All this is about a stutter under load and has turned worse.
Finally sorted everything airbox rubbers. New fuel lines
That's a fiddly tank to work on. Now I'm fuel starved. I used "prime" to prime carbs. Started first time. Good job I didn't go out. Engine splutter and stops. Re prime, starts no prob then stops. Repeat.There's enough petrol.
Something's not "sucking"? What do you think? Thanks. T
Homer, with gravity feed fuel you have to have all the stars aligned to avoid problems. I too had starvation issues after years of flawless performance. The single most common issues are fuel line routing and fuel filter.
Use the search function, you will find pictures of proper and improper routing. The line that connects to the tank goes under the split lines after it winds around the top of carb #3. This looks wrong but it keeps the line from getting pinched.
Fuel filter, if you have one, take it off!!! The gravity feed system will work with a new filter most of the time, as the filter clogs the fuel flow is reduced and will cause what you describe.
Did you recently do any work on your filler cap? I had a problem after working on my fill cap, put a simple part in upside down. I should have tossed it.
Tells all recent work performed, it will help us help you.
FJ1100 has gravity feed and no fuel pump. From what I understand fuel line routing is pretty critical to avoid pinching or otherwise restricting flow. I am sure someone will be around shortly to explain the fix.
Another possibility is a plugged gas cap. Try running the bike with the cap open an dsee what happens. With a gravity feed system it does not take much to slow or stop the fuel flow.
Er thank you for the very speedy replies. Yes I have been fiddling like Nero. What started as a stutter is now no go. The thing is, the carbs fill in seconds when I turn to "prime". Then I turn back to normal or " on" I can't read it. So yes I replaced the fuel line. If it was pinched is it still possible to prime but then not function in the normal position. I must admit its a pain tank off tank on. A strange design.Oh, no filter. And took the ball bearing out of the cap...yes I had that problem I used to ride with a spare key in the cap. Ta again.
Quote from: homerfj1100 on June 02, 2015, 12:02:17 PM
Er thank you for the very speedy replies. Yes I have been fiddling like Nero. What started as a stutter is now no go. The thing is, the carbs fill in seconds when I turn to "prime". Then I turn back to normal or " on" I can't read it. So yes I replaced the fuel line. If it was pinched is it still possible to prime but then not function in the normal position. I must admit its a pain tank off tank on. A strange design.Oh, no filter. And took the ball bearing out of the cap...yes I had that problem I used to ride with a spare key in the cap. Ta again.
For fuel to flow into and thru the system, with petcock in "normal/on" position, there hasta be gas in the tank. There hasta be a correctly functioning petcock. And, importantly, the engine hasta be running and supplying constant vacuum to the petcock. It's vacuum supplied by running engine that "opens" the petcock when it's in on/normal position.
What the other guys have said is also applicable, especially abt. paying close attention to hose routing.
FjLee Lee Carkenord 84 FJ1100 Denver CO
Thanks. So before I start playing with the petcock, sort out the lines. There may be no vacuum. There are so many tubes under there, some go nowhere, really, just to the outside. T.
Could be the vacuum diaphragm on the fuel valve, or possibly a build up of sludge on the internal screen of the fuel valve standpipe.
Pull the fuel valve out of the tank and check it.
Perform the suck your petcock test.
http://www.fjowners.com/index.php?topic=9787.msg95549#msg95549 (http://www.fjowners.com/index.php?topic=9787.msg95549#msg95549)
That test sounds dreadful but if necessary I'm up to it :good2: Ta.
Quote from: homerfj1100 on June 02, 2015, 03:00:45 PM
That test sounds dreadful but if necessary I'm up to it :good2: Ta.
My '86 failed this test, replaced with an '84/'85, lost the reserve and gained the prime function.
That's right. I have no reserve. I have a 'prime'. Could I simply run the bike on 'prime' ?. Would that be OK? It's obviously not correct. Interesting. T.
Quote from: homerfj1100 on June 02, 2015, 04:17:05 PM
That's right. I have no reserve. I have a 'prime'. Could I simply run the bike on 'prime' ?. Would that be OK? It's obviously not correct. Interesting. T.
The vacuum actuated petcock is an important safety feature. This stops the fuel from flowing when the engine is off. I would use prime if I had to to get home, but not all the time. Lets find the root cause(s) and fix them so your FJ runs as it should. Do the easy tests first. Verify your fuel line routing is correct.
I found the old thread that shows proper routing of fuel line.
http://www.fjowners.com/index.php?topic=9266.msg87760#msg87760 (http://www.fjowners.com/index.php?topic=9266.msg87760#msg87760)
Thank you so much. Of course there is a time difference. Here it's 11.40pm so it will be tomorrow when I check. Routing first, then other possibilities. I have to say, being English, in Spain, it's fascinating that someone from the US would make such valuable contributions. I was a teacher, not a mechanic. Thus, I know limited amounts of tech.
Why not try to keep my bike alive? I might as well.
There's an underlying simple answer to this. It's finding it that's difficult.
It's a fuelling problem. Got to be.
Let's give it until Saturday. If I fail, I blame myself. Thanks. T.
To check the fuel line routing, you have to lift your Tank. At that point, might as well take it off, drain it, pull the fuel petcock off the bottom of the tank and start from square one. There is a screen inside the tank on the Fuel Petcock outlets. It will have two different heights. The normal run outlet will be the higher one, the Prime, or Reserve is the lower one. Make sure the screen is clean.
In the Prime position the fuel valve is manually open all the time. In the normal run position, the vacuum diaphragm will shut the fuel off when the Bike is not running, otherwise you are depending on your floats and needles to seal completely in order to keep from flooding the engine with raw fuel. Causing a Hydrolock condition that can break shit, very nasty.....
If you have a Mitivac or even a chunk of hose and a good hard suck on the diaphragm to verify its function, could be a cracked diaphragm, or a pinched vacuum hose leading to it.
Then ensure the fuel hose is correctly routed and reinstall the tank.
I lifted the tank, all was well. Then I rested the back end of the tank on some cloths. Also found a tube on the right going nowhere ( not fuel) and stuck it on the right side of the end carb. Irrelevant as its been off b4.
Prime. Choke. Start first time.
Prime off, choke still on. Fine. Revs rising. Choke off. Blip throttle.
Fine. No pops no bangs strong tickover.
15 minutes later, still running. Smooth revvy throttle blips. So carefull lowered the tank . Still running, no prob. I thought I'll go around the block. Out of driveway. Bottom of road. Stops. No start.
Someone helped be push it back up the road. I've got it on charge now and will try to repeat the process. Does that provide more info? Ta. Tony
Quote from: homerfj1100 on June 03, 2015, 07:42:26 AM
I lifted the tank, all was well. Then I rested the back end of the tank on some cloths. Also found a tube on the right going nowhere ( not fuel) and stuck it on the right side of the end carb. Irrelevant as its been off b4.
Prime. Choke. Start first time.
Prime off, choke still on. Fine. Revs rising. Choke off. Blip throttle.
Fine. No pops no bangs strong tickover.
15 minutes later, still running. Smooth revvy throttle blips. So carefull lowered the tank . Still running, no prob. I thought I'll go around the block. Out of driveway. Bottom of road. Stops. No start.
Someone helped be push it back up the road. I've got it on charge now and will try to repeat the process. Does that provide more info? Ta. Tony
So you confirmed that the fuel line is routed properly, good. Did you perform the suck test? This will tell you if the petcock and or vacuum line has a leak.
Why is it on the charger, is there enough power to keep it running or is battery going dead?
Not sure where to write this, above on below
Anyhow, no not performed the suck test yet. I'm wondering, as it did so well, with the tank raised an inch on some rags, that I could try and repeat it.
The battery is a month old but because of this particular problem it has been hammered.
I thought it a good idea to give it a fresh charge for more attempts at starting. Thanks. T
Quote from: copper linked=topic=14031.msg141732#msg141732 date=1433345236
Why is it on the charger, is there enough power to keep it running or is battery going dead?
Quote from: homerfj1100 on June 03, 2015, 10:35:17 AM
Anyhow, no not performed the suck test yet.
Turn the petcock to off, lift the tank high enough to pull the vacuum line off of the #2 intake boot (the other end connected to the petcock) and suck on it. If it vacuum locks then all is good, if you can keep sucking then you need to fix this first. It may be a cracked hose so test the hose as well if you fail the suck test. It is possible that all this hassle is over $0.50 of vacuum line. And you don't need the battery for this test so get after it dude.
When you say turn the petcock to off, you mean "on" don't you? Only 2 positions (I think) on and prime. I shall try. It looks to be an awkward job as the tank won't lift too high without pulling the fuel line off the petcock. T.
Quote from: homerfj1100 on June 03, 2015, 11:49:26 AM
When you say turn the petcock to off, you mean "on" don't you? Only 2 positions (I think) on and prime. I shall try. It looks to be an awkward job as the tank won't lift too high without pulling the fuel line off the petcock. T.
Oops, you are correct "On" and "PRI". If you have to disconnect the line from the tank then have a safe place for fuel to drain to while doing this test (I used an empty water bottle). You will know in the first 2 to 5 seconds if it passes or fails. A pass takes 1 to 2 seconds to get a vacuum lock.
Okeedokee. I took the tank off then removed the vacuum hose from the carb. I don't think it had ever moved. There was a tear or split near the end. I attached it to the petcock and sucked the end. Fuel flowed out of the petcock. So the vacuum works. I cut the split end andcre attached everything properly. My problem now is getting the bloody thing running for more than 20 seconds. There's fuel, the vacuum works (unless the carb isn't making a vacuum). How long can I leave it on "prime", or should I? Thanks T.
Quote from: homerfj1100 on June 04, 2015, 08:47:06 AM
Okeedokee. I took the tank off then removed the vacuum hose from the carb. I don't think it had ever moved. There was a tear or split near the end. I attached it to the petcock and sucked the end. Fuel flowed out of the petcock. So the vacuum works. I cut the split end andcre attached everything properly. My problem now is getting the bloody thing running for more than 20 seconds. There's fuel, the vacuum works (unless the carb isn't making a vacuum). How long can I leave it on "prime", or should I? Thanks T.
The test is not making fuel flow.
You will know in the first 2 to 5 seconds if it passes or fails. A pass takes 1 to 2 seconds to get a vacuum lock.
Did you feel the that you could not suck any more? Or did you keep sucking air to keep the fuel flowing?
I could keep fuel flowing on my '86 but I had to keep sucking, air kept leaking in. It should feel like sucking on a straw with the end completely pinched off.
Believe it or not the bike acted like bikes do. It started. And ran for 15. So threw my helmet on and turned right out of the gate. Uphill. Then left. Uphill. All OK except for that stutter on load that I don't think will go without a carb clean.
However, top of hill turned around and was thinking of going down to the petrol station.
I thought... Nah, I'll go back up the hill. It's very windy and my leg felt cold (and wet). Stopped. Fuel everywhere. Kill switch and coasted back to the house.
Yep the fuel line had come off. So, at least I didn't have to push this time! I need to secure that line with something better than the wire clip Yamaha provided.
T
Quote from: homerfj1100 on June 02, 2015, 12:02:17 PM
Er thank you for the very speedy replies. Yes I have been fiddling like Nero. What started as a stutter is now no go. The thing is, the carbs fill in seconds when I turn to "prime". Then I turn back to normal or " on" I can't read it. So yes I replaced the fuel line. If it was pinched is it still possible to prime but then not function in the normal position. I must admit its a pain tank off tank on. A strange design.Oh, no filter. And took the ball bearing out of the cap...yes I had that problem I used to ride with a spare key in the cap. Ta again.
Will removing the ball bearing from the gas cap prevent a disruption with the gas cap ventilation system and guarantee the tank will remain at atmospheric pressure? I am getting the fuel starvation issue with my '85 after about a half hour of 'enthusiastic' highway riding. Thanks!
Is your fuel line routed correctly?
https://fjowners.com/index.php?topic=18286.0
Quote from: Pat Conlon on October 21, 2023, 07:44:07 PM
Is your fuel line routed correctly?
https://fjowners.com/index.php?topic=18286.0
Yessir. I've checked all the fuel starvation related boxes in this thread including rebuilding the gas cap. I get great power through the rev range as well. I get the stutter and bog after burning about two gallons. I am going to ride tonight and leave the spare key in the cap so I can crack it when the bogging occurs. My bike is a Cali model. I removed the canisters and did all the necessary alterations, except fiddle with the gas cap beyond rebuilding it.
According to the info in the thread below the bearing provides detent for the keyhole cover. I believe you'd want to remove the flapper (orange piece) if venting is an issue.
https://www.fjowners.com/index.php?topic=2024.0 (https://www.fjowners.com/index.php?topic=2024.0)
The early 84/85 gas caps didn't have the flapper valves. They had a small ball bearing that acted as a 1 way valve. I took mine out. The Calif. model FJ's have a special sealed tank system that vented any tank vapors back into the carbs when the engine was running, and when the engine was off, vented tank vapors thru charcoal canisters. When you take this system off the bike I found that I had to modify the cap so to equalize internal tank pressures with outside pressures.
Miker you could be experiencing a failing vacuum petcock...a common problem. One moment fine, next, bam...no gas...
I have not had good luck rebuilding the vacuum diaphragms...I suggest you buy a new petcock from RPM before they are no longer available.
Cheers. Pat
Quote from: Pat Conlon on October 22, 2023, 11:46:40 AM
The early 84/85 gas caps didn't have the flapper valves. They had a small ball bearing that acted as a 1 way valve. I took mine out. The Calif. model FJ's have a special sealed tank system that vented any tank vapors back into the carbs when the engine was running, and when the engine was off, vented tank vapors thru charcoal canisters. When you take this system off the bike I found that I had to modify the cap so to equalize internal tank pressures with outside pressures.
Miker you could be experiencing a failing vacuum petcock...a common problem. One moment fine, next, bam...no gas...
I have not had good luck rebuilding the vacuum diaphragms...I suggest you buy a new petcock from RPM before they are no longer available.
Cheers. Pat
Thanks as always Pat! I'll remove the ball bearing.
Opening the gas cap didn't work. I'll check out the petcock from RPM.