VicS
Well-Known Member
But you cannot bypass the pump ... can you ?
I'm beginning to despair of ever getting my Malta O/B to run properly
- Thread starter davidej
- Start date
davidej
Well-Known Member
Sorry I have created some confusion.
I have PM ed QBhoy not lw395. The former posted that he had a Malta carb in pieces at present so would give me some hints.
Just to go back a bit. The pump is an integral part of the carb and I can't see how you could bypass it. One could perhaps remove the little reed valves so fuel could flow straight through.
However the diaphragms were replaced last year, and i have twice opened the drain plug on the float chamber immediately after the engine had stopped. Fuel came out which is why I think it may be more than fuel starvation.
I have PM ed QBhoy not lw395. The former posted that he had a Malta carb in pieces at present so would give me some hints.
Just to go back a bit. The pump is an integral part of the carb and I can't see how you could bypass it. One could perhaps remove the little reed valves so fuel could flow straight through.
However the diaphragms were replaced last year, and i have twice opened the drain plug on the float chamber immediately after the engine had stopped. Fuel came out which is why I think it may be more than fuel starvation.
VicS
Well-Known Member
Have you checked the float height setting... ( 12 -16 mm measured as described in the W/S manual )
lw395
Well-Known Member
OK, if the pump cannot be bypassed, you could feed the carb via the pump from a burette, if you felt that would help see the flow of fuel.
Sometimes you just have to try stuff a little differently to confirm what you think is happening.
But really I suspect this is all about the carb, either something is assembled wrong or a jet or airway is blocked, or a gasket is damaged, that kind of thing.
Sometimes you have to go back to the beginning.
Maybe it's worth re-reading the whole thread and then revisiting everything.
It is frustrating trying to make suggestions at a distance, when you feel that if you could see the engine you'd know what is wrong.
It wouldn't hurt to put a strobe on it.
A fresh batch of fuel is another box ticked.
You could take the head off the leg and look at the exhaust.
It's just a matter of eliminating every possibility before either pulling it apart to look at the crank seals or worse or junking it/trading it in.
Maybe put it aside until you can borrow a carb from a running engine.
Sometimes you just have to try stuff a little differently to confirm what you think is happening.
But really I suspect this is all about the carb, either something is assembled wrong or a jet or airway is blocked, or a gasket is damaged, that kind of thing.
Sometimes you have to go back to the beginning.
Maybe it's worth re-reading the whole thread and then revisiting everything.
It is frustrating trying to make suggestions at a distance, when you feel that if you could see the engine you'd know what is wrong.
It wouldn't hurt to put a strobe on it.
A fresh batch of fuel is another box ticked.
You could take the head off the leg and look at the exhaust.
It's just a matter of eliminating every possibility before either pulling it apart to look at the crank seals or worse or junking it/trading it in.
Maybe put it aside until you can borrow a carb from a running engine.
earlybird
Well-Known Member
I'd tend to go with the earlier suggestion that it's likely a crankcase seal problem. A 2-stroke Malta will now be a fairly elderly engine, with plenty of time for deterioration/wear.
Interesting strip-down project for current circumstances.
Interesting strip-down project for current circumstances.
anoccasionalyachtsman
Well-Known Member
But 2 years ago a carb clean cured the same problem....
coaster63
Well-Known Member
Hi. having read this thread with interest. being a malta. owner since first introduced & still have my 2nd one , you seem to have covered all of the usual suspects so certainly bite the bullet & remove power-head to check lower crank seal for damage due to corrosion. which. then kills negative crankcase pressure to draw fuel airmix through reed valves , initial startup is achieved because crankcase is flooded out but soon burnt of so stopping. Another odd fault I found. on another malta I fettled for someone. that I admit. really stumped me at the time was - on inspection spotted that the steel piston liner ports were not inline with casing ports. so heated dissembled power head & rotated liner back into position ,whether this had come about through overheating or bad manufacture i'll never know but it certainly ran alot healthier from then on. with 2 strokes its all about airflow for performance,
hope input helps at all , you may not think so at the moment but the malta is a cracking engine. good luck.
hope input helps at all , you may not think so at the moment but the malta is a cracking engine. good luck.
lw395
Well-Known Member
While that indicates a carb clean is in order, it doesn't rule out anything else.
The 'same problem' is the universal outboard problem 'it doesn't work'.
davidej
Well-Known Member
Hi
Sorry posted in error
Sorry posted in error
Last edited:
anoccasionalyachtsman
Well-Known Member
If you can wait a day I'll have been up to my workshop and could have a look at my spare. I do remember the rubber bung and cleaning in there, but not what it actually hid.
Refueler
Well-Known Member
Exactly ..... like I said about my Vire 6 ... keep spraying fuel mist at air intake and she'd run all day .... till you stopped spraying !!
Its the first thing I would do if I was OP ...... if it keeps running ... bob's proverbial ....
Refueler
Well-Known Member
Yep ... but before that I would be spraying direct into air intake to prove engine is OK ... if that works ok ... then garvity feed the carb - if it now fails - we know its the carb.
My way of thinking is to attack the problem from its working and then steps back till it doesn't.
Spray - it works - Engines ok. Most likely crankcase seals ok as well as its drawing the fuel you spray.
next
Gravity feed to carb - if it works - then its supply problem to carb ... if it doesn't - then its a carb problem.
Yellow Ballad
Well-Known Member
Racing revs on a 2 stroke from cold certainly sounds like an air leak, possibly crankseals but it would be hard to start and would normally require the engine to be spun at a higher rpm for longer than a pull start could achieve. Probably the carb to cylinder gasket? But with an airleak you'll normally be killing the engine manually rather than it dieing out itself (unless it's flooded, burning the fuel and enough fuel isn't getting through)
Be wary about easy start sprays on 2 strokes, they won't lubricate main bearings. You'll probably get away with it for a few seconds but don't let it run long.
I would cast my eye over the jets and airways again, blast carb cleaner through them and give them a poke, although people say to use a soft metal I find a strand of push bike cable is small enough to clear the blockages on pilot jets (the problem comes when people try and force bigger stuff through the jet, mini screwdrivers and the like). The amount of times I've told customers to clean the jets and they come back to say it's still not running and spend a small fortune other stuff. They're at their end and bring the carbs in and the jets are still blocked, I clean them properly, give them the carbs back and I get a phone call saying it's running spot on. Just because you can see light through them doesn't mean they're not blocked.
I did have a merc 2.2 that had a cracked head due to salt blockage, it would actually run for a bit but gradually got worse and worse. I did everything I could and decided to whip the head off and as soon as I did the corner dropped off!
Be wary about easy start sprays on 2 strokes, they won't lubricate main bearings. You'll probably get away with it for a few seconds but don't let it run long.
I would cast my eye over the jets and airways again, blast carb cleaner through them and give them a poke, although people say to use a soft metal I find a strand of push bike cable is small enough to clear the blockages on pilot jets (the problem comes when people try and force bigger stuff through the jet, mini screwdrivers and the like). The amount of times I've told customers to clean the jets and they come back to say it's still not running and spend a small fortune other stuff. They're at their end and bring the carbs in and the jets are still blocked, I clean them properly, give them the carbs back and I get a phone call saying it's running spot on. Just because you can see light through them doesn't mean they're not blocked.
I did have a merc 2.2 that had a cracked head due to salt blockage, it would actually run for a bit but gradually got worse and worse. I did everything I could and decided to whip the head off and as soon as I did the corner dropped off!
RichardS
N/A
It is nearly always my first approach and has been for the last 50 years as described in post #7.
Over the past 10 years I have often mentioned this technique on here and nearly always get slammed for posting nonsense. It finally looks as if the worm has turned.
Richard
Refueler
Well-Known Member
It should GUSH out .... you could have fuel in there but if its not a full chamber - then its staved.
Refueler
Well-Known Member
It is nearly always my first approach and has been for the last 50 years as described in post #7.
Over the past 10 years I have often mentioned this technique on here and nearly always get slammed for posting nonsense. It finally looks as if the worm has turned.
Richard
Maybe we should form a club ? The old ways are the good ways club ?
I've even resorted to filling a pipe and blowing it into a carb if I cannot spray ...
With great respect to many experienced and learned people here - I do think the OP should try the easy stuff first before dismantling all and sundry.
1. We can only go by his info.
2. Nowhere do I read that he has tried spraying fuel mix in the air intake to see if it keeps running.
3. Some suggestions TBH - I think risk OP having to give the engine to service to not only fix the original problem - but maybe results of 'advice'.
My Father went all way into town with an appliance for dealer to fix it. Dealer had till next day. Fault ? Blown Fuse.
Start simple - THEN go for the technical stuff.
Yellow Ballad
Well-Known Member
Just read you've had a good go at the pilot jet, I would try and get the main out though.
Have you got the rubber plug someone mentioned earlier in the pilot jet casting after the jet is screwed in? There's a passage from the main jet to feed the pilot. Again a good blast of air should clear this.
Have you got the rubber plug someone mentioned earlier in the pilot jet casting after the jet is screwed in? There's a passage from the main jet to feed the pilot. Again a good blast of air should clear this.
Attachments
davidej
Well-Known Member
I have spent about two hours this afternoon disassembling the carb, very carefully cleaning and then blasting with cleaner every jet and passage, checking the pump and finally re-installing with fresh fuel mixed today
Same as usual. Started easily, ran for about 10 secs then died. It wouldn't restart even with fuel sprayed in the intake.
Unless some kind forumite is willing to lend me a working carb to try as a control experiment, i am goin to go with the crankcase leak theory.
It cant be too difficult to get at the bottom two(?) seals but the top one will be much harder. Presumably is is likely to be at the bottom where corrosion is likely to occur
Same as usual. Started easily, ran for about 10 secs then died. It wouldn't restart even with fuel sprayed in the intake.
Unless some kind forumite is willing to lend me a working carb to try as a control experiment, i am goin to go with the crankcase leak theory.
It cant be too difficult to get at the bottom two(?) seals but the top one will be much harder. Presumably is is likely to be at the bottom where corrosion is likely to occur
Yellow Ballad
Well-Known Member
Have you got a spare plug? Once it cuts out, clip on a plug to the cap and check for a spark straight away. I had a nightmare with a Honda ATV that ran for 10 seconds or so and it turned out to be the CDI. Took a while to find as firstly CDIs are pretty reliable and if they pack up they tend to pack up and secondly the time it took us to get the plug out to check the spark it had come back. I'm guessing the capacitor was breaking down. Obviously primary/ignition coil is breaking down that could be an issue.
For what they cost and the time it would take stick some new crank seals in but even if they were worn, once the engine is started you can normally tickle the throttle to keep the engine going as there's enough crankcase pressure in a running engine. It would however normally pop and puff with little power and struggle to start.
For what they cost and the time it would take stick some new crank seals in but even if they were worn, once the engine is started you can normally tickle the throttle to keep the engine going as there's enough crankcase pressure in a running engine. It would however normally pop and puff with little power and struggle to start.
davidej
Well-Known Member
Yes I put the bung back. I saw the passage from the main jet casing to feed the pilot but what slightly confused me was that that item 20 screws right up to item 19. So how does the fuel get into the casing of re main jet to pass through to the pilot?
I might try the spare plug trick tomorrow before I start taking the whole thing apart.
