling skiiers and tubes, I have to roll into the throttle and it does fine. Basically, it falls on its face for a second or two and then builds power.
2 - Temperature gauge never gets over 145 degrees. I can let it idle for 15 minutes in Texas 100 degree heat and it gets to 140 and holds.
3 - When running at the lake trying to diagnose the stumble, I could hit the gas in neutral and hear a single beep/alarm. No idea what this beep is supposed to indicate
I reluctantly took the boat to a local shop. It was an awful experience full of delays, escuses, and odd conversations leading me to believe they were not competent. Being out of the country, the boat was with them for 3 weeks. Upon my return I told them I was picking it up regardless of what they had or had not done. Suddenly, they told me they had fixed the issues. Upon putting the boat in the water, it runs almost the exact same as it did before they worked on it. Here is what they did:
Raylar wires - I provided in advance
AC Delco plugs - I provided in advance
Cleaned/adjusted the IAC
Scanned engine and only got old codes. There were no misfire codes.
Checked the fuel pressure and said it was within spec
Scanned the engine for temperature and said it was cycling at 158-161 degrees
Based on my experience with the shop, I have no idea if they ever scanned the PCM or checked the fuel pressure. I have confirmed they swapped the plugs and wires. I'm wondering if all my issues are based around the motor never getting up to operating temperature? This assumes the gauge is correct and the shop didn't scan the PCM and I likely have a thermostat stuck open. I'm guessing if the motor is always cold then it is in a closed loop PCM program and it is running pig rich for protection. Does that seem logical? It might also explain the stumble/hesitation. One other issue might be the fuel/water seperator. It was changed in February by the previous owner but, the boat sat from February to June with 0 gas in the tank. I'm wondering if it might have accumulated some moisture and that led to the filter getting instantly clogged or some way not letting fuel to flow properly?
This week, I crawled all over the motor looking for any sensors not connected or any leaks. I found none. I did pull the IAC and make sure it was clean and installed properly. In addition, I cheaned the spark arrestor and checked all the wires to ensure they were tight on the coils and plugs. We're putting it in the water tomorrow and hoping for better results but, think I'm grasping at straws with these small changes. I'd just like to rule out any of the simple fixes before I ultimately get another shop to scan the engine for the issue.
I'm planning to drop the boat off in Fort Worth with a large, reputable Mercruiser shop in 2 weeks but, hoping you folks can lend some advice for anything I haven't checked yet.
Thanks,
Todd
Last edited by ToddEdge; 09-04-2015 at 04:40 PM.
09-04-2015, 11:12 PM
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I did notice a lot of very knowledgeable and detailed responses from "BUP" when I did some wildcard searches on this site earlier. I also saw he is in Fort Worth. Hopefully he'll chime in and I might just drop the boat off with him if he has a shop, which it sounds like he might.
Thanks - Todd
Thanks - Todd
09-04-2015, 11:19 PM
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^^^ that's funny. Vindictor 101 thanks for the heads for both of us here.
I am NOT the large shop he is talking about. I never was the biggest in the DFW area nor the smallest either.
Anyways I know my way around the 496's whether its Mercruiser , Volvo, PCM, Crusader or Indmar but my experiences do not stop there either. I am still currently trained from the OEM's.
Here is the deal this boat owner (OP) is not far from me at all. With that said, I am willing to help but on a business level only sorry about that, yes as a paid for a job hopefully well completed on my part. My reasons for not posting the help is one its not fair for my local paying customers to fix other boaters over the net for free that are very close to me. This is the only way I make a living - working on boats. Number 2 the OP is willing to pay another shop in which will be a commission shop to fix and or try to fix his app anyways, so who better than possible me to at least look at it in the area. .
The choice is up to the boat owner in this case the OP.
If you want to scroll threw threads all about the 496 to see if anything stands out to help and especially anything that I posted that would be a good start as well but maybe a lot of time doing so on your part.
Do not forget I have NLA CAM sensors if needed to test with if in fact this is an older 496.
Anyways I am sure others might give me a plug or 2 for the possible person to bring in their boat app to fix especially being very close in the area.
I will ask this info beforehand - what year and what is the engine serial number ?
If you need my info I would be willing to see you this Monday or the next couple of days after that
the choice is yours or whomever and I am not going to toot my our horn about working on boats but if anyone else wants to recommend my services that's fine by me. Thanks and I can pass on my contact info if needed for the help..
I am NOT the large shop he is talking about. I never was the biggest in the DFW area nor the smallest either.
Anyways I know my way around the 496's whether its Mercruiser , Volvo, PCM, Crusader or Indmar but my experiences do not stop there either. I am still currently trained from the OEM's.
Here is the deal this boat owner (OP) is not far from me at all. With that said, I am willing to help but on a business level only sorry about that, yes as a paid for a job hopefully well completed on my part. My reasons for not posting the help is one its not fair for my local paying customers to fix other boaters over the net for free that are very close to me. This is the only way I make a living - working on boats. Number 2 the OP is willing to pay another shop in which will be a commission shop to fix and or try to fix his app anyways, so who better than possible me to at least look at it in the area. .
The choice is up to the boat owner in this case the OP.
If you want to scroll threw threads all about the 496 to see if anything stands out to help and especially anything that I posted that would be a good start as well but maybe a lot of time doing so on your part.
Do not forget I have NLA CAM sensors if needed to test with if in fact this is an older 496.
Anyways I am sure others might give me a plug or 2 for the possible person to bring in their boat app to fix especially being very close in the area.
I will ask this info beforehand - what year and what is the engine serial number ?
If you need my info I would be willing to see you this Monday or the next couple of days after that
the choice is yours or whomever and I am not going to toot my our horn about working on boats but if anyone else wants to recommend my services that's fine by me. Thanks and I can pass on my contact info if needed for the help..
Last edited by BUP; 09-04-2015 at 11:22 PM.
09-04-2015, 11:20 PM
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You go right from neutral to more than 25% throttle ? Instead of engaging into gear first and then applying your desired throttle % ?
09-04-2015, 11:23 PM
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09-04-2015, 11:25 PM
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^^^ that's funny. Vindictor 101 thanks for the heads for both of us here.
I am NOT the large shop he is talking about. I never was the biggest in the DFW area nor the smallest either.
Anyways I know my way around the 496's whether its Mercruiser , Volvo, PCM, Crusader or Indmar but my experiences do not stop there either. I am still currently trained from the OEM's.
Here is the deal this boat owner (OP) is not far from me at all. With that said, I am willing to help but on a business level only sorry about that, yes as a paid for a job hopefully well completed on my part. My reasons for not posting the help is one its not fair for my local paying customers to fix other boaters over the net for free that are very close to me. This is the only way I make a living - working on boats. Number 2 the OP is willing to pay another shop in which will be a commission shop to fix and or try to fix his app anyways, so who better than possible me to at least look at it in the area. .
The choice is up to the boat owner in this case the OP.
If you want to scroll threw threads all about the 496 to see if anything stands out to help and especially anything that I posted that would be a good start as well but maybe a lot of time doing so on your part.
Do not forget I have NLA CAM sensors if needed to test with if in fact this is an older 496.
Anyways I am sure others might give me a plug or 2 for the possible person to bring in their boat app to fix especially being very close in the area.
I will ask this info beforehand - what year and what is the engine serial number ?
If you need my info I would be willing to see you this Monday or the next couple of days after that
the choice is yours or whomever and I am not going to toot my our horn about working on boats but if anyone else wants to recommend my services that's fine by me. Thanks and I can pass on my contact info if needed for the help..
I am NOT the large shop he is talking about. I never was the biggest in the DFW area nor the smallest either.
Anyways I know my way around the 496's whether its Mercruiser , Volvo, PCM, Crusader or Indmar but my experiences do not stop there either. I am still currently trained from the OEM's.
Here is the deal this boat owner (OP) is not far from me at all. With that said, I am willing to help but on a business level only sorry about that, yes as a paid for a job hopefully well completed on my part. My reasons for not posting the help is one its not fair for my local paying customers to fix other boaters over the net for free that are very close to me. This is the only way I make a living - working on boats. Number 2 the OP is willing to pay another shop in which will be a commission shop to fix and or try to fix his app anyways, so who better than possible me to at least look at it in the area. .
The choice is up to the boat owner in this case the OP.
If you want to scroll threw threads all about the 496 to see if anything stands out to help and especially anything that I posted that would be a good start as well but maybe a lot of time doing so on your part.
Do not forget I have NLA CAM sensors if needed to test with if in fact this is an older 496.
Anyways I am sure others might give me a plug or 2 for the possible person to bring in their boat app to fix especially being very close in the area.
I will ask this info beforehand - what year and what is the engine serial number ?
If you need my info I would be willing to see you this Monday or the next couple of days after that
the choice is yours or whomever and I am not going to toot my our horn about working on boats but if anyone else wants to recommend my services that's fine by me. Thanks and I can pass on my contact info if needed for the help..
Thanks - Todd
09-04-2015, 11:26 PM
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I meant that I put it in forward gear and then quickly give it gas to pull kids on the tubes, etc.
Thanks - Todd
