three cyls only

[chiz]

Any usual suspects for non working #1 cylinder I got spark at the plug pulling the cap off when engine is running does not alter how the engine sounds in any way.
   
                            T Chiz

[Millietant]

Any usual suspects for non working #1 cylinder I got spark at the plug pulling the cap off when engine is running does not alter how the engine sounds in any way.
   
                            T Chiz

Not sure I fully understand your description Chiz, but am I right in thinking that - you have a good spark at the #1 spark plug electrode, but pulling the plug lead off, with the #1 spark plug in, makes no difference to the way the bike runs ?

If that's the case, my first thought would be a blocked jet, or a stuck-closed float valve in the #1 carb stopping fuel from getting into the carb - has the bike been parked up for a while (gelled up float chamber/passageway/jets), or did it just stop running on #1 cylinder out of the blue in everyday use?.

Can't see it being an ignition system issue as the FJ has 2 cylinders per coil and if the #1 plug is sparking properly, its not the plug, lead or cap.

Hope that's helpful as a starting point.

[chiz]

Yes to the above it just seems strange that one carb would F up  I'm thinking something in the more expensive category.

[Millietant]

I had the same symptoms but with my #2 cylinder after my FJ had been parked up for quite a few months.

When I took the carbs off, for some reason, only the #2 carb float bowl had bright green goopy gel in it, the jets and choke circuit were blocked. I took it apart and put the body, bowl and jets in a sonic cleaner.

The diaphragm on that carb had a couple of pin holes in it (and none of the others did) so I figured that maybe had something to do with why only that carb gelled up a bit (but that could just be a coincidental fluke).

Once everything was cleaned, put back together and a replacement slide and diaphragm fitted, the bike ran again on all 4 cylinders, but it didn't run great - so I had the carbs apart a couple more times (and fitted the RPM o ring and bolt kit) before I eventually got it sorted so that it ran beautifully on all 4.

It wasn't a really expensive fix (apart from the $50 shipping, taxes and fees on "importing" a $24.99 kit) but a time consuming one - and I'm glad a biking neighbour, who is also a friend, has a good sonic bath.

[T Legg]

You said you have spark at the plug when you pulled the cap off while it was running . Did you remove the plug and check if the spark plug is good and is sparking at the electrode ?

[chiz]

I actually put a spark checker into the plug cap as I had plug caps reading OPEN on my meter and still don't understand what make these things go bad!!! anyway got a good spark on the spark checker so I pulled the plug and checked the spark there which was also good. I was thinking of squirting some ether down there while the bike was running to see if #1 picks up.... maybe today.

[T Legg]

Does the exhaust tube for that cylinder stay cold when running?

[ribbert]

Spark plugs have been known to fail only under pressure, that is, show a healthy spark when resting on top of the motor but fail when installed and running. Not suggesting that is likely your problem, more that it's a possibility that should be eliminated (swap plugs with another cylinder)

Noel

[chiz]

Fixed it again but don't know how.....not a clue duh. Oh well.

[Pat Conlon]

Sorry I missed this post...

Next time #1 goes cold...switch the plug leads with #4. See if the problem moves to #4.
The FJ uses a wasted spark ignition #1 and #4 fires simultaneously (from same coil) also true with #2 and 3 which uses the same coil.

If the problem moves from #1 to #4 you know it's something ignition related (plug/cap/wire, not coil)
If after switching, #1 stays cold then it's fuel related (carb)

[Urban_Legend]

Spark plugs have been known to fail only under pressure, that is, show a healthy spark when resting on top of the motor but fail when installed and running. Not suggesting that is likely your problem, more that it's a possibility that should be eliminated (swap plugs with another cylinder)

Noel

This is the exact issue I just had with Sparkles. New set of plugs and all fixed.

[ribbert]

Sorry I missed this post...

Next time #1 goes cold...switch the plug leads with #4. See if the problem moves to #4.
The FJ uses a wasted spark ignition #1 and #4 fires simultaneously (from same coil) also true with #2 and 3 which uses the same coil.

If the problem moves from #1 to #4 you know it's something ignition related (plug/cap/wire, not coil)
If after switching, #1 stays cold then it's fuel related (carb)

...what if it's a plug?

Noel

[chiz]

look fine but getting a set today

[chiz]

OK  I have made some troubling discoveries today... I believe that cyl #1 will work sometimes and considering what I discovered I am not sure why this happens sometimes....  I checked the temp of the exhaust again and #1 was down again so I squirted some eather with zero result I confirmed what ether does when squirted into a good cyl it bogs it at first, #1 nothing happens. There was really no suction at the carb when I opened the throttle compared to other carbs.
   I removed the carb bank and checked compression on all cyls #1 was at 130 this kind of sent me for a loop as the engine should run decent with this.. Anyway with  starter pressed #1 does seem to produce noticeable less suck when I put my palm over the carb mounting rubbers.
    It would be revealing  to do a leak down presumably but I don't have one, I think the head needs to be inspected... Do any of you guy's concur or have any tip's or stuff I overlooked?
Chiz

[T Legg]

130 seems ok especially if you are at higher altitudes. How does it compare to the other cylinders. Valve or compression problems aren't usually intermittent . It still sounds like an electrical problem to me . If you connect a timing light up you can see if it's not sparking in real time while your working on it. Be sure to put the new plugs in or swap spark plug to a different cylinder like Noel suggested. I suppose if there was a crack in the spark plug porcelain insulator the timing light would still flash even though the spark was shorted through the threads to the head instead of jumping the gap of the electrode.