Newbie - 3.8L Stalls/No Power

[ogryry]

Hello Everyone,

First post here. Brand spanking new to the boating world and already questioning how (why??) I ended up here...

My brother and I picked up a 1983 Wellcraft Bowrider which seemed to be in great condition (it is in appearance!) but quickly learned it was not mechanically sound like the previous owner said it was. We never put the boat in the water prior to purchasing (won't do that again!) but it fired right up and sound great on the trailer. For $2k we figured it was worth a shot...

Our first trip out we noticed the boat had some issues because as soon as we left the no wake zone and gave it some throttle it stalled. Tried again and it got up and going but was low on power and took a long time to get up on plane. We cruised around for a bit and accepted the fact that we had some work to do. Jumped in the water and swam for a bit then got back in to head back to the dock and boat would not go at all. Every time we put it in gear it would die or it would shortly there after with just a touch of throttle. Had to get towed in by a personal watercraft....

We figured the boat hadn't been used much as of late, the PO had already purchased a new boat, and came to the conclusion that a carb rebuild and fuel system freshening up wouldn't be a bad idea. So we rebuilt the carb, replaced both filters and the line going from tank to engine. In the process we blew out all lines and the pickup to ensure it was clear and the tank vent wasn't plugged. All good.

Took it back out and it was better. Still low on power but no stalling and it would get on plane more quickly.

The next weekend we bring the family out. What a disaster. Same **** as before. Boat wouldn't take throttle and coming back into the dock it was stalling EVERY time we put in gear. Seems the heat is having an influence on performance somewhat because the longer we're out the worse it gets but temp never goes over 165-170F.

Plugs didn't look bad but replaced them just for grins. No change. Cap and rotor are new and wires look good. But I am thinking the problem may still be ignition related....

I've read that the distributor cam should alternate between sharp angles and rounded lobes. Something relating to the odd firing order of the GM V6.? We pulled the rotor to inspect and it looks like alternating lobes may have been sharp angles at one point. Not having another to compare it to I'm not sure if this is normal or not:

https://i.imgur.com/kIUchEI.jpg

Assuming this cam is worn, could the increased dwell from the rounded lobes be causing the timing to be retarded and it's resulting in lost power?

The plan was to replace the points and check timing and go out again but am I wasting my time with this distributor the way it is? If anyone can chime in we'd certainly appreciate some guidance.

TIA!!!

 

[Scott Danforth]

My brother and I picked up a 1983 Wellcraft Bowrider which seemed to be in great condition (it is in appearance!) but quickly learned it was not mechanically sound like the previous owner said it was. We never put the boat in the water prior to purchasing (won't do that again!) but it fired right up and sound great on the trailer. For $2k we figured it was worth a shot...

you probably over-paid considering the motor and drive are obsolete, and OMC has been out of business for 20+ years

I've read that the distributor cam should alternate between sharp angles and rounded lobes.

your cam lobs are fine on the dizzy. they are not worn

The plan was to replace the points and check timing

buying new points and condensor, filing them (yes, you even file new points), initially setting them, and verifying with a dwell meter should have been done when you first pulled up to your house. along with changing cap/rotor/wires/plugs, the gear box fluids (you have 3 gear boxes on the OMC stringer) and engine oil/filter. you will also want to pull the lower unit and replace the water pump and inspect the splines on the vertical drive shaft.

go back to the carb. if you did not pass a wire thru every passage to ensure its clean, its not clean.

when you drop the lower, do not damage the lower shift cable. they are $500 if you can find one.

 

[kenny nunez]

It may be better to convert your distributor to a Petronics electronic . That way you will never have to worry about getting the dwell or point gap right. To check the centrfigal advance twist the rotor back and forth to see if it springs back. Make sure the timing is correct.
Do as teg above post says with the carburetor. You said that the fuel tank suction tube is clear, did you remove it. I have seen small filters inside the tube that you could blow air through it but when fuel hit it it would start to plug itself . Shove a piece of wire through it to be sure.

 

[211libwtfo]

I'd check your anti siphon valve it's probably right at the tank where it tuns to gas line it's a lil springing check ball. $5 part. Screwed me for about a month of this and that last season.

 

[ogryry]

It may be better to convert your distributor to a Petronics electronic . That way you will never have to worry about getting the dwell or point gap right. To check the centrfigal advance twist the rotor back and forth to see if it springs back. Make sure the timing is correct.
Do as teg above post says with the carburetor. You said that the fuel tank suction tube is clear, did you remove it. I have seen small filters inside the tube that you could blow air through it but when fuel hit it it would start to plug itself . Shove a piece of wire through it to be sure.

If it were option for this engine we'd do it but from what I've read the 3.8 is an unusual bird and has an odd firing order that will not allow it.

With that said, we did get the boat back in the water after installing new points and adjusting timing. Good news: power is there now and gets up to speed quickly. Certainly enough to pull a skier! But it still isn't perfect...

The idle speed should be between 400-600 RPM but when it's adjusted that low it isn't happy. About 70% of the time it will die when you put in gear. And the longer we're out there the worse it seems to get. Bring idle speed up to 900 or so and the problem goes away but I've read that a high idle is bad when shifting into gear.

When the carb was built we set the idle air screws to 1.5 turns as stated in the instructions. The OMC manual says to adjust these screws so RPM is at highest speed. Can anyone tell me how much they should need to be adjusted to see a difference? I went about 1/2 a turn in both directions and didn't notice any change.

R

 

[Redrig]

yes , change those points asap . glad to see you did that .

I got my boat after it sat around for 10 years . I didnt know much about boats then , and ran the boat for the first couple of seasons on the old points . Boy was that a mistake , after new properly set points it was a world of difference .