2007 F115 TLR Running Issues

[Andrew3754]

Bought a used 2007 F115 TLR 133 hours from Craigslist and it had issues with it not running correctly, sounded like it was running on 3 cylinders. I took it to a factory authorized service and they checked everything and replaced many parts.
This was on inspection to buy the motor.
They checked compression and did a leak down test, all good. Replaced spark plugs, all fuel filters and cleaned the vst tank, sent the injectors out for cleaning. After that, it still didn't run good so they replaced the wiring harness complete, per Yamaha, that wasn't the problem so they replaced the computer, once again per Yamaha and it got much better, but still not 100%.
They sent me home with the motor and I completed the purchase with the guy, he paid for the repair btw.
I installed the motor on my boat and went for a sea trial and the motor was missing badly at all ranges and got worse. I took it back to them and they checked everything over on the computer and seemed through. They noted it still had an issue so I left it.
They synced the vacuum in the intake, #4 was different so they adjusted that, now running even better, but not 100% I took the boat home and to sea trial. Although much better the motor has a miss or stumbling and it seems to be real noticeable at 2000 to 3000 rpm and then sort of smooths out, but not completely. Then at full throttle its starts missing or stumbling again at 5300 and won’t go over 5600. It doesn't matter if it's in the water or out of the water you can hear it missing or a little poping at 2500 rpm real good. This motor looks very clean and it has been sitting a while prior to these issues. They checked for clean fuel and other things as well.
Does anyone have any ideas.

[leveehog]

Fuel?

Must have good supply of clean fuel. Lack of fuel or air in fuel would cause these types of motor skips.

1 - Clean carb float bowls and needles of dirt or buildup. be sure needles have no worn flat spots or rough scratches. If these stick temporarily you will have skips in fuel flow. While you are here remove and clean the fuel jets. IMPORTANT: Set the correct float height. Too low and carb will starve for fuel, too high and it will flood. My pro V P150 TLRP float height is 1500 mm (0.6 in)

2 - Clean boat fuel tank by removing fuel gage and siphon trash or water from bottom of tank. Jack up one side of boat to get it all. Change boat filter if you find any.

3 - disconnect fuel line at motor fuel filter inlet. Connect a 12 in piece of clear vinyl tube, a vacuum gage (can get a fuel combination vacuum, pressure test gage a auto parts store for about $20), and a siphon suction pump to the fuel line. Suck on fuel line and watch for air bubbles in the clear tube. If you have any air, Check all hoses and tighten clamps, boat filter gasket, and even intake tube in fuel tank. you should be able to pull 6 in hg on tube with no leaks. If you have any bubbles you haven't fixed it yet. may need to double clamp all connections or replace primer bulb. If you don't get good fuel flow check for obstructions: Collapsed line, fuel filter, or strainer on end of tank intake tube.

Good luck.

[leveehog]

Fuel?

I can't take credit for the fuel supply testing procedure. Photos of the test equipment and full procedure is found here.

HOW TO: Testing your boats fuel system. Page: 1 - iboats Boating Forums | 290505

[Andrew3754]

Must have good supply of clean fuel. Lack of fuel or air in fuel would cause these types of motor skips.

1 - Clean carb float bowls and needles of dirt or buildup. be sure needles have no worn flat spots or rough scratches. If these stick temporarily you will have skips in fuel flow. While you are here remove and clean the fuel jets. IMPORTANT: Set the correct float height. Too low and carb will starve for fuel, too high and it will flood. My pro V P150 TLRP float height is 1500 mm (0.6 in)

2 - Clean boat fuel tank by removing fuel gage and siphon trash or water from bottom of tank. Jack up one side of boat to get it all. Change boat filter if you find any.

3 - disconnect fuel line at motor fuel filter inlet. Connect a 12 in piece of clear vinyl tube, a vacuum gage (can get a fuel combination vacuum, pressure test gage a auto parts store for about $20), and a siphon suction pump to the fuel line. Suck on fuel line and watch for air bubbles in the clear tube. If you have any air, Check all hoses and tighten clamps, boat filter gasket, and even intake tube in fuel tank. you should be able to pull 6 in hg on tube with no leaks. If you have any bubbles you haven't fixed it yet. may need to double clamp all connections or replace primer bulb. If you don't get good fuel flow check for obstructions: Collapsed line, fuel filter, or strainer on end of tank intake tube.

Good luck.

The motor is fuel injected? The fuel is brand new and we also ran it with and external tank of fresh gas to be sure. Same result. The fuel lines are all brand new marine grade 5/16" and the bulb is also brand new, clamps on everything. Fuel pressure at the fuel rail is holding steady at 40psi at idle and higher rpm up to 3500 running it in the driveway.

[leveehog]

Then you've covered fuel

Sorry, I could have looked up the motor to see if it was fuel injected and 2 or 4 stroke. anyway sounds like you have fuel end completely checked out.

[rodbolt17]

actually, "all per Yamaha" is an outright lie.

I would be embaressed as a tech to call Yamaha to diagnose an issue.

all I ever call them for is autherizition or to cover my arse.

after 4 5.3L v8's I did. its a good thing I did leakdowns,manifold leak tests and documented when I called,who I talked with and what was recommended.

the lawsuits have commenced.

[boscoe99]

actually, "all per Yamaha" is an outright lie.

I would be embaressed as a tech to call Yamaha to diagnose an issue.

all I ever call them for is autherizition or to cover my arse.

after 4 5.3L v8's I did. its a good thing I did leakdowns,manifold leak tests and documented when I called,who I talked with and what was recommended.

the lawsuits have commenced.

"actually, "all per Yamaha" is an outright lie." Agreed.

How in the world is some guy that works for Yamaha, sitting at a cubicle tens/hundreds/thousands of miles from the motor, in a position to tell a mechanic what is wrong with a motor or what needs to be done to that motor? It should not come as any surprise, but he is not. Some of those Yamaha guys are not even actual marine mechanics and if they are they may not have any actual experience with a particular model.

It should embarrass any marine mechanic to have to call a motor maker for help. The motor maker is depending upon the mechanic for that help, particularly if it is a warranty issue. The only time the mechanic should be calling Yamaha is to report precisely what the problem is and what parts are needed to fix it. Yamaha then gives the guy the authorization to proceed to do the work.

But Rodbolt, tell us what you mean about "the lawsuits have commenced".

[TownsendsFJR1300]

Did they check valve clearances?

You can have a tight valve cold (passes leak down test) and when heated up, doesn't seal fully..

[boscoe99]

Did they check valve clearances?

You can have a tight valve cold (passes leak down test) and when heated up, doesn't seal fully..

I thought the "leak down" test was the cats meow and the only and final solution to determining a mechanical problem within a motor?

Tried to insert a smilie but no joy.

[TownsendsFJR1300]

Yes it is.

However if there's .005" clearance allowance for the exhaust valves and your is at .001" cold, your engine will still pass the leak down test as tight, no leakage(or very little) past the exhaust valves.

Once its running and to temp, clearances change, valves (in this case) may not close fully and run crappy, not sealing fully as the clearances are too tight.

Most engines have looser exhaust valve clearances than the intake valves because they of course run hotter (with hot exhaust gases).

IMO, when your doing a leak down test, your at TDC for that cylinder anyway, pulling a valve cover and spec'ing the clearances (especially with an on-going problem) is a must..