OMC 5.7 acceleration problem - pics included

[bergerandfries]

Re: OMC 5.7 acceleration problem - pics included

Want to sell your old carb?

I was going to say, hold onto that old carb until you're SURE the new carb is working. NEW=Never Ever Worked before...

And then unload it...

 

[Crapduster]

Re: OMC 5.7 acceleration problem - pics included

I was going to say, hold onto that old carb until you're SURE the new carb is working. NEW=Never Ever Worked before...

And then unload it...

My carb, if it was cleaned up and rebuilt, is definitely in better shape than the rebuilt one I got today. Nothing major, but you can tell that the parts on the rebuilt one have been dinked and clanked around in cleaning and through rebuilds. It is clean enough to eat off of and I am guessing it will purr like a kitten and the boat will run great, just saying the parts that make up the carb have been around the block a few times. It also has modifications so I am not sure it started life as a marine carb. Not happy about that if it turns out to be the case. I have to run the model number to find out what it was/is. Mine is original, nineteen years old and has been rebuilt once to my knowledge.

For those interested...
My carb model number: 17059286
Rebuilt carb model number: 17059213

With the core charge, probably what I will do is have mine rebuilt (after I etch everything) and keep it for a spare. Only a little over $100 with the core charge I hope they will credit me, to have it cleaned, rebuilt and flowed. I will have the boat for awhile and it will have the stock 5.7 in it so might as well keep a spare.

If something changes and I sell the original, I will come back to the person who asked first and give them first right of refusal on buying.

 

[rodbolt]

Re: OMC 5.7 acceleration problem - pics included

and whats funny is all the OMC experts missed the oppertunity to point out the ESA has absolutly NOTHING with shifting INTO gear and should only trigger when shifting OUT of gear.
shoot a good pic of the shift transfer, I cant see if yours has the overstroke cams or not.
if they are not adjusted correctly or the lower cable is bad it will cause the ESA to stay on and the engine will simply shake and dance.
instead of the petronixs,Diodes and ESA simply install the delco EST kit and wire the shift interupt switch like a mercruiser.
quick simple and cheap.
hard shifting INTO gear indicates issues NOT related to engine problems.

 

[Crapduster]

Re: OMC 5.7 acceleration problem - pics included

Rodbolt, I believe you are right on the money, I think I was short on details regarding the shifting problem. Shifting into gear is fine, it is getting it back to neutral from fwd or reverse that is a pain. Made for some interesting trailer loading. Let's just say until I know it is fixed, I will be "drifting" onto the trailer and using the winch to get the boat situated. Much safer that way for now.

Do any of these pictures show enough of the overstroke microswitch and other components? Click on the thumbnail for the full size picture. I guess only the third pic actually has the microswitches in it. The other two are just for looks. I will get a better picture of all that today.

 

[rodbolt]

Re: OMC 5.7 acceleration problem - pics included

yes, your rig has the shift interupt switch(the one with the arm and roller) and the overstroke switch(the upper one).
how this system works is as the control shift cable starts moving out of gear the lower switch closes the upper is already closed.
as the shift switch closes the ESA detects this cable movement and causes the ign system to misfire allowing the shift clutch to pull away from the dogs on the gear.
the dogs on the gear and clutch are cut at about a 7 degree back angle aiding in locking them together.
if you cannot unload either the input shaft or the propshaft its can be very difficult to impossible to move the clutch away from the dog.
thats the reason for the shift interrupt ESA setup.
some setups however tended to overstroke the cable going INTO gear causing the shift cut switch to close in an in gear position.
the cams on the overstroke switch open the circuit for the shift cut switch eliminating the shift cut switch when the cable is in any ingear position.
thats why both shift cut,shift cable and cable overstroke adjustments are absolutly critical on that setup.
its also why for about the price of the ESA module I can convert to EST and wire it like a mercruiser and eliminate a raft of issues.
when coming out of any in gear position back to N the overstroke cams release the overstroke switch allowing that switch to close about the same time as the arm on the shift cut switch closes the shift cut circuit.
if the overstroke cams are improperly adjusted the shift cut circuit will remain open regaurdless of shift cut switch position.

 

[Maclin]

Re: OMC 5.7 acceleration problem - pics included

It will be interesting to see if the CD ignition and electric fuel pump fix your undiagnosed condition(s), good luck with all of this

 

[full stringer]

Re: OMC 5.7 acceleration problem - pics included

make sure your carb is a marine carb i bought from national carbs as advertised as a marine carb and they sent a auto carb mine was a holley 600cfm problem with it was the metering blocks are different in a marine carb and the throttle shafts are sealed in marine not so on auto carbs as well as there should be j tubes on the top for overflowing fuel to reenter the carb not spill outside and the marine carbs have a extra fuel nipple from fuel pump in case the diaphram leaks on the fuel pump it will send the fuel to carb not all over the bilge so be careful bro and happy boating

 

[Crapduster]

Re: OMC 5.7 acceleration problem - pics included

It will be interesting to see if the CD ignition and electric fuel pump fix your undiagnosed condition(s), good luck with all of this

Maclin, amen! And may the hail-mary attempt find its way to the endzone for a blissfull rendezvous with beautiful harmonious engine tones of 550-600rpm in gear at idle and an eager and easily manipulated shift/clutchdog/cable/esa/thingymajigger. Followed by years of un-eventful, no breakdown/fix/repair on the water days of sunning and puttzing around on the boat next season and seasons to follow.

Pray for me, but more importantly, pray for my engine and boat... for I am about to work on them!

Lucky for me I have a West Marine about 5 minutes from the house. They are pricey, but I can always find what I can't find at sporting goods stores, Sears, Wally-mart, etc... Today I picked up some new fuel/water separating fuel filters and some bilge absorber mats in case I spill while working on things. Before I put the new carb on, I will replace the large fuel filter. Also got an inline screen type filter that will go between the tank and the pump. That Holley red marine electric pump is something else. So much bigger and well built than the "whatever it is" electric fuel pump that is on there now.

 

[ChasR]

Re: OMC 5.7 acceleration problem - pics included

I came late to this party but found the story interesting. The Quadrajet carb has been used by GM on a variety of engines and is considered a good performer in the automotive industry. I have rebuilt a dozon of them. However they all have a common flaw. I live in the Northwest and in the winter when it is wet they tend to pickup water and start missing. We used to fix the problem (back in the 60's) by revving up the engine and manually closing the choke, sucking the water thru the jets.
Good Luck

Chas

 

[Crapduster]

Re: OMC 5.7 acceleration problem - 23nov09 update

Re: OMC 5.7 acceleration problem - 23nov09 update

Made some progress this weekend. Got the new rebuilt carb on and the new ESA module from CDI installed; verified old ESA not working and new one is. Changed plugs and found that for whatever reason, one side were gapped all at least .042 and on the other side none were gapped more than .033 ...it was like whoever changed them last, gapped one side and then forgot to gap the other side. I gapped them all to .035.

I should finish up the installation of the Holley red fuel pump this week and some other odds/ends...wrong size v-belt for power steering/hyd pump (two sizes too big and too much slack in belt... Just little stuff that I keep finding, where previous owners didn't take the time to make sure it was done right or the right parts were installed. I am making a list of part #'s for everything I replace, so if I ever sell, the next owner won't have to track it all down.

I should get a chance to put it in the water by the end of the week and see how everything is running.

To summarize the changes so far:

New rebuilt Rochester Q-jet
New plugs gapped to .035
New ESA from CDI
New Holley red marine fuel pump
All new 3/8 hose and fittings from tank to carb
New fuel/water separating filter

I'll update the thread again after I have the boat out for some test runs... the results are what everyone wants to hear about anyway.

Thanks again for all the comments and help to-date. I will do my best to contribute back in the form of continued documentation of the process and what I encounter as I get the gremlins worked out.

 

[Maclin]

Re: OMC 5.7 acceleration problem - pics included

Did this model of OMC have an electric fuel pump standard? If not, what safety measures are you taking to make sure the pump does not run on in the event of an emergency?

 

[HT32BSX115]

Re: OMC 5.7 acceleration problem - pics included

Howdy,


Long thread....

After reading most of the last responses, I noticed that you have not "fixed" the main plug. (Maybe you did)

You need to pull the main plug completely apart, clean up the pins and receptacle, and push it COMPLETELY together. If it won't go completely together (which it appears that the last person gave up on) you need to determine the reason (bent pins, corrosion in the plug, etc), fix it and push it back together.

Poor electrical connections are frequently the cause of many problems in all boats.


One other thing, if the red cable (your pic below) requires too much force to move when shifting INTO gear (FWD/REV), it will overcome the light spring loading of the ESA actuator (#37 & #40 below... picture from Doug Russell parts) and ACTUATE the ESA every time you try to shift into gear...

As Rodbolt indicated, it should (and will) take enough force to move it (#37 below) when shifting OUT OF gear, because the of the undercut clutch dogs.



Cheers,


Rick

 

[Crapduster]

Re: OMC 5.7 acceleration problem - pics included

Did this model of OMC have an electric fuel pump standard? If not, what safety measures are you taking to make sure the pump does not run on in the event of an emergency?

The original motor had a mechanical pump. The reman'd engine that was put in never had a mechanical pump installed. It has a plate blocking off where the mechanical pump would go. Not sure if the electric fuel pump and other incorrect things were a last owner "special" or if the last boat yard to work on it did some real shoddy stuff.

I am hooking it up per the instructions with the fuel pump. I plan on using the oil pressure relay, but honestly I haven't examined the instructions close enough yet. This is why I am so slow, If I am not sure how to do it right the first time, I will take forever to figure it out, and then do it right.

I can tell you that right now the fuel pump that was there when I got the boat catches its +12v from the back of the alternator. It was like they just used the closest place that a hot wire was present and didn't think safety at all.

I know there is also an alternative besides using the oil pressure sensor and I will examine that wiring diagram as well to understand the safest and best way to hook it up for my setup.

I also plan on hooking up the line between the pump and secondary vacuum in case the new fuel pump leaks, the gas will be drawn into the carb/engine instead of leaking in the bilge.

 

[Crapduster]

Re: OMC 5.7 acceleration problem - pics included

Howdy,


Long thread....

After reading most of the last responses, I noticed that you have not "fixed" the main plug. (Maybe you did)

You need to pull the main plug completely apart, clean up the pins and receptacle, and push it COMPLETELY together. If it won't go completely together (which it appears that the last person gave up on) you need to determine the reason (bent pins, corrosion in the plug, etc), fix it and push it back together.

Poor electrical connections are frequently the cause of many problems in all boats.


One other thing, if the red cable (your pic below) requires too much force to move when shifting INTO gear (FWD/REV), it will overcome the light spring loading of the ESA actuator (#37 & #40 below... picture from Doug Russell parts) and ACTUATE the ESA every time you try to shift into gear...

As Rodbolt indicated, it should (and will) take enough force to move it (#37 below) when shifting OUT OF gear, because the of the undercut clutch dogs.

Hi, thanks for advice! I have taken care of the electrical connections. Those are in good shape now.


It shifts into fwd/rev like butter. I would say that to get it out of gear takes about 20-30lbs of torque from my arm to pull it out of gear. So much so, in fact, that my hand usually smashes against the throttle lever and by the end of the day my hand is bruised on top from shifting stupid boat gears

 

[HT32BSX115]

Re: OMC 5.7 acceleration problem - pics included

Any "Dog-clutch" Cobra that's hard to shift out of gear when loaded (meaning, prop in the water) is usually due to a bad/non-functional ESA or the linkage that operates it is seriously out of adjustment.

And, I might add, if you continue to shift it that way it will cause damage to the lower shift cable/mechanism etc....

 

[Silvertip]

Re: OMC 5.7 acceleration problem - pics included

Why is it you want to replace what appears to be a very nice carb when there are so many other things -- cheap things -- that cost you little or nothing to verify before spending that kind of money. Checking plug condition, timing, fuel pressure, etc cost nothing. Verify those things first, then rebuild the carb.

 

[bruceb58]

Re: OMC 5.7 acceleration problem - pics included

Also, with the newer ESAs, the overstroke switch is no longer needed so don't worry about it's adjustment.

 

[Crapduster]

Re: OMC 5.7 acceleration problem - pics included

Also, with the newer ESAs, the overstroke switch is no longer needed so don't worry about it's adjustment.

Is that because the newer ESA's munge the ignition for a timed period?

The one I have on there is brand spanking new from CDI and I verified that it worked by tipping the microswitch arm, but I didn't hold it to see if it would auto cut-off after a period of time.

Thanks for all the comments guys, after some turkey and pie tomorrow I am going to try and finish up the rest of the work and drop it in the water for some testing.

Silvertip: I have the extra income to be able to throw money at this problem for now. Also, I have an 86' two stroke suzuki outboard that I spend most of my mechanic time working on. I am on-call for a small computer company and my job consumes a lot of my time. I am lucky when I get a chance to work on it, so I want to maximize my potential for getting it fixed and starting with new and/or professionally rebuilt and tested parts takes much of the guesswork out of it for me. Plus, with buying the new rebuilt carb, I get some free phone support from the guys that rebuilt it. I am counting on them to help me fine tune everything if it needs it.

 

[Crapduster]

Re: OMC 5.7 acceleration problem - pics included

Any "Dog-clutch" Cobra that's hard to shift out of gear when loaded (meaning, prop in the water) is usually due to a bad/non-functional ESA or the linkage that operates it is seriously out of adjustment.

And, I might add, if you continue to shift it that way it will cause damage to the lower shift cable/mechanism etc....

Man O' Man, you're telling me. I cringe every time I had to shift out of gear the first and last time I put it in the water. After that I made up my mind I was going to fix the gremlins before making any serious attempt at using the boat. I think it also had something to do with the motor idling too high and surging and otherwise acting like the carb had serious issues. I have read a lot on the internet about OMC and shifting problems and the common theme is that you start at the carb and work backward troubleshooting. This whole process would be much quicker if I didn't have to trailer the boat to the lake just to test my new parts out. This time I am bringing my portable toolbox and some other odds and ends and may try to work out some kinks while floating around the lake. Based on where the shifter seems to go in/out of neutral, I think you're probably right about needing adjustment. Last time on the water I was focused on the motor issue and wasn't paying so much attention, other than it was hard to shift out-of gear, to shifting problems. This time it's on the list to get figured out and adjust if necessary.

I will update the thread in a few days. Happy Thanksgiving! From Texas, y'all.

 

[Crapduster]

Re: OMC 5.7 acceleration problem - Update 30nov2009

Re: OMC 5.7 acceleration problem - Update 30nov2009

I finally got a chance to test run the boat for a few hours on Sunday. It accelerates much, much better and the idle is steady and smooth now. But I still have some problems and I believe they were probably created by some of the changes I made, I think they are mostly electrical gremlins now. I could write a book about every tiny detail that I have done, but I want to give the basics and if there are questions or criticisms, let'em roll; it helps.

Maclin, you can stop rolling on the floor laughing now! Save it, cause you'll probably bust a gut on the next paragraph after this list...

These are the things that were done prior to the test run:

• new plugs gapped properly
• newly rebuilt qjet from National Carb
• new Holly marine red electric fuel pump
• new esa from cdi (verified to work properly after install)
• new fuel/water filter/separator
• new 3/8" I.D. fuel fitting and hose from the tank to the carb

I swear i'm not a complete boob, but I will get lazy on things here and there. The electric choke and the fuel pump are hooked up to the back of the alternator. This is where the original crappy fuel pump was hooked up, because whatever that connection is, it is switched when the key is switched to run because I hear the fuel pump, and the pressure gauge goes to 6lbs and I can watch the choke open after some time. I am not saying it is right, but that is where both are hooked up currently. That being said, I think the fuel pump is not getting enough current and that is causing the fuel pressure to fluctuate and the engine to be starved at the upper RPM ranges. I have an inline fuel pressure gauge and at idle it is rock solid 6lbs, under some load, it swings between 2-6lbs wildly, but the engine doesn't seem to bog or be affected. It is only when I get up into the higher RPM range and then hammer it, that I get a 1 second noticeable delay before what I believe is the fuel pump trying to catch up. The problem is reproducible 100% of the time and at the same operating RPM range. For example, I am on plane and around 2800-3600RPM and can nail it up to a certain point and no hesitation, just instant response and power. Try the same thing already running around 3700-4200rpm and the engine will bog for a split second before it catches up and gets going... every time.

I will post some pictures of all this so it makes more sense what I am talking about as far as the fuel pump layout and what not.

The fuel pump is mounted as low as I could get it without it being in the bilge and it is about one foot away from the tank fitting. The Holly manual said to mount it below the tank or at least low enough so it could form a siphon if pulling from the top of the tank. The intake on my fuel pump is about an inch or two below the lowest point of the tank. As I understand it, the Holly pumps are push and not pull type pumps and need to be gravity fed.

Here is another one, at high speeds when trying to trim up, the voltage drag is so much, that it causes the engine to bog until I let off the trim. The voltage indicator swings to 8-9 volts until I let up and then right back to normal of 14. It's not the ESA malfunctioning and munging the engine... anyone got any ideas. I will get it all sorted out eventually, but any advice to make it go quicker would be appreciated.

Any of my "theories" sound accurate?

I am seriously considering just having my original carb rebuilt by National Carb and going back to the manual choke and also ditching the electric fuel pump for a new Holley marine mechanical pump. Puts everything back to factory and gets rid of two pesky electrical connections from the choke and electric pump. When I started on all this I was sold that this was the way to go, but the more I understand (or don't understand) about electrical systems, the more it just makes me want to eliminate any unnecessary electrical connections into the stock wiring. I can tell you that the stupid aftermarket radio, cheap amp and crap speakers are getting yanked out of there today. That radio has so many connections, it just makes a complete birds nest under my dash. The amp and speakers are not hooked up right anyway, and the only good part about the whole radio and system that was put in (not by me), is that there is a good size positive and negative wire already run from the back of the boat directly from one of the batteries. I am leaving those wires in so they can be used for a bus bar or something similar in the future.

Well, it turned out to be a long post anyway, but it covers most everything.

Last question is that if everything is running perfect and the engine is developing all it's HP and torque, it just seems like the boat takes longer to get on plane than I would like, and feels like it is struggling. That is with only 1/2 tank of gas (30 gals) and me in the boat... add a full tank and 4-5 adults and I wonder how long I have to plow water before getting on plane. Prop is aluminum 3blade 14.5x19p non-cupped. I am thinking about going to a SS 4blade 14.125"x18P. Most of the boating during the season will be tubing, skiing and stop and go type action all day, so don't mind losing a couple of MPH in top-end, but would really like to give this boat a much better hole-shot to get on plane quicker. Boat is about 20' in the water, 22'10" overall and estimated weight is 4800lbs with full fuel and rated passenger load. Thoughts?

Thank you,

The CrappieDuster