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This J10RENA won't get a 14' aluminum boat up on plane like it used to.

It makes Whaaa... sound at full throttle.

The carb cover and cam roller have been upgraded.
The upper seal doesn't seem to have any leaks.
The carburetor is clean, and has a new kit.
New fuel pump and lines, including spark plugs.
The fuel line from tank to motor works on other motors.
I checked for vacuum leaks using soapy water on what could be reached.
There was a 1/2 to 7/16" spark jump.
I swapped out coils for two others and no change.
It won't start with full choke even after bulb is pumpe uphard.
Pumping the bulb at full throttle has no effect.
The cam roller was adjusted like the OEM manual said to do. The throttle plate should start to open when the roller is lined up with the index mark. At full throttle, the throttle plate should be straight up and down.

The carb is so simple, you can see that it is clean, when apart.

So if it is a fuel problem, what to check next?

This motor was bought new and used 3x as a kicker motor from the previous owner. I put about 15 hours on it before the cam roller failed, without a problem.

Any chance the prop is slipping?

It's not uncommon for the rubber sleeve between the prop and the hub to deteriorate and slip at higher rpms.

Take a grease pencil (or something similar) and put a mark on the hub as close to the prop shaft as you can and a second mark on the actual prop adjacent to the first one, then run the motor under normal conditions for a bit.

When you haul it back out, observe the marks. If they are no longer lined up, you need to "re-hub".

It's sometimes difficult to troubleshoot without a tach, but if the motor "sounds" like it's getting full rpms at the top end, then you probably don't have a fuel problem...

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Graham

Yes, Plywood is "real" wood

A "professional" is someone who gets paid for their work - it doesn't necessarily mean they are good at it

1) Compression test be sure it's not hosed before going any farther.
2) Set the needles to light touchdown, then back out 1-3/4 turn.
2a) be sure you have the ignition timing back to OEM spec before going any further.
3) after a WOT run (or what passes for WOT at this point) pull plugs, what colour are they (I'm going to bet black, and carboned) Indicates a flooder, typically that small johnnie has probs with the carb when they are left in a tilted position a long time. Who knows why. Sticking float, sunk float, put together wrong (there isn't much to them, but still possible.) needle/seat not sealing, dissolved/gooified (not exactly a technical term, but descriptive) pieces of fuel lines/pump getting stuck in the carb. (using Ethanol oxy fuel, or adding some mystery-mix chemical to the fuel?)

None of the above, or white /light grey ash on plugs... Check carb base gasket for seal.
Upper or lower nozzle well gasket missing/hosed.
Nozzle well hosed, on wrong.
that is the carb with the mystery-gasket under the cover, be sure you have the proper gasket for the cover, of the passages are blocked.

Is there allot of signs from fuel being expelled from the carb throat?

Last, weak, missing, broken/damaged chipped, bent, delaminated, loose, sticky, gooey, or otherwise-jacked-up reed valve(s), or leaking reed plate gaskets. The manifold cover cracks easy, careful when torquing it down. a bad reed set may exhibit reduced compression, or an unstable manifold vacuum. When they are bad starting is a PITA. Sometimes (ok, once in a while) you get lucky, and can hear they wheezing when you turn the engine over. The reeds came in both GRP, and stainless steel. GRP is easiy wrecked by laquer reducer based carb solvents. I seem to remember a check ball that likes to get corroded from alky fuel, it's in the reed plate. Reeds are most critical at low vacuum, such as startup, and loaded low RPM WOT operation. If it lost a leaf, you get to go fish it out of the crank case, that's a 12 pack job on any day. The major hassle is going to be getting everything else back to the original settings.

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Some plan to stroll through Saint Peter's Gates, I plan to go through them at 150mph... backwards... in a screaming ball of flame, with a glimmer belt wrapped around my head, and a NOx button in my hand.

I forgot to mention the compression was 120-122 inch pounds.
The reeds look ok and I held a business card in front of the carb throat at full throttle and it came up dry.
The lower nozzle gasket looks ok.
The cap gasket is ok.
The prop isn't slipping.
The only timing on this motor has to do with adjusting the roller cam on the index mark and the throttle plate at full throttle. This was done as shown in the OEM manual.
The float bowl gasket looks ok.
Can't say for sure on the plug color, it's not here right now. Trying to get some new ideas. If memory serves it was if anything blackish but not built up with carbon.
I tried the starting carb setting but it had to be opened more than usual, say 3-4 turns to idle correctly.

Spray about 5cc of 2-stroke oil (misting oil better) into the cyl through the plug hole, and recheck compression. Be sure the throttle is open. You are low by about 18%-not exactly earth shattering. It doesn't look like it's worth going down that road any further, it's not significant enough to cause a flat power band.

My first step would be to confirm the proper prop pitch for my application, be sure there is no drag on the prop in neutral, and that it spins quietly. (thinking hosed carrier bearing) verifying there was not excessive mechanical drag in the leg, a viz on the lube would confirm a chattering bushing, or chewed up gears. proper viscosity gear lube. At only 9 ponies, it doesn't take much to keep it down. I have seen 5 hp held down by a tractor-mechanic type filling the case with 180 wt. Anyone done a water pump kit? getting the little vanes bent the wrong way can cause a load of strange parasitic drag.

Dump the fuel. Mix up some new premix with a synthetic oil.

Change the plug to a new plug. I am thinking a possible crack in the porcelain, they idle, and will work at low power, but once there is an sort of cyl pressure, the resistance is too high, and the plug arcs internally. Normally shows as a high speed miss, but it can cause a weak cylinder. Don't use chump-ion sparkplugs, they are total garbage, only good for weedeaters, and mopeds.

Be sure tank is sealed for a pressurized system, and vented if it's a pumped system. Yep, it sounds obvious, but you would be amazed at the amount of grief a tank full of pressurized fuel can be when it's supposed to be at atmospheric pressure, or vice-versa.

Then after, and only after the above I would feel confident the engine was ready for a real diagnosis.

A WOT spark plug visual to confirm a proper F/A mix. Looking for a nice medium-dark tan-anything else is an indicator of our problem. If it's grey, white, or shows signs of heat-stop now. No more running lean or it's going to be hosed for good go right to a case leakdown test. (not a cyl test.) If the plug is black, sooty, oily, then continue by running WOT and cutting fuel flow. Pinch the line shut between pump and carb while running WOT on load, in water. (or just unplug fuel line, although that will take longer to affect it.) You are either going to get an engine that just starts to dog, and dies, or suddenly surges into power, and dies. This test runs the motor lean, don't get carried away, and do it 10 times, thrice is enough to confirm condition. If it surges into power as it goes lean your carb job missed something, and the engine is running slobbering-rich - or the carb is sick of being taken apart, and needs to be replaced. A fuel pressure gauge on the inlet to the carb really helps the battle for this test. Should see a min of 1-1/2psi, more than 5 and something is wrong.

Assuming you have the carb cleaned, and put together right, with all the bits. The ign is functional, and setup right, it's time to move to more drastic steps. If I were doing it, I would see if I could bum a known-good carb from someone to test, or just find a used virgin carb from one of the marine junk yards.

Are there any major oil-residue spots on the engine/housing? might find a hint there. A good pressure wash with some purple stuff to degrease it, Check the exhaust idle and run ports. if they are filled with critter-nest, corrosion, general garbage, the engine may not be scavenging properly, excessive back pressure can really hold a 2-stroke down. A partially blocked idle port will allow the engine to idle, and need extra-rich setup, but won't allow the engine to breath enough to build RPM. Another common affliction if engine is left tilted, and not run for long periods of time.

At this point, if I were doing it, I would pressure test the case before going much farther. Intra-case leak, case damage (I am thinking of frost damage) damaged shaft seals, leaking baskets. The only sure way to test them all is to pressurize the case. Any 2stroke should be able to hold 8 PSI in the case for 10 minutes. Any more than a 2 psi drop is going to cause grief - It should also hold 6psi over night. At 6 psi any leak is a bad leak.

Never pressurize the case past 10 psi... ever. If you do there is a pretty good chance you are going to hear a pop, followed by tinkling sounds as the case becomes dust-bunny fodder.

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Some plan to stroll through Saint Peter's Gates, I plan to go through them at 150mph... backwards... in a screaming ball of flame, with a glimmer belt wrapped around my head, and a NOx button in my hand.

Okay crazy ideas............................The strange noise gives me some crazy thoughts like the running parts may also be an issue, even with the hard starting issue, maybe jamming? Maybe, maybe not..

Something is not right. are you sure that the shaft and gears are in proper working order? Have you dumped the lower unit to see if there is water in the oil which can create binding, or slipping? Howabout the linkage at the block? Have you looked at the shifting mechanism while in gear and manually pushed it? Is the prop spinning on the hub spline? Put the engine in gear with the engine not running and see if you cans pin the prop while holding the top of the crank plate for the lack of another description.

You say the reeds looked ok and you had no blow back through the carb (so the reeds are not chipped or broken) but I wouldn't totally discount them yet at this point.

As noted, if they are gummed, such that maybe only half the petals are "opening" that would cause fuel starvation at higher rpms.

For the minimal amount of work to pull them (unless you are postive they are ok) ensure that all the petals are sitting open to spec.

_________________
Graham

Yes, Plywood is "real" wood

A "professional" is someone who gets paid for their work - it doesn't necessarily mean they are good at it

This motor has never left Florida so frost damage is out.

Is there a synthetic 2 cycle oil? Or just use it as a pre-mix?

No water in the gear case. I don't have any reason to think there is a problem with gear alignment.

What is WOT?

I use 80-90 gear oil

The prop was marked and didn't move under a load. It worked fine before so the pitch should be ok.

The reeds or blocked idle port could be a possibility. Where is the idle port?

The exhaust ports had a lot of fuel and oil coming out until the fuel pump was changed.

It will be 4 months before I can work on the motor again, but your ideas might turn something up.

I don't understand the question about pre-mix and synthetic oil.If there is no oil injection,you have to pre-mix

WOT is " Wide Open Throttle"

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Boat building can best be defined as an endless series of
tragedies obscured by the occasional miracle, followed by a good bottle of beer.

Don't Dream Your Life, Live Your Dream

It is a 2-cycle so I use 50:1

The idle port is actually a pretty common place to see "funk" plugging up a motor. It is not so common in area where motors are run regularly, but in the case of stored, seasonal, or seldom used aux engines it will drive you batty trying to diagnose.

Johnson built the small chassis as both a low, and a high exhaust for some time through the mid 80's early 90's.

Any motor with a submerged exhaust will have one. 2-strokes don't have the ability to overcome a high exhaust backpressure. When the leg is fully submerged, the water pressure will be too much for the engine to overcome, and the engine never starts to breath enough to build power. Typically a plugged engine will act allot like what you are describing. I have seen them fool long-time marine mechanics more than once. (usually makes for a great cheap-motor buy as long as it hasn't been played with too much.)

Also if it's a high exhaust, it won't have an idle port, but it will have a muffler with internal baffle plates. Hornets absolutely love to move in when the motor is idle for a long time. You would think the motor would be able to blow the nest out, but it might/might not. It is possible for the exhaust to become so plugged that cooling water backwashes into the cylinder. (typically lower one in multis) Occasionally you can observe steam, and smell exhaust in the tell tale stream. Some of the bigger multis will be able to actually beat the water in the cooling back down at idle, and overheat.

Diagnosis is simple, look for funk/dead bugs/nest material/dead mice. Or you can use a vacuum gauge on the base of the carb: run until the vacuum peaks, back off a few 100 rpm, and watch the reading. If the exhaust if the culprit you will see the vacuum steadily decline, followed by an RPM decline. closing the throttle a little will have little or no effect.

In the end, this problem will turn out to be a F/A ratio, or breathing problem. Eliminate exhaust backpressure, and case leaks (both cause slightly low compression in 2-stroke.) then the only choice will be the carb. May as well eliminate everything else before going down that road.

50:1 is per mfgr recommendation, Although when I as worried about an engine breathing problem I usually fall back to 32:1 for diagnostic running. Any lean-run problems are also running the engine with inadequate lubrication. The reason for a synthetic oils is simple, synthetics will take heat, and inadequate film thickness far better than dino-oil.

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Some plan to stroll through Saint Peter's Gates, I plan to go through them at 150mph... backwards... in a screaming ball of flame, with a glimmer belt wrapped around my head, and a NOx button in my hand.

Mine has two exhaust ports just below the hood and seemed to be shooting out water normally. Where exactly on the carb do you connect a vacuum gauge and will any gauge work?

Caber

The more I think about it, the plugged up case sounds right considering all that oil coming out the ports and all the sitting around it has done. That oil would collect lots of garbage. Do I need to take the middle leg off to clean it or just clean the ports?

The reeds setting sounds like the other possibility that needs to be checked.

The muffler is in the top of the leg on those little johnnies. It's not a hard teardown, not much to it. Also check water riser tube at the same time, they have an affinity for coming out of the inlet on the powerhead, and sliding down on the pump. Not the problem, but a point to check while putting it together.

The real indicator of the problem is all the residue you are seeing. Running 50:1 should have none at all. If you think about it, even 25:1 in an old weed-eater never leaves a gloopey mess all over. It is telling you there is a breathing problem, or an over-rich condition. Nothing else will make that kind of mess. Once you have fixed/verified open exhaust flow, and no strange case leaks, the only option left is a carb. If the muffler is full of oil-tar it's going to need to get a solvent bath no matter what, makes it a good place to go next.

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Some plan to stroll through Saint Peter's Gates, I plan to go through them at 150mph... backwards... in a screaming ball of flame, with a glimmer belt wrapped around my head, and a NOx button in my hand.

I guess I forgot to mention the fuel pump was bad and pumping all that crap out the exhaust for quite awhile and sat all summer in Florida.