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Ok folks, I need some help with this one. I have an 05 yamaha f150. Here's my problem, I'll start by telling a quick story to explain: We went striper fishing this AM, cranked the boat easily, ran to the first spot, slowed to about 5knots to mark some fish. Anchored up fished a while, then trolled about 3-5 knots for 20 mins or so to another spot. Cranked up from there and ran 10 miles no trouble at all. When the day was over, I dropped my dad off at the dock and was going to shoot down the river at WOT before trailering. When I got ready to floor it, the engine hesitated (almost missed) then took off but quickly slowed back down. I went to the fuel bulb (primer bulb) and it wasn't hard at all. A few pumps and it was back to normal, and I accelerated normally.
Here's the thing: shouldn't the bulb stay hard all the time? It seems that when the engine is idling, or better yet at a slow troll, I lose fuel pressure. Eventually the engine will cut off, but to prevent this I just pump the bulb a few times every 10 mins or so. It seems like something is wrong. The engine should run all day w/o having to worry about the fuel pressure. I replaced my fuel/water separator filter which helped but did not solve the problem. It's almost like the engine is starved for gas at low rpm. At higher rpm (1000+) she runs fine. I don't think it is the low pressure pumps b/c the engine runs fine otherwise. I have also replaced the engine mounted fuel filter. Could it possibly be that my racor doesn't offer a sufficient flow rate (seems that would effect higher rather than lower speeds however)? I'm baffled by this "problem" b/c the engine runs great and if you pump the bulb every so often, I don't have the least bit of trouble. I've asked numerous people about this and no one can really figure it out. Thanks for any advice/help/thoughts/suggestions!
Most of my broker customers sea trial the smaller boats (both gas & diesel) on fresh fuel from carry on cans. They have learned to not trust the old fuel and spoil a sale.
I have pumped out two boats today for one of my commercial customer accounts, again BAD GAS.
rbhankins: I think you're on to something, I will be inspecting the lines very closely. I recently had to change my fuel line from the tank to the racor filter...I wonder if it could be kinked somehow despite the fact that the fuel line is extremely thick and reinforced to prevent such as issue. $2 of hose from napa can test that.
Absolute: I'm going to add Sea Foam and give the fuel system a good cleaning. Don't think it's a fuel issue ( I always treat my fuel with Stabil) but the system could probably use a little cleaning for maintenance. Thanks for the suggestion.
Here's the thing: shouldn't the bulb stay hard all the time? It seems that when the engine is idling, or better yet at a slow troll, I lose fuel pressure. Eventually the engine will cut off, but to prevent this I just pump the bulb a few times every 10 mins or so. It seems like something is wrong. The engine should run all day w/o having to worry about the fuel pressure. I replaced my fuel/water separator filter which helped but did not solve the problem. It's almost like the engine is starved for gas at low rpm. At higher rpm (1000+) she runs fine. I don't think it is the low pressure pumps b/c the engine runs fine otherwise. I have also replaced the engine mounted fuel filter. Could it possibly be that my racor doesn't offer a sufficient flow rate (seems that would effect higher rather than lower speeds however)? I'm baffled by this "problem" b/c the engine runs great and if you pump the bulb every so often, I don't have the least bit of trouble. I've asked numerous people about this and no one can really figure it out. Thanks for any advice/help/thoughts/suggestions!
If the engine is running, the primer bulb will never stay firm. It is under vacuum(normally) when the engine is running. When the engine is off, there is no vacuum there. So if you pump it, it will get hard and remain hard if there are no leaks after it in the fuel system. Start the engine, it will start using fuel, and that will go from a pressure area, to a vacuum area. Am I making sense? Hope so.
But.....you did find something out. You pumped the primer while it was running bad, and the engine liked that. What that means in part is that the engine is not getting enough fuel to it to run correctly.
You said you changed the boat fuel filter. Did you do anything with the fuel filter on the engine? The reason I ask is that the 05 F150 use the older style fuel filter bowl on the engine with the black ring that holds the filter cup up into the base. Those cups can swell up and you may think its all the way seated, but in reality it may not be. If it is installed correctly, you shouldn't see any threads on the base of the filter assy. The black ring should be covering them all.
Take the cowling off. Engine off. Pump the primer bulb till it gets firm. Then go and look by that engine fuel filter in the clear bowl. Any fuel leaking out of it? Wipe it with your hand. If there is, that is your problem. Or part of the problem.
Check it out and report back
Andy
__________________ Andy Munao Our new parts site: www.simyamaha.com Yamaha Outboard Sales, Parts and Service 1-800-213-3323 parts@shipyardisland.com Click the logo to see our THT Vendor Forum
Thanks Andy, I will hopefully get to that tomorrow pending the rain. And again, I sincerely appreciate your help with the impeller, I got everything changed and she pisses like a champ! Would have ordered the parts from ya but I needed them in a hurry, hopefully next time will be from maintenance and not from error.
Look on the fuel pick up on top of the fuel tank. Most boats have anti-siphon valve that the fuel line connects to. I recommend if you have one to replace it with a straight though fitting and see if your problem goes away. The anti-siphon is there in case the fuel line is cut and falls into the bilge, it will stop fuel from running into the bilge. They are known for causing the problems you are having.
yes I have replaced the bulb and hose and yes the arrow is pointing in the correct direction (towards the engine)
as far as checking the anti-siphon valve, I don't think I can get to the fuel tank very easily (if at all). There's no deck hatch for access to the tank that I'm aware of...I'll do some more investigating but unless I missed something i can't get to that valve
Andy: I checked the engine mounted filter, it is screwed all the way on and no apparent leaks. I checked all the fuel lines and found no signs of any leaking/holes.
What I learned today: The problem occurs at random. I trolled around a good deal today w/o any problems, then randomly the engine sorta bogged down and nearly shut off. 3 pumps and everything was back to normal. I'm beginning to think it's more trouble than it's worth. I would like to check that anti-siphon valve if I can figure out how to get to it...seems like if it randomly sticks then that could explain my problem and why is doesn't seem to have any regularity. It's more of a hassle than a problem, as I don't think it's an engine related issue. If anyone has any other ideas, I'm open to them! Thanks!
I checked the engine mounted filter, it is screwed all the way on and no apparent leaks.
Still seems that air is being induced into your fuel system. Did you observe that engine mounted filter while underway? Was it completely full of fuel at all times? Watch it to see if the fuel level falls inside the canister (so that there is an air pocket at the top) and into which fuel is pouring in from the top. That was my confirmation of air being inducted into the fuel system. I drove around for a bit with the cowling removed. For me, I found that the screw on cap to the canister was loose, even though it has that anti-backoff gizmo. Not coincidentally, I'm talking about an '05 F150.
I had a customer where his boat would bog down sometimes.... when I cleaned the tank I picked up 1) the foil cover under a screw on cap for his fuel additive bottle and 2) what looked to be a piece of clear plastic, maybe from a cigarette pack.
These apparently would get sucked up against the fuel pickup tube and restrick the fuel flow.
You can very easily run your boat on an external fuel tank and hose etc.
This will eliminate your built in fuel system.
You said you replaced a hose, that is a red flag to me.
-Rob
I agree. It is 6 gallon can time. If you can't recreate the problem on a seperate gas can but can on your main then figure what is going on with the fuel delivery. If it acts up on the 6 gallon (with new hose) then figure out what is wrong with the motor.
Andy: I checked the engine mounted filter, it is screwed all the way on and no apparent leaks. I checked all the fuel lines and found no signs of any leaking/holes.
What I learned today: The problem occurs at random. I trolled around a good deal today w/o any problems, then randomly the engine sorta bogged down and nearly shut off. 3 pumps and everything was back to normal. I'm beginning to think it's more trouble than it's worth. I would like to check that anti-siphon valve if I can figure out how to get to it...seems like if it randomly sticks then that could explain my problem and why is doesn't seem to have any regularity. It's more of a hassle than a problem, as I don't think it's an engine related issue. If anyone has any other ideas, I'm open to them! Thanks!
What kind of boat is it? You have to have access the the fuel line connections on the tank. The 6 gal can is a good idea. But you will still have to get to the fuel line connection on the tank at some point. Their has to be a way to get to them. My money is on the anti-siphon valve.
had the exact same problem with a carbed merc black max. I checked the anti syphon valve and there wasn't one. I was told outboards don't use them because the bulb acts like one(??), either way there wasn"t one and I was the original ownwr and the boat was 2 months old. What I DID find was the fittings where the hose attached to the tank were loose, there was no pipie compound and I could wiggle everything. At idle the fuel pump made 1/2psi and would suck mostly air. The motor would eventually use up the fuel I had primed by hand with the bulb. At above idle, the fuel pump had enough strength to pull fuel/air back to the motor and it ran fine. I had even changed the fuel pump thinking it had a cracked diaghram. Once I tightened everything at the tankl, it ran perfect. So:
1- There should be an inspection hatch where your fuel line meets the tank, check for tightness, cracks, etc.
2- try the 6 gallon tank test to isolate is it the motor or fuel system.
3- if the motor(doubt it), does that motor have a low pressure fuel pump?
good luck.
Andy: I checked the engine mounted filter, it is screwed all the way on and no apparent leaks. I checked all the fuel lines and found no signs of any leaking/holes.
What I learned today: The problem occurs at random. I trolled around a good deal today w/o any problems, then randomly the engine sorta bogged down and nearly shut off. 3 pumps and everything was back to normal. I'm beginning to think it's more trouble than it's worth. I would like to check that anti-siphon valve if I can figure out how to get to it...seems like if it randomly sticks then that could explain my problem and why is doesn't seem to have any regularity. It's more of a hassle than a problem, as I don't think it's an engine related issue. If anyone has any other ideas, I'm open to them! Thanks!
Well that engine filter is one item you can check off the list.
Usually if a anti-siphon is stuck or restricted this will create higher fuel system vaccum and you will find your primer buld sucked flat because of the high vaccum. Same with a clogged fuel tank pickup tube filter. Either restriction will create higher vaccum.
Since you probably don't have the ability to check the fuel system vaccum, I would start checking the fuel hose from the primer bulb back to the tank. That includes the boat fuel filter base fittings and hose connections, the boat filter seating itself, the hoses running from the filter base back to the tank fitting and the fittings on the tank itself.
I had a boat a couple of years back that was showing the same systems. We found the boat fuel filter base plug fittings on the ports not being used, we just threaded in hand tight. So check those.
The 6 gallon tank is a great idea too. But when you have a problem that is so intermittent, you might need to roll thru a few tanks to verify that its OK. But if the problem is still there with the portable tank, at least you will know its engine related.
Andy
__________________ Andy Munao Our new parts site: www.simyamaha.com Yamaha Outboard Sales, Parts and Service 1-800-213-3323 parts@shipyardisland.com Click the logo to see our THT Vendor Forum
Yamaha F150 Idle Problem 
