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1986 Commander 300 stalling in fwd |
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KENO 
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 Topic: 1986 Commander 300 stalling in fwdPosted: May-12-2022 at 5:59am |
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Other places like Tucson Mike mentioned earlier would be the intake manifold to heads area. The
!2 bolts holding the manifold to the heads should be 23 to 25 ft lbs torque. Did you replace both gaskets at the spacer. One above and one below? Take the PCV valve out and plug the end hole with your finger and see if it has any effect on the idle/vacuum. For the timing, attach the timing light pickup to #1 plug wire, aim it at the timing pointer at around the 1 o'clock position when looking at the harmonic balancer and you should see the timing marks on the balancer as the light flashes You should see somewhere in the 6 to 12ish degrees before TDC range Are you starting out with the idle mixture screws at about 1 1/2 turns open and adjusting idle from there? |
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apetroy8784
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Posted: May-11-2022 at 6:47pm |
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Ok the good news is the transmission works! I disconnected the prop shaft and it ran fine in both fwd and rev.
As far as vacuum leaks, I got impatient and decided to the manifold gasket. It looked a little battered so I went ahead and replaced it. The engine still stalls in gear but it idles much lower now, ~950rpm so I think I'm on the right track. Is there anywhere other than the carb/spacer I should check for leaks? And how do I verify the timing setting? Thanks!
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MrMcD
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Posted: May-06-2022 at 9:04pm |
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A lot of shops use Brake Clean to find vacuum leaks. It burns like gasoline and works well for a quick test without leaving much residue to clean up. Most garages always have a can handy when needed.
Also works to test lean conditions in computer controlled cars. Spray a little into the intake and watch the O2 sensors quickly pick up on the richer fuel mix.
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MourningWood
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Posted: May-06-2022 at 8:47pm |
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A good friend struggled with '83 Commander-powered Nautique. Same symptoms. Tuned it. Bought new carb. Only slight improvements. I helped adjust carb and set timing, noticing a vacuum leak. Changed the intake manifold gaskets and...voila!! ran/runs like a champ. As noted, easy test. Better with a vacuum gauge.
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1964 Dunphy X-55 "One 'N Dun"
'I measured twice, cut three times, and it's still too short!" |
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TucsonMike
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Posted: May-06-2022 at 7:01pm |
+1 on a possible vacuum leak, since the different carb didn’t fix it. One trick is to spray carb cleaner at the suspected leaking area. Idle will improve immediately if you’ve found the leak. Consider manifold to head area too. Does it emit black smoke at idle? That indicates too rich, which would indicate a carb problem. On my 1994 with a Holley 4160 and somewhat similar symptoms (plus a little black smoke and smelling rich at idle), the secondary metering block screws were loose. That’s probably not your problem, though, since it happens with 2 different carbs. What idle speed are you running? One possible fix is just up the idle a bit and not worry about it.
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SkierMike
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MrMcD
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Posted: May-06-2022 at 1:32pm |
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So if the air screw advice was backwards, the simple test will be to open each an extra 1/2 turn to slightly richer the mix for a stronger idle. If he dies going into gear my assumption is the idle is lean, a lean idle has no torque so they die when dropped into gear.
Maybe his carb has issues inside but the first test would be to richen the mix a little and verify the timing setting.
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KENO
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Posted: May-06-2022 at 7:27am |
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They're the same carburetor with a few minor differences none of which affect their ability to function as a marine carburetor no matter what year they were made or who owned the factory at any given time..
But, back your tuning advice,.........the idle mixture screws get turned out to richen the idle mixture
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MrMcD
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Posted: May-05-2022 at 8:48pm |
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Ken, my history was from 1983, not 2022, I am sure that Webber has an improved model available. I was with Federal Mogul who owned Carter at the time, we partnered with Webber to build the AFB for us. The Legal team left loopholes in that contract and Webber used them to sell the AFB to Edelbrock first and later to build it for themself. Bad legal advice caused that to happen. Webber cashed in and so did Edelbrock but FM got out of the Carb business completely by the late 1990’s. I am sure the modern version Webber sells has improved Marine use ability so my advice above is not accurate.
Webber also picked up the rights to build the Rochester Quadrajet so they sell them new now also. Webber has a good Carburetor factory.
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KENO
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Posted: May-05-2022 at 7:25pm |
Not too sure if you're describing a marine Holley 4160 or a marine Edelbrock, but with either one, the idle mixture screws are controlling the flow of an already emulsified fuel/air mix and it's discharged out the curb idle port below the throttle plate. It doesn't control the flow of only air or only gas but the emulsified mixture of the two. And,,,,,,,,turning the screws out (counterclockwise) on either carburetor richens the idle mixture (more emulsified mix flowing out the curb idle port. You should probably tell Mercruiser how bad a Weber is on a zillion or so Chevy V6 and V8 marine engines over the years, they may have a different opinion
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MrMcD
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Posted: May-05-2022 at 2:09pm |
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I ran my 78 Nautique with a Edelbrock (Carter AFB) carb for a couple years, I switched back to a Holley and it worked much better in the Marine environment.
A couple issues with the Carter on the Nautique. As stated it does not like the angle so you end up needing to lower the floats, a Marine engine trying to turn a prop at idle speed needs a very strong idle you can give it a few adjustments to help. You can take 2* off the idle timing and that helps a little. It gives a slower but stronger idle. When you adjust the air screws on the Carb, 2 screws in the front lower part of the carb, adjust them as instructed to reach top vacuum or top idle speed, then to help on a Boat engine screw them back in 1/2 turn each. It makes a slightly richer idle mix and helps keep it strong when dropping in gear. After these two adjustments you can increase the idle speed with the idle screw to your desired RPM in gear. I fought that carb as stated for 2 years and I really like the Carter design, which is also sold by Edelbrock and Webber, but in the boat the Holley just works better, is not affected so much by the tilting as boats turn, accelerate and even when you let off the gas and the nose drops. Carter designs work great in passenger cars and trucks but not so well in boats and even in 4x4 Jeeps and Trucks that do serious off reading in my opinion.
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KENO
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Posted: May-05-2022 at 6:02am |
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Thinking some more about this, I really don't think it's a transmission issue at all since you can quickly shift and give it gas and it goes forward and drives (or at least it did with last year's carburetor) and you mention that you drove it to the lift. Since you're on a lift, you can unbolt the coupling halves on the lift and run it without worrying about sinking it if the shaft packing leaked a lot when the shaft was uncoupled. It shouldn't leak any more than normal, but ya never know. A couple of the gaskets in the link below, one under the spacer and one above should ensure that you don't have a leak at the spacer. They're big and wide enough to cover any gaps that other base gaskets might not. That's assuming you have the normal stock spacer that Commander used along with PCM, Indmar etc but when the Edelbrock was put on, who knows what was done as far as the spacer and gaskets I think you're on the right track with checking for a vacuum leak and you should probably do that before uncoupling the shaft. |
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apetroy8784
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Posted: May-04-2022 at 6:13pm |
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I was also wondering about bad gaskets. While it's on the trailer I'm going to check for a vacuum leak.
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apetroy8784
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Posted: May-04-2022 at 6:10pm |
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Ok. I was reading some other threads and actually hopped in the water today and gave the prop a spin while it was on the lift. It felt smooth cw and maybe a slight hitch ccw but nothing too major. Hopefully I'll be able to get it up on the trailer and start taking things apart. Thanks for the help!
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KENO
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Posted: May-04-2022 at 5:34pm |
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Since you have the same issue with a new carburetor ( a non marine Holley, by the way), but it not being marine isn't the cause of your problems, I'd do the following...........
With the boat on the trailer, spin the shaft by hand to see how easy or hard it spins, then unbolt the coupling halves and separate them, then with cooling water supplied to the engine, start it and shift the transmission into forward and reverse and see if you have the same results or if it spins and stays spinning in forward and reverse. That'll at least tell you if the transmission works OK with no load. Then you can check the alignment when bolting things back together
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apetroy8784
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Posted: May-04-2022 at 1:12pm |
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Been a few months, had to pull the boat for the winter and wasn't able to work on it. Finally had some nice weather and got it back in the water. Went ahead and slapped my friends brand new carb on it to see if I could get away with just tuning it and things somehow have gotten worse. With his carb on, I can't get the engine to stabilize in fwd or rev at all.
When I bought the boat I was told the transmission had been rebuilt within a year but I'm starting to worry it's the transmission or maybe the shaft is unaligned. The only other thing I can think is the fuel is no good after sitting all winter. Any thoughts are appreciated. Here's another video with the new carb. Seems like the screw gets through one turn. |
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apetroy8784
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Posted: November-10-2021 at 5:37pm |
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Thanks so much for the input! Yes the issues is with the boat in the water. I'm going to try tuning/cleaning the carb first, if that doesn't do it I'll probably just move ahead with a replacement.
Also I'll get on that fuel line ASAP!
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GottaSki
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Posted: November-09-2021 at 6:04am |
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Nice engine, lustful manifolds. Take good care of them don't let them freeze
There is no transmission kickdown Unfortunately carb stands out as wrong , we know original and replacement Holley's here best, with some exceptions. Likely some schmutz in the ebrock carb somewhere. Address fuel filtration first else repeat taking it apart no matter what carb is on it. I dislike the leakomattic pham cartridge separator and replace with modern spin on element system The Edelbrock will protest the angle somewhere in it's operating range unless leveled. Fastest remedy may be straight to a holley marine 600 configured for the Ford or quick fuel M600. And quality felpro gasket |
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"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."
River Rat to Mole |
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KENO
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Posted: November-09-2021 at 6:02am |
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Are you having this problem with the boat in the water or is this with it on the trailer with no load on it.
I'm guessing that it's in the water and the reason that it shifts into reverse just fine is because there's a lot less load on the engine because the prop is a lot less efficient in reverse putting less load on the engine. On the slow shift into forward, with more load on the engine, it stalls, due to carburetor issues. Your "kickdown lever" is really the shift lever, it doesn't do anything else other than put it in forward, neutral or reverse and your cables are set up right. 2 separate cables from the shifter, one goes to the carburetor and the other to the transmission shift lever I'd start out by adjusting your idle mixture screws on the carburetor to richen up your idle mixture, this will help with the transition from idle speed to higher speeds without stalling or bogging. It may be as easy as that. You get through that transition now with your quick shift and lots of throttle. You have an Edelbrock carburetor on the engine and the link below will give you tuning info, showing where the idle mixture screws are You could also have accelerator pump issues or dirty carburetor issues, but I'd start with the mixture screws and if needed you would be popping the top off the carburetor to access the accelerator pump and maybe clean the carburetor if it's dirty inside, especially the small idle passages. Your video also shows a plastic fuel filter in your rubber fuel line. The rubber line should meet USCG specs and the filter should meet a trash can since it doesn't meet USCG specs for fire resistance. It also looks like it's missing a hose clamp on the filter inlet The fuel line should say USCG A1-15 or A1-10 on it. It resists an external flame better than automotive stuff. And here's a picture to help you figure out if it's a marine Edelbrock. Look for the number stamped into the right front mounting ear  |
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apetroy8784
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Posted: November-08-2021 at 4:21pm |
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Starts great and runs fine in idle. Stalls when shifting into fwd unless I quick shift it and give it a lot of throttle. Shifts into rev just fine. In fwd, starts running pretty rough then after about a minute the RPMs drop off until it stalls. Initial thoughts are transmission kickdown lever giving it problems shifting into fwd and/or a carb issue. Any thoughts/ideas welcome.
First video is the kickdown lever, the engine takes rev just fine then struggles with fwd. I'm not sure it's tuned properly and it's also linked directly to the throttle as opposed to the carb as I've seen on other models. Previous owner claims the transmission was rebuilt so I'm wondering if that was done then and it's non-standard. Second video is engine just quitting on a slower shift into fwd. |
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apetroy8784 wrote: