fj running great 10 miles

[JOMPPA10]

i have guestion my fj running great abouth 10 miles then she stops. First symphtom is that she start runnig rough and dont respond throttle
abouth half mile and then stop. What coud couse that?
ive asked that same question another thread and make all things: carb cleaning etc..
And bike is -90 with fuel pump not gravity fed. Fuel pump is facom automotive pump,i changed that because
original pump got broken and point repair kit last 2 veeks.

[MOTOMYSZOR]

It looks like blocked vacuum system in fuel cap.

When Your FJ will start running rough, just stop and open fuel tank cap. If You will hear hissing of air sucked in to tank You will be sure.

[JOMPPA10]

It looks like blocked vacuum system in fuel cap.

When Your FJ will start running rough, just stop and open fuel tank cap. If You will hear hissing of air sucked in to tank You will be sure.

noup ewerything breath well from tank

everythig done with tank and fuelcap flappes gone etc..

[FJmonkey]

It looks like blocked vacuum system in fuel cap.

When Your FJ will start running rough, just stop and open fuel tank cap. If You will hear hissing of air sucked in to tank You will be sure.

noup ewerything breath well from tank

everythig done with tank and fuelcap flappes gone etc..

Did you remove the flapper valves? Or the the white plastic part that holds the flappers? If put in upside down, the white plastic bit will cause the tank to vacuum lock. Don't ask me how I know...

[JOMPPA10]

It looks like blocked vacuum system in fuel cap.

When Your FJ will start running rough, just stop and open fuel tank cap. If You will hear hissing of air sucked in to tank You will be sure.

noup ewerything breath well from tank

everythig done with tank and fuelcap flappes gone etc..

Did you remove the flapper valves? Or the the white plastic part that holds the flappers? If put in upside down, the white plastic bit will cause the tank to vacuum lock. Don't ask me how I know...

noup i remowed Ewery thing from airpassage to tank to air, in here vere i live we dont have any emission laws abouth mc , but wery stright laws aboth cars co2 shoud be under 100 etc.. no v8:s etc..

[FJmonkey]

Sounds like it might be your fuel petcock. If it develops a vacuum leak it will starve the carbs as well. Do the suck test.

http://www.fjowners.com/index.php?topic=9787.msg95549#msg95549

[JOMPPA10]

Sounds like it might be your fuel petcock. If it develops a vacuum leak it will starve the carbs as well. Do the suck test.

http://www.fjowners.com/index.php?topic=9787.msg95549#msg95549

there is only one line wich goes to fuelpump and breather hose from fuelcap still bike is 90 3cw

[ribbert]

Sounds like it might be your fuel petcock. If it develops a vacuum leak it will starve the carbs as well. Do the suck test.

http://www.fjowners.com/index.php?topic=9787.msg95549#msg95549

there is only one line wich goes to fuelpump and breather hose from fuelcap still bike is 90 3cw

There is a 90 deg elbow under the LHS of the tank where the fuel line exits, it has an 8mm square plastic tap to shut the fuel off (for removing the tank) did you fiddle with that at all?

When did the problem start and is it why you replaced the points and then the pump?

What made you think the points lasted only two weeks?

Is the pump suitable?

Does the fuel line still have the spring around the outside of it?

Will is restart after a period of time, if so, how long?

Does the problem change depending whether the motor is hot or cold to start with?

Have you got plenty of fuel in it, that is, not near reserve?

Have you removed the fuel line from the pump to the carbies and turned the ignition on to see if fuel pumps out for a few seconds?

You say the tank is breathing, but have cracked the cap after it dies to make sure?

How old is the fuel filter and is the fuel flowing freely through it?

Are you remembering to push the choke off?

How many times have you repeated this cycle of 10 miles then dying?

10 miles is way further than you would get with dirty carbs unless the bowls were slowly running dry (insufficient fuel supply)

What you describe is classic fuel starvation. For it to happen after 10 miles is strange. It is further than you would get on full bowls if they were not being replenished and suggests the supply is not keeping up with demand rather than no supply at all.

Your description sounds like fuel starvation but the other thing that's happening over that ten miles is your engine is getting hot which introduces all sorts of other possibilities.

The key to homing in on the problem is to establish beyond doubt whether you're running out of fuel of spark. Diagnosing over the net is difficult but all those checks above won't take long and least then, even if it doesn't fix it, you'll have half dozen things you can eliminate as a possible cause.

If you don't have any luck, a good, old school mechanic could tell by the seat of his pants what's going on. Might be worth the investment, even if you just pay to have it diagnosed and then do the work yourself.

If need be, there are ways we can describe they may help you establish these things yourself.

Noel

[FJmonkey]

there is only one line wich goes to fuelpump and breather hose from fuelcap still bike is 90 3cw

I forgot your FJ is FP not GF... The suck test is for GF (Gravity Feed) like my '86. Sorry...

"my fj running great abouth 10 miles then she stops. First symphtom is that she start runnig rough and dont respond throttle"

This sounds like a fuel delivery problem. Your fuel pump may be cutting out, fuel filter may be clogged. The contact points can be cleaned/sanded to last longer. Also check your filter, make sure it is not clogged.

[JOMPPA10]

and bike has n.1 exhaust pipe much cooler (ican touch it) when she stops. is it fuel or electric problem, no
fuel smell when istop few minutes and she running fine again.
btw all carbs cleaned good abouth 10 times

[JOMPPA10]

and bike has n.1 exhaust pipe much cooler (ican touch it) when she stops. is it fuel or electric problem, no
fuel smell when istop few minutes and she running fine again.
btw all carbs cleaned good abouth 10 times

new fuelpump so called original Yamaha fj fuelpump
from amazon hope it helps
current is facom automotive pump

[scotiafj]

  mines was doing the same thing tho it took ages to start again ..turns out it was crap in the tank..blocking the fuel tap filter ..ie the small gauze one attached to the tap..take tap out and swirl and drain tank then reinstalled tap.. when bike was under load and fuel was getting drawn to tap the crap was also getting drawn to it and blocking it thats why it would restart ok after it had stopped as there wasnt crap getting drawn to the tap and settled back down..sounds like thats what yours is doing .. I would remove the tap and then just remove the small filter from it ..that way any crap that was still in the tank after you drained it would get caught by the one under the tank ... I jus used a large in line auto motive one..works just the same as the yamaha one and costs less .. hope this helps ??

[IceFJ]

and bike has n.1 exhaust pipe much cooler (ican touch it) when she stops. is it fuel or electric problem, no
fuel smell when istop few minutes and she running fine again.
btw all carbs cleaned good abouth 10 times

I had #4 cylinder colder than the rest a while ago and it turned out being bad spark plug causing it to run rough
Just a thought....