1996 ocean pro power surges

[popobowa]

Dear all,
i've got a 21' Seaswirl (In Africa, with NO assistance) powered by a 1996 evinrude 150 Ocean pro with ois. Engine starts and idles fine, when accelerating I get power surges throughout the revband. But engine only gets up to 4000rpm and max 4500 during surges (1-3 sec). When cruising it sometimes makes a clanking (not so much pinking, low octane) sound.
I've replaced : Stator/optical sensor/Powerpack/ coils and leads. Cleaned carbs, checked fuel lines. Fitted an inline automotive fuel pump (Bulb stays hard at all revs).
Still i get intermittent power surges. One thing I noticed , is the top left Spark plug stays black but dry while the others are dark brown. If I x-change the plug with another position the new one stays black in that top left position while the other gets to be brown after 5min of running. Would this mean the new coil is bad? Unfortunately I've given the old coils to a friend.....Any Ideas
thnx

 

[Haffiman]

Re: 1996 ocean pro power surges

Check out the vapor pump (Small fuel-like pump on top of separator) and separator that it is no membrane leak or fuel leak into the crank case from those units.

 

[popobowa]

Re: 1996 ocean pro power surges

thnx, will check that. How would a leak into the crankcase keep a spark plug black (not wet though)? Black means richer mixture.
At idle the spkplug has regular blue spark. I replaced the top coil with the old one yesterday....still same problem...so not the coil.

 

[popobowa]

Re: 1996 ocean pro power surges

Oh..I forgot: the "chk eng" light is mostly on....cant be fuel pressure though, with the inline el. pump installed the Primer Bulb stays hard at all times (and when opening the carb drain plugs , fuel spurt out under pressure. Maybe faulty pressure sensor? where do I find that?

 

[Haffiman]

Re: 1996 ocean pro power surges

Have you done a compression check on the cylinders?
The 'black' plug is a sign of flooding. It might be from the carb, it might be from the vapor pump leaking fuel in the pulse line or the needle valve in vapor tank leaking. Both needs to be checked out.
It is a danger running the electric feed pump as it might force fuel pressure on the carbs higher than the VRO pump. If the oil is still connected, it means that you may force fuel without oil into the carbs.
Never liked electric 'primer' pumps without by-pass functions.

 

[popobowa]

Re: 1996 ocean pro power surges

Haffiman, thnx for the response . I've run it yesterday with the old Powerpack installed and voila! the black plug turned brown! ( it did fire with the other new pack too, with plug remaining black ) but i still have the same surges with a bit more power.
I then ran the engine with the electric pump disconnected (from 12V) but remaining in line....and the bulb got soft and started to collapse. Aware that the el. pump inline might cause restriction too I'll remove it and check the fuel line from tank to Engine fuel pump once more..the fault MUST be there?
Can the bulb itself be a problem? I never had them giving me problems over years of boating.

 

[Haffiman]

Re: 1996 ocean pro power surges

Check out the anti siphon valve at the top of the fuel tank.
Inside a spring loaded ball that prevents fuel from flowing freely from tank in case of fuel leakage.
It is a USCG requirement that does not apply in Africa -remove the ball and spring!!
The primer bulbs may create problems in flow, seen and experienced that before! Try to 'clamp' it vertical with fuel flowing 'UP'.

 

[popobowa]

Re: 1996 ocean pro power surges

So, I had it on the water today running the following experiments:
1)bypassed the returnvalve (antisyphon) by sticking the fuelline directly into the tank...no difference
2)attached another fuel host to the mesh-filter going into the Vaportank (etc) assy, bypassing the primerbulb....no difference
3) back to the standard assy......same perf. no difference!

I did notice that , when having removed the intake silencer,the top left carb spurts fuel every now and then (2-3 sec)...that might account for black plug. (the other5 carbs dont). Iopened that carb and bent the floater metal plate so it would clost the valve earlier.....no difference!!

Chk eng light stayed on during all these trial runs!! now it could only be what...air leak in fuel assy on the engine? I tend to want to use this engine as a mooring!...but i know its a small issue,,must be?

any more good ideaas?
thnx
Stefan

 

[Haffiman]

Re: 1996 ocean pro power surges

Swap the carbs and see if the problem follows the carb or stays with the cylinder.

 

[popobowa]

Re: 1996 ocean pro power surges

Will do...but that surely cannot account for the surges (and lack of top power) and the "chk eng" light lit at all times?!
How do I determine which are the "vapour" tank and -pump? Is the Vapour tank on top of the fuel screen (entry point of fuel)?

 

[Haffiman]

Re: 1996 ocean pro power surges

#37 here:
http://www.marineengine.com/parts/j...vinrude&section=Fuel+Bracket+&+Components

 

[popobowa]

Re: 1996 ocean pro power surges

Thnx for the link..I should've thought of something lake that myself! I went out again this afternoon, didnt want to open up any of the Vapor/VRO pump assy. while boat is moored..looks too complicated to loose a small bit into the lagoon!
What i noticed..and doesn't make sense to me...is that from the moment the ignition is on and the
system runs the check...the chk eng light remains on while th rest of the lights go off. Surely it shouldn't register a fuel restriction as the engine is not yet running ....there cannot be any vacuum!? If I disconnect the vacuum sensor,(grey plastic, two leads, under vacuum tank), the light stays on. I dont know if the light and horn should stay off if disconnected or should show alarm?

Any way, they are only an alarm and do not interfere with engine performance....the power surges and limit to 4000+/- rpm persists.

As a summary i can say:
between the pick up screen in the tank bottom and the fuel VRO/vapor pump assy. on the engine there is no restriction. The "chk eng" (vacuum?) sensor might be faulty but that wouln't cause the surges. I did run the engine on the open sea at speed (with the autopilot on) and squeezed the bulb.....there might have been a slight improvement...but not as significant as the power surges...meaning I am not yet getting to full power.

The upper left spkplug is still darker (black brown) than the others and still spurts fuel into the carb irregularily....why could it be only the one?

Irgds
Stefan

 

[Haffiman]

Re: 1996 ocean pro power surges

Most likely you have a faulty system check gauge.
It seems that you either has not enough fuel pressure to properly feed the cyl 1 carb, but I'm more inclined to believe you have a leaking membrane in the vacuum pump. Try to pull off the hose #36 while engine is running. Any fuel in that hose, the membrane is shot. If clean fuel in #75 and #39, your needle valve in the separator is not sealing, flooding the separator.
Even pull off the hoses #7 and #56 and check that no fuel is coming when engine is running.
I am a bit afraid to ask for a comp test??

 

[popobowa]

Re: 1996 ocean pro power surges

I Took the boat out of the water for other maintenance and wont be able to run under load. In Idle it willingly revs to over 6000rpm. I'll xchange the carb position and chk the hoses you recommended for fuel...thnx ..will be back in a few days.

 

[ondarvr]

Re: 1996 ocean pro power surges

Revving the motor in neutral means nothing, but it can destroy your motor, so it's best to not do it.