Magnum Problem -- URGENT By ellpee (Read 2,822 times)

[marcystoy]

ellpee - update on mine. Called the dealer I brought it from spoke to their mechanic and he suggested that I replace the fuel filter. So went to Napa and got new filter that can be seen through. Also got some translucent fuel line and put it on. Tested out and the fuel is not even making it to the filter. Called and waiting for them to return call.

BTW - I to could not find small enough clamps either.

Don

[ellpee]

You'n'me, Bro. On mine, though, no problem at all with fuel getting from the tank thru the pump and the tubes to the carb. Fuel gushes out when starter cranks.

Just made another run around town (SMALL town) looking for smaller clamps, no such luck. Saw something on line called QuikClamps that looks promising, also heard that the trickle irrigation world has some really small clamps that are intended for 1/4" trickle tubes and the like, but didn't find them in my little town, where "trickle irrigation" is a foreign language. I also have a PDI how-to document that suggests zip ties, and if I can't find anything better I might have to resort to that.

All that, though, is peripheral chatter. I took out a couple screws on the carb earlier that I think were the cover to the "vacuum chamber." Spring inside, big rubber diaphragm, long needle thingie protruding through the bottom into the carb. All that looked fine, no obvious crud floating around, and the "needle" didn't appear to have any kind of hole thorugh it that could be clogged. Re-installed it all. Cranked several times, no start or even a near-start.

[rapidjim]

ellpee:

Get a can of carb cleaner, disconnect the air filter tube from the carb, spray a small amount of carb cleaner directly into the throat of the carb abd see what happens when you crank it.

Jim

[ellpee]

Will do, Jim. If the problem is crud in the jets, will that clear it, do you suppose? I'm dreading having to get that deep into the bowels of the carb. D8

Tried cranking it again this morning while stone cold, nothing. Good cranking, but no firing at all. Did notice that if I add throttle while cranking it cranks faster, but I'm guessing that's normal. One other thing I haven't done is actually remove and inspect the spark plug, and replace it with an NGK or US brand if it isn't one already.

[marcystoy]

ellpee - seen some good PDI videos on youtube. I went out this morning and changed all fuel lines and vacuum tubing. Took the air intake off and put my hand over it to chock it. Got gas on my hand, so i put the air intake back on and it fired right up ran for a few seconds and died, but started right back up.

I took it for a quick spin around the block and it did not sputter once.

Maybe if you get your lines swapped out that will work for you also.

Message me if you want the link to the vid. It's for a 49cc scooter but i found them very helpful.

Don

[alleyoop]

First thing you guys want to do is MAKE SURE the plug is firing:

1. Take the plug out or use a spare one if you have one.
2. Stick the BOOT CAP on it and hold it against the VALVE COVER.
3. Crank the motor over and see if the SPARK PLUG IS FIREING.

IF IT IS FIRING CHECK FOR A FUEL DELIVERY PROBLEM:

Take the VACUUM HOSE going to the PETCOCK or "Y" or "T" and hold it up and pour about a TEASPOON of gas Into the VACUUM HOSE and let it run DIRECTLY into the INTAKE MANIFOLD. Put the hose back on and Try to start it.
1. It shoud fire at least one and may start and die.
A. If it does then we now know no fuel is being sucked into the MOTOR.

If so then NEXT CHECK if fuel is getting to the CARB:

1. Take the FUEL HOSE off the CARB stick it in a container or cup whatever.
2. Crank the motor over Fuel should stream out in pretty good squirts.
3. If it just dribbles out or nothing then Check for VACUUM:
VACUUM:
Take the Vacuum hose off the PECTCOCK or Fuel Pump and SUCK ON IT.
1. If fuel comes out then you have a VACUUM PROBLEM by the INTAKE MANIFOLD or motor.
2. If NO FUEL COMES out then the PETCOCK or Fuel PUMP OR the TANK'S OUTLET IS CLOGGED.
a. Disconnect the FUEL HOSE ON THE PETCOCK COMING FROM THE TANK. FUEL should come out if not the TANK OUTLET IS CLOGGED.

If YOUR TANK has the PETCOCK attached to the bottom of the TANK REPLACE IT, those are CRAP types PETCOCKs because they have a plastic Piece about 2 inchs on the end of it into the tank. THEY GET clogged and will not allow fuel to come out.

If fuel flow from tank is good and you have SPARK then IT IS ONE OF TWO THINGS:

The PILOT JET PASSAGE is CLOGGED and or you have LOW COMPRESSION and your VALVES NEED TO BE ADJUSTED.
Alleyoop

[58george58]

I had similar problem with fuel line leaks, used small tie wraps instead of clamps.

[58george58]

[replyingto=ellpee]ellpee[/replyingto]Hello

I have a 250cc SHEN SUNL scooter. It was running rough and would go into gear as soon as it started. The throttle cable was to tight, there is an adjustment underneath one of the brake handles. That's where it is on the SHEN. I don't think you should have that much play in your throttle cable.

[ellpee]

Referring back to one of my earlier posts, the fuel line into the carb puts out good solid squirts when I crank the engine, so from that I assume three things: (1) the entire fuel path from tank to carb is open and functioning as it should, (2) the fuel pump is functioning as it should, and (3) since the fuel pump is vacuum driven, the vacuum supply must be up to specs.

From my own limited knowledge and all your helpful posts, I therefore see only two other possibilities, spark or carburetor innards. I verified that I have good spark FROM THE BOOT, but that doesn't rule out a defective plug, so that's my very next step; will do it per your description, Alley, and see what I see.

If that checks out okay, I'll move on to the carb, but in baby steps, first by trying that carb cleaner test. Rather than disconnecting the air cleaner, would it accomplish the same thing if I squirted some into the carb bowl overflow vent that has that little 90-degree, goes-nowhere hose on it? The less disassembly, the happier I'll be.

When all this is over, George, I do think I'll adjust out at least some of the slack in the throttle cable. It's enough right now that I could see the cable jumping off that little metal wheel on the side of the carb, and that certainly couldn't be a good thing.

[ellpee]

Some other random thoughts in the name of general education:

"Vacuum tube going to the petcock"? As far as I can tell I have two vacuum hoses coming off different places at the "output" end of the carb; they meet up at a "Y" connector and come out the other side as one hose going from the Y to the fuel pump. No petcock visible anywhere there, and I have yet to get a good look at my fuel tank to know if there's a petcock there.

I found and ordered some smaller clamps on EBay (pause for a laugh -- a lot of what one finds there comes from China!), but I may also solve my hose clamp problem by putting the smaller hose snugly into a small piece of larger hose, and using the readily available larger clamps on that. The latter are nominally supposed to be good for 1/4" to 5/8", but cranking them down tight on 1/4" hose, or even 3/8", is a big of a challenge.

[strikeout]Valve cover? Where the heck is the valve cover on this thing? [/strikeout] Belay that -- dumb question. Has to be at the top of the cylinder, and I found several UTube videos showing that to be the case.

Finally, at I said in my OP, I'm replacing things as I go -- fuse holder, hoses, clamps, some electrical connectors, everything I get access to as my problem search progresses. Should've done that on Day 1.

[alleyoop]

The throttle cable GRIP should only have no more than 1/4 of an inch of PLAY BEFORE it actually pulls on the CABLE to open the BUTTERFLY.
So here is how to adjust it where it connects to the bracket on the carb:
Alleyoop

[ellpee]

Easy enough, thanks, Alley. As I said, I have to give mine a pretty good twist before that pulley starts to turn.

[marcystoy]

ellpee - fuel pump (petcock) is in your 3rd pic. On our trike the the one that you have labeled fuel in from tank ( is the line from tank also that is where my fuel filter was located. Tube to the y is a vacuum line, the on you have to the card is correct. The two connector at the Y that goes to the carb area one connects to your intake manifold and the other one to the carb its self. the one going to the carb on mine was very loose even with a clamp on it. I changed all the vacuum hoses. Also you should see 2 electric wires just below the hose to the lower part of card. The smaller wire was really loose on mine I also crimped it together so it fit snug.

Hope my posts are of some help to ya.

Don

[ellpee]

Yup, everything here is helpful in one way or another, since I've only lived in scooterworld since November. I guess the sheer number of my cries for help somehow qualified me as a "Senior," but in matters scoot I sure don't feel like more than maybe a new sophomore.

And now -- wait for it -- the Magnum is up and running. It was the spark plug. I had a good strong spark off the boot, but when I pulled the plug -- which, by the way, was torqued way tighter than any other plug I've ever encountered -- put it in the boot and held it to ground, there was only an occasional, feeble spark. The electrode was covered with black gunk, and after I cleaned that off I had a killer spark every time. Plug (an NGK, by the way) back in, one short crank, vroom. Just like it was before the incident.

So aside from doing as much PDI stuff as I'm capable of, I'm good to go again. Of course there's still the question why, at just 180 miles, my plug was that funky. All my scooting so far has been at or above 5000' (our house is around 7500'), and I've read here and there that factory mixture settings may not cut it at high altitude. So if in a couple hundred miles it happens again, and believe me I'll be watching for it, the next thread I'm likely to start will be asking for help -- ideally pictures -- of what to turn to adjust the mixture, and whether leaner or richer is the correct recipe.

So you're calling the fuel pump a petcock? I always thought that was some kind of an on/off switch for liquid flow, and there's no such switch on or anywhere near my fuel pump as far as I can see. Somebody else mentioned one at the bottom of the gas tank, which makes sense, but I haven't yet gotten a good look at the gas tank.

Oh, a PS about that throttle cable adjustment: it's easy in concept, but on my scoot that nut one needs to loosen is in a Godawful position that just about calls for a special around-the-corner wrench to loosen it. So that bit will have to wait until I find the right tool, or can slip some mechanic $20 to do it for me.

[marcystoy]

ellpee - great to hear that is up and running. That was my first thing to check since I had a start issue with the wife's first trike in April 2013. So you are up one on me there as a newbie! Everything that I was seeing and reading they referred to the fuel pump as a petcock. I personally had never heard of a petcock, always a fuel pump to me.

Just glad it was nothing serious for either one of us.

Don