Engine tune-up

[Leo]

I have a 1995 Sunsetter with a 5.7L with Carburetor engine that is running terrible. When first put in water this year it ran fine from the launch to my dock( about a 15 minute run at various speeds). Then boat sat for 3 weeks on my lift under canopy. When I finally was able to get out to the lake for my 1st weekend the boat started as it normally does, I typically have to pump throttle in nuetral prior to starting.

However the following symptons occured

Severe dieseling/stumbling at idle and worse when putting in gear, stalls when applying throttle at a slow rate( forward and reverse), difficult to restart, surges at low speed, does not have power at full throttle, top speeds 25-30mph, overall very rough.

Of course I assume it is either fuel issue, cylinder ignition issues or both, so I decided my first course was to basically change plugs, wires, rotor, cap and fuel filter, of course timing would need to be checked, but I have never done before.

My dealer will do this basic tune-up for $200 but having to take boat out of water and trailer it 1.5 hrs away is a pain, so I was thinking of buying parts myself, and of course figure out how to set timing.

I am pretty handy and feel comfortable with changing the plugs, wires, filter, dist cap. But rotor and timing I have no experience with.

What do you guys/gals think? Should I just suck it up and take to dealer or try and tackle it myself??

[kiley]

I have a 1995 Sunsetter with a 5.7L with Carburetor engine that is running terrible. When first put in water this year it ran fine from the launch to my dock( about a 15 minute run at various speeds). Then boat sat for 3 weeks on my lift under canopy. When I finally was able to get out to the lake for my 1st weekend the boat started as it normally does, I typically have to pump throttle in nuetral prior to starting.

However the following symptons occured

Severe dieseling/stumbling at idle and worse when putting in gear, stalls when applying throttle at a slow rate( forward and reverse), difficult to restart, surges at low speed, does not have power at full throttle, top speeds 25-30mph, overall very rough.

Of course I assume it is either fuel issue, cylinder ignition issues or both, so I decided my first course was to basically change plugs, wires, rotor, cap and fuel filter, of course timing would need to be checked, but I have never done before.

My dealer will do this basic tune-up for $200 but having to take boat out of water and trailer it 1.5 hrs away is a pain, so I was thinking of buying parts myself, and of course figure out how to set timing.

I am pretty handy and feel comfortable with changing the plugs, wires, filter, dist cap. But rotor and timing I have no experience with.

What do you guys/gals think? Should I just suck it up and take to dealer or try and tackle it myself??

Was the fuel filter changed as part of winterization?

I would do it myself. After the cap is off, the rotor lifts right off and the new one goes on. It is keyed, so it will only go on in one position. Pretty simple.

My guess is that the timing isnt off, so that shouldnt have to be reset.

Everything is pretty easy work to do, just take your time.

[Leo]

No the filter was not replaced when winterized by dealer last year. I assumed it was but I checked with them.

Since i have your ear I noticed you have a 95 sunsetter, any idea where I can find a new rub rail insert( the rubber extrusion only) the dealer states that Malibu does not make replacement parts for this anymore. ( it is different cross section than the newer boats)

[Bill_AirJunky]

The tune up is a great idea. And can be over a couple of beers while the boat is sitting on the lift.

When you replace the distributor cap, replace one wire at a time & be sure your putting it on the new cap in the right position. And like Kiley said, the rotor is right there underneath. It might be a little tough to pull off but is just a press fit.

I'd also look at the fuel filter & make sure your not having fuel issues. Spray some carb cleaner down the throat of the carb, make sure you have good clean fuel in the tank, etc.

Parts can all be bought at your local auto parts store. I've had pretty good luck with the guys from Napa having the right books, catalogs & background to find it all. And prices are a lot less expensive than my dealer.

And if it comes down to it, ask around about any on water service guys in your area. This time of year there are usually quite a few guys that would rather work that way than be stuck in a shop.

[Surfin247]

If the basics listed above don't do the trick. It is probably old gas or your carb needs to be rebuilt. Put some K100 or Startron in the tank and filll up with fresh gas and try to run out the old gas. Last rebuild carb. One other thing to check if your engine is the Mercruiser 5.7L is the choke. If electric check the wire that runs from the choke to the back of the altenator. It is a brown wire make sure it has a good connection. You can also see if the choke assembly gets hot with the engine running to let you know the choke is working. Sometimes that wire gets knocked off. It is probably a good idea to check all the wires including the spark plug wires for good connection. These too can get dislodged during the winterizing and dewinterizing process.

[bigD]

$200.00 bucks is cheap for a dealer to change all those parts. heck the plugs wires cap rotor & fuel filter would be around $100 or more depending on your year.

I'd do a carb rebuild, if it's never had one I'm sure it's way past due for a good cleaning/rebuild.

[Monk]

$200.00 bucks is cheap for a dealer to change all those parts. heck the plugs wires cap rotor & fuel filter would be around $100 or more depending on your year.

I'd do a carb rebuild, if it's never had one I'm sure it's way past due for a good cleaning/rebuild.

Not to hijack this post. How often do you need to rebuild a carb. Putting around 75 hour on the boat a year. Last total rebuild has been going on 6-7 years. Boat is running great. The only thing, it does not like prolonged surfing at low speeds. Wants to start acting like it wants to stall, never does. Until we get it running back up to speed, then everything is back to normal. Any thoughts/suggestions? Impeller fuel/water separator and all fluids changed this spring. This is not new, this has been happening since we started surfing 3-4 years ago.

[bigD]

$200.00 bucks is cheap for a dealer to change all those parts. heck the plugs wires cap rotor & fuel filter would be around $100 or more depending on your year.

I'd do a carb rebuild, if it's never had one I'm sure it's way past due for a good cleaning/rebuild.

Not to hijack this post. How often do you need to rebuild a carb. Putting around 75 hour on the boat a year. Last total rebuild has been going on 6-7 years. Boat is running great. The only thing, it does not like prolonged surfing at low speeds. Wants to start acting like it wants to stall, never does. Until we get it running back up to speed, then everything is back to normal. Any thoughts/suggestions? Impeller fuel/water separator and all fluids changed this spring. This is not new, this has been happening since we started surfing 3-4 years ago.

If you've tuned up your boat and it's still not running just right, it's probably time to inspect the carb witch would require taking it apart and rebuilding it with fresh gasket's and other ware items, and if you have a Holley a major contributor to a rich condition is a bad power valve which could have a ruptured diaphragm. Theres always a chance something made it's way past the fuel filter or through a bowl vent tube that could clog a jet or passage and cause the boat to run as you described.

[JasonK]

Empty your water seperating fuel filter into a clear container and inspect it. might have water in it. Mine typ. has a very small amount of orange liquid. ??? I empty it every spring. and replace every summer.

My 1990 mercruiser has a water seperating fuel filter and this year it decided to cause problems. I had the problem that it would cut out and then stall when going fast (like it ran out of gas). It would run fine at slow cruise.

I tried a bunch of tests, but the only thing that solved the problem was to bypass the filter. Might want to try that.

Also, I installed a new fuel pump ($100). And I swear my boat picked up 3 mph.

[Monk]

$200.00 bucks is cheap for a dealer to change all those parts. heck the plugs wires cap rotor & fuel filter would be around $100 or more depending on your year.

I'd do a carb rebuild, if it's never had one I'm sure it's way past due for a good cleaning/rebuild.

Not to hijack this post. How often do you need to rebuild a carb. Putting around 75 hour on the boat a year. Last total rebuild has been going on 6-7 years. Boat is running great. The only thing, it does not like prolonged surfing at low speeds. Wants to start acting like it wants to stall, never does. Until we get it running back up to speed, then everything is back to normal. Any thoughts/suggestions? Impeller fuel/water separator and all fluids changed this spring. This is not new, this has been happening since we started surfing 3-4 years ago.

If you've tuned up your boat and it's still not running just right, it's probably time to inspect the carb witch would require taking it apart and rebuilding it with fresh gasket's and other ware items, and if you have a Holley a major contributor to a rich condition is a bad power valve which could have a ruptured diaphragm. Theres always a chance something made it's way past the fuel filter or through a bowl vent tube that could clog a jet or passage and cause the boat to run as you described.

What do you need to do to tune up a engine, between rebuilds? No idea if our carb is a Holley. How would I be able to tell? Going to the lake this weekend can check then. Edited June 10, 2009 by Monk

[JayHoy]

The carb will have clear markings saying holley on it

Edited June 10, 2009 by JayHoy

[Monk]

The carb will have clear markings saying holley on it

OK will look, on the inside under the air filter or on the side of the carb. Just asking I'll find it.

[martinarcher]

Everyone always blames the poor carb. I would be willing to bet quite a bit that the carb is fine. I would first do your tune up. It is money well spent before even taking a look at rebuilding the carb. Another thing to do is verify you have proper fuel pressure. I had a similar issue to you last year with my boat. I ended up doing the full tune up....

1. New plugs

2. New wires

3. New cap and rotor

4. New coil (replaced the aftermarket Accel Hot Shot with the same coil_

5. Tried a stock coil with a external ballast resistor from my father in laws old Dodge Dart since the Accel coil seemed to be getting too hot with the internal resistor.

6. Tried a Pertronix Coil since the ignition module was a Pertronix Ignitor.

7. Changed fuel/water separator

8. Changed fuel filter

9. Cleaned carb with Berryman's B-12

10. Checked timing with a light - it was off 2 degrees so I corrected it by rotating the distributor

After all this I still had the same symptoms. I figured ti was either low fuel pressure or the carb itself. I really doubted the Rochester Quadrajet carb needed work. I have had GM vehicles with Quadrajets on them in the past and I have never had trouble with them so I went after the fuel route...

I added a Mr. Gasket fuel pressure gauge between the carb and the fuel pump to watch fuel pressure. I figured it was a useful tool for future diagnostics as well as it was a well spent $30.

I noticed under throttle and acceleration the pressure was only 2-3 psi and at idle the pressure was about 5 psi.

I then ordered a new fuel pump. While changing it I noticed the vent line to the carb from the fuel pump was clogged so I also replaced the line. I put the new pump in and it has been running great ever since. The fuel pressure at idle is now 8.5 psi and under really hard pulls it only dips to about 4-5 psi.

I'd check everything you can before disturbing the carb unless you like rebuilding carbs.

Edited June 11, 2009 by martinarcher

[Monk]

Everyone always blames the poor carb. I would be willing to bet quite a bit that the carb is fine. I would first do your tune up. It is money well spent before even taking a look at rebuilding the carb. Another thing to do is verify you have proper fuel pressure. I had a similar issue to you last year with my boat. I ended up doing the full tune up....

1. New plugs

2. New wires

3. New cap and rotor

4. New coil (replaced the aftermarket Accel Hot Shot with the same coil_

5. Tried a stock coil with a external ballast resistor from my father in laws old Dodge Dart since the Accel coil seemed to be getting too hot with the internal resistor.

6. Tried a Pertronix Coil since the ignition module was a Pertronix Ignitor.

7. Changed fuel/water separator

8. Changed fuel filter

9. Cleaned carb with Berryman's B-12

10. Checked timing with a light - it was off 2 degrees so I corrected it by rotating the distributor

After all this I still had the same symptoms. I figured ti was either low fuel pressure or the carb itself. I really doubted the Rochester Quadrajet carb needed work. I have had GM vehicles with Quadrajets on them in the past and I have never had trouble with them so I went after the fuel route...

I added a Mr. Gasket fuel pressure gauge between the carb and the fuel pump to watch fuel pressure. I figured it was a useful tool for future diagnostics as well as it was a well spent $30.

I noticed under throttle and acceleration the pressure was only 2-3 psi and at idle the pressure was about 5 psi.

I then ordered a new fuel pump. While changing it I noticed the vent line to the carb from the fuel pump was clogged so I also replaced the line. I put the new pump in and it has been running great ever since. The fuel pressure at idle is now 8.5 psi and under really hard pulls it only dips to about 4-5 psi.

I'd check everything you can before disturbing the carb unless you like rebuilding carbs.

No I do not like rebuilding carbs or paying the dollars to have them rebuild. A lot to digest, thanks you for the suggestions. I have alway replaced the plugs each year along with fuel/water separator ours are the same filter. And clean the air filter with a degreaser and the carb with a carb cleaner. For the rest I do not know if those other items, have been changed since the carb was rebuild. So I will be going to the auto parts shop tonight for new wires, new cap and rotor, and see if they have the aftermarket Accel Hot Shot coil. Never changed these item before, on a scale of 1-10 what will be the difficulty I will have on my hands this weekend. On Sunday after everyone has left and it just me and my neighbor across the lake if I get myself into trouble. Edited June 11, 2009 by Monk

[martinarcher]

Everyone always blames the poor carb. I would be willing to bet quite a bit that the carb is fine. I would first do your tune up. It is money well spent before even taking a look at rebuilding the carb. Another thing to do is verify you have proper fuel pressure. I had a similar issue to you last year with my boat. I ended up doing the full tune up....

1. New plugs

2. New wires

3. New cap and rotor

4. New coil (replaced the aftermarket Accel Hot Shot with the same coil_

5. Tried a stock coil with a external ballast resistor from my father in laws old Dodge Dart since the Accel coil seemed to be getting too hot with the internal resistor.

6. Tried a Pertronix Coil since the ignition module was a Pertronix Ignitor.

7. Changed fuel/water separator

8. Changed fuel filter

9. Cleaned carb with Berryman's B-12

10. Checked timing with a light - it was off 2 degrees so I corrected it by rotating the distributor

After all this I still had the same symptoms. I figured ti was either low fuel pressure or the carb itself. I really doubted the Rochester Quadrajet carb needed work. I have had GM vehicles with Quadrajets on them in the past and I have never had trouble with them so I went after the fuel route...

I added a Mr. Gasket fuel pressure gauge between the carb and the fuel pump to watch fuel pressure. I figured it was a useful tool for future diagnostics as well as it was a well spent $30.

I noticed under throttle and acceleration the pressure was only 2-3 psi and at idle the pressure was about 5 psi.

I then ordered a new fuel pump. While changing it I noticed the vent line to the carb from the fuel pump was clogged so I also replaced the line. I put the new pump in and it has been running great ever since. The fuel pressure at idle is now 8.5 psi and under really hard pulls it only dips to about 4-5 psi.

I'd check everything you can before disturbing the carb unless you like rebuilding carbs.

No I do not like rebuilding carbs or paying the dollars to have them rebuild. A lot to digest, thanks you for the suggestions. I have alway replaced the plugs each year along with fuel/water separator ours are the same filter. And clean the air filter with a degreaser and the carb with a carb cleaner. For the rest I do not know if those other items, have been changed since the carb was rebuild. So I will be going to the auto parts shop tonight for new wires, new cap and rotor, and see if they have the aftermarket Accel Hot Shot coil. Never changed these item before, on a scale of 1-10 what will be the difficulty I will have on my hands this weekend. On Sunday after everyone has left and it just me and my neighbor across the lake if I get myself into trouble.

Dang I typed up a good long response and lost it before I got to post it......

To recap. I ended up with a Pertronix Coil only because my boat originally had a points distributor and has been converted to an electronic ignition module made by Pertronix called the Ignitor. I figured I would stick with the recommended coil for the conversion unit in the boat. I think the Accel Coil would have been fine and had ran the boat without a problem for years, but in fault finding I guess I got a little to focused on the ignition instead of giving the fuel delivery system a fair look and replaced unnecessary parts.

To test your coil, pull a plug and re-attach it to the spark plug wire. Lay the plug on the engine mount or the block (this grounds the plug itself). Turn the key and crank the engine while watching the plug. If the Coil and ignition system are good, you should hear a snapping and see a strong spark between the gap of the plug while the engine tries to start or runs on the other seven cylinders. If the spark seems weak the ignition system should be looked at closely. If the spark is strong I would lean toward fuel delivery or possibly carburetion.

Don't forget there is probably a fuel filter in the carburetor body as well. I also changed that filter during my episode.

Regardless the tune up mentioned in the beginning of the thread is money well spent and eliminates many factors that could be usual suspects. Good luck and let us know how it goes!

If you are at all handy I would rate the coil/cap/rotor/wire changing a 2 out of 10 in difficulty. Especially on a Direct Drive boat since you can get right beside the motor.

Edited June 11, 2009 by martinarcher

[Monk]

Everyone always blames the poor carb. I would be willing to bet quite a bit that the carb is fine. I would first do your tune up. It is money well spent before even taking a look at rebuilding the carb. Another thing to do is verify you have proper fuel pressure. I had a similar issue to you last year with my boat. I ended up doing the full tune up....

1. New plugs

2. New wires

3. New cap and rotor

4. New coil (replaced the aftermarket Accel Hot Shot with the same coil_

5. Tried a stock coil with a external ballast resistor from my father in laws old Dodge Dart since the Accel coil seemed to be getting too hot with the internal resistor.

6. Tried a Pertronix Coil since the ignition module was a Pertronix Ignitor.

7. Changed fuel/water separator

8. Changed fuel filter

9. Cleaned carb with Berryman's B-12

10. Checked timing with a light - it was off 2 degrees so I corrected it by rotating the distributor

After all this I still had the same symptoms. I figured ti was either low fuel pressure or the carb itself. I really doubted the Rochester Quadrajet carb needed work. I have had GM vehicles with Quadrajets on them in the past and I have never had trouble with them so I went after the fuel route...

I added a Mr. Gasket fuel pressure gauge between the carb and the fuel pump to watch fuel pressure. I figured it was a useful tool for future diagnostics as well as it was a well spent $30.

I noticed under throttle and acceleration the pressure was only 2-3 psi and at idle the pressure was about 5 psi.

I then ordered a new fuel pump. While changing it I noticed the vent line to the carb from the fuel pump was clogged so I also replaced the line. I put the new pump in and it has been running great ever since. The fuel pressure at idle is now 8.5 psi and under really hard pulls it only dips to about 4-5 psi.

I'd check everything you can before disturbing the carb unless you like rebuilding carbs.

No I do not like rebuilding carbs or paying the dollars to have them rebuild. A lot to digest, thanks you for the suggestions. I have alway replaced the plugs each year along with fuel/water separator ours are the same filter. And clean the air filter with a degreaser and the carb with a carb cleaner. For the rest I do not know if those other items, have been changed since the carb was rebuild. So I will be going to the auto parts shop tonight for new wires, new cap and rotor, and see if they have the aftermarket Accel Hot Shot coil. Never changed these item before, on a scale of 1-10 what will be the difficulty I will have on my hands this weekend. On Sunday after everyone has left and it just me and my neighbor across the lake if I get myself into trouble.

Dang I typed up a good long response and lost it before I got to post it......

To recap. I ended up with a Pertronix Coil only because my boat originally had a points distributor and has been converted to an electronic ignition module made by Pertronix called the Ignitor. I figured I would stick with the recommended coil for the conversion unit in the boat. I think the Accel Coil would have been fine and had ran the boat without a problem for years, but in fault finding I guess I got a little to focused on the ignition instead of giving the fuel delivery system a fair look and replaced unnecessary parts.

To test your coil, pull a plug and re-attach it to the spark plug wire. Lay the plug on the engine mount or the block (this grounds the plug itself). Turn the key and crank the engine while watching the plug. If the Coil and ignition system are good, you should hear a snapping and see a strong spark between the gap of the plug while the engine tries to start or runs on the other seven cylinders. If the spark seems weak the ignition system should be looked at closely. If the spark is strong I would lean toward fuel delivery or possibly carburetor.

Don't forget there is probably a fuel filter in the carburetor body as well. I also changed that filter during my episode.

Regardless the tune up mentioned in the beginning of the thread is money well spent and eliminates many factors that could be usual suspects. Good luck and let us know how it goes!

If you are at all handy I would rate the coil/cap/rotor/wire changing a 2 out of 10 in difficulty. Especially on a Direct Drive boat since you can get right beside the motor.

Great I love a 2 out of 10 difficulty for a weekend boat project. I will go with what coil is on the boat now, need to check this once I get to the lake. Is this something I will need to order or will I be able to pick this up at the local auto parts store. Thanks so much for the outline on how to test the coil, had no clue on that one. Regarding the fuel filter inside the carburetor body, I have clean and check the carb every spring and fall for as long as we have owned this boat, never saw or more important never changed a fuel filter that was in or around the carb body. I will look and take some photo to make sure we do/do not have a filter in or around the carb. I will keep you all posted on the outcome. Thanks so much for the help and the tech information, could never had started this project without it. To the lake we go.

[martinarcher]

Good deal. Good luck and take lots of pics.

The parts store should be able to get you a cap/rotor/plugs/wires. The carb filter might be a special order. I took mine into the parts store after pulling it out and the guy was cool enough to go back and compare it to everything on the shelf. He didn't get it exactly but it is incredibly close.

I'm not sure if your boat will have the Quadrajet or the Weber carburetor. Mine is a Quadrajet. The fuel filter is right behind where the fuel line enters the carb body. To change it on mine you simply unscrew the fuel fitting and pull the fuel line off the carb - the filter is right inside the carb body. Just pull it out and change it.

Here is a pic of mine. The filter is in the carb body where I circled it in red...

[Monk]

Thanks for the pic's of your setup. Great help to see the location. I will be taking a lot of photos of our setup, to bring back this weekend for future conversations like this one. Once again thanks of all the help.