Bth8
18.06.2021 18:58:53
The mechanical throttle linkage is fine however.
See full version: Thread: Surging/Idle Trouble with 4-Stroke Outboard
The mechanical throttle linkage is fine however.
Hey all, I've been having some trouble with an '08 Nissan 6HP outboard.
It is a relatively new engine. more
Nissan is Tohatsu--maybe you'll have better luck getting a manual through them.more
Is there a small inline filter on board the engine? It will look like a little white or opaque canister in the line upstream of the carb. If so, swap that out, fill with fresh fuel and try again. Alsom check the sparkplug's electrode for proper gap etc.
Hell, just get a new plug, fresh fuel, change the filter if there is one. Them try it. If no go, then bring it in for service. here
I've had the motor for about a year and it's mostly used for maneuvering around launching ramps and mooring fields, plus it gets laid down on its side for long periods (the correct side at least).
When I first started the engine after completing the filter/injector work, I noticed that the idle was 'hunting' between 600 - 900 rpm with a little cough or stumble at the low rpm each time. Anyway - I took the boat out for a power run and the engine ran great. Back at the dock, the 'hunting' idle was unchanged after running for 20 minutes a varied RPM. Turned engine off and then re-started it ( twice) to find that the idle is now holding steady at 1100 rpm
Hello all, here is a little background: 2004 f150, 500 hrs - slowly developed a hesitation/stumble that occurred when advancing throttle from idle - also had lost top end power and would not hold steady RPM above 3700.
After replacing : the VST filter, inline filter above VST, water/fuel separation filter, front bowl mounted filter, plugs . and having injectors professionally cleaned, the stumble/hesitation is gone and top end power is back. BUT - I now have a new problem : more
Any ideas on where to start or what to look for ? Thanks in advance for any advice or assistance you fellows could offer. JB more
I have had crankcase leaks cause surging. I worked on a 4hp Evinrude that had a rhythmic surge at WOT and sometimes at lower speeds too. That one had a casting flaw in the crankcase. Once that was fixed the surge went away. Just thinking of possibilities. Look for any places under the cowl around the powerhead that may be getting dampened by fuel mix.
-Ben
Sure does sound like a fuel issue… What kind of fuel line and primer bulb are you using? If it’s an aftermarket line, the inner barrier in the hose will come apart and restrict fuel flow. Pull the fuel line connectors off each end and have a look inside. You can usually see it when you look inside the fuel line. If aftermarket, I would replace it now, cause it will eventually come apart anyway. The aftermarket fuel line quick connectors don’t seal right either…. and can suck air (vaccume leak) while underway… another possible cause of surging. You mentioned that squeezing the primer bulb made no difference? A plugged fuel supply line cannot be overcame by squeezing the bulb. [links]
As Ben noted, surging can be caused by crankcase leaks or some other source of air leaks, perhaps in the fuel line or a bad carburetor or reed plate gasket. here
On a totally unrelated note, does anyone want to buy a ’63 15HP Gale Buccaneer that runs great in a barrel? (joke)
If so, the prop hub may be bad. if not, your motor is not making proper power for some unknown reason. here
Does the engine rev up, or just run at just above idle? 6MPH is probably somewhere around 2000RPM, on most boats. Do your RPMs exceed 2000? more
Did you do the link and sync as per the instructions in the service manual? See link below. I only ask because I have a V1750 and out of the water it would rev up fine but in the water it wouldn't do over 2000rpm. I chased all sorts of minor issues wasting my time until I finally did the step by step link and sync and problems went away. It was weird because the previous owner claimed to be driving the boat before I bought it but that must have been a lie. [links]