85 omc sea drive

[sems7874]

I have been getting my dad?s boat squared away, fixing one thing after another because he has let it sit for years at a clip. Now he has given it to me. It?s an 86 wellcraft center console open fisherman with a 115 omc sea drive. I have been having a fuel issue with it and can?t seem to figure it out. I have taken it to numerous shops and they refuse to work on sea drives even with me telling them I don?t care what it costs, and really the only reason I took it to a shop is I have not got any more time to mess with it because I work a million hours. The boat runs great if it?s not in the water. It idles great and revs out fine but as soon as you put it in the water and it gets that load on the motor it just takes a dump. I have noticed that the filter is not staying full on the engine in or out of the water. I have replaced all the fuel lines, the carbs, fuel tank, the fuel filters (the one on the motor and the fuel/ water sep), the fuel pump (vro $$$) and a boat load of other stuff literally and still can?t figure this thing out. The boat and motor both have only 30 hours on it and the engine runs real well so I hate to give up on this thing but on the same turn it?s driving me insane. I am a master tech and have been building racing engines for the past 25 years so I have some idea on how things work. I even thought to check the vacuum because the pump runs off vacuum and checked the compression in the motor and that all checked out good. Anyone with any suggestions would be greatly appreciated. Heck I would even be willing to pay a reward for advice that could lead me in the right direction. that?s how desperate I am, or if anyone knows someone who might work on the sea drives. I live in central Florida Saint Petersburg.

 

[tashasdaddy]

Re: 85 omc sea drive

adjust the idle speed up, on muffs, and fine tune in the water in gear, no back pressure on the exhaust on muffs. clogged pick screen in fuel tank. air leak in fuel line.

 

[jonesg]

Re: 85 omc sea drive

What is the idle speed on dry land?
During all these layup periods have the carbs ever been cleaned and rebuilt?

 

[sems7874]

Re: 85 omc sea drive

carbs are brand new. fuel lines all new, fuel tank is new, and no air leaks in lines. fuel pump is new, fuel filters are new. the idle should not matter cause the fuel filter runs out of gas regardless of land or water.

 

[SgtScrounge]

Re: 85 omc sea drive

Check the fuel tank vent screen for a clog.

 

[sems7874]

Re: 85 omc sea drive

new fuel tank and screen is clear

 

[sems7874]

Re: 85 omc sea drive

I appriciate the reply's. because it just takes one idea the someone has not thought of to figure this out. Again thanks and keep em coming. It really stinks because the motor runs so well and the boat even though its old it has been kept in cover storage and still looks as new as the day we bought it. again thanks

 

[jonesg]

Re: 85 omc sea drive

The filter on the engine doesn't tend to stay full once the engine starts running, its the bowls that have to stay full , the filter is just feeding the bowls and you often just see a trickle of fuel flowing through it.

The idle rpm on dry land should be quite high as theres no backpressure.
If the idle is set on land at 700rpm it will not idle in the water.

I have a J150 and it idles around 1100 on the hose, that drops to a very smooth 700 in the water. Thats very typical.

I can appreciate the frustration, you install all new fuel delivery systems and it won't run, but its just something very simple you have missed.

Outboards are a bit "different'.

 

[sems7874]

Re: 85 omc sea drive

yeh thats what i am thinking but i just cant put my finger on it. i dont remember what i set the idle to but it does idle hi on land and idle fine in the water. the filter always stayed full since we bought the boat new. i even replaced the vacuum line from the motor to the pump and still got nothing. my problem and the reason i threw a new fuel system at it is because i work a million hours and dont have much time to mess with it. everytime i get into it i get a call from work to fly out and go tune a motor for a client. thats why i took it to the shops but they refuse to work on sea drives. i even have a buddy that owns a marine shop and he is very good but he wont touch it either. i am willing to pay whatever to get it going for 2 reasons. one so i can use it this lifetime and 2 its the first new boat my dad ever owned and before my grandfather passed he told my dad never to get rid of it. also i fint it hard to go buy a new boat when this boat is almost new. the hatch doors are tinted glass and most i have seen on other boats of its age look white from age this thing litterally looks like it just rolled off the showroom floor. again thanks for the shot. eventualy someone is going to come up with something i have not.

 

[tx1961whaler]

Re: 85 omc sea drive

If it has a primer bulb in the fuel line, does it change anything if you pump it when it's starting to die?

 

[tashasdaddy]

Re: 85 omc sea drive

suggestion, borrow a 3 gallon fuel tank, and a different fuel hose. i have been working on a rude 200, could not keep it running, tried a portable tank, nothing wrong with the motor, clogged anti siphon valve in tank. pump could not suck fuel.

 

[sems7874]

Re: 85 omc sea drive

on land with the muffs the only thing it changes is that it fills the fuel filter. the engine does not run and differently. it runs good with or without pumping it. its when i get it in the water and add that torque to the prop then it starves. you cant pump the ball fast enough to make it run off idle. i was wondering what the vacuum reading i should be getting from the engine to the fuel pump. i did check for vacuum and there seemed to be plenty and the oil injection seems to pushing plenty of oil. mybe its a hair off. not sure what it should be but oil is heavier than fuel so i just figure its enough

 

[tashasdaddy]

Re: 85 omc sea drive

just what are the compression reading on all 4 cylinders.

 

[jonesg]

Re: 85 omc sea drive

The good news is you've attracted the curiosity of a couple of the forum experts, strongly suggest you follow their directions, they'll get to the bottom of it,

I'll just follow, interested to see what it ends up being.

 

[sems7874]

Re: 85 omc sea drive

I did go buy a 6 gal tank with fuel line and pump ball and bypassed the boats tank and same results.

 

[sems7874]

Re: 85 omc sea drive

compression is about 98 on all 4 cyl give or take a few lbs. Trust me i have been a master tech for 25 years and i never disreguard anyones advice. I have been stumped at times and took a few to think about and just someone would say something and it would lead to an idea to solve the problem. weather they have half the years i do i have had it pan out simpley because there are always ideas out there better or different than mine. two heads are better than one i always say. not sure what the vacuum should be from the engine to the fuel pump but it did seem sufficiant. anyone know a solid number it should range in?
again thank you for the ideas

 

[tx1961whaler]

Re: 85 omc sea drive

Darn.
Compression good. Spark good. Leaves fuel---something that affects all of the carbs at once----leaves the fuel pump. Do you have still the old one to try as a shot in the dark? The only other thing I can even guess at is if the spark is crapping out under load, and an inductive timing light hooked up to it when you're running it will show that. But take TD's advice, keep your fingers out of the flywheel when it's running....
What plugs are you running?

 

[sems7874]

Re: 85 omc sea drive

I had that idea also about throwing the old fuel pump back on just for kicks and giggles. will try that when i get back this weekend. I am using a bosh plug and i did throw a timing light at it when i tuned the motor in and had no skip in spark. also it is deffinetly fuel because i just cant get the fuel filter to even stay half full. i will go ahead and throw the old pump at it when i get in town and let ya know how that turns out. I am sure i am going to kick myself when this problem shows itself with the simplicity of it but i really think it is going to be something stupid like that. I am going to replace all the fuel lines when i change the pump back out even though it has all been changed out in the past few weeks and let ya know how it works out. Thanks for all the help

 

[tx1961whaler]

Re: 85 omc sea drive

I had that idea also about throwing the old fuel pump back on just for kicks and giggles. will try that when i get back this weekend. I am using a bosh plug and i did throw a timing light at it when i tuned the motor in and had no skip in spark. also it is deffinetly fuel because i just cant get the fuel filter to even stay half full. i will go ahead and throw the old pump at it when i get in town and let ya know how that turns out. I am sure i am going to kick myself when this problem shows itself with the simplicity of it but i really think it is going to be something stupid like that. I am going to replace all the fuel lines when i change the pump back out even though it has all been changed out in the past few weeks and let ya know how it works out. Thanks for all the help

A couple of things:
Those are the wrong plugs. Get the proper Champions for your motor. This could be 100% of the problem. Boat motors are very particular about which spark plug is used, to the point of destruction (e.g. NGK's melt holes in pistons....)
It is also very common and expected for the fuel filter to be half empty when running, so don't take the fact that it's not full to be an issue. The boat tank is open vented, so the level in the filter can move around.

 

[sems7874]

Re: 85 omc sea drive

we have been running the ngk for years but with that in mind i will grab some champions. its also not that the filter just goes half full but it litterally empties and the only fuel going in or out of the filter is a slight trickle which is fine when running on land because there is no torque on the prop but as soon as you add that factor you can see that that trickle is just not enough