OMC 5.7 acceleration problem - pics included

[Crapduster]

First, I know this is long, but I wanted to be detailed and put some effort into the post, I plan on following up on this thread with pictures and results as work progresses from the friendly help I receive. I work on computers and are around them all day, so I check back at least a few times a day on my thread.

I am going to post a few pics in the thread and then a link to photobucket for the rest so the thread is not pic heavy.


I have several questions and I have nice pics to back up the questions. If I can get a few folks to look and comment it sure would back-up what I *think* I already know. Some background; the engine is a 2005 reman'd with 75 hours on it, the carburetor appears to be the original from 1990 and it looks like an adapter plate was used to put it on the new engine, but I don't know... that's why I took good pics so more eyes can see it. Everything is in great working order, but I suspect the carb is garbage at this point. From maintenance records I could tell it was rebuilt in 2002 with a rebuild kit. It is now rusty, dirty and probably varnished. What do the pics say? I plan on buying a reman'd carb with an electric choke and not rebuilding mine. Is there one that will bolt directly to the manifold instead of using an adapter plate? Is that an adapter plate? See pics below.

The carb at the top of this page (link below) is the one I am thinking of, but would like advice if there is a better carburetor. Here is the link:
http://www.nationalcarburetors.com/marinecarburetorsforless/fourbarrelrochester.aspx


I can say that everything seems to run pretty good until you get on it and then it spits , sputters and feels like real loss of power trying to get on plane. When on plane and cruising can feel it minor surge/miss/surge/miss sometimes and don't seen to be developing full power. I think it is also idling too high after it has warmed up and that is also making it infamously hard to shift in/out of gear.

I know for sure that the manifold choke is not working right. In the pics, the engine is cold and the choke is partly open, I can put my finger on it and push it close completely; new carb with electric choke should take care of it and several other problems. Plugs, wires, points and distributor are 10 hours old. Fuel is fresh and treated, water separating fuel filter in place with no water in it after a couple hour test run.

So the things I want to replace before putting the boat on the water again are the carb with a reman'd one from here: http://www.nationalcarburetors.com/marinecarburetorsforless/fourbarrelrochester.aspx

A Pertronix solid state ignition like this: http://www.pertronix.com/prod/ig/ignitor/default.aspx

And a new ESA compatible with the Pertronix from here: http://www.marineengine.com/newparts/part_details.php?pnum=CDI123-9898-P&ptype=&Engine=&Model=


Anything else I should replace while I am at it? Is there a different brand I should be using for any of the those three things I listed?

Replacing these three things and verifying they all work after install will most likely take care of idling, acceleration, timing and shifting problems correct?

Here is a link to the photobucket page with all the pictures. Please take a look: http://s104.photobucket.com/albums/m172/themot/OMC/

Thanks,

Tom

 

[John_S]

Re: OMC 5.7 acceleration problem - pics included

I don't see any adapter plate. I suspect you are talking about the lowest section of the carb. Carb looks to rather clean for a 1990. Choke setting may be correct for OMC. What does the manual say? Carb looks rebuildable to me. From description, sounds like accel pump may be bad, and rest needs a thorough cleaning.

Was a tune-up recently done? I didn't notice in the post if it was there. ie plugs, points, dist cap, rotor, timing idle mixture, idle speed, choke, etc. If issue persists, then it probably is carb related. I know you want to replace in mass, but would recommend not doing that.

 

[Crapduster]

Re: OMC 5.7 acceleration problem - pics included

Hi imported_John_S,

From the maintenance records that came with the boat, it looks like the carb was rebuilt in 2002 when the first of two replacement engines was installed (this is why I thought maybe an adapter plate on the carb...because of the newer engine). Since then, a second engine was installed in 2005 and the carb was re-used then as well, but no indication of cleaning or rebuild in 2005; I am thinking the carb hasn't had any love since the rebuild in 2002 and I have no history on the boat usage from then till now. The plugs/wires/distributor was the last owners attempt to fix what I am working on now. Last owner just didn't know how to research on the internet and couldn't afford hours and hours of shop time. Everything I have read so far really point to the accelerator pump.

I absolutely understand from a technical standpoint there are lots of things left to check that I haven't done; I am looking at the likely suspects first here. The "low hanging fruit" if you will.

Since I am not a carb guy at all, and the cost of having one rebuilt is $180 or around $225 for nice reman'd one with a core charge, that is not too bad and it would give me some warranty, some phone support and the knowledge that it is probably pretty close to spec as possible.

Should I rebuild/replace my carb first and then trial it before making other changes (the ESA and pertronix)? I am ok with spending several hundred dollars to make this right, I am all about getting it running the way it was intended and not looking to cheap out on this one. I understand my mechanical limitations and I am willing to farm that work out.

In the case of the engine replacements, they were both performed at West Marine in Florida as an expensive professional install that was done over periods of months. The engines were factory reman's from a place out of Colorado. The second engine was a warranty replacement of the first engine that was replaced in 2002. This is all based on paperwork/receipts and dates on the paperwork that came with the boat.

Thanks,

Tom

 

[peanutbay1]

Re: OMC 5.7 acceleration problem - pics included

I had an 89 omc 5.0 that surged exactly like your describing. Many dollars later this is what it turned out to be.

1)The petronix electronic ignition was installed in the incorrect rotatation position.
2) By positioning it to the correct engine rotation postion the motor needed retimed.
3) The timing advance cam mechanism was stuck and needed cleaned and lubed. If you look down the center shaft of the distributor it has a small wick that needs oiled periodically. Also make sure you dont have any broken springs or arms in the timing advance mechanism.

Your picks of the carb look exactly like my carb so I dont think you have an adapter plate with a different carb. All I can tell you is we did everything under the sun as far as a tune up goes and in the end the problems and fixes listed above made the engine hit peak rpms a run a steady 50MPH all day long. Hope this helps.

Also the rodchester carb on your engine is stock and easy and cheap to rebuild. Like the kit is under $40 and it takes a few hours to do the job complete. I think you have timing advance problems over carboration. I remember mine have high idle sometimes low idle other times. After my fixes all was better. Rebuild the carb to be sure as it can't hurt..

 

[Maclin]

Re: OMC 5.7 acceleration problem - pics included

I will go on the basis of the engine being in good electrical tune regarding the ignition, that the dwell and timing are in spec and that the distributor mechanical advance is working properly.

The choke does not sound like a problem to me yet. The plate will not be jammed tightly closed usually, you should be able to move it without it slamming back. As soon as the engine starts the plate will start to open anyway, and should. It should just not fully open for a couple of minutes.

The high idle after it warms up sounds like a vacuum problem in or around the carb, or just plugged passages in the carb and the idle has to be set high enough to get some fuel from the main circuits. If it is a really old carb then the throttle shaft bushings may be worn to the point that they are allowing a lot of air in (one source of a vacuum leak) and need rebushed, if so then it is time for a new carb. If the throttle shafts are still tight but the carb has not been gone thru in a while, or has just sat for a while then it would definitely be worth a rebuild attempt first.

I would not put the pertronix in until it is running right with what you have now. Changing too many things at once is not a good way to eliminate problems, but it is a good way to introduce complexity. The points ignition will work just fine as long as it is all set to spec.

 

[Bondo]

Re: OMC 5.7 acceleration problem - pics included

Ayuh,...

If you would Resize these pictures to 480x640,....
Myself,+ many others might give you some Answers,....

Did I mention I HATE side-scrolling......

 

[Crapduster]

Re: OMC 5.7 acceleration problem - pics included

I am going to go with changing the carb out first and wait on the ESA and Pertronix and other things. Mutliple folks have said one thing at a time and I am going to take that advice.

I am going to go ahead and order a reman'd identical to the one I have now. I know I could probably rebuild mine, but between the time I work and have available, versus the cost of just getting one that has been professionally cleaned and rebuilt it makes sense for me to go that route for $220 or so bucks.

It will be a few weeks before I get the carb ordered and installed and trial the boat. I will keep looking at the thread and keep posting, but I won't have any updates on fixes for a few weeks.

I am pretty excited about getting the carburetor replaced. I really think the carb is the culprit here, but I also read some posts from some folks with similar problems with different fixes. I am not ruling anything out yet.

 

[Crapduster]

Re: OMC 5.7 acceleration problem - pics included

Ayuh,...

If you would Resize these pictures to 480x640,....
Myself,+ many others might give you some Answers,....

Did I mention I HATE side-scrolling......

Ok, everything resized to 640x480 or smaller. For the record, most folks have their monitors set to 1024x768 which is what the pictures were sized to. That was resized from the original of something like 1920x1080 (you would've really, really hated side-scrolling that...)

I decided on tackling the carb first, but I would really like to hear what everyone has to say. The more info the better. I do use the search function a lot and try to answer my own questions first before asking.

I have another smaller fishing boat that has an 1986 Suzuki 85hp two stroke and I have taught myself to fix and repair most things on that engine... (with much help from forum members from multiple boards), but this is a new boat and new set of procedures and troubleshooting to learn.

Many thanks! for the comments and advice thus far.

Kind regards,

Tom

 

[Bondo]

Re: OMC 5.7 acceleration problem - pics included

Ok, everything resized to 640x480 or smaller.

ahhh, Nope,... Only the Top 1 is resized....

I have my monitor set so my screen is Filled by the iboats page....Whatever that might be...
And,...
Somewhere in these forums are the Picture posting guidelines, which state that 480x640 is the Recommended sizing...

Sorry to be such a Pain in the azz,...
But Free Help sometimes costs the effort of making Readable postings...

 

[Apollo75]

Re: OMC 5.7 acceleration problem - pics included

The carb has no oil on it that is why it rusted

Need to spray some wd-40 around that thing every now and then --- and get a good pump oil can and oil the throttle shafts, choke plate shafts, air valve shafts, and everything else that rubs, etc.,

Replacing the carb is an option --- I rebuild mine --- your choice

The new ignition is a nice touch --- no worries I guess.

The other new fangeled thing --- ESD --- never heard of it --- does it make the engine miss when you shift ?

These are my opinions

Have Fun

OFM

 

[bruceb58]

Re: OMC 5.7 acceleration problem - pics included

Why is your engine connector not plugged in all the way?

 

[Crapduster]

Re: OMC 5.7 acceleration problem - pics included

Why is your engine connector not plugged in all the way?

You're talking about the picture with the disconnected wire in my hand correct? If I remember from all the reading I have done, this is not needed when the newer model ESA from OMC was installed. My assumption is that this is the "no longer needed two wire plug" that used to go to the old style ESA, but that is why I took a picture.

 

[Crapduster]

Re: OMC 5.7 acceleration problem - pics included

ahhh, Nope,... Only the Top 1 is resized....

I have my monitor set so my screen is Filled by the iboats page....Whatever that might be...
And,...
Somewhere in these forums are the Picture posting guidelines, which state that 480x640 is the Recommended sizing...

Sorry to be such a Pain in the azz,...
But Free Help sometimes costs the effort of making Readable postings...

I only resized the pictures that are linked to the forum, the other pictures that are on the photobucket page I did not resize on purpose.

I assure you the ones that are linked in this forum are all resized to 640x480 per the forum gudielines. By the way, 640 is the screen width and 480 is the height. I work on servers, routers, switches and all things computer for a living; it's my day job... trust me on this one.

Try hitting CTRL+F5 or just F5 at the same time while you are on the page and it will force the browser to re-pull new content from the site. Most likely your browser cache is still hanging on to the old large sized pictures.

Thanks,

Tom


Edit: Sorry, you are %150 correct. I am resizing that picture now down to 640x480.

 

[Crapduster]

Re: OMC 5.7 acceleration problem - pics included

The other new fangeled thing --- ESD --- never heard of it --- does it make the engine miss when you shift ?

The ESA does exactly that, it causes the engine to stumble just long enough to make shifting into gear easy. Mine ain't so easy right now. From what I understand from reading, you start troubleshooting hard shifting at the carburetor on OMC equipped boats.

Found this here:

http://www.sterndrive.info/id24.html

I am troubleshooting the carb problems right now, but I do believe that once I get those worked out, it is going to have the secondary effect of improving or eliminating the hard shift common in OMC setups that are running porrly or not properly tuned.

Thanks,

Tom

 

[Crapduster]

Re: OMC 5.7 acceleration problem - pics included

I only resized the pictures that are linked to the forum, the other pictures that are on the photobucket page I did not resize on purpose.

I assure you the ones that are linked in this forum are all resized to 640x480 per the forum gudielines. By the way, 640 is the screen width and 480 is the height. I work on servers, routers, switches and all things computer for a living; it's my day job... trust me on this one.

Try hitting CTRL+F5 or just F5 at the same time while you are on the page and it will force the browser to re-pull new content from the site. Most likely your browser cache is still hanging on to the old large sized pictures.

Thanks,

Tom

**********************************


Nevermind, You are correct sir! I like my crow served cold with a side of humility.

I am fixing that picture now. I had one that I did not resize and it makes the post difficult to read.

Sorry bout' that,

Tom

 

[John_S]

Re: OMC 5.7 acceleration problem - pics included

You're talking about the picture with the disconnected wire in my hand correct? If I remember from all the reading I have done, this is not needed when the newer model ESA from OMC was installed. My assumption is that this is the "no longer needed two wire plug" that used to go to the old style ESA, but that is why I took a picture.

I assumed he was talking about the large connector in picture 4. It doesn't look seated to me, either, but not familiar with OMC plugs.


PS: Even if you don't want to do the replacement part of the tune-up, at least go thru all the adjustments and checks. As another poster pointed out, could easily be stuck advance weights. Even with a replacement carb, you have to adjust idle mixture, idle speed, and choke. If you went with the electric choke version of Q-jet, you will probably have different rods and jets than current carb.

 

[Howard Sterndrive]

Re: OMC 5.7 acceleration problem - pics included

that carb looks bloody new to me...I've never seen one so clean

this however, as everyone is pointing out, certainly looks like an issue

 

[Apollo75]

Re: OMC 5.7 acceleration problem - pics included

The ESA does exactly that, it causes the engine to stumble just long enough to make shifting into gear easy. Mine ain't so easy right now. From what I understand from reading, you start troubleshooting hard shifting at the carburetor on OMC equipped boats.

Found this here:

http://www.sterndrive.info/id24.html

Thanks,

Tom

Thank you Crapduster

Best of luck

OFM

 

[Crapduster]

Re: OMC 5.7 acceleration problem - pics included

that carb looks bloody new to me...I've never seen one so clean

this however, as everyone is pointing out, certainly looks like an issue

I am not going to feel so smart if this is part of the problem. I am going to go up to where the boat is right now and look at that. I thought it was supposed to be like that, (y'all can stop rolling on the floor laughing now) but honestly never tried to re-seat it or even touch it. I thought this was part of the newer ESA, but if I was smarter, I wouldn't be asking dumb questions here.

I will be back in just a little bit after I look at this thing and take another picture or two.

Thank you for pointing this out, let me go check it out and take some pictures and I will post back what I found in an hour or two.

Thanks! Tom

 

[bruceb58]

Re: OMC 5.7 acceleration problem - pics included

Not talkng about the two contact ESA connector. We are talking about the 8 contact large engine connector.