48 will only start using full throttle

[ba_50]

The motor is:
1996 J48ESLEDC
04071701

This motor is new to me but the last owner said he had the carb kits replaced every year. It idled and started but wouldn't increase speed, like the high speed jets were plugged.

I put new gaskets on the top of each carburetor and ended up cleaning them 3x. It did have the green stuff in them originally.

A new fuel pump kit was put in and pumps fuel.

It will only start at full throttle and if brought back towards neutral will die. It smokes badly and runs at rough idle. Tried 2 other plugs and have spark at both cylinders. The new fuel has enzyme treatment added and the motor has new fuel lines. The float needles looked normal and not bloated like they look after sitting in carb cleaner and such. The floats were level. The compression is 120 & 124.

This ones got me stumped.Thanks.

 

[jtexas]

Re: 48 will only start using full throttle

Try this slow speed needle adjustment procedure:
http://forums.iboats.com/showthread.php?t=167352

 

[ba_50]

Re: 48 will only start using full throttle

Try this slow speed needle adjustment procedure:
http://forums.iboats.com/showthread.php?t=167352

Each carburetor has one adjustment and had little if any effect when adjusting.

 

[oldcatamount]

Re: 48 will only start using full throttle

Have you done a "synch/link re-adjustment on the carb linkage? It's possible the timing is out of wack a little.

 

[jtexas]

Re: 48 will only start using full throttle

just to be sure -- at first it would idle ok but not accelerate, and now it won't idle? and never has run right since you bought it?

your new diaphram "wasn't the best" -- was it damaged? any chance it's leaking fuel into the pulse line?

are the plugs wet or dry after idling? clean or fouled?

almost sounds like the spark plug wires are crossed, or maybe cross-firing. Have you had the flywheel off for any reason?

 

[ba_50]

Re: 48 will only start using full throttle

just to be sure -- at first it would idle ok but not accelerate, and now it won't idle? and never has run right since you bought it?

your new diaphram "wasn't the best" -- was it damaged? any chance it's leaking fuel into the pulse line?

are the plugs wet or dry after idling? clean or fouled?

almost sounds like the spark plug wires are crossed, or maybe cross-firing. Have you had the flywheel off for any reason?

At first it would idle but wouldn't power up.
Now it will only start at full throttle and only idle with the lever all the way forward.
The plugs are wet.
The top coil wire goes to the top cylinder, bottom to bottom. Neither has a white line on it to tell for sure. but I think it's right.

The diaphragm looks ok.

The previous owner said it ran ok after cleaning the carbs before and no linkage adjustments have been made.

 

[cr2k]

Re: 48 will only start using full throttle

You may need to take to a shop. Those carbs have lots of tiny passages the can be damaged by not cleaning with the right objects, i.e. using a torch tip cleaner will open up the jets beyond the correct size and cause poor running. There are several places where gunk can build up that escape a lot of people.

 

[ba_50]

Re: 48 will only start using full throttle

You may need to take to a shop. Those carbs have lots of tiny passages the can be damaged by not cleaning with the right objects, i.e. using a torch tip cleaner will open up the jets beyond the correct size and cause poor running. There are several places where gunk can build up that escape a lot of people.

CR2K

I'd like nothing better than to unload it on a mechanic, but I can't afford parts let alone $60-90 an hour. Unemployed and no Unemployment insurance you see.

I figure I can do just about as good as the mechanics can on these old motors, just get stumped once in awhile. The stories I could tell you about some of their "fixes". Mostly non-fixes at that.

Wish I had a spare fuel pump to try.

 

[jtexas]

Re: 48 will only start using full throttle

agree, carb rebuild is pretty basic DIY maintenance, but cr2k makes a good point, just a little bit of scoring in the jets will cause problems. I usually have good results just soaking 'em overnight. Carb rebuild doesn't always require link sync adjustments but you should go through it anyway just to be sure. Doesn't usually affect idle though.

Is it spitting up fuel at idle? Does gas run out the carb throats if you pump the primer bulb when the motor is tilted up?

I'd make sure it's hitting on both cylinders: engine idling, pull then replace the plug wires, one at a time, giving the engine a second or two to respond; use a plastic or insulated tool. If the engine doesn't shut off, or RPMs drop drastically, that cylinder's not making power.

Sometimes a spark at the plugs isn't good enough. Do a spark test (not a "spark plug" test): get an inline spark tester (couple bucks at autozone), set the gap for 7/16", clip it to the engine block, attach the plug leads (one at a time) and look for a strong blue spark while cranking. If it can't jump a half-inch gap in the open air without a spark plug, it's not firing in the hole under heat & compression. You can fabricate a spark tester with a piece of wood, a nail, a jumper wire and a screw (or the top half of an old plug, whatever) that fits the plug boot, just be sure to ground it to the engine block.

If spark checks out ok, try pumping the primer bulb it with fuel pump pulse line disconnected, then the primer solenoid (outlet to carb), to be sure they aren't flooding the motor.

sorry to hear about the job situation, BTDT.

 

[ba_50]

Re: 48 will only start using full throttle

Jtexas

I've been told marine carbs shouldn't be soaked because of a sealant covering. Some do, and some don't, just trying to avoid it if possible.

Too late today to try your ideas. I've done most of them before, so shouldn't be a problem.
Do you mean disconnect the primer solenoid?

 

[jtexas]

Re: 48 will only start using full throttle

just take the discharge hose off to make sure no fuel is flowing through there unless you activate the choke.

 

[Silvertip]

Re: 48 will only start using full throttle

The primer solenoid is leaking thus causing an extremely rich mixture. Or the red lever is turned to the manual position and it should be in the automatic setting.

 

[surrender]

Re: 48 will only start using full throttle

If it will only start with the lever at full throttle (timing advanced to full) i say you have a timing issue. mine did that when I replaced the stator. i hadnt torqued down the flywheel nut and sheared the woodfur key. motor would start only with lever at full. Looked down and realized that the flywheel had rotated, screwed up timing. fixed that and motor has been great ever since.

 

[ba_50]

Re: 48 will only start using full throttle

The top cylinder is dead. I swapped plugs and coil wires and the top one didn't drop off. The plug had a little moisture but not much.

I disconnected the solenoid wire and it didn't help.

Is the red choke lever supposed to be perpendicular to the cylinder or straight up?

Someone taped a piece of plastic tubing on the throttle cam screw. It didn't affect it running with it on or off.

I cleaned the contact plates on back of the coil.
So I'm thinking the top carburetor isn't supplying gas.

 

[Silvertip]

Re: 48 will only start using full throttle

If you think the top carb is not supplying fuel, put some fuel/oil mix in a spray bottle and squirt some in the intake. If the engine picks up you found the problem. However, if the plugs are quickly covered with sooty black deposits, the engine is running rich -- not lean. If you disconnected the primer solenoid wire and the red lever is in the manual position, it would prove nothing. That's why they call it the MANUAL position. If you kill the battery you can still rope start the engine but there would be no way to choke it. Therefore you set the red lever so it points away from the solenoid body for manual and in-line with it for automatic (push the key) mode. Left in the manual position it will flood the engine thus causing hard starting and very rich running.

 

[ba_50]

Re: 48 will only start using full throttle

I forgot to mention that I sprayed some fuel in the carb throat and it had no effect.
I also disconnected the vacuum line to the fuel pump and pumped the bulb which had no effect.

For just a few seconds the motor started to run normally when the throttle plates were opened than ran rough again.

The porcilan ? part of the plug had a light coating of soot while the electrode was clean and with just a little moisture.

It will be tomorrow before I can pick up a spark tester.

 

[Silvertip]

Re: 48 will only start using full throttle

Have you checked the position of the red knob on the primer solenoid? You don't need a spark checker to check spark. Remove the plug, connect the wire and hold the plug against the block. Have someone crank the engine. Spark? Yes or no? Pulling the vacuum line to the fuel pump and pumping the primer bulb does nothing because vacuum is required to operate the pump. The priimer bulb gets firm because the fuel going through the system fills the float bowl in the carb and the needle and seat shuts off the flow. I think you are "shotgunning" this problem and not using a very logical approach. To start a cold carbed two stroke "requires" that that the fast idle lever be raised a bit to open the throttle. They also require lots of prime. They also need spark and it has to happen at the right time. Miss any of these and it won't run. You either have a spark problem or a fuel problem or both. While timing may be a factor it usually is not and would be the very last thing to investigate. Do the simple stuff first and stop jumping around from one system to the next.

 

[ba_50]

Re: 48 will only start using full throttle

Have you checked the position of the red knob on the primer solenoid? You don't need a spark checker to check spark. Remove the plug, connect the wire and hold the plug against the block. Have someone crank the engine. Spark? Yes or no? Pulling the vacuum line to the fuel pump and pumping the primer bulb does nothing because vacuum is required to operate the pump. The priimer bulb gets firm because the fuel going through the system fills the float bowl in the carb and the needle and seat shuts off the flow. I think you are "shotgunning" this problem and not using a very logical approach. To start a cold carbed two stroke "requires" that that the fast idle lever be raised a bit to open the throttle. They also require lots of prime. They also need spark and it has to happen at the right time. Miss any of these and it won't run. You either have a spark problem or a fuel problem or both. While timing may be a factor it usually is not and would be the very last thing to investigate. Do the simple stuff first and stop jumping around from one system to the next.

Silvertip,

Yes, I am shotgunning, just like most of the responses one gets on forums. Like I stated in the first post, there is a spark from both wires. I took the fuel pump out of the system to see if it was flooding the carb and it doesn't seem to be. I just keep trying to eliminate each potential problem until I get to the cause. It is frustrating, especially since I would rather operate than fix motors, but what else can one do? It would be great if we could look at the symptoms and know the answer. Just fuel and spark issues can be complicated. Even the guys with all the very expensive computer equipment can't figure out some really basic problems. Oh well, just have to keep plugging. Hope I didn't ramble on too long.

Like Jtexas said, you can have a spark but not enough to work under pressure. Maybe that is why it won't fire when fuel is introduced into the throat. I hope to get a spark checker today. The red lever is now in line with the cylinder and solenoid body.

 

[seahorse5]

Re: 48 will only start using full throttle

Put a timing light on #1 cylinder and watch the flashes while someone starts and keeps the motor running.

If the center timing magnet came loose in the flywheel, you will have the same symptoms - the motor won't run right unless the throttle is advanced.

You should pull the flywheel and grab the center magnet and see if it will turn or wobble.

 

[ba_50]

Re: 48 will only start using full throttle

I have an auto timing light!

Also wondering if it is a stuck reed valve and not letting fuel get to the cylinder.