Difficult Cold Start.Mercruiser 305

[Kiwi Phil]

Mercruiser 305. 228hp. Serial 6260005. 1984<br />There is no choke on this motor.<br />I have a lot of difficulty starting it from cold.<br />The previous owner, plus the Mariner Mechanic, tell me to pump the throttle a couple of times and it will start. <br />It dosn't do that for me, infact I wonder if I end up flooding it, as I believe I can hear it backfire at times. It takes ages to start, and I really mean ages.Of course I have pumped it quite a few times by then.<br />The plugs are clean. <br />Once it has run for a few minutes, if I switch it off, it will re-start immediately, every time, all day.<br />Did this motor come with a choke?<br />How do you go about starting this motor easily, without giving your batteries hell?<br />Does anyone have any advice or experience with this motor as I sure could do with.<br />Many thanks.

 

[rodbolt]

Re: Difficult Cold Start.Mercruiser 305

hello<br /> the only way you will ever get a decent cold start is to replace the choke or carb. depends on how and why there is no choke. the reason for a choke is that a cold engine requires a very rich initial fuel mix to start. as the intake gets wet and the fuel vapors become heated the mix can be leaned out. the auto choke function does this quite well. the backfire either indicates its way to lean and burning in the intake or you may also have other problems. fix the choke first and see.<br /> good luck and keep posting

 

[crazy charlie]

Re: Difficult Cold Start.Mercruiser 305

I am sure there was a choke at one time.I would get a new choke for the carb.You can try to manually choke the carb as someone cranks the motor.This will confirm what you need.You can also try not pumping the throttle until after you are cranking the motor.I had the same motor and thats how I did it.Charlie

 

[Fishermark]

Re: Difficult Cold Start.Mercruiser 305

The 305 that I recently took out of my boat had a four barrel carb (Quadrajet) with a mechanical choke. There was a little bi-metal spring on the intake manifold that had a little metal cover on it.

 

[airman]

Re: Difficult Cold Start.Mercruiser 305

Check your ignition as well. I have a pair of Chrysler 400's and they were hell to start until I converted to electronic ignition. Similar symptoms to yours. As for a starting procedure, I would suggest pumping the throttle 5-8 times, then leaving it full forward while you crank. Essentially you are intentionally slightly flooding the engine. A flooded engine with no choke will start pretty well if the throttle is wide open. Peek down the carb after you have pumped the throttle and make sure there is a little raw fuel in the manifold before you start cranking.

 

[RatFish]

Re: Difficult Cold Start.Mercruiser 305

I have never come across an internal combustion engine that did not have some sort of choke and/or primer mechanism for cold engine starts.

 

[John Carpenter]

Re: Difficult Cold Start.Mercruiser 305

Same engine & same problem. I installed electronic ignition last Spring & while I am glad to no longer have points to fool with...it did nothing for the hard starting problem.FWIW, I do have a working automatic choke. Mine only does it if it has sat for awhile, if it's just overnight it starts right up. My feeling is that this is clearly a fuel related problem. It helps mine considerably if I shut off the fuel valve when I leave the boat...preventing fuel from draining back towards the tank.<br />Not a cure, but I start mine by first pumping the throttle 7 or 8 times, then cranking for a few seconds at full throttle. Pump another 4 or 5 times and she starts right up

 

[bob58]

Re: Difficult Cold Start.Mercruiser 305

@ Relentless, try installing a check valve in your fuel line. Keeps the fuel from siphoning back to the tank and you don't have to wonder if you shut your shutoff valve or not.<br /><br />@ Kiwi Phil, if the choke butterfly is still on the airhorn of your carb, you should be able to fit it with either electric, manifold bi-metal or manual chokes found at auto parts stores.

 

[Kiwi Phil]

Re: Difficult Cold Start.Mercruiser 305

Thank you everybody for your assistance.<br />Have just returned from the Marina. The motor has a Rochester Quadrajet Carb, and someone has removed the choke. <br />Asked the Marina Mechanic and apparantly it is a common practice here. <br />Anyway, 2 full pumps with the throttle (as was suggested) and it starts straight up. If it stalls, then 2 more full pumps and it starts again.<br />Before I was giving it a series of small pumps etc and generally ball'sing myself up. <br />Now I know what to do, I'm happy. Many thanks everybody. Much appreciated.<br />Cheers<br />Phil<br />PS I am not mechanically minded at all. My brothers who build roadsters/drag machines/rods reckon I could stuff a cannon ball