Cold blooded 5.7l in lieu of coil replacement....

[burtonrider11]

Okay, so I am changing course here with regard to replacing my ignition coil in the hopes of getting our boat started easier when cold. Here is the lowdown:

Last June we purchased a 1997 Starcraft 2010SS. Engine is Merc 5.7l 2 barrel motor I believe this is a Vortec motor S/N 0K010675.

When we purchased it, the owner had told me the original carb had gone bad and it had been replaced. I believe the new carb to be an OEM MerCarb.

Owner also said "She starts hard, but she always starts." I have found this to be true. When I first got the boat home, I tried starting her in the driveway (I always do this prior to heading to the ramp). I pumped the throttle twice, and advanced it slightly in neutral. I could not get it started, I ended draining the batteries and smelled gas, so my assumption was that I flooded it.

I took a break, charged the batteries and notice the butterfly valve at the top was shut, I used a screwdriver to prop it open. After doing this, it seemed to help and starting became easier, though not always automatically.

Later on in the year, I fiddled with the electric choke which was set all the way to lean, I set it in the middle which seemed to help a bit as well. In the fall, I replaced the starter, plugs, wires, cap and rotor. Starting didn't become any easier, though she ran WAY better, picking up 4mph at WOT. I haven't fiddled with the choke again, though I think I may go back to setting it lean.

I have noticed that when starting it, if it doesn't start, but I wait 20 minutes, she seems to start easier. When she's warm, even after anchoring up for 5,6,7 hours, no problems. When she's running, she idles smooth at 650 RPM's (again when warm), she accelerates crisply and pulls very strong from 3,000 to 4,000 RPM. No hesitation, no bogging, she just goes.

This is not my first carbureted boat, but I don't recall having these issues with previous boats. I am mechanically inclined, but I know NOTHING about carbs and I don't dare mess with them unless it's electric choke or the idle adjustments.

As I write this, I wonder if the carb might be dripping fuel and flooding the motor while she sits. This might explain why cranking it and waiting 20 minutes makes for easier starts? Again, I have no idea how to re-build a carb. If I have to buy new, I would consider getting a 4 barrel and intake as well, though I don't want to go down that road.....I just want our boat to start like I know it should, a couple pumps, a little throttle advance and boom!

If I left anything out, please let me know!

 

[Scott Danforth]

could be a needle/seat issue.

Im leaning toward a choke setting.

next time its cold, try pumping twice, then bring the throttle to about 40% in neutral. as the motor fires, pull er back down to about 1500 RPM. after 3 minutes of running, your choke should be near full open. It should start to open with just the key on, and be nearly open after 5 minutes with simply the key on.

why did you have to replace the starter?

 

[bruceb58]

I would change your starting technique. Give it one advance of the throttle and bring it back to 1/4 open and start from there keeping in mind that you want to pull back the throttle once it starts so you don't over rev.

Definitely not your coil.

EDIT: I think I was typing at same time as Scott!

 

[Scott Danforth]

Bruce, thats because great minds think alike

 

[burtonrider11]

could be a needle/seat issue.

Im leaning toward a choke setting.

next time its cold, try pumping twice, then bring the throttle to about 40% in neutral. as the motor fires, pull er back down to about 1500 RPM. after 3 minutes of running, your choke should be near full open. It should start to open with just the key on, and be nearly open after 5 minutes with simply the key on.

why did you have to replace the starter?

I've tried every sequence of starting imaginable. I have tried doing it the method that you are describing to a T and she doesn't like it. She doesn't like to fire when I do this, she just cranks and I can smell gas. When I do try to start it, it's not like she fires and won't stay running.....She flat out won't fire. Once she is running, I let her idle between 900-1200 rpm's. The idle is smooth and once warm, she idles right back down to 650-700 and will sit there all day if I let her. Which leads me to believe that I am either starting with a partially flooded motor and/or flooding it when trying to start.

I replaced the starter because the old one died. You could hear the solenoid click and that was it. It doesn't surprise since it probably had a much harder life than a normal starter as it probably had to do more to start than most

 

[burtonrider11]

Also, I haven't watch the choke plate very closely, is it possible the spring/wire inside there has gone bad and doesn't want to open anymore? It's still winter here in MI, so it will be a month before I pull her out to summerize and prep. However, I am thinking I should just throw the key to the ON position to see if that opens the choke at all.

 

[burtonrider11]

Okay one other thing. Oftentimes, when trying to start, she will crank and crank and after a bit, say 10 seconds, she will "burp" back up thru the carb when I stop cranking. There is a very fine mist that comes up and it is gas....

 

[bruceb58]

However, I am thinking I should just throw the key to the ON position to see if that opens the choke at all.

Only if you push the throttle forward to make it close first

Your starting problem isn't the choke not opening.

Is your choke plate completely closed before you start? You might adjust it so that it's slightly open.

 

[Bt Doctur]

With the engine cold, advance the throttle slightly, loosen the screws and close the choke plate using a 1/8th inch drill bit as a tool to measure the opening.,tighten screws
While your looking down the carb throat, have someone pump the throttle while you look to see how much gas squirts from the accel pump. should be a good healthy squirt
Turn the key to "on" ,choke plate should open fully in about 5-10 minutes
Some carbed engines will need to be "tickled" to keep then running when cold. Meaning you need to move the throttle back and forth to keep it running for a few seconds

 

[ihc1470]

I do not claim to be a marine tech as my expertise is auto or truck but the principles are for the most part the same. Your statement the choke was sit all the way lean gets my attention especially when you state the choke plate was closed and sticking a screwdriver in to hold it open helped. Since I am not sure what carb your working with I am making some guesses but almost any carb I have ever seen you can sit the choke so lean that the choke plate never closes. Yet your indicating that it is closed so I am a little confused. The one thing no one has mentioned that I noticed; what is the choke pull off doing and is that adjustment sit correctly? You can fiddle all you want with choke sittings but if the pull off is not doing its thing you will never get it to run right cold and often they will not start correctly either. Does the carb have fuel in it when starting cold? That is what your checking by pulling the flame arrestor and looking down into the carb while pumping the throttle. If you can see a good squirt of fuel from the accelerator pump then you should have fuel if not then check out why not. Since you state you can smell fuel I am guessing there is fuel. Probably not the issue but what is the compression on this engine? I once had a Honda CX500 motorcycle that the compression was down to 85 lbs. Very hard to start first thing in the morning but then it ran great the rest of the day. I could not tell any real difference in power either just the hard starting problem. The original owner said the original carb had gone bad makes me wonder if he was trying to correct this hard starting issue and thought the carb would fix it. Did he indicate what that carb was or was not doing by chance?

 

[NHGuy]

IHC is kinda right, but do what the doctor says.
BTW, if mine sits all week it just won't start quick. Has to get some fuel from the supply to the cylinders. So part of your cranking and pumping does that.
If you go to the boat and look at the carb cold is the choke closed? It should be.
Some carbs need you to move the throttle to allow the choke to close when cold.. After your no touch look, go give the gas a pump and see if the choke closes then.
But then check that it is set as the doc says. He does this for a living.

 

[burtonrider11]

I'll try to post some pictures later. However, I hopped on board this weekend to look at things. When I advance the throttle to "unload" the choke it flips closed - and by closed I mean completely closed. There is definitely no room for a 1/8" drill bit or anything else for that matter.

I did see in the MerCruiser manual the area to adjust the electric choke which I have done previously, would I need the key on to see if this is changing the plate position? I don't see any other area for true adjustment of said choke plate....

 

[burtonrider11]

This is probably the photo that best shows everything. Hopefully you can see it.

 

[burtonrider11]

Sorry, apparently I can only post microscopic picture

 

[ihc1470]

There are several adjustments to make an automatic choke work correctly. The only thing about the electric one is there is a heating element to warm the spring and release the tension. Other styles use a heat tube to bring the hot air up off the exhaust manifold, Again these are basics that will apply to most carbs, Your choke housing should have some markings there is an index mark and from there you can go rich or lean, That is if you can adjust the element, EPA starting requiring them to be fixed in place at least in auto applications, One sitting you to check need to see if correct is the choke pull off setting, That opens the choke back up as soon as the engine starts so it will not flood, The manual should tell you how to check it. Some carbs are checked at the top of the choke plate and others on the bottom side so you do need the book. That is were the drill bits come in. Last setting is the timing of the fast idle cam, Again the book is needed to give you the correct settings, Not all marine carbs seem to have the fast idle cam. By the way most carbs I have ever worked on (automotive) the choke plate closed all the way for starting purposes. The pull off will open it back up if working correctly as soon as your running. Maybe some carb numbers and model would help.

 

[burtonrider11]

There are several adjustments to make an automatic choke work correctly. The only thing about the electric one is there is a heating element to warm the spring and release the tension. Other styles use a heat tube to bring the hot air up off the exhaust manifold, Again these are basics that will apply to most carbs, Your choke housing should have some markings there is an index mark and from there you can go rich or lean, That is if you can adjust the element, EPA starting requiring them to be fixed in place at least in auto applications, One sitting you to check need to see if correct is the choke pull off setting, That opens the choke back up as soon as the engine starts so it will not flood, The manual should tell you how to check it. Some carbs are checked at the top of the choke plate and others on the bottom side so you do need the book. That is were the drill bits come in. Last setting is the timing of the fast idle cam, Again the book is needed to give you the correct settings, Not all marine carbs seem to have the fast idle cam. By the way most carbs I have ever worked on (automotive) the choke plate closed all the way for starting purposes. The pull off will open it back up if working correctly as soon as your running. Maybe some carb numbers and model would help.

Thanks, I don't believe there to be a fast idle cam in marine applications, but I could certainly be wrong. I will double check the carb as soon as I can to see about serial numbers. I do believe it to be a MerCarb, which I think someone had said is a Rochester carb....however I maybe wrong...

 

[ihc1470]

Sorry I had to run off and drive a school bus for awhile. Another thing you might check if it is truly adjustable and not fixed is the choke thermostat cover in relationship to the index marks. What I mean by that is loosen the screws and turn the housing in the lean direction until the choke plate opens completely. Then go back towards rich until the choke plate just closes tight. See how much further you need to turn to get back to the index mark. You should have to go some more to get some tension on the spring. Just trying to get an idea about your thermostat. On the fast idle cam I am not sure either. Seems like the 2 barrel Rochesters that I have worked on did have one but also seems like some of the Holley from years past did not, so I don't know. With a throttle lever set up you really don't need it as much as an auto application as you can set it by hand. That's where some numbers off the carb will help.

 

[bruceb58]

Boats do not have fast idle cams.

 

[burtonrider11]

Sorry I had to run off and drive a school bus for awhile. Another thing you might check if it is truly adjustable and not fixed is the choke thermostat cover in relationship to the index marks. What I mean by that is loosen the screws and turn the housing in the lean direction until the choke plate opens completely. Then go back towards rich until the choke plate just closes tight. See how much further you need to turn to get back to the index mark. You should have to go some more to get some tension on the spring. Just trying to get an idea about your thermostat. On the fast idle cam I am not sure either. Seems like the 2 barrel Rochesters that I have worked on did have one but also seems like some of the Holley from years past did not, so I don't know. With a throttle lever set up you really don't need it as much as an auto application as you can set it by hand. That's where some numbers off the carb will help.

Yes, there is an adjustment area and scribed marks over the thermostat housing. I have played around with this in the past, but I didn't note the plate moving or adjusting with any change to the thermostat housing. I'll try unloading the choke plate and adjusting again to see if that makes any difference at all.

It sounds like what you and BTdoctor are saying is that adjusting the thermostat cover, it should also adjust the choke plate correspondingly. IE, setting it to the "rich" setting would force the plate closed and for a longer duration, whereas, setting it to "lean" should open the choke plate and have it open quicker.

 

[ihc1470]

Yes you are getting the concept. These are from the instruction sheet on the 2g that I did for my 120 HP. The basics should be about the same. Figure 5 shows what I believe yours uses for a choke pull off. It is a little piston inside the choke housing. Figure 7 shows the choke cover. Item 4 on the instruction sheet is the fast idle cam and I know it was on the carb I did. It is what the idle screw hit. It was not a stepped cam like most auto applications use. It does hold the throttle open a little when the engine is cold. Did you get any GM numbers off the carb? If so I might have the specs. Be happy to look anyway.