Slow starting engine

Discussion in 'Gas Engines/Drives/Transmissions/Props' started by Loyd Dinneen, Jan 23, 2018.

  1. Loyd Dinneen

    Loyd Dinneen Member

    254
    Jul 29, 2017
    Las Vegas
    1977 Sea ray 240 SDA cruiser w/ twin 470 mercs.
    Twin 470 Mercruisers
    I have a mercruiser pair of 470's in my 1977 weekender 240 srv and I have a problem with the port engine when starting cold it doesn't without help. At first I noticed the choke wasn't closing so I adjusted the choke to the 1/8" gape and when you put the throttle forward it goes into position but the engine cranks but doesn't want to start without the help of quick start (I know bad idea).It fires right up then and perfectly after running for a couple minutes you can then turn it off and when restarted it fires right up. I suspect it is a fuel delivery issue when cold but not sure where to start, the electric choke assembly is no longer available from the dealer. The other engine fires right up and the choke works like it should and set in the middle on the adjustment as where I have the other cranked most of the way to the left. I thought about using butane as a starting agent as I just don't like ether only if I can't get this figured out. Any suggestions would be helpful, I'm restoring this boat back to it's original condition and look plus an inverter for the fridge. The only things I'm missing is the vent assembly at transom and the alcohol stove. Does anyone know if these boats came with a battery charger? Sorry to get off topic but this boat is really looking good right now and would like to get it in the water.
     
  2. Espos4

    Espos4 Active Member

    512
    Jan 1, 2017
    Long Island NY
    2007 240 Sundeck
    350 MAG Bravo 3 W/DTS
    Does the accelerator pump on the port engine carburetor work properly?

    You should see a shot of gasoline into the primaries when the throttle lever is moved forward.
     
  3. NorCal Boater

    NorCal Boater Well-Known Member SILVER Sponsor

    Jan 24, 2008
    Covington, LA
    Cobalt CM23
    GM SB 383" Stroker" Alpha Gen I
    I would look at the accelerator pump as Espes4 suggested as well as looking for the check valve in the fuel line to that motor. I'm not sure of your carburetor but many have a check ball in the incoming fuel line and some fuel tanks have a check ball in the pick up line at the tank.

    It sounds to me like fuel is seeping back to the tank and robbing the carb of fuel after sitting for a while. I would look there. To confirm this first determine....does each carb have a dedicated pickup from the tank? If yes swap the fuel lines and see if the problem stays with the port motor. If it does, swap carbs and try it again.

    Shawn
     
  4. Loyd Dinneen

    Loyd Dinneen Member

    254
    Jul 29, 2017
    Las Vegas
    1977 Sea ray 240 SDA cruiser w/ twin 470 mercs.
    Twin 470 Mercruisers
    I will check the accelerator pump action. I work on it on my own mostly so I will get some help to activate the throttle. I kind of suspect that as well. Each engine has a dedicated fuel hose from the fuel tank so I will try the line switch and see if that works.
    The carbs are 2 barrel rochesters.
     
  5. NorCal Boater

    NorCal Boater Well-Known Member SILVER Sponsor

    Jan 24, 2008
    Covington, LA
    Cobalt CM23
    GM SB 383" Stroker" Alpha Gen I
    You can buy rebuild kits for those for about 15 bucks online.
     
  6. Loyd Dinneen

    Loyd Dinneen Member

    254
    Jul 29, 2017
    Las Vegas
    1977 Sea ray 240 SDA cruiser w/ twin 470 mercs.
    Twin 470 Mercruisers
    I have looked at the rebuilding option, I tested the accelerator pump no fuel at the first but once I started the engine (with ether ) and turned it off it worked fine and actually almost flooded the engine. I think that I am losing the prime for the fuel in the pump and fuel lines and it takes that fuel to start. Nor cal boater I think may have the right idea. What I am going to to do is raise the level of the hose so it has a loop in it that will keep the fuel from draining back and if that does the trick I will hunt down a check valve for that hose, it looks like it has been changed so if there was one it has been discarded not knowing what it was. Didn't do a line switch as it is hard to get to and really don't want to break the seal at the fittings. Thanks for all your help.
     
  7. hottoddie

    hottoddie Well-Known Member

    Jan 11, 2012
    Boston/Cape Cod
    1986 Sea Ray 390 Express
    Garmin 4212 Chartplotter
    Garmin 24 HD Radar
    Garmin GSD 22 Sounder
    Garm
    454 Crusaders
    I think you will find that the fuel is either leaking from the bowl internally or evaporating. If leaking internally a carb rebuild should take care of the issue. I've never seen fuel drain out of a carburetor back thru the fuel hose. Fuel pumps have internal check valve that prevent that from occurring. Carburetor are vented to the atmosphere and fuel will evaporate from the bowl over several days and require the engine be cranked a few revolutions to refill the carb bowl before the engine will start. If the choke is electric it may have a heat sensitive resistor that allows the choke to be open or closed depending on engine temperature.
     
  8. Loyd Dinneen

    Loyd Dinneen Member

    254
    Jul 29, 2017
    Las Vegas
    1977 Sea ray 240 SDA cruiser w/ twin 470 mercs.
    Twin 470 Mercruisers
    What you say makes alot of sense, when I tried the throttle before starting there was no fuel mist in the carb which you would expect to see when advancing the throttle a couple of times. The kits are not expensive so I think I will try that, sure won't hurt anything thats for sure. It does have a electric choke and the plate does move but I now have it fully adjusted.
     
  9. NorCal Boater

    NorCal Boater Well-Known Member SILVER Sponsor

    Jan 24, 2008
    Covington, LA
    Cobalt CM23
    GM SB 383" Stroker" Alpha Gen I
    I definitely have seen gas drift back to the tank. My '85 Cobalt that I am restoring had hard starting issue years ago and we were advised it was the check valve on the fuel tank pickup. We replaced it and it solved the problem we were having.

    Shawn
     
  10. hottoddie

    hottoddie Well-Known Member

    Jan 11, 2012
    Boston/Cape Cod
    1986 Sea Ray 390 Express
    Garmin 4212 Chartplotter
    Garmin 24 HD Radar
    Garmin GSD 22 Sounder
    Garm
    454 Crusaders
    The check valve at the tank is usually responsible for fuel starvation under all conditions not just start up. If the boat is not starving for fuel at high rpm then the tank check valve would be ok. Once it passes thru the fuel pump and into the carb it can't flow back thru the pump to the tank.
     
  11. Loyd Dinneen

    Loyd Dinneen Member

    254
    Jul 29, 2017
    Las Vegas
    1977 Sea ray 240 SDA cruiser w/ twin 470 mercs.
    Twin 470 Mercruisers
    I am going to put check valves on the tank hoses just to make sure, Right now I am trying to track down carb kits to rebuild the carb that don't cost an arm and a leg. This year of motor the carb # isn't coming up on many sites.
     
  12. NorCal Boater

    NorCal Boater Well-Known Member SILVER Sponsor

    Jan 24, 2008
    Covington, LA
    Cobalt CM23
    GM SB 383" Stroker" Alpha Gen I
    OK
     
  13. aquaholic

    aquaholic Member

    77
    Jul 7, 2009
    new jersey
    37 express cruz, 3126 cats, all new garmin electronics,
    3126 cats
    i would buy another carb, rebuilding them old 2 barrels never really works out, and in a boat your asking for trouble
     
  14. Loyd Dinneen

    Loyd Dinneen Member

    254
    Jul 29, 2017
    Las Vegas
    1977 Sea ray 240 SDA cruiser w/ twin 470 mercs.
    Twin 470 Mercruisers
    Buying another carb is not a option as they want in the range of 300.00 plus and the ones I've looked at are not the same as the one on my boat they have a different fuel line setup. If you clean the old carb properly, adjust the float to specs, replace all the components, and tighten everything down properly then the carb will be like new. The float adjustment and air fuel needle adjustment is the most important in the rebuild get that right and the carb will run like new. The easy way out is buying a new carb and just pull a r&r.
     
  15. Thornton69

    Thornton69 Active Member

    290
    Sep 15, 2014
    Northern BC
    1980 24.5' SR custom hardtop
    1984 18' Valco sled
    1984 20' Alicraft- sold
    5.7 260 Merc/ Bravo 2
    Evanrude 115/80 jet
    It sounds like you have a faulty lift pump. As hottoddie said, they have internal check valves that should not allow fuel to drain back. If you are on a limited budget and want to try to pinpoint your problem, maybe you could try swapping lift pumps and or carbs between engines and see if the problem follows. Not sure if they or counter rotating or if it even makes a difference for those components. If you add a check valve between the tank and the lift pump you will want to make sure it has a very low crack pressure. Otherwise you may be complicating things further. If it is between the pump and carb then would not be as much a problem. Guessing that is a steel line though.
     
  16. Loyd Dinneen

    Loyd Dinneen Member

    254
    Jul 29, 2017
    Las Vegas
    1977 Sea ray 240 SDA cruiser w/ twin 470 mercs.
    Twin 470 Mercruisers
    From what I can see it looks like the prior owner was also fighting this problem as there is a new fuel pump and a new starter on that engine. One thing that hasn't been checked is the in carb fuel filter. Some of them have a built in check valve and when I first got the boat the fuel line fitting where the filter goes was loose and leaking a little suggesting perhaps they had changed it or maybe removed it altogether, another thing to check. The starboard engine is counter rotating and I really don't want to start switching and swapping parts, can cause more problems than I already have. I really need to give it a real good tuneup the wire set looks to be kind of mixed up one wire is from a import car. Looks like a south of the border tuneup had been performed on it. I will get into it again tomorrow if it doesn't blow too hard suppose to have up to 50mph gusts. Thanks again everyone for all your help.
     
  17. NorCal Boater

    NorCal Boater Well-Known Member SILVER Sponsor

    Jan 24, 2008
    Covington, LA
    Cobalt CM23
    GM SB 383" Stroker" Alpha Gen I
    Those 2-barrel carbs are easily rebuildable. I had never reuilt a carb before but had seen it done a hundred times. I set my laptop up on a bench, pulled up a You Tube how-to video on that carb and got after it. It took about 30 minutes and the motor ran perfectly.
     
  18. BillK2632

    BillK2632 Well-Known Member SILVER Sponsor

    Jun 25, 2009
    Lake Norman, NC
    1999 185 Bowrider,
    Mercruiser 4.3, Alpha I
    +1, had never rebuilt a carburetor, when I started having issues with my Mercarb I decided to give a rebuild a try. Figured worst case I totally screw it up and turn it in for a professionally rebuilt one and I am only out the $30 rebuild kit. I ordered the kit from Mikes Carburetors' and followed his video. Took me the better part of a weekend to do it, but when it was done, I put it back on it the motor fired right up - some minor fine tuning and it was worked perfectly ever since. Worst part was when my wife caught me with the carburetor disassembled on the kitchen table.
     
  19. Loyd Dinneen

    Loyd Dinneen Member

    254
    Jul 29, 2017
    Las Vegas
    1977 Sea ray 240 SDA cruiser w/ twin 470 mercs.
    Twin 470 Mercruisers
    Yep kitchen table rebuild can get you in hot water. LOL I have also rebuilt a few carbs and they are not that hard to do. The only thing that I found you have to watch out for is make sure all little ball bearings and bits are removed before using compressed air to blow out the carb only made that mistake once and cost me another carb. The most expensive part of the deal is the carb soak solution if you want to do it right. This carb looks to be a simple rebuild it just takes paying attention and maybe taking pictures if something looks complicated or you may think may be something you will overlook. Float and air fuel adjustment is very important. I thought I had got the carb # but I am missing one # so I will have to go back out to the boat stand a bit on my head and look at it again also look at how many needle adjustments it has makes a difference between Mercruiser and Rodchester. I'm seeing kit prices from 15.00 to 60.00 depending the carb, I will try your Mikes Carb and check their prices what ever the price I will be rebuilding the carb have to fix this problem. Thanks everyone
     
  20. NorCal Boater

    NorCal Boater Well-Known Member SILVER Sponsor

    Jan 24, 2008
    Covington, LA
    Cobalt CM23
    GM SB 383" Stroker" Alpha Gen I
    I think I paid $18.
     

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