Chino California help

[yamaha fj rider]

Wish I could join you To much work and can't ride with a broken wrist.

Kurt

[FJmonkey]

Here is an update. I took a ride yesterday, same route as before with freeway, stop and go and a cool down period while I had lunch. Zero issues. I decided to make the ride longer, I need the problem to happen again to learn what the hell is causing it. More stop and go, this is when I had the issue last ride, not this time. Up Bouquet canyon and to the reservoir, I kept going. Palmdale in my mirrors, Angels Forest highway, Pat would love this road, nothing but high speed sweepers through the hills. Angels Crest to stop at Newcomb's ranch for a drink and bio-break. 120 miles and zero issues, I hate problems like this.... Met a guy that was a short time member that had a 92, he liked the bike but he sold it. Found out about us after he sold it. Signed up and sold off his extra parts. But I digress, back to the update.

Headed back home, about 4 miles from Newcomb's I felt the subtle loss of power. It was happening, I quickly switched to Reserve and checked voltage. Voltage was reading 14.3. I found that I could get the engine to keep power by shifting down and keep the RPMs up. Makes cornering really choppy like being in the wrong gear on a two stroke. This went on for another 2 miles like this till the condition degraded rather suddenly and stalled like it did near Chino. I know I had plenty of fuel, I filled up that morning and only went 120 miles or so another 60/70 before the fuel light comes on. Interestingly though, this is about the same amount of fuel when it stalled in Chino... Another voltage check and with the RPMs dropping so was the voltage, with the engine stopped voltage was 12.5/6. I opened the cap, ran the starter a few short bursts (voltage dropped to 9.5 while cranking but the starter had good cranking speed) and no cough. I add choke and it fires right up. I re-close the cap, switch back off Reserve, take the choke off and run the 15 miles back home with zero issues.

I am still puzzled. After the last two issues I got it started and it ran for miles with no issues. It seems fuel supply related, twice now I had about the same amount of fuel in the tank (60 miles or a little over a Gal + reserve). Switching to Reserve has no noticeable effect. Opening the cap (flappers already missing) and giving it some choke seems to get the engine fired back up. With the flappers gone there should be zero vacuum in the tank. I wish I had a spare key to allow me to open and close the cap while riding. I guess I really need to see if the bowels are empty when she cuts out. Then I can focus on or eliminate it as a fuel issue. I will take a look and see if I can install a temporary sight tube on one of the outside carb bowels. I think I saw this on a post to determine float height. It will need to be secure from vibration and the air rushing past it. I am open to your thoughts and opinions, and I appreciate the help you have already provided.  Stay thirsty for Kookaloo my friends....

[Flynt]

Mark...  Isn't this sounding like the fuel line routing problem?  When your tank gets lower and you have less head pressure is when it appears to happen.  Maybe line routing or fuel filter should be gone over carefully...

Don't know how you guys live without a fuel pump anyway, maybe just fit one to eliminate a host of needless issues?

Frank

[FJmonkey]

Mark...  Isn't this sounding like the fuel line routing problem?  When your tank gets lower and you have less head pressure is when it appears to happen.  Maybe line routing or fuel filter should be gone over carefully...

Don't know how you guys live without a fuel pump anyway, maybe just fit one to eliminate a host of needless issues?

Frank

I have reviewed the line routing a few times and it seems proper. But if the head pressure is the issue then it should be more consistent or grow worse as the fuel level drops. My ride the day after Chino was on the same tank without filling up. And it ran well for miles at freeway speed. After the stall (at slow speed, less demand for fuel) it ran well all the way home at freeway speed, I was just getting the soft red glow of the fuel light at 185 miles on the trip meeter when I got home. So it is hard to say, a pinched line is simply smaller and will only let so much fuel through at a given pressure. As the pressure drops, the flow is also reduced. I stalled at low speed then ran at sustained freeway speeds for the 15+ miles home. The symptoms don't add up.

Similar to a clogged filter, which I don't have. I had the petcock off last year when I wired it up as a precaution. While it was off I cleaned out the filter screen. It was not too dirty but it was out of the tank already.

Can the fuel line have intermittent problems? Same goes for the petcock. One member 56 CHEVY said he had similar issues and changed out the petcock. Never had the issue since.

[Marsh White]

Do you have an OEM or aftermarket fuel filter?   Definitely fuel related.   Not a voltage problem.   The FJ can run off of the battery alone (with no incoming power)  down to 10.2 volts.   Sounds exactly what I experienced once with 2 different types of aftermarket fuel filters.  I switched back to the OEM filter and the problem was solved.

[FJmonkey]

Do you have an OEM or aftermarket fuel filter?   Definitely fuel related.   Not a voltage problem.   The FJ can run off of the battery alone (with no incoming power)  down to 10.2 volts.   Sounds exactly what I experienced once with 2 different types of aftermarket fuel filters.  I switched back to the OEM filter and the problem was solved.

Now I have to pull the tank again, I did not think I had a fuel filter. If I do then I am clearly not changing it when I need to. I don't see a fuel filter in the parts fiche for an 86'. But that does not mean one was not added.

[yamaha fj rider]

+1 on fuel petcock, don't you have that vacuum operated one. How old is it? Fuel level gets low and less pressure (weight of fuel) pushing fuel through the petcock and the bike quits running. Hope this helps. If the tank could pressurize bike would stay running longer. JMHO. Hope this helps.   

Kurt 

[FJmonkey]

+1 on fuel petcock, don't you have that vacuum operated one. How old is it? Fuel level gets low and less pressure (weight of fuel) pushing fuel through the petcock and the bike quits running. Hope this helps. If the tank could pressurize bike would stay running longer. JMHO. Hope this helps.   

Kurt 

I am leaning towards the petcock as the source of intermittent failure. A pinched fuel line or clogged filter are constant conditions. Filters don't unclog them selves then clog up again. They get enough crap in them and like a pinched line restrict flow. Randy is bringing a spare for me to the Napa rally. Easy to change out and I will know that part is not 26 years old. 

[yamaha fj rider]

Hope you get this sorted out and have a great rally. Maybe next early spring after my wrist heals you can show me some of the great roads in SoCal.

Kurt

[Pat Conlon]

Get a 84/85 petcock, that way you have a prime function to use...
Also check that your 2 bowl vent hoses are open and unobstructed

[FJmonkey]

Get a 84/85 petcock, that way you have a prime function to use...
Also check that your 2 bowl vent hoses are open and unobstructed

It looks like it has the vacuum feature to stop the flow with the engine off. Does it still have the electronic reserve function? It cost less than the 86/87 unit. Good advise, thanks. I will have the tank off today to check a few things, I will include these vent hoses.

[FJ1100mjk]

It does not have an electric reserve function.

[FJmonkey]

It does not have an electric reserve function.

Thanks, losing this feature seems like an upgrade.

[Flynt]

Can the fuel line have intermittent problems?

What if the line expands and is pinching as it heats up...  while moving at freeway speed and getting some additional cooling, everything's fine.  You could be right at the point where a little heat makes the line pinch shut when you slow down and the engine heat is radiating out.

Thinking out loud...  just get a pump and be done with this voodoo.

Frank

[FJmonkey]

What if the line expands and is pinching as it heats up...  while moving at freeway speed and getting some additional cooling, everything's fine.  You could be right at the point where a little heat makes the line pinch shut when you slow down and the engine heat is radiating out.

Thinking out loud...  just get a pump and be done with this voodoo.

Frank

I doubt the line's rate of expansion will vary that much from cold to hot, but you are thinking about possibilities. To switch to a pump will take some changes, the carbs need some different bits to deal with the added pressure. I may decide to fit the 86' with a pump just to say I did. Just not in the next few days....