Bizzare running FJ

[rhubarbray]

Hi all. I`ve got a strange one for you.
First off, I have an `88 FJ12 that`s all stock except for a Pipercross air filter. Now the problem. NO power under load. It will rev when in neutral if you give it a handful of throttle. Pull in the clutch, it will still rev, put in in gear, it will still rev. Go to take off and it will fall flat on it`s face, in first! I`ve had the bike out earlier in the year so it did run.

Now, I`ve had the carbs apart twice and checked every passage I can find. I`ve checked for seized float pins, leaky seats and changed the o-rings on the seats. Checked the diaphragms for pinholes and tears and checked the pilots, mains, and tubes for blockages. I`ve had the carbs mounts off and resealed them. Checked the entire harness for shorts/chafes/and pinched wires. Cleaned and checked all the connectors and switches and sprayed them with Deoxit. I`ve bypassed the sidestand switch, the clutch switch, the fuel pump relay, and then the fuel pump itself. I`ve checked the cam timing and valve clearances. I`ve checked the airbox for mousenests.

Now for the wierd. If I can coax it up to 3-3500 it will suddenly kick in and take off,....but not always. I`ve also pulled the choke knob out a bit and it will help a lot,....but not always.

I have a second hand CDI coming, and then I`m stumped.

I still think it`s a carb issue but I can`t see how.

Anyone?

Ray

[Dan Filetti]

Ray-

You've sure done a lot of homework, that helps.  My money is on the carb still being blocked.  Not that I'm an expert, but for me the key seems to be the 3-3500 rpm bit.  I know certain jets do not come into play until above certain rpms so I guess you have a clogged idle-jet -someone check me on that. 

As to why you did not find it on either of your two cleanings, not sure, -did you use professor Raforth's outstanding instructions?  Were you using liberal amounts of spraying and soaking in Berryman's B-12 AND compressed air?

Have you checked you float LEVEL?

As to why the power return is intermittent after 3-3500 rpm  - perhaps a smart carb guy can provide a plausible explanation for that.

But again, I'm guessing on it be a carb issue.

Good luck.

Dan

[weymouth399]

Ray
Try pulling the choke on a little, if it is a restriction in they pilot jet that should bypass pilot jet. with the enrichment valve if it don't pick up I doubt there's blockage
poss try different filter, or w/clean air box try no filter (do not ride it this way) static test in shop.
hope this helps Bob

[andyb]

Vacuum leak.

[SlowOldGuy]

You are describing the exact symptoms of clogged idle jets or circuit.  Did you remove the idle mixture screws and make sure the circuit was unobstructed?

DavidR.

[rhubarbray]

Ok, I`ve just pulled the carbs for the third time. I pulled the diaphragms and looked for the tiniest pinhole,..nothing. There was some slight wear where they fold over so I did the forum approved repair with the Pliastidip to see if anything would change but I`m not holding my breath as there were no holes to start with.
  I realize that my symptoms sound like all 4 pilots are plugged and normally I`d agree. I just pulled the pilots, looked through them, they looked clear and just to be sure I ran a bristle from a brush down the hole to make sure there wasn`t a tiny piece of glass there. I then blew contact cleaner into the pilot jet access hole,...it came out the air jet at the carb inlet. I then blocked that and cleaner came out the idle mixture hole (I didn`t even take out the screw) and the three holes by the edge of the butterfly.
  As for the vacuum leak, all mounts are pliable with no cracks, the vacuum nipples at the top of the mounts are good and the mounts themselves have been remounted with Threebond to the head.

As to the fuel level, I haven`t checked that. I`ve done float height but I can certainly do the fuel height tomorrow.

If it`s not raining tomorrow, I`ll try it again.

Anything else I can try?

Ray

[WS]

Hello Ray, sounds like a hard one. First I would check the valve clearance. Than a compression check. Do you have a synchronizer to balance the carbs? If not it is hard to do the job right. Also check the little o-rings under the mixture screws? Make sure they are in good condition. Good luck Werner

[fjrpierre]

I was interested in the Pipercross air filter and read this in the cleaning instructions

Pipercross Cleaning Instructions
The cleaning of a Pipercross air filter should be carried out as below. Failure to do this could result in damage to the air filter or even the vehicle.

Remove excess dirt by gently brushing the filter.
Apply cleaning additive (C9003 or C9000) liberally. Massage in with soft brush. Allow to soak for around 5 minutes.
Flush the filter out with warm water from the clean side of the foam to the dirty side.
Allow the filter to dry naturally (do not apply any heat to the filter!!)
Lightly apply dirt retention additive (C9007 or C9001) on the dirty (black) side of the foam.
Steps 2-4 may need to be repeated until the filter is clean. Do not over oil the foam as this will cause a lack of performance.
Pipercross Air Filters

Perhaps your lack of performance is related ? Have you tried going back to stock filters?

[andyb]

That's the same way any foam or gauze filter is oiled, with the absolute minimum oil on it to work or airflow goes into the toilet.

Almost wondering if there's an engine issue after reading all this though, i.e., jumped a tooth on the camchain.  A compression check would be the fast way to check that.

[rhubarbray]

The cam timing and valve clearances have been checked. I have two valves that are .0005" tight and they`re going to be changed out this morning. Compression check I haven`t done but I can. And Pierre, I`m starting to lean to the filter as well. Not sure why it would run and then not but I can clean and check. I don`t have a stock filter but then again, that`s why I bought the one you can clean and reuse!
I know for a fact the o-rings are there under the mixture screws and as for condition, they`re ok. Not great as they`re a little flat but I have to pull them out rather than having them fall out when I tip the carbs over to get the screw out. Does anyone have the size of the o-rings so I can go get new ones? they`ll be about 2mm x 1mm wall? Guessing.

[andyb]

3mm ID x 1mm section

[SlowOldGuy]

How do the plugs look?

[fj1289]

How old is your battery?  The FJ igintion system needs a good strong battery.  I've had similar problems when the battery starts to go. 

Good luck and keep us posted - you will find the kookaloo again!

[andyb]

How do the plugs look?

Actually, fouled plugs could do this also, the spark being blown out when the throttle's opened.  Shouldn't run at higher revs then, unless enough combustion temp is being produced to cause them to clean up a bit though.

[ccsct203]

Check and make sure you have all your spark plug boots seated well and while you are at it check for spark on all four plug wires.
I bet thats it.