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94 Detroit 6v92TA 550hp

Old 06-10-2019, 01:53 PM
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Default 94 Detroit 6v92TA 550hp

Hi everyone. I have read everything I can find about the problem I am having and still no luck. I have a pair of 6v92 2 stroke engines with 1030 hrs on each. I recently had the boat haul to get the shaft and rudder seals done along with have the props reconditioned. When the boat was put back in the water, i drove 250 miles with black sooty diesel smoke pouring out of the starboard engine. The entire boat was covered in black. It would not go over 1800 rpms. I've recently had both turbos rebuilt, changed all fuel filters, cleaned air filters, bottom is clean, props are like new. I did however coat the props with a zinc spray. It will start right up at any given time, It will idle fine and run 3000 rpms in the slip. I can run 1500rpms (12knts) and no smoke. But as soon as i push it to 1800rpms or more, black smoke all over the back of the boat. Any suggestions would be great. Would bad injectors cause it to run any different? Or blow black or white smoke? I was told black smoke is from a lack of air not fuel. Really confused. Thanks.
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Old 06-10-2019, 02:03 PM
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since you had it worked on, make sure a rag wasn't left somewhere in the intake.. Sounds like starving for air, so intake or turbo.
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Old 06-10-2019, 02:07 PM
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Air starvation
Stuck turbo
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Old 06-10-2019, 02:16 PM
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Most obvious cause would be the Turbo, You're getting too much fuel in relation to the air so you know you are either getting too much fuel or not enough air. Check your air filter and all your intake hoses for holes leaks and obstructions. Make sure your turbo spins freely, if that all checks out next would be stuck injector maybe?
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Old 06-10-2019, 02:35 PM
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Is it a DDEC? If so DDEC mechanic can plug a computer in to check injectors. Where are you located?
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Old 06-10-2019, 02:43 PM
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I had both turbos rebuilt and this is the only one giving me issues. I took them off and put them back on so I am positive nothing was left inside the turbo or intake. I have had the boat out about 6 times for about 20 hours back and fourth to the sandbar and no issues at all. Would a stuck injector cause black smoke? It seems to run too good to be a bad injector but I dont know. I did notice the air filter was sucked in pretty good from air starvation. It was soaked and cleaned to like new condition. Would there possibly be residue left over inside that needs to be burned off over time? No it is not DDEC.
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Old 06-10-2019, 02:45 PM
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Originally Posted by Kballard81 View Post
Hi everyone. I have read everything I can find about the problem I am having and still no luck. I have a pair of 6v92 2 stroke engines with 1030 hrs on each. I recently had the boat haul to get the shaft and rudder seals done along with have the props reconditioned. When the boat was put back in the water, i drove 250 miles with black sooty diesel smoke pouring out of the starboard engine. The entire boat was covered in black. It would not go over 1800 rpms. I've recently had both turbos rebuilt, changed all fuel filters, cleaned air filters, bottom is clean, props are like new. I did however coat the props with a zinc spray. It will start right up at any given time, It will idle fine and run 3000 rpms in the slip. I can run 1500rpms (12knts) and no smoke. But as soon as i push it to 1800rpms or more, black smoke all over the back of the boat. Any suggestions would be great. Would bad injectors cause it to run any different? Or blow black or white smoke? I was told black smoke is from a lack of air not fuel. Really confused. Thanks.
Max RPM on these engines is 2350. How are you getting 3000 in your slip? That is a huge problem and will blow those engines up. Also, 1500 RPMís producing a speed of 12 knots seems slow to me. I have the same engines in a 43 foot Hatteras. 1500 RPM on my boat will produce speeds of 14-15 knots and at 1800 I am running 18 knots. Curious as to how you are able to turn those engines 650 RPMís above their max and why you are right struggling at speed with at reasonable RPMís.
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Old 06-10-2019, 02:47 PM
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Possible bent rod from tipping it down at haul. Was it hard to start?
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Old 06-10-2019, 02:49 PM
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Originally Posted by keysbearfl View Post


Max RPM on these engines is 2350. How are you getting 3000 in your slip? That is a huge problem and will blow those engines up. Also, 1500 RPMís producing a speed of 12 knots seems slow to me. I have the same engines in a 43 foot Hatteras. 1500 RPM on my boat will produce speeds of 14-15 knots and at 1800 I am running 18 knots. Curious as to how you are able to turn those engines 650 RPMís above their max and why you are right struggling at speed with at reasonable RPMís.
Some pretty good points here. If it was running good before the work was done, I'm guessing it's air flow related. Bad injectors can give you black smoke also, but your turbos should be spooling around the 1500-1600 mark so that's most likely your issue
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Old 06-10-2019, 02:50 PM
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Not sure why it will go that high in the slip unless the gauge is wrong but it seems right. I dont let it sit there for more the a few seconds and i slowly creep it up to that rpm. Ive only done it once just to see if it would smoke at idle with higher rpms and to see if injectors were firing. It will however run about 2200rpms at 18-19knts but smokes really bad now. It weighs 41K lbs so that may be top speed for it. Im not sure. Engine starts right up and idles at 500-600 perfectly
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Old 06-10-2019, 02:59 PM
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Originally Posted by Kballard81 View Post
Not sure why it will go that high in the slip unless the gauge is wrong but it seems right. I dont let it sit there for more the a few seconds and i slowly creep it up to that rpm. Ive only done it once just to see if it would smoke at idle with higher rpms and to see if injectors were firing. It will however run about 2200rpms at 18-19knts but smokes really bad now. It weighs 41K lbs so that may be top speed for it. Im not sure. Engine starts right up and idles at 500-600 perfectly
It's missing 150 RMPs if it will only turn 2200. Are these DDEC or mechanical? I think it's a turbo issue if it will turn up in the slip without a load on it.
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Old 06-10-2019, 03:01 PM
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Originally Posted by Kballard81 View Post
Not sure why it will go that high in the slip unless the gauge is wrong but it seems right. I dont let it sit there for more the a few seconds and i slowly creep it up to that rpm. Ive only done it once just to see if it would smoke at idle with higher rpms and to see if injectors were firing. It will however run about 2200rpms at 18-19knts but smokes really bad now. It weighs 41K lbs so that may be top speed for it. Im not sure. Engine starts right up and idles at 500-600 perfectly
What boat are these engines in? If your tachs are actually showing that you are turning 3000 RPM in the slip under no load then I would encourage you to have them checked and calibrated.. These engines canít turn 3000 RPM. They will explode. I never rum mine above 1900. They turn 2300 but to actually spool them up tp 2300 for ANY length of time invites more problems you do not need.
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Old 06-10-2019, 03:04 PM
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Originally Posted by Kballard81 View Post
I had both turbos rebuilt and this is the only one giving me issues. I took them off and put them back on so I am positive nothing was left inside the turbo or intake. I have had the boat out about 6 times for about 20 hours back and fourth to the sandbar and no issues at all. Would a stuck injector cause black smoke? It seems to run too good to be a bad injector but I dont know.I did notice the air filter was sucked in pretty good from air starvation. It was soaked and cleaned to like new condition. Would there possibly be residue left over inside that needs to be burned off over time? No it is not DDEC.
Fix that first. If still smoking check turbo. Even though it was recently rebuilt, doesn't mean it's not stuck. A chunk of carbon between a vane and the housing will stop a turbo.

If you just run the smoky engine, can you hear the turbo spool up?
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Old 06-10-2019, 03:21 PM
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Yea you can hear the turbo spool just fine Both engines sound identical. With the air filter off you can definitely feel the turbo sucking air into it. Its not dirty or anything on the fins. They are in a 48' bertram
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Old 06-10-2019, 03:34 PM
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Originally Posted by Kballard81 View Post
I had both turbos rebuilt and this is the only one giving me issues. I took them off and put them back on so I am positive nothing was left inside the turbo or intake. I have had the boat out about 6 times for about 20 hours back and fourth to the sandbar and no issues at all. Would a stuck injector cause black smoke? It seems to run too good to be a bad injector but I dont know. I did notice the air filter was sucked in pretty good from air starvation. It was soaked and cleaned to like new condition. Would there possibly be residue left over inside that needs to be burned off over time? No it is not DDEC.
Air filter sucked in isn't right, I'm assuming you have airseps? I clean mine good with Super Clean spray from autozone and then spray K&N filter lube on them, did you saturate too much? You said you removed filter and ran it? What happened then? Do both engines run off same tank?
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Old 06-10-2019, 03:48 PM
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I took the filter off to run in the slip only. I havent added any lube to them yet. Engines run on separate tanks but were both filled at the same time last week.
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Old 06-10-2019, 03:56 PM
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Run it with the filter off under a load for a short bit. If it still smokes swap turbos and see if the other engine does the same thing. It could be over fueling and trying to burn all of it but sounds turbo related.
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Old 06-10-2019, 04:05 PM
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You worked on the props. Possibility they messed one prop up and added pitch(exactly what happened to me years ago and was a nightmare to figure out because...why would you look at the props that were just reconditioned). FYI, maybe a 46 Bertram since they didn't make a 48.
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Old 06-10-2019, 04:06 PM
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Any way to run both off port tank? Did it run fine before you did all this work? While itís usually something stupid before you look at harder stuff the 2200 at load is concerning. Did you get over 2300 before props were redone? Did prop shop make a mistake or do you think a wheel was dinked, I would hate for you to have to get a diver at this point to pull wheels to check them but should be considered.
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Old 06-10-2019, 04:30 PM
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Originally Posted by Castawaychris View Post
Run it with the filter off under a load for a short bit. If it still smokes swap turbos and see if the other engine does the same thing. It could be over fueling and trying to burn all of it but sounds turbo related.
This X 2
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