Help needed! 4.3 omc cobra

[Doral90]

Thanks everyone for checking out my post. I am in need of some help. I purchased my first boat last year, it’s a 1990 Doral eclipse with 4.3 omc cobra, from what I can tell I believe it is the 4 barrel HO engine/carb. I am not very mechanically inclined and would like to ask those who may know more about my boat. The boat ran good last year, but I did notice a few things that I would like addressed.

1) engine bogs down on hard acceleration. I have a hard time pulling up a water skier because as soon as I punch the throttle down the anyone would bog down and hesitate.

2) engine does not seem to be running at max rpm range either

3) if I touch the trim while running beyond 3/4 throttle the engine would bog down again.

if anyone has any insight on what may be the cause of this please advise. I have talked with a couple mechanics about this one said it couldn’t be the carburetor and another said could just be the points and need a tune up. I’m going to be getting it tuned up this year so that should address the latter suggestions.

 

[211libwtfo]

I would be willing to bet that when the trim is pressed and bogs it could be corroded connections some where at the battery or solenoids or maybe an alternator with a bad rectifier.

 

[Doral90]

Thanks for the response. I also read that it could be the ground on the tilt trim motor.

 

[211libwtfo]

There was an issue with the site earlier I think but I’m sure some way more experienced folks on here will chime in. Oh and sorry I think they say “ayuh welcome aboard”!?!? That was supposed to come last post. But happy and safe boating. This is a great site you’ll find any answer you’ll ever need with great people. Very knowledgeable.

 

[Maclin]

Can you tell us what pitch prop you are running? Also, have you done a compression check on the engine yet? You may have a combination of things going on.

 

[bruceb58]

Check all your connections...at the battery, ground at engine, battery cable at starter...

What you are experiencing is a voltage drop caused by the large current of the trim motor and it's dropping the voltage to your ignition.

Take all the cables off, bot negative and positive, and sand them until they are shiny metal and reinstall.

I had the exact same problem and it was a bad connection at the starter solenoid. Once everything was cleaned up, it solved the issue.

 

[Doral90]

My prop is a 19 I believe. I have not done a compression test on the engine either. I will have this done, then I’ll have a good idea of what I’m getting myself into. The boat was sitting for 3 years before I bought it last April. People I bought it from worked on it themselves, now they seemed quite knowledgeable but I’m not sure they were doing things to spec

 

[Bondo]

Ayuh,..... Welcome Aboard,..... Problems #s 1, 'n 2 are probably tellin' ya the carb is in need of a rebuild,....

Bruce gives the cure for problem # 3,....

A compression test will tell ya the motor's general overall health,.....

 

[Bondo]

Oh and sorry I think they say “ayuh welcome aboard”!?!? That was supposed to come last post.

Ayuh,.... Don't make me copyright my openin' line,......

 

[Doral90]

Appreciate all the quick replies! Thanks so much everyone. Looks like I have a good plan going forward on how to get the boat running perfect!

 

[Lou C]

I had this same problem with nearly the same engine, I replaced all the battery cables and used marine terminals crimped on, then bolted marine quality battery clamps to the terminals. This eliminated that problem. This is an old boat and it has not been used much in the last several years, so do not be surprised if the fuel system and ignition system need to be gone through. If it still has the original carburetor it will most likely need to be rebuilt. If its a '90 and not an '89 it should have either a Holley 2bbl or 4bbl. One last thing that can cause running problems that is often overlooked is a corroded anti siphon valve on the gas tank fuel line fitting.

 

[southkogs]

Ayuh,.... Don't make me copyright my openin' line,......

Bondo! ... you're officially iconic. :clap2:

 

[Doral90]

I was able to get the OMC manual last year and from all the pictures I was pretty sure it is the holly 4 barrel carb. It looked as though my engine was the 205 hp 4.3 HO. Any idea how to get a carb kit? Wondering on total costs with the rebuild.

I have another question for you all. My power steering pump is leaking. I have put some leak stopper in there but no luck. Is it easy to find a replacement for this?

 

[Lou C]

Holley support is quite good, you can call their tech support (try to get the carb number off of the air horn) and you can buy it right on their website, or

http://www.crowleymarine.com/parts/94442.cfm

 

[211libwtfo]

Ayuh,.... Don't make me copyright my openin' line,......

No no no need for copyrights but it’s sooo iconic I’d pay to use it. But I’ll refrain. I think the site was having issues and didn’t want this lil fella to not get the red carpet treatment as I, soo I extend the well wishes.

 

[Bondo]

Ayuh,.... Yer welcome to Welcome new posters,....

It's the Ayuh, that I've made Mine,....

 

[Scott Danforth]

holley trick kit (complete rebuild kit) is only about $35 thru sites like summit racing and not much more on the holley site.. why spend $60 thru crowley.

post the number on your air-horn, or look up the kit on holley's website

 

[Doral90]

Boat is in storage right now, I’m going to have to get it out to see what the carb number is. What kind of difficulty level am I looking at to rebuild the carb??

 

[Scott Danforth]

the hardest part about rebuilding a holley carb is getting all the gasket material off.

a spray can of gasket remover and a plastic scrapper or putty knife works.

second hard part is chasing all the passages with a fine piece of wire. normally it takes me about a half-hour to strip it down, let it sit over-night, then about 1-2 hours of scraping gaskets and probing the passages, and re-assembly. actual work is just under 3 hours

if you havent done one before, take lots of pics of the linkages prior to pulling apart.

most of the problems comes from gunk in the fuel settling out and plugging bottom passages.

 

[Lou C]

There is a you tube vid where someone did a rebuild on a Holley 4160 on an OMC 5.8 Ford, it is pretty easy to follow....