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powbmps

What are these spark plugs telling me?

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powbmps

These plugs are from cylinders 2,4,6 & 8 (from left to right).  1,3,5 & 7 mirror these four, so 7 & 8 are the odd ones.  I've looked at quite a few spark plug links, and haven't found anything that looks quite the same.  Have been getting some oil on the plug threads (not from the valve covers), but compression is good in all eight cylinders and vacuum in motor is good.  New plug wires (checked resistance), new rotor, cap and sensor, timed to 10 degrees BDTC (5.7 Vortec).  New Edelbrock 1409 carburator (checked floats, etc.).  Carter 6-8 psi electric fuel pump, with fuel pressure regulator ~5.5 psi.  New fuel filters.  Cleaned pickup in gas tank.  I have been struggling with some bogging (and even stalling) when initially pulling a skier up.  It's driving me crazy! 

plugs.jpg

Edited by powbmps

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malibu2004

PVC. My buddy and I struggled with this exact issue for about 6 weeks this summer. He had purchased the wrong PCV. 

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powbmps
Just now, malibu2004 said:

PVC. My buddy and I struggled with this exact issue for about 6 weeks this summer. He had purchased the wrong PCV. 

Do you mean the valves coming off the top of the valve covers?  Mine are just open plastic elbows.  I ran the breather hoses from them to a vented catch can (instead of to the flame arrestor).

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Woodski

@powbmps:  upon a quick casual observation, it looks like there might be just some slight oil consumption, mixture does not look lean (tan coloring on ceramic), idle mixture may be a touch on the lean side as normally you get some black soot on the outer ring and of course the engine is tilted rearward and #8 is rich particularly after shutting off from an idle.  I would consider trying to get maybe slightly richer idle but maybe first try to get a bit more accelerator pump squirt either via adjusting the pump on the lever (multiple holes) or getting a bigger nozzle.  For my setup, I increased the accel nozzle to a 45 (from 35 IIRC) and moved the lever to maximize the stroke, which should help the bogging issue.

As a side note, I installed aluminum heads / intake / exhaust manifolds which accentuate the initial acceleration bog when the engine is cold, so if you have any aluminum components along the fuel mixing path, it aggravates bogging when not warmed up.  My solution is to at least get the temp gauge moving via one moderate acceleration when the engine is cold.  Besides, I am kind of a fanatic to make sure the oil is at least warmed up a bit before I twist the throttle to pull up a skier or footer.  Cold engines are a bit like getting out of bed in the morning, need a little TLC and stretching of the muscles.

Oil on the plug threads and sealing ring is not uncommon, I see the same thing and have good compression and leak down numbers.

Edited by Woodski

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powbmps
2 minutes ago, Woodski said:

@powbmps:  upon a quick casual observation, it looks like there might be just some slight oil consumption, mixture does not look lean (tan coloring on ceramic), idle mixture may be a touch on the lean side as normally you get some black soot on the outer ring and of course the engine is tilted rearward and #8 is rich particularly after shutting off from an idle.  I would consider trying to get maybe slightly richer idle but maybe first try to get a bit more accelerator pump squirt either via adjusting the pump on the lever (multiple holes) or getting a bigger nozzle.  For my setup, I increased the accel nozzle to a 45 (from 35 IIRC) and moved the lever to maximize the stroke, which should help the bogging issue.

Do you have the 1410 carb?  The 1409 I have came with a .028 nozzle.  Nozzle kit comes with .024, .033 and .045.  Maybe I'll give the .033 a shot, and move the lever to the closest hole.

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MadMan

Carbureted  direct drives have the problem of the carb being angled back.  When you accelerate, this angle gets worse and gas can dribble of the booster venturis instead of being pulled by vacuum.  This super rich condition could be causing the bog. Plugs 7 & 8 being dark indicate this is happening because this extra fuel just runs down inside the intake manifold to these cylinders.  I had the same problem on a previous boat and fixed it by installing an angled carb wedge under the carb.

Edited by MadMan

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powbmps
1 minute ago, MadMan said:

Carbureted  direct drives have the problem of the carb being angled back.  When you accelerate, this angle gets worse and gas can dribble of the booster venturis instead of being pulled by vacuum.  This super rich condition could be causing the bog. Plugs 7 & 8 being dark indicate this is happening because this extra fuel just runs down inside the intake manifold to these cylinders.  I had the same problem on a previous boat and fixed it by installing an angled carb wedge under the carb.

That makes sense, but I've already got a wedge in there.  If this were the case, would larger accelerator pump jets make the problem worse?

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MadMan
52 minutes ago, powbmps said:

That makes sense, but I've already got a wedge in there.  If this were the case, would larger accelerator pump jets make the problem worse?

Yes, a larger accelerator pump would make it worse.  You could try lowering the float level a bit, just make sure it is high enough for fuel the fuel to make it through the transfer slot to the accelerator pump plunger.

You can also look down the carb with the engine idling to verify that no fuel is dribbling out of the secondary booster venturis. 

Ov course, if this isn't the problem it could be the opposite as stated above.

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Rednucleus

If after the initial bog at acceleration it catches up and runs well, then I would increase accelerator pump output 1st. That says not enough fuel to me.

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Woodski

@powbmps:  Mine is a Weber, closer to 1410 but with different calibration parts, basically 3 step needles rather than 2 step ones.  I installed a .045 nozzle from the .033 original.  I would actually guess the opposite, it is the front leaner cylinders complaining rather than cooperating, but could be either condition as Madman noted.  Wedge helps, but engine angle itself allowing unmixed fuel to run towards back of engine is culprit IMO.  To get a true mixture test you need to run a clean cut and check plugs from that rather than after idling up to dock/lift/trailer as that will tend to contaminate the results via longish idle, but still a worthy check either way.  The other items to check include if any shaft gap (primary and secondary) which allows air to enter and fit of the venturi's are tight.  These carbs seem to be somewhat dirt sensitive for response, so make sure internals are clean.

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malibu2004
2 hours ago, powbmps said:

Do you mean the valves coming off the top of the valve covers?  Mine are just open plastic elbows.  I ran the breather hoses from them to a vented catch can (instead of to the flame arrestor).

It's a valve https://en.wikipedia.org/wiki/Crankcase_ventilation_system it should go back into the carb manifold/base. 

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malibu2004

So my buddies boat is a 1992? MC Prostar 190 with a Ford Motor.

I argued change the pcv, plugs, wire, distributor, coil everything so you know where the boat is at it's cheap and easy. Instead he parted it while we trouble shot it. He would purchase new plugs and it wouldn't work. Then a new PCV, blah blah blah. He was dead set on the carb being screwed up. I said change the parts but he purchased a carb instead for $6 or 700. He put the new carb on same problem like I said. So then he got into bigger fuel nozzles and other deals. I showed him how his spark plug cable where bad and other parts. Reluctantly we swapped all the parts that you would do for a tune up. Now the the parts where swapped out for new I thought we had a great chance to figure it. The boat was running better with the new carb on but we couldn't get the boat to stall/stagger when we adjusted it. It was blowing black smoke out the exhaust and stalling on acceleration. Called Holly and they couldn't figure it out. We put the old carb back on. I said it was getting to much air but he had purchased a new PCV. Then a friend stopped by and mentioned the PCV again. We figured out he had purchased the wrong PCV and it was letting in to much air. Swapped it out PCV and now it runs like a champ with the OLD CARB that we rebuilt. So now he has a new carb collecting dust. 

 

My point is your boat has run just fine for years and years as have others with the original carb so why not rebuild it and put it back on in. Keep it all original. 

 

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powbmps
37 minutes ago, malibu2004 said:

So my buddies boat is a 1992? MC Prostar 190 with a Ford Motor.

I argued change the pcv, plugs, wire, distributor, coil everything so you know where the boat is at it's cheap and easy. Instead he parted it while we trouble shot it. He would purchase new plugs and it wouldn't work. Then a new PCV, blah blah blah. He was dead set on the carb being screwed up. I said change the parts but he purchased a carb instead for $6 or 700. He put the new carb on same problem like I said. So then he got into bigger fuel nozzles and other deals. I showed him how his spark plug cable where bad and other parts. Reluctantly we swapped all the parts that you would do for a tune up. Now the the parts where swapped out for new I thought we had a great chance to figure it. The boat was running better with the new carb on but we couldn't get the boat to stall/stagger when we adjusted it. It was blowing black smoke out the exhaust and stalling on acceleration. Called Holly and they couldn't figure it out. We put the old carb back on. I said it was getting to much air but he had purchased a new PCV. Then a friend stopped by and mentioned the PCV again. We figured out he had purchased the wrong PCV and it was letting in to much air. Swapped it out PCV and now it runs like a champ with the OLD CARB that we rebuilt. So now he has a new carb collecting dust. 

 

My point is your boat has run just fine for years and years as have others with the original carb so why not rebuild it and put it back on in. Keep it all original. 

 

I see where you are coming from, but the boat I have came with valveless PCV valves (for the lack of a better term).  It seems that some did, and some didn't.  The valve covers on mine vent to the spark arrestor (stock configuration).  I did not have any bogging issues on the old motor, but it needed to be replaced for other reasons.  Part of troubleshooting the bogging on my new motor was getting a new carb, but unfortunately that wasn't the issue.  Just have to suck up that pointless cost and try to figure out what the issue actually is.    

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powbmps

Couple observations after skiing this morning.....

1. Boat does not operate well on four cylinders.  Boat started right up, but would not stay running.  Realized that I had forgot to connect plug wires for 2,4,6 & 8 :whistle:.  That's what I get for trying to troubleshoot and take work calls at the same time.

2. Choice of fuel regulator may play a role.  I was using a Mr. Gasket fuel regulator, which would arbitrarily wander from about 3.5 to 6 p.s.i.  Replaced it with a Holley unit that is holding a consistent pressure (set to 5.5 psi now).  No stalling and only a slight hesitation.   Plugs 6 & 8 were also bone dry when I got back home.  Wondering if maybe the varying fuel pressure was creating a problem????

Still going to experiment with some different accelerator pump nozzles to see what that does.

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powbmps

New set of plugs.  Two times out skiing.  1, 3 and 5 look pretty much brand new.  7 has a light coating of black around 2/3 rds of the plug (not as dark as it looks in the photo).  Second plug from the left has marks that look almost like cracks in the porcelain, but I think they are just marks on the surface.  

Running the stiffest springs and .43 accelerator pump nozzle in the carb.  Fuel pressure is 5.5 at idle.  Still bogs at take off.  Not sure what to make of it.

20161001_181546.jpg

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Yeaitsslo

Do they smell like rubbing alcohol? To me and my motorcycle drag racing days I'd say those are on the lean side. 

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powbmps
8 minutes ago, Yeaitsslo said:

Do they smell like rubbing alcohol? To me and my motorcycle drag racing days I'd say those are on the lean side. 

They don't really smell like anything, they have been sitting on my desk overnight, but I've been obsessively Googling, and would agree with you.  I recently switched from a 140 thermostat to a 160, as I didn't feel the engine was running hot enough.  Could this be contributing to the issue?  Other than that, I'm not sure what I can do to make it run richer.  Bigger jets in the carb, or different metering rods?  I've brought the timing back down to 10 at idle, so it shouldn't be too far advanced.

Edited by powbmps

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Yeaitsslo

I didn't read through this whole post but have you done a compression and or leak down test?   

 

have you checked for intake leaks??? An intake leak will make a motor run lean. Even the smallest ones. 

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powbmps
16 minutes ago, Yeaitsslo said:

I didn't read through this whole post but have you done a compression and or leak down test?   

 

have you checked for intake leaks??? An intake leak will make a motor run lean. Even the smallest ones. 

Compression is good, but I haven't done a leak down test.  Sprayed some carb cleaner around the intake and carb base, with a vacuum gauge and tach hooked up.  Couldn't find any leakes.  Engine vacuum is good at ~18 to 20.  Carb is new and adjusted correctly.  

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Steve B.

I think this is fairly common in our inboards. I've noticed it for30 years or so. My take is the angle of the engine allows some amount of leakdown towards the back cylinders.

Steve B.

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Woodski

@powbmps:  Those plugs look on the lean side to me, from what I have seen although a small sample size in number of different boats, there is usually more of a soot ring on the similar to #7 after checking plugs which includes an idle back to the dock or lift.  Lean mixture would contribute to the bog off idle.  As noted the engine tilt contributes to #7 showing richer.

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powbmps
14 minutes ago, Woodski said:

@powbmps:  Those plugs look on the lean side to me, from what I have seen although a small sample size in number of different boats, there is usually more of a soot ring on the similar to #7 after checking plugs which includes an idle back to the dock or lift.  Lean mixture would contribute to the bog off idle.  As noted the engine tilt contributes to #7 showing richer.

The old set of plugs looked better.  Not sure what I did to lean it out like this (unless the 160 vs. 140 thermostat makes a difference).  Edelbrock has suggested that I try a different set of metering rods to get more fuel in there.  Ordered the .065 x .037 (vs. the stock .068 x .047).  The next step would be a primary jet/rod combo.

Edited by powbmps

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powbmps

One thing I have noticed with my setup is that the carb spacer has not been sealing properly with my intake (not something that causes a vacuum leak though).  No one sells a gasket that seals the circled area.  The angled spacer I have looks like the other attached photo, so when you bolt it down, there is a gap that allows air to pass through from one side of the intake to the other.  I just added a thin strip if carb gasket material between the spacer and the intake.  It sounds like that could help improve the initial throttle response.  Hoping to test it out later this week.

 

3252116_L_158504eb.jpg

download.jpg

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Woodski

@powbmps:  Are you running a cast iron or aluminum intake manifold?  If aluminum, I have noticed that until the manifold has some temperature build up, the engine will tend to bog just after throttle application (enough to pull up a skier).  Adding throttle if it happens quickly restores to smooth acceleration, it does not do it if engine is just slightly warmed up.  Also, do you have Perfect Pass & the answer is yes, are you running it turned on or off?  Perfect Pass is very sensitive to throttle return spring tension and can create a situation where the engine bogs or de-throttles (sic) on acceleration.  Edelbrock offers a variety of intake manifold configurations, one that actually has a larger open slot in the area you are missing a seal.  I don't know if changing it will make much of a difference given such a small slot but it does open up a cross signal.

Edited by Woodski

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powbmps
18 minutes ago, Woodski said:

@powbmps:  Are you running a cast iron or aluminum intake manifold?  If aluminum, I have noticed that until the manifold has some temperature build up, the engine will tend to bog just after throttle application (enough to pull up a skier).  Adding throttle if it happens quickly restores to smooth acceleration, it does not do it if engine is just slightly warmed up.  Also, do you have Perfect Pass & the answer is yes, are you running it turned on or off?  Perfect Pass is very sensitive to throttle return spring tension and can create a situation where the engine bogs or de-throttles (sic) on acceleration.  Edelbrock offers a variety of intake manifold configurations, one that actually has a larger open slot in the area you are missing a seal.  I don't know if changing it will make much of a difference given such a small slot but it does open up a cross signal.

The manifold is aluminum (same one as in the photo), but my bogging issue doesn't change once it's warmed up.  No Perfect Pass.  I'll report back once I try the different metering rods.

I just noticed this on Edelbrock's website (regarding the 2116 manifold):

Performer Series Intake Manifolds

1) The long equal length runners in the Performer EPS manifold create a very strong signal to the carburetor. In some applications, the stock rods or jets may need changing for best overall performance. Refer to your carburetor owner's manual for details.

2) Performer manifolds deliver excellent drivability and power utilizing stock distributor settings. Some applications may benefit from resetting the initial advance ±2° from the factory specification.

3) Aftermarket ignitions and more aggressive advance curves may be used with Performer packages. 

So maybe 12 degrees at idle is okay with this setup???

Edited by powbmps

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