3.0L, DDIS, lots of new parts, low power, won't plane...

[emilime75]

Hello. This will be a long one, as it's an ongoing thing with a long lapse in-between. My friends bought a boat, it's a Bayliner Capri, 18', open bow with the 3.0L I/O. It needed work, we did the work...new floor and carpet, new vinyl, new(rebuilt) cylinder head, rebuilt carb, flushed old fuel/cleaned out fuel tank, new fuel pump, new fuel lines, new inline filter, spark plugs, ignition wires, new 3 blade stainless prop(I forget the pitch, but verified it was correct)...

Boat ran great, used it for a a season with no issues. Friends then decide they need a bigger, better boat and bought one. This Bayliner got put away, intended to get sold, but never did. When they moved, it came to me to be stored temporarily...it's now been nearly 4 years, LOL, and the friends decided I've "temporarily" held on to it long enough, and that I can have it if I want it...not really sure I do.

The problem...some time at the end of that first season, or maybe the beginning of the next and right before they bought the bigger boat, this Bayliner started having issues. It would fire up and idle well, but was low on power and would not get on plane. We checked/replaced fuel filters and lines for debris, rechecked base timing and idle speed, spark plugs... nothing looked amiss, but problem wasn't sorted and this is when it was put away for a few years. The boat was winterized, don't really think it would've been bad gas and I'm fairly certain we tried fresh fuel at the time...but it was years ago.

So, coming back to it, I'll go through all of this stuff again. New plugs, fresh fuel, make sure carbs are clean/good...the usual suspects. My real question is about the DDIS ignition. Is it possible it isn't advancing as it should, but still functional enough to let the boat run? Base time is supposed to be 8 degrees BTDC, and ramp/advance 26 degrees between 1k and 2.6k RPM for a total of 34 degrees of timing. Just looking for possibilities beyond the usual stuff, as all that was new/good when it started misbehaving. If I recall, it did reach, or come close to, WOT RPM even though it was very low on power.

Thanks.

 

[Scott Danforth]

go back to fuel. if you have old fuel, drain it, dispose of it, and start over.

go back to the carb. by clean/good, did you pull the carb apart and chase every passage?

did you change the fuel filters

 

[Bondo]

Ayuh,.... Agreed,.... Most likely a fuel delivery issue, not an ignition issue,....

 

[Rick Stephens]

A great place to start since it is so easy, and get a baseline, is get compression readings. Tells so much, rings, valves, wear and tear.

 

[emilime75]

Yes, I will do all of the typical checks and tasks needed to get a long idle boat back to running condition. I know my post was long, but in it it describes all that was done originally, and the problem that cropped up.

The reason I am suspect of the DDIS is,

A: It's DDIS, and
B: The boat reached WOT RPM while not having enough power to get up to speed and plane.

It's my understanding that low power due to a fueling issue wouldn't allow the engine to rev to WOT RPM under load...is this an incorrect assumption?

Either way, let's forget about all that. Really, I'm just hoping for some insight and whether, or not, the DDIS can be functional enough to start/idle the engine, but not advance timing as it should based on RPM.

 

[Scott06]

You can check it with a timing light. I don't know the specs but would expect you'd have 22-26 degrees total advance by 2800-3000 rpm. If you have that I'd look elsewhere, if not you can troubleshoot the DDIS. Most DDIS parts are No longer available so I you do have something wrong you probably would need to upgrade the system to a delco voyager .

 

[Maclin]

I do not quite understand getting to WOT rpm in the water and still saying "low on power".

If the engine truly hits 4600 rpm in forward while in the water then it is not low on power. If the boat is not moving then the prop hub may be spun, or the engine coupler spun or splines rounded off.

When in the water in forward, when you push the throttle all the way down does boat move? If it starts moving, does the engine rev slowly? Or does the engine rev quickly on up to 4600 rpm? What does the boat do, does it stay in the same relative plowing position and speed stay the same?

You may have a very heavy boat from waterlogging, bet even then the engine would be severely loaded down and not see anywhere close to top rpm's.

 

[Bondo]

B: The boat reached WOT RPM while not having enough power to get up to speed and plane.

Ayuh,..... If ya mean, In Neutral,..?? That's Irrelevant,....