Thanks again everyone. I'll keep working on this and report back with any progress. Very grateful for this site and its users.
Confusion: Fuel Tank and Fuel Pump on Adventure 208
- Thread starter Jonah
- Start date
Hi everyone,
I think that after many months, I may finally have resolved this issue. Thanks again to everyone who chimed in. I'll explain below, but it seems that I may have been getting air in my fuel lines.
I had a mechanic visit me today, and we took a look at things while the boat was on its trailer in the back yard. We removed the main/large access panel on the floor of the cockpit, and had a good look at everything. Fortunately, the tank itself looks fine. Unfortunately, the pickup tube on this model is welded to the tank, and so we couldn't easily determine whether it might be cracked below the fuel line. To eliminate that possibility, we inserted a replacement pickup tube into the old one, which screwed right into the threading of the original. We also found that the brass fitting from the pickup tube to the main fuel hose wasn't tightened down properly, which may have been allowing air into the hose there. We replaced that brass fitting. We also found that the main hose from the tank to the water separator was beginning to deteriorate. Although we couldn't find any obvious leaks, we replaced that section of the hose. The water separator itself looked fine, and showed not signs of deterioration or corrosion to allow air into the filter. The hose from the water separator to the outboard also looked fine, but we went ahead and replaced the primer bulb just to be safe.
Most importantly, we found that the original brass fitting on the original pickup tube was actually a 'T' fitting, which allowed fuel to flow into a secondary fuel hose. That hose ran to a small spare tank, located under the port-side stern seat. It had once been used for the previous owner's kicker. Apparently it was designed to pull fuel from the main tank and then store a gallon or so for the kicker. Unfortunately, it seems that when the kicker was removed, the hose from the spare tank to the kicker was not properly sealed, which had allowed some air to flow back into the spare tank (which was empty), and potentially down the other hose back to the brass "T" fitting at the main tank's pickup tube. That hose, and also the bottom of the spare tank itself, were a bit wet, suggesting that some fuel might have leaked out. (Or that could have been from pressure-washing the boat recently, but either way, the secondary hose had not been properly sealed off.) So, we removed the spare tank and both hoses attached to it.
With the new pickup tube, new fitting, and new hose running directly to the water separator (no secondary hose to a non-existent kicker), she fired right up with exactly half a tank of fuel. Before we seal up the access panel, I'm going to lower the bow (so as to 'lower' the fuel level at the pickup tube to what would be about 1/4 of a tank) and see if she runs smoothly then. Hopefully that'll be it!
Attaching some photos of the kicker tank that was removed. For me, they only show in full if you open them in a new tab.
I think that after many months, I may finally have resolved this issue. Thanks again to everyone who chimed in. I'll explain below, but it seems that I may have been getting air in my fuel lines.
I had a mechanic visit me today, and we took a look at things while the boat was on its trailer in the back yard. We removed the main/large access panel on the floor of the cockpit, and had a good look at everything. Fortunately, the tank itself looks fine. Unfortunately, the pickup tube on this model is welded to the tank, and so we couldn't easily determine whether it might be cracked below the fuel line. To eliminate that possibility, we inserted a replacement pickup tube into the old one, which screwed right into the threading of the original. We also found that the brass fitting from the pickup tube to the main fuel hose wasn't tightened down properly, which may have been allowing air into the hose there. We replaced that brass fitting. We also found that the main hose from the tank to the water separator was beginning to deteriorate. Although we couldn't find any obvious leaks, we replaced that section of the hose. The water separator itself looked fine, and showed not signs of deterioration or corrosion to allow air into the filter. The hose from the water separator to the outboard also looked fine, but we went ahead and replaced the primer bulb just to be safe.
Most importantly, we found that the original brass fitting on the original pickup tube was actually a 'T' fitting, which allowed fuel to flow into a secondary fuel hose. That hose ran to a small spare tank, located under the port-side stern seat. It had once been used for the previous owner's kicker. Apparently it was designed to pull fuel from the main tank and then store a gallon or so for the kicker. Unfortunately, it seems that when the kicker was removed, the hose from the spare tank to the kicker was not properly sealed, which had allowed some air to flow back into the spare tank (which was empty), and potentially down the other hose back to the brass "T" fitting at the main tank's pickup tube. That hose, and also the bottom of the spare tank itself, were a bit wet, suggesting that some fuel might have leaked out. (Or that could have been from pressure-washing the boat recently, but either way, the secondary hose had not been properly sealed off.) So, we removed the spare tank and both hoses attached to it.
With the new pickup tube, new fitting, and new hose running directly to the water separator (no secondary hose to a non-existent kicker), she fired right up with exactly half a tank of fuel. Before we seal up the access panel, I'm going to lower the bow (so as to 'lower' the fuel level at the pickup tube to what would be about 1/4 of a tank) and see if she runs smoothly then. Hopefully that'll be it!
Attaching some photos of the kicker tank that was removed. For me, they only show in full if you open them in a new tab.
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Alaskastreamin
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That T fitting was probably your problem. That extra hose running into an empty tank (that had to be vented) was causing your air leak. I would guess that at around 1/2 tank the suction required to draw up the fuel overcame the resistance in the unused spare tank.
Don't you love gremlins? Glad you figured it out (hopefully). Thanks for sharing the results..
Don't you love gremlins? Glad you figured it out (hopefully). Thanks for sharing the results..
Yamama
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In the future, you might want to consider replacing your sending unit (if it is the original type) with a WEMA unit. The WEMA units are more accurate than the old ones with the pivoting arm with float type. http://wemausa.3dcartstores.com/Fuel-or ... n_p_9.html?
Hi everyone,
Unfortunately, the work that I mentioned above did not solve the problem. I put the boat in the water today, and it happened twice within the first 30 minutes. Fortunately, the new primer bulb works better than the old one, and so on both occasions I was able to pump it until it was firm, then start the engine again. On the first occasion, the bulb was empty, and it took about 10 primes to get it firm again. On the second occasion, the bulb was only half-empty, but I could hear the gas 'gurgling' (suggesting there was some air in it), and it took about 5 pumps to get it firm.
Given the work that my mechanic did (above), I think it's highly unlikely that I still have an air leak anywhere on the tank-side of the primer bulb, and I'm inclined to think that the problem must be in the outboard. Much earlier in this thread, Seasick said:
If anyone has any other ideas along these lines, please chime in. Seasick, I'd be grateful for any further information on the lift pump.
Unfortunately, the work that I mentioned above did not solve the problem. I put the boat in the water today, and it happened twice within the first 30 minutes. Fortunately, the new primer bulb works better than the old one, and so on both occasions I was able to pump it until it was firm, then start the engine again. On the first occasion, the bulb was empty, and it took about 10 primes to get it firm again. On the second occasion, the bulb was only half-empty, but I could hear the gas 'gurgling' (suggesting there was some air in it), and it took about 5 pumps to get it firm.
Given the work that my mechanic did (above), I think it's highly unlikely that I still have an air leak anywhere on the tank-side of the primer bulb, and I'm inclined to think that the problem must be in the outboard. Much earlier in this thread, Seasick said:
seasick said:
If anyone has any other ideas along these lines, please chime in. Seasick, I'd be grateful for any further information on the lift pump.
I am not all that versed on the vtec but my understanding is performs a similar function to the low pressure pumps on the Yamis. If it were bad, I would expect issues starting but not after running. Since you can run for a while, I would suspect fuel starvation. One way to verify that is to run at high speed/load and see how long it takes for the problem to happen. Then try again but at lower speed. If it takes a lot longer or doesn't happen at all then you can be pretty certain that there is insufficient fuel flow.Jonah said:
Have you tried to run with a portable tank? Its a pain to do so but it can help isolate where the problem may be. Three things I have seen that cab cause this are a bad anti-siphon valve. The valve is located at the tank where the pickup tube is and looks just like a regular fitting, straight or 90 degree.
The second is a bad fuel line where the inside has collapsed into itself or pieces have peeled off restricting gas flow. The third is a blocked vent. To check that run with the gas cap off and see what happens,
I hope you find the culprit.
Jonah said:
If the water fule separator is only half ful when the motor stalled, that tells me that it is starved for fuel. If the primer bulb collapsed then the vent, fuel hose or antisiphon valve is plugged. Of course the pickup tube screen ( if there is one) could be plugged too.
If the bulb did not collapse but the water separator filter is half full then your are most likely sucking air. There is a leak upstream of the filter towards the tank or possible in the tank ( that would mean a broken pickup tube.)
First thing to check if you suspect air is the gasket on the spin on filter.
Hi everyone,
Thanks again for your input, and thanks especially to Seasick for several insightful posts on this thread. In the end, it seems that I should have simply left the thread 'concluded' in my earlier post on March 8th, when I posted photos of the air leak I'd found in the old fuel line to an empty spare tank for the previous owner's kicker. That really did seem to solve the problem. When I wrote again on April 29th that the problem had not been solved, I think I was experiencing a one-time occurrence of having some air in my fuel lines from when we removed and replaced them all in March. I say that because the problem occurred twice in the first 20 minutes of riding, and hasn't happened again since.
After my April post, I had the same mechanic visit again, and we took the boat out for about an hour. About 10 minutes at idle, about 20 minutes at 4,000RPM, another 15 minutes at 5,000RPM, and even a few minutes at WOT. The problem didn't happen once. During that time, we tested the high-pressure pump, following the instructions in the E-TEC service manual, and it all checked out fine. I then took the boat out twice more, for a total of another hour or running time, and the problem never occurred. For both of those hour-long outings, I kept the fuel level below a half-tank, which was when the problem would always happen. Since then, I've gone ahead and filled her up, believing the problem to have been solved.
So, Seasick, I think you were right about sucking air, but I think that problem was resolved back in March. I think I panicked in April over what was really a one-time occurrence of air in the lines, from having removed and replaced all the fuel lines the month before. I should add that I did not prime the outboard before firing it up that day, which was the first run of the season since replacing the fuel lines.
Thanks again to everyone for all the help on this thread. I've learned a lot and am very grateful.
Thanks again for your input, and thanks especially to Seasick for several insightful posts on this thread. In the end, it seems that I should have simply left the thread 'concluded' in my earlier post on March 8th, when I posted photos of the air leak I'd found in the old fuel line to an empty spare tank for the previous owner's kicker. That really did seem to solve the problem. When I wrote again on April 29th that the problem had not been solved, I think I was experiencing a one-time occurrence of having some air in my fuel lines from when we removed and replaced them all in March. I say that because the problem occurred twice in the first 20 minutes of riding, and hasn't happened again since.
After my April post, I had the same mechanic visit again, and we took the boat out for about an hour. About 10 minutes at idle, about 20 minutes at 4,000RPM, another 15 minutes at 5,000RPM, and even a few minutes at WOT. The problem didn't happen once. During that time, we tested the high-pressure pump, following the instructions in the E-TEC service manual, and it all checked out fine. I then took the boat out twice more, for a total of another hour or running time, and the problem never occurred. For both of those hour-long outings, I kept the fuel level below a half-tank, which was when the problem would always happen. Since then, I've gone ahead and filled her up, believing the problem to have been solved.
So, Seasick, I think you were right about sucking air, but I think that problem was resolved back in March. I think I panicked in April over what was really a one-time occurrence of air in the lines, from having removed and replaced all the fuel lines the month before. I should add that I did not prime the outboard before firing it up that day, which was the first run of the season since replacing the fuel lines.
Thanks again to everyone for all the help on this thread. I've learned a lot and am very grateful.
Edit to add: I posted after reading page 1, without realizing there were 2, which I don't have time to read at the moment, or seeing the date, so if irrelevant, please disregard.
Ethanol gas can do all sorts of things to fuel lines and tanks. Including separation of the layers within your fuel line, like an embolism or plaque in your arteries. This includes your line from tank to vent, as well as tank to engine. If you are not venting, the engine will starve when the air is sucked out of the tank. With all that has been said, I would make sure my vent line was clear, or replace it, then run a new, ethanol-safe line from the pick-up on the tank to the engine, with a new bulb, and see if that cures your problem. If it is hard to run under the deck, run it out the inspection port, and on top of the deck to test the result.
But before I did all that, I would run the boat on a portable 6 gallon tank, just to make sure the problem was in the boat, and not the engine.
Ethanol gas can do all sorts of things to fuel lines and tanks. Including separation of the layers within your fuel line, like an embolism or plaque in your arteries. This includes your line from tank to vent, as well as tank to engine. If you are not venting, the engine will starve when the air is sucked out of the tank. With all that has been said, I would make sure my vent line was clear, or replace it, then run a new, ethanol-safe line from the pick-up on the tank to the engine, with a new bulb, and see if that cures your problem. If it is hard to run under the deck, run it out the inspection port, and on top of the deck to test the result.
But before I did all that, I would run the boat on a portable 6 gallon tank, just to make sure the problem was in the boat, and not the engine.
SARGolden
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Jonah, Seasick, BobP, Anybody still out there from this thread?
I'm a new owner of a 1995 Adventure 208. I've also been chasing a mystery. It has a 1995 150 Yamaha 2-stroke with lots of hours. But the engine ran solidly for the first 2 months I operated her. 5200+ RPM at WOT and speed through the water of about 30 Knots. One morning we went out and with no other apparent side-effects or issues, she'd only make 4200 RPM at WOT with speed of about 20 Knots. She's been that way ever since. I took her to the local shop. They did a full tune-up, checked compression, fuel filters, hoses, bulbs, water separator etc. and disassembled and rebuilt the carburation. Then took her out again, no change other than running smoother (up to 4300 now) and now starting flawlessly. There is no other symptom than the RPM limit (almost like a governor).
I found your thread very helpful and in particular, BobP made a comment that a piece of sealant caught in the pick-up tube could limit RPM (makes sense). I haven't had my deck up yet but my question is that in order to check such a thing, what would one do? My boat is a similar vintage to yours so I expect that the pick-up tube would also be welded to the tank (I know that I have a metal tank not the newer plastic one). I suppose that I could disconnect the fitting and blow something (Air or gasoline) backwards but there would be no guarantees that whatever it is would be dislodged and even so, the gremlin would remain in the system to come back again later. Is there a way to replace the pick-up tube without taking a blow-torch or angle grinder (spark generator) to the tank?
Any guidance you can give me would be appreciated.
Thanks,
SARgolden
Ocean Park WA
I'm a new owner of a 1995 Adventure 208. I've also been chasing a mystery. It has a 1995 150 Yamaha 2-stroke with lots of hours. But the engine ran solidly for the first 2 months I operated her. 5200+ RPM at WOT and speed through the water of about 30 Knots. One morning we went out and with no other apparent side-effects or issues, she'd only make 4200 RPM at WOT with speed of about 20 Knots. She's been that way ever since. I took her to the local shop. They did a full tune-up, checked compression, fuel filters, hoses, bulbs, water separator etc. and disassembled and rebuilt the carburation. Then took her out again, no change other than running smoother (up to 4300 now) and now starting flawlessly. There is no other symptom than the RPM limit (almost like a governor).
I found your thread very helpful and in particular, BobP made a comment that a piece of sealant caught in the pick-up tube could limit RPM (makes sense). I haven't had my deck up yet but my question is that in order to check such a thing, what would one do? My boat is a similar vintage to yours so I expect that the pick-up tube would also be welded to the tank (I know that I have a metal tank not the newer plastic one). I suppose that I could disconnect the fitting and blow something (Air or gasoline) backwards but there would be no guarantees that whatever it is would be dislodged and even so, the gremlin would remain in the system to come back again later. Is there a way to replace the pick-up tube without taking a blow-torch or angle grinder (spark generator) to the tank?
Any guidance you can give me would be appreciated.
Thanks,
SARgolden
Ocean Park WA
Hi there,
Sorry to hear about the trouble! I can't think of anything that would cause the limit to RPMs, unless someone came and swapped your propellor with one with a different pitch when you weren't looking. You didn't damage your prop in any way, did you? Or, I wonder whether it's possible for an outboard of that age to have any kind of buildup in the lower unit that would prevent the prop from spinning as freely? Probably not, but just a thought.
I think you may be on to something in considering BobP's comment. Who knows if that's the problem, but one thing you could try is what I did along the way, which was to insert a new, plastic pickup tube into your original. The plastic inserts come pretty long, so you can stick it in to test the length and keep trimming the bottom until you've got it just the right length. It's threaded at the top and so screws right into the original tube. That might force out anything clogging the original, and it would also eliminate the possibility of an air leak anywhere near the top of the original pickup tube. At the very least, it's a cheap and simple way to isolate the problem.
Something else that came up earlier in this thread is the possibility that the bottom of the tank is bulging upward. If so, then it could be pressing up against the bottom of the pickup tube and cutting off flow. I can't remember who it was, but someone once had this problem. I can't think of any way to test this other than sticking some kind of (clean!) metal rod down your pickup tube, and seeing if you're able to force the bottom of the tank downward at all (without poking a hole in the bottom, of course!).
Curious to hear if others have any good advice for you.
Sorry to hear about the trouble! I can't think of anything that would cause the limit to RPMs, unless someone came and swapped your propellor with one with a different pitch when you weren't looking. You didn't damage your prop in any way, did you? Or, I wonder whether it's possible for an outboard of that age to have any kind of buildup in the lower unit that would prevent the prop from spinning as freely? Probably not, but just a thought.
I think you may be on to something in considering BobP's comment. Who knows if that's the problem, but one thing you could try is what I did along the way, which was to insert a new, plastic pickup tube into your original. The plastic inserts come pretty long, so you can stick it in to test the length and keep trimming the bottom until you've got it just the right length. It's threaded at the top and so screws right into the original tube. That might force out anything clogging the original, and it would also eliminate the possibility of an air leak anywhere near the top of the original pickup tube. At the very least, it's a cheap and simple way to isolate the problem.
Something else that came up earlier in this thread is the possibility that the bottom of the tank is bulging upward. If so, then it could be pressing up against the bottom of the pickup tube and cutting off flow. I can't remember who it was, but someone once had this problem. I can't think of any way to test this other than sticking some kind of (clean!) metal rod down your pickup tube, and seeing if you're able to force the bottom of the tank downward at all (without poking a hole in the bottom, of course!).
Curious to hear if others have any good advice for you.
Search... start off with eliminating as much of the fuel system as you can. Plumb a portable tank into the engine, as close as possible. If it runs great with that setup, start back tracking. If it still doesn't run, you know the issue is on the engine side. I'd start with that and then post back. It will eliminate a whole lot of guessing on our end. One other thing I would do first... run with the fuel fill cap off.
enfish
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I had that exact symptom once with my 1995 175 Yamaha 2-stroke. Just a few hours after a service, the RPM's maxed out at 4200. Normal WOT was 5300 RPM. It turned out we had a bad spark plug. Problem went away when we changed the plugs again. I assume as part of the tune up, they would have changed the plugs, but you never know...
Eric
If the engine maxes out at 4200 or whatever AND at that max it runs fine ( no surging and no sputtering) I doubt it is a fuel starvation issue. A few things come to mind; electrical relating to spark or something as simple as the throttle linkage is out of adjustment. Checking the throttle adjustments is easy if something came loose but a royal pain if the synchronization of the carbs is needed. For multiple carbs you need a multi port sync tool ( multi port manometer) . You can make one but they don't work as well as the real thing. Connect the linkages but don't adjust any screws! (OK the master idle set screw can be adjusted but based on your issues, it doesn't need to be.) Make sure that the throttle plates are opening all the way. Make sure the throttle control cable is secured properly and that its mounting hasn't shifted.
Electrical/spark issues are also a possibility. That a bit tougher to isolate since the issue is at speed and not idle. I must admit that I am not sure what the best way is to diagnose a high rev spark issue. I generally don't encourage running a motor at the dock in gear and at speed but that is how I probably would approach the issue. Make sure the boat is well tied off, shift into gear, and increase throttle to see what happens. Be careful, there could be a lot of force on the lines. Double up.
Also note that it is not a good idea to rev a motor like that while not in gear. Some motors won't allow you to do that. I think yours will.
The idea presented about running off of a portable tank is good to eliminate starvation issues but you need to plumb the portable tank to the motor directly ( or its fuel line) bypassing the separator, most hoses, etc.
If you have a clear motor mounted filter, take a look at it at various stages, It should not be empty and it shouldn't generally be completely full.
Electrical/spark issues are also a possibility. That a bit tougher to isolate since the issue is at speed and not idle. I must admit that I am not sure what the best way is to diagnose a high rev spark issue. I generally don't encourage running a motor at the dock in gear and at speed but that is how I probably would approach the issue. Make sure the boat is well tied off, shift into gear, and increase throttle to see what happens. Be careful, there could be a lot of force on the lines. Double up.
Also note that it is not a good idea to rev a motor like that while not in gear. Some motors won't allow you to do that. I think yours will.
The idea presented about running off of a portable tank is good to eliminate starvation issues but you need to plumb the portable tank to the motor directly ( or its fuel line) bypassing the separator, most hoses, etc.
If you have a clear motor mounted filter, take a look at it at various stages, It should not be empty and it shouldn't generally be completely full.