2004 50 hp 4 stroke stalling out

[Houston_Al]

Hola,

My F50TLRC starts and runs for a few seconds, then dies out.

A little background: I was guilty of letting this outboard sit for a few years and knew I would have issues. I have piddled with it for a few months now and think I am close, but not quite. After removing carburetor assembly and rebuilding the carbs using carb cleaner and replacing several parts, along with cleaning out my gas tank and replacing fuel line (with primer bulb) and using new fuel, I cranked it up and it ran decent. But, after just running on a few occasions, I started accelerating, gently, since I am using ear muffs (no test propeller). It would hesitate and sometimes stall out. So after reading things online and talking with some people, it seemed like a new fuel pump could resolve this.

I put a new fuel pump on and now I have this issue. What gives, could a new fuel pump actually make this thing stall like this after it had been running/idling before replacement? One thing I noticed is that on new fuel pump, the piston that protrudes was actually slightly farther out than on old fuel pump, and would return to this same position after depression.

Thanks for any info on this.

[99yam40]

Those 4 stroke carbs need to be set properly with special equipment.
Might need to have a Yamaha guy/shop with the proper equipment set them for you

[Houston_Al]

I appreciate the advice, since I am by no means an expert on these. But, I am hoping not to go there, we'll see. The thing is it was running before replacing the fuel pump and from checking my Seloc, it indicated that if my idle was good, then I would not have to make adjustments syncing my carbs. Are you saying that carbs out of sync could also cause this hestitation or stalling, even though it is running at idle?

Thanks again..

[99yam40]

If I had to guess what the problem was from changing the fuel pump, I think something from the lines or pump when disconnecting and hooking back up hit the carbs and caused some plugging inside if things changed.

A 4 tube/channel manometer is needed to properly set up the carbs
if something is running lean it will not have the power to accelerate

[Houston_Al]

I managed to get it running regularly again and I beleive the new fuel pump has helped since it does not sputter or heisitate, as much. But, it is not at 100%. After reading on this more, I agree, the carbs are probably not excatly synced. But, not sure if I will invest in a monometer or check first with a shop to see what they would charge. Guess it's the old cost/benefit question, should I spend on equipment that may not use that often or take it in if reasonable? We'll see.

I read somewhere about a carbtuner (www.carbtune.com) that I am guessing is same as a monometer. Not sure if it would just easily connect to my motor, though. Does anyone have experience hooking this or something similar up? From Seloc, once I have it connected, it looks like I would need to adjust carbs 1, 2 and 3 to be in line with #4 carb on bottom?

- Appreciate the help

[TownsendsFJR1300]

I managed to get it running regularly again and I beleive the new fuel pump has helped since it does not sputter or heisitate, as much. But, it is not at 100%. After reading on this more, I agree, the carbs are probably not excatly synced. But, not sure if I will invest in a monometer or check first with a shop to see what they would charge. Guess it's the old cost/benefit question, should I spend on equipment that may not use that often or take it in if reasonable? We'll see.

I read somewhere about a carbtuner (www.carbtune.com) that I am guessing is same as a monometer. Not sure if it would just easily connect to my motor, though. Does anyone have experience hooking this or something similar up? From Seloc, once I have it connected, it looks like I would need to adjust carbs 1, 2 and 3 to be in line with #4 carb on bottom?

- Appreciate the help

I have that Morgan Carbtune. And yes, it is a manometer. Excellent piece of equipment, 1mm increments in the scale, no liquids, paid for itself after the first use.. Once its done, you know its done correctly...

There should either be some nipple on each carb to attach the vacuum hose to or a threaded hole. The Carbtune does come with threaded, plastic fittings(likly will fit your engine if needed).

[boscoe99]

Just think how much more pleasurable owning an outboard motor would be if they did not have so many carburetors that can and will foul up.

Let's see. Instead of one carburetor with larger size passageways that are less prone to being fouled, let's use three, four or six that each have smaller passageways still.

More weight, more complexity, more cost, more maintenance, higher probability of a running problem, etc. What a brilliant idea.

[TownsendsFJR1300]

Just think how much more pleasurable owning an outboard motor would be if they did not have so many carburetors that can and will foul up.

Let's see. Instead of one carburetor with larger size passageways that are less prone to being fouled, let's use three, four or six that each have smaller passageways still.

More weight, more complexity, more cost, more maintenance, higher probability of a running problem, etc. What a brilliant idea.

Can you say, job security?? Lots of parts,maintainance labor, etc???

[robert graham]

Just think how much more pleasurable owning an outboard motor would be if they did not have so many carburetors that can and will foul up.

Let's see. Instead of one carburetor with larger size passageways that are less prone to being fouled, let's use three, four or six that each have smaller passageways still.

More weight, more complexity, more cost, more maintenance, higher probability of a running problem, etc. What a brilliant idea.

It does seem like 1 big carb with intake manifold to each cylinder would be simpler/better....but maybe the performance would suffer?...

[Houston_Al]

Ok, I went ahead and got the carbtune pro. After some back and forth with idle adjustments and some stalling out, I finally got the thing hooked up and giving me some readings. I had to make a few adjustments to get them in sync and it does seem better during idle and when I gas on it. But, there is that one point when I START accelerating that it hesitates and sometimes stalls out. I ran out of daylight when messing with this other day, so I was thinking to hook it up again to see if I can make them all sync up at a higher reading on the carbtune to see if any difference.

Does any one know if this would make a difference, or is there something else I can adjust to get this to not stall out when starting to accelerate (God forbid this TPS I've read about)?

Again, appreciate any info given...

[TownsendsFJR1300]

I haven't done it with the OB but on my 600cc, 100HP Yamaha, inline 4 motorcycle engine I use the Carbtune on it. It has a red line of 14,000 RPM.

Per the Motorcycle manual you set idle to spec and adjust the sync to within 10mm. I have mine set to within 3mm's.

Not mentioned, is to check and re-adjust (for this paricular engine) at 4,000 RPM's. You'd be surprised how much a difference it makes in smoothness, etc. You ca get a happy medium between 4k and idle 1,300 RPM's

Obviously, YOUR engine does not rev that high but checking the sync at slightly higher RPM won't hurt.

Do you have any major jumping with any cylinder? The valves should be adjusted within spec for an accurate sync.