boat bogs down when in gear

The motor runs like a champ when its on the earmuffs out of the water. Docked it yesterday, started up quick like it always does, i got to deeper water and opened it up and it started to go but then it just stopped about 1/3 throttle. If you'd give it any more throttle it sounded like it wanted to die. We limped the boat around like that all day, no problems other than that. It sounds to me like lack of fuel.

Last year i resealed and cleaned all three WB carbs because it wasn't running the best. After i cleaned the carbs it ran like a brand new motor all season. The one mistake i did was when we put it up for the winter i didn't drain the carbs or run the fuel out of it. so I'm thinking its something with the carbs again.

The vent tube on the gas tank is kinked so I'm gonna get new hose for that today. Also how do i tell if the plugs are bad? i haven't changed plugs on it in a couple of years. They aren't the plugs like in a truck, it doesn't have the hook on the end where the spark bounces off, its just flat on the end of the plug. The bottom plug is pretty black and fouled, think I'm gonna do a compression test and see what that tells me.

This is the first time the boats been on the water this year. Like i said when in gear (about 1/3 throttle) the motor seems to bog down. But when you just rev the motor (not in gear) it works fine?

its a 1980 something mercury 80hp.

 

I'd guess carb related too. usual problem is the float chambers dry out and any residual aromatics stick on things like the float needle, idle mixture cone and passageways etc etc. Note especially the idle mixture screw, which also shows up with uneven idling. Just remember to count the turns in (to lock out) before you remove them.....

It can also be the accelerator pump passageway and jet if you have one on that type of engine. Recently had to strip at least three different carbs for minor problems, pretty much all related to lack of use even though a couple managed 30+ hours without fault. However as the proportion of aromatics in unleaded fuel (UK) is around 5% you are never sure what is actually gumming it up. Not sure about US fuel but I think you have more ethanol and probably a different mix of aromatics. Ethanol does faster damage to any 'rubber' diapghrams than very old leaded fuel did so if yo have any, check the condition and 'stiffness'.

 

I've had three engines that did that, could never figure out the problem, so I called two of them ******* POS and got rid of them. The third time a mechanic said "Oh yeah", replaced the (cracked) ignition coil in 2 minutes and it's been fine ever since.

Not to say it's not carbs and old fuel, that's common and happens to me almost every year, but check the coil (s) first before doing the carbs.

 

Is there any way to test the coils?

The coils are what the other end of the spark plug attaches to, right?

Thanks for the advice

 

I would think so but how to test it is a mystery to me, as is where the spark plug wires go. Sometimes each plug has it's own coil, sometimes the plug wires go to a distributor and then that goes to one coil.

 

The fuel is half new and half old from last season but it had stabilizer in it. I would think if it was a carb issue it wouldn't matter if it was in gear or not but I don't know? I really don't want to take those carbs off and clean them again.

I think my coil is attached to the plug wires because I tried pulling on them and they didn't come out of the coil.

So it's either ignition or gas. Hmmm. Still need to fix that vent tube for the gas tank. It's just really confusing as to why it runs perfect out of water. Even when in water revving and idle is normal, just when in gear.

Looks like 3 coils and plugs are $150. Just hate to spend it if the coils are still good.

 

Coils can be checked with a cheap circuit tester you get at an electronics store, if there is no circuit when you connect your tester to both terminals, it is kaput. Check also that the plug leads are carrying current. But it sounds more like a fuel problem to me.

 

If it is a fuel issue where should a start first? All the lines I replaced last year when I resealed the carbs. How can I test the fuel pump? The fuel filter is good.
As of right now the only problem I can see is the kinked vent hose.

If I do the carbs could I just spray some seafoam in them instead of taking all three carbs completely off?

That's all of the fuel system that I know of.

Tank- clean
Vent- kinked
Fuel line- good
Carbs- cleaned last year
Fuel pump- unknown
Fuel filter- good

 

You should get a workshop manual for it, always a sound investment. Follow the checks listed in that. But the fuel pump would seem a likely one to check out.

 

Hey 1bad79, What ended up being the resolution? I bought a 2002 Sea Ray 176 Bow Rider and it runs decent in neutral or with ear muffs but when I put it in drive my max speed is like 18mph and it doesn't rev very high.

 

Check all of the items that is noted in the previous post.
Is your tank a built in? If so, it may have anti siphon valves at the top of the tank. These can look like normal brass fittings but contain a small check valve. They can get crudded up and
not open all the way thus providing a fuel restriction.
The o-ring where the fuel line connects to the engine might need to be replaced as they can let air into the line.