miss when fuel at 2 bars

[Yamamike]

I seem to remember seeing a post about the suction screens in the fuel tank? My 83 runs a little rough when the fuel gets down to 2 bars on the gauge.

Any suggestions?

[videoarizona]

I seem to remember seeing a post about the suction screens in the fuel tank? My 83 runs a little rough when the fuel gets down to 2 bars on the gauge.

Any suggestions?

 

You can drop the petcock and see if the filters over the screens are clogged. Either that or you have junk or water in the fuel and it's being picked up as the tank gets low...

[Flyinfool]

My first guess would be fuel pump is getting weak.

First half of tank fuel level is above floats so pump does not have to work as hard. End of tank pump has to lift fuel up to the carbs.

[cowpuc]

Got great advice going thus far IMHO.. First thing I would ask myself is whether or not I am 100% positive the fuel gauge/sending unit is functioning properly and I am not just running out of fuel. Next I would activate the fuel pump on and off with the kill switch and listen to the fuel pump to see if its pumping consistently. Then I would double check the flow valve on the tank vent and make sure it is wide open, while I got it off the hose I would blow hard on the vent hose into the tank and see if the stumble clears up = could mean weak pump if it does. Then I would replace the fuel filter down on the pump which should be replaced regularly anyway = not out anything if it doesnt help. Next I would pull the seat, open the tank up by removing the sending unit - take my pen light and look in the tank and see whats in there - good time to take a mirror or your finger tip and check on the roof of the tank for rust stalagtites.. Remove the remaining fuel and do the pet cock thing...

The pumps on the MK1's seem to be more durable than the newer stuff - no idea if that is factual but it sure seems to me that is so from all the fuel pump issues I have read about on here.. 6 MK1's and only one pump failure to date here and that was a points issue = still carry a spare pump though cause me and Murph never got along well..

 

Ok,, I'll shut up

[Marcarl]

Running with Fool's idea, could be the fuel filter.

[Condor]

On an '83 there's probably a whole bunch of cr@p in the bottom of your tank. Put the petcock on reserve and see if it still misses...or dies... You'll know whether the tank needs to be cleaned out.....

[Yamamike]

Thank you all for the info...a few more questions arise from all this but first here's what I've done so far.

1. drained tank
   
2. remove petcock...no filter screen at all and no reserve feature
   
3. remove fuel level sensor to have a look...this baby is super clean and no sign of water
   

New questions;

1. will the petcock from 84 and on first gen fit?
   
2. not saying the filter should not be replaced but if it was dirty, I would this the problem would be there whether the tank is full or near empty
   
3. where is this flow valve
   

[Yamamike]

OK I found what looks like a check valve about half way down the breather hose. Is this what you`re talking about Cowpuc.

 

I have to wonder if it`s actually a filter since it seems to have very little restriction whether i suck or blow on it!

[Yamamike]

All right...finally found my parts list and this valve Cowpuc referred to seems to be a roll over valve. If that`s correct, it would indeed be a check valve and I should not be able to blow through it...am I right

[Freebird]

That would be correct. Unless you get under the bike and blow from the other direction.

[Yamamike]

Hi again...how does one test this fuel pump? Is it possible to disable the pressure switch?