Cummins Marine Diesel Repower Specialists › Forums › Cummins Marine Engines › 370 B Won’t go above 2100

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  • May 26, 2020 at 5:54 am #98189

    James Graham
    Participant
    Vessel Name: WIDGEON
    Engines: 330 B
    Location: Cohasset, MA
    Country: USA

    32 Holland put up for winter, ran perfectly. Launched over weekend and engine won’t go over 2100. Plenty of throttle left. Went to 3000 in fall. No prop change, no nothing changed.
    No smoke, runs smooth up to 2100.
    All filters new, no air restrictions. Ran with fuel from a can, ran without air cleaner.
    Have not adjusted aneroid yet, but not sure how much to turn star wheel for adjustment.
    Thinking maybe the shaft that operates diaphram froze up over winter
    Seems to want to go but not getting fuel.
    Stuck aneroid?
    Any suggestions appreciated.
    Thanks,
    Jim

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  • July 8, 2020 at 3:54 pm #100596

    kennethmobley
    Participant

    Don,
    The boat is in New Zealand and they were custom made by a glass fab shop.
    Ken

    July 7, 2020 at 7:07 pm #100551

    Don Gardner
    Participant
    Vessel Name: OUR TIME
    Engines: Cummins 6bta 5.9 m3. 330
    Location: Blaine WA
    Country: USA

    Ken
    Pretty interesting. Do you know where the boat is that you found pictures of, or where they got the stationary ones?

    Don

    July 7, 2020 at 5:03 pm #100544

    kennethmobley
    Participant

    Don,
    Check this out: https://www.westmarine.com/buy/zipwake–750s-dynamic-trim-control-system–19606664?cm_mmc=PS-_-Google-_-GSC%3EBrand-_-19606664&product_id=19606664&creative=343879478155&device=c&matchtype=&network=g&gclid=Cj0KCQjwupD4BRD4ARIsABJMmZ8F4V_3YPjMOVbT0TFSxPD9t_3piKqTbwq3SAs_r6XF8RywfcUEU0waAkP2EALw_wcB

    Also their website looks like it was put together by some pretty smart people.

    July 7, 2020 at 4:57 pm #100543

    Don Gardner
    Participant
    Vessel Name: OUR TIME
    Engines: Cummins 6bta 5.9 m3. 330
    Location: Blaine WA
    Country: USA

    Ken,
    Never seen anything like that! I’m not on facebook. I have considered larger tabs but no room to go larger.

    Don

    July 7, 2020 at 4:27 pm #100538

    kennethmobley
    Participant

    Thanks Don. I am very interested in your results and getting this 4100 running right. Cummins warranty nearly out. I found some really eye opening real world info on the Maxum owners group on Facebook. Its also a 4100 SCR and has 330s with factory props. He also has the squat problem and installed a fixed system similar to zip wake.
    Here are his performance numbers:
    2200 rpm = 18 knots
    2400 rpm is where I cruise = 21 knots
    2800 rpm is max = 27.5 knots.
    At 2400 rpm itā€™s using 80 liters per hour for both. Was 95 liters per hour before extra tab blades went on. Boost was 19psi before blades, now 14-15 psi.
    The running picture is before tabs lower and after tabs upper.

    July 7, 2020 at 4:04 pm #100537

    Don Gardner
    Participant
    Vessel Name: OUR TIME
    Engines: Cummins 6bta 5.9 m3. 330
    Location: Blaine WA
    Country: USA

    KEN,
    Somehow I missed your reply. Yes. 1999 Maxum 4100 SCR with a TNT lift platform on the back. That and the dingy add about 1200# hanging off the back. Makes the boat squat pretty good.

    Don

    July 7, 2020 at 12:03 pm #100526

    Mike Uliasz
    Participant
    Vessel Name: Runnin' Down a Dream
    Engines: Cummins 6bta-M3 370hp
    Location: Mathews, VA
    Country: United States

    Fuel Solenoid question

    Tony,
    Been following this thread and going thru LOW POWER / LOW RPM AND NO DARK SMOKE trouble shooting steps. Fuel solenoid it staying fully extended at fuel throttle (motor off). I can push the solenoid into the retracted position by hand. Had mechanic inspect the engines at purchase, said throttle cables are stretched and it was not hitting WOT. My mechanic buddy helping me thinks different. Looking for guidance on next steps. Replace the throttle cables first to insure throttle levers hit stops? or remove the solenoids, fully retract level like in low power write-up and test ride?

    1) Tachs have been checked for accuracy at the dock in neutral, yes, 1500 = 1518, 2000 = 2060 & just under 3000 = 3038
    2) No load RPM WOT at the dock? 3000 RMPs for both motors

    3) Throttle levers on the injection pump hit the stops? No, according to mechanic (stretch throttle cables). Is that required for the fuel solenoid to fully retract? I’m not exactly sure where the stops are.

    4) Any dark or grey smoke at 2800-WOT in gear? No
    5) Last time the aftercoolers were off the engines, on the bench and cores out? done July, 2019 SBMAR kits

    pic 1 & 2 port engine, 3 & 4 SB. 45408232 & 45407742

    Thanks

    July 5, 2020 at 6:08 pm #100432

    Don Gardner
    Participant
    Vessel Name: OUR TIME
    Engines: Cummins 6bta 5.9 m3. 330
    Location: Blaine WA
    Country: USA

    There is the Prop Shop and Prop Shop LTD. Both in Mukilteo. Used to be one. Owned by John Sittaur. They spit apart and as John is a friend of a friend I will be using his shop. They both do the same thing and are good at what they do.

    July 5, 2020 at 5:41 pm #100427

    Tony Athens
    Moderator
    Vessel Name: Local Banks
    Engines: QSB 6.7 550 HP
    Location: Oxnard, CA
    Country: USA

    Good company and good guys up there ( I work directly with Gary and Susan mostly) . They know me well and have been to my shop.

    July 5, 2020 at 12:00 pm #100421

    Don Gardner
    Participant
    Vessel Name: OUR TIME
    Engines: Cummins 6bta 5.9 m3. 330
    Location: Blaine WA
    Country: USA

    OK. I am taking them to John at the “Prop Shop” in Mukilteo, WA. He’s been in the business for many many years. I had a long talk with him a couple of weeks ago and he seems to be on the same page as you. I will ask him to send me a scan and let you make the decision as to what should be done.

    July 5, 2020 at 11:11 am #100416

    Tony Athens
    Moderator
    Vessel Name: Local Banks
    Engines: QSB 6.7 550 HP
    Location: Oxnard, CA
    Country: USA

    Save yourself some $$ and hassle.. Get them scanned ( they have to do that anyway) and send me the results.. Let me make the call as to what to do..

    July 5, 2020 at 10:46 am #100414

    Don Gardner
    Participant
    Vessel Name: OUR TIME
    Engines: Cummins 6bta 5.9 m3. 330
    Location: Blaine WA
    Country: USA

    Tony,
    I agree. Had the bottom cleaned a couple of days ago. Took it out for a test run this morning. Calm seas. A little less fuel and two people on board.(maybe 700 pounds lighter than last test run). 2800 WOT both engines both out and back into marina. The props will come off this week and go to the Prop Shop. I will post the results after they are back on. Thanks for all of your help.

    Don

    July 5, 2020 at 8:26 am #100408

    Tony Athens
    Moderator
    Vessel Name: Local Banks
    Engines: QSB 6.7 550 HP
    Location: Oxnard, CA
    Country: USA

    Don

    Your engines are substantially over propped–It’s that simple–You are making boost, your no-load it good but you are asking too much..Accept it or your engine will die with it..

    July 5, 2020 at 8:18 am #100407

    kennethmobley
    Participant

    Don,
    I think your no-load rpm is within spec but want to see what Tony says. I’m 2750 out of gear and 2450 in gear. I believe I’m supposed to be around 300 rpm higher than 330s. I still need to verify tachs.
    Maxum 4100 scr? I just repowered to 370’s so curious on your performance numbers as I feel overpropped too.
    Thanks,
    Ken

    June 29, 2020 at 8:03 am #100161

    Don Gardner
    Participant
    Vessel Name: OUR TIME
    Engines: Cummins 6bta 5.9 m3. 330
    Location: Blaine WA
    Country: USA

    Tony,
    No load RPMS Port 3126 Starboard 3035

    Verified with laser tach.

    June 28, 2020 at 3:41 pm #100141

    Tony Athens
    Moderator
    Vessel Name: Local Banks
    Engines: QSB 6.7 550 HP
    Location: Oxnard, CA
    Country: USA

    So your tach reading have been verified with a strobe at 2600 RPM?————————If you tachs read 2600 at WOT and are accurate, and you are making 25+ PSI of boost, you way are over popped. I’d still like to know what your no load MAX RPM is. That is a BASIC check that needs to be verified.

    June 28, 2020 at 10:32 am #100133

    Don Gardner
    Participant
    Vessel Name: OUR TIME
    Engines: Cummins 6bta 5.9 m3. 330
    Location: Blaine WA
    Country: USA

    Props are stamped 22×23.

    June 28, 2020 at 9:37 am #100131

    Don Gardner
    Participant
    Vessel Name: OUR TIME
    Engines: Cummins 6bta 5.9 m3. 330
    Location: Blaine WA
    Country: USA

    Although the mechanic said he verified the tachs, when I came to the boat and we did a sea trial, I asked him to verify them again. The port Taiwan reading 365 rpms higher than the laser tach showed. The starboard was 65 rpms higher. We calibrated the tachs and were able to run 2625 on port and 2655 on starboard. I fired the mechanic and had a long conversation with his manager. We loaded the boat up. Fuel, water, dinghy,etc. Adding about 2000#. With 4 people on board we could only reach 2400 rpms. Both engines. I personally verified with a laser tach. We get a lot of growth in our marina so we are going to have the bottom cleaned again, take it out to see where the rpms are, (fully loaded) and send the props in to be repitched. Tony had earlier said 3″+ needed to be taken out of the pitch. After what I have just explained, Tony’s comments would be greatly appreciated.

    June 28, 2020 at 6:13 am #100128

    kennethmobley
    Participant

    Maxum 4100 SCR?

    Don,
    Having similar issues. Did you figure anything out yet? What size props?
    Thanks,
    Ken

    June 2, 2020 at 7:34 am #98562

    Don Gardner
    Participant
    Vessel Name: OUR TIME
    Engines: Cummins 6bta 5.9 m3. 330
    Location: Blaine WA
    Country: USA

    The engines have always run up to 2950 to 3000 until one day the starboard engine wouldn’t. After having it hauled and the bottom painted, it ran up fine again. Then it wouldn’t a few weeks later. The bottom was cleaned by a diver. (Before and after pic show it is clean) Still won’t run up. It seems to me that if it was a prop issue it would be smoking and the problem would not come and go. The only smoke is a little bit when getting over the hump. Also, when I do get up to 2600, the boat speed is the same as when everything ran fine.I am just trying to understand how that can be related to the props. (or the starboard prop since that engine is the one with the issue)

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