3.0 Mercruiser help...fuel issues?

[hoowahfun]

Wow thats crazy. Hopefully they'll get it straightened out.

 

[mizestang]

Checked plugs again to see if any were fouled, nope. Started again, adjusted timing to get a smooth idle, dies after 10 sec. Its like the fuel is falling off. I don't know carbs, but it really does seem to be related to this rebuild.

 

[mizestang]

Maybe check your anti-siphon valve and the inlet screen on the pickup tube from the tank. You could be getting gas, just not enough, and something is restricting the line.

Also if you left your tank half empty over the winter you could have condensation that formed and you now have water in your tank. Maybe collect some of the gas from the fuel filter and let it sit in a jar a bit and see if it has any water in it.

Replaced Anti-siphon valve, same issue.

 

[hoowahfun]

Shop said the carb wasnt properly done and that is the problem. The tech could keep it running if he constantly gased the throttle. WTF? Paid 200 for professional job.

How long was he able to keep it running? Did he get the carb straightened out?

 

[mizestang]

How long was he able to keep it running? Did he get the carb straightened out?

The tech could keep it going if continuous throttle was given. I was able to keep it alive for about 10 seconds with no throttle. Carb guy is supposed to call me in an hour.

 

[TurtleTamer]

Do you mean above "idle" throttle (but at steady-state) or he had to keep pumping it to keep it running? If he had to keep it cracked above idle then maybe the idle speed adjuster screw needs to be turned in a bit to open the plates some or the mixture screw is grossly out of adjustment. If you pulled the carb and took it somewhere to have it replaced, these are two adjustments that will NEED to be addressed after install to run it. If he put it back on the boat and called it good, he should have set it.

If he had to keep pumping it, then it sounds like the idle circuit is fully plugged and it's running off the accelerator pump. Severely retarded timing can also require the throttle to be higher or even the throttle to be pumped, but you'd hear the exhaust very loudly and probably get steam from the still-burning fuel exiting the exhaust valves and hitting your riser water. It can be hard to get the timing right to run it when you've lost your reference but you can tell if you're too far advanced when the starter gets slow at the compression stroke of the firing cylinder (it pretty much stops the engine briefly). Back it off about ten degrees from there and you should be ok. Time it with a light ASAP when you get it running enough to do so (but you probably know that).

It should be warm enough as well to run without the choke. I wired mine open when I was having issues so that I could rule it out.

 

[mizestang]

Do you mean above "idle" throttle (but at steady-state) or he had to keep pumping it to keep it running? If he had to keep it cracked above idle then maybe the idle speed adjuster screw needs to be turned in a bit to open the plates some or the mixture screw is grossly out of adjustment. If you pulled the carb and took it somewhere to have it replaced, these are two adjustments that will NEED to be addressed after install to run it. If he put it back on the boat and called it good, he should have set it.

If he had to keep pumping it, then it sounds like the idle circuit is fully plugged and it's running off the accelerator pump. Severely retarded timing can also require the throttle to be higher or even the throttle to be pumped, but you'd hear the exhaust very loudly and probably get steam from the still-burning fuel exiting the exhaust valves and hitting your riser water. It can be hard to get the timing right to run it when you've lost your reference but you can tell if you're too far advanced when the starter gets slow at the compression stroke of the firing cylinder (it pretty much stops the engine briefly). Back it off about ten degrees from there and you should be ok. Time it with a light ASAP when you get it running enough to do so (but you probably know that).

It should be warm enough as well to run without the choke. I wired mine open when I was having issues so that I could rule it out.

He had to keep pumping the throttle for gas to keep it running. Dropped it off today at another shop hoping to get an answer. I'll post back

 

[hoowahfun]

Sure sounds like something is not clean or set up right with the carb if it will run with throttle applied, but not at idle.

 

[kerberos824]

As the owner of a 2003 Bayliner with the same setup, I'm anxiously waiting for an update. I hope it's worked out for you. I'm getting ready to do a carb rebuild, but am a little intimidated. First time rebuilding a carb, but there's so much on YouTube that I hope I can just follow along.

Hope you get your issues sorted, and come back to finish the story!

 

[TurtleTamer]

As the owner of a 2003 Bayliner with the same setup, I'm anxiously waiting for an update. I hope it's worked out for you. I'm getting ready to do a carb rebuild, but am a little intimidated. First time rebuilding a carb, but there's so much on YouTube that I hope I can just follow along.

Hope you get your issues sorted, and come back to finish the story!

You're right. With Youtube, it's pretty straightforward.

 

[mizestang]

Update** Shop said, bad gas, timing messed up, needed marine plugs, although the cross reference listed the Autolite plugs I put in, missing clip piece from the professional carb rebuild

and now its purring like a kitty! Guy said 1/2 tank was water. Not sure how that could be since I put 17 gallons of fresh gas in. Now I will only run 91 octane. Thanks to everyone who helped me trouble shoot. Note to self.....drain ALL gas before winterizing! At least I have freshly tuned motor now.

 

[hoowahfun]

Glad you got it worked out

 

[mizestang]

UPDATE*** Not so fast I guess. Brought it to the water today. VERY hard starting. Had to pump the hell out of the throttle all the way to WOT for it to start. Never did that before. After it starts its perfect. Is there some adjustment on these carbs I need to do so that it fires right away?

 

[hoowahfun]

How many times did you pump it vs. what you used to do?

 

[mizestang]

How many times did you pump it vs. what you used to do?

Oh man, I had to pump it like 10 times all the way to WOT until it catches, then it runs fine. Before, about 2 or 3 pumps, then it would start and I would hold it at 2000 rpms until it smoothed out. The dealer said it sounds like the accelerator pump in the carb, but I just had it rebuilt.

 

[kerberos824]

I bought a tank of gas for my car the other day at a Sunoco down the road for me. Absolutely had water in the gas. Car ran like garbage for a few miles - hopefully it wasn't much, and I didn't do anything permanent. But it stalled twice. So apparently these things still happen...

If my Bayliner hasn't been started in a month or two, it usually ends up taking 10 pumps total to get it. I'll start with 5, crank it, and if it doesn't go right away, will pump it 5 more times and then it usually starts right up. This was before all the work it needed. But, that was fairly typical.

 

[hoowahfun]

Could be the accelerator pump wasn't set up properly if they put in a new one. It may not getting the full stroke to pump in enough fuel.

 

[Scott06]

If it sits the carb bowl can dry out. Most likely the first five pumps there isn't much if any fuel in the carb, when you crank it then the fuel bowl gets refilled from fuel pump.

 

[hoowahfun]

If it sits the carb bowl can dry out. Most likely the first five pumps there isn't much if any fuel in the carb, when you crank it then the fuel bowl gets refilled from fuel pump.

I don't think the bowl will dry out in a few days....maybe after a few months, but not days.

I would take your boat back to the shop and have them verify they actually adjusted the accelerator pump per the specs.

 

[hoowahfun]

Note to self.....drain ALL gas before winterizing! At least I have freshly tuned motor now.

Personally, I would rather have a full tank than an empty one. An empty tank will just allow condensation to form and collect water over the winter months. Having a full tank is less likely to do that.