Hard Start

[0ldog]

I have a Starcraft 1810 w/ 4.3 MC w/ 2bbl Rochester I believe. When cold the only way I get it started is prime w/ gas thru carb. Once it?s been running and warm, starts like a dream. No problem WOT. before everyone tells me it?s not getting gas I can figure that out myself. I go to local MC tech and he says check anti syphon value and ball should rattle and If it doesn?t just knock out ball and try it. No change. Am I correct in that this valve prevents the tank from emptying is the hose is ruptured on the engine end of the system. Shouldn?t it also function as a mechanism to prevent the gas from draining back out the line to the pump? I know the oil pressure switch will prevent the fuel pump from running until proper pressure is achieved. If I remove it?s leads and tie them together, and problem is corrected that would tell me it?s the switch, correct? I videoed the choke and it seems to be working properly. This is a new to me and I wish it wasn?t boat. Thanks John

 

[Don S]

Re: Hard Start

Do you use the throttle only button on the control, pump the throttle a time or two and leave the throttle up about 1/4 to start?

 

[0ldog]

Hard Start

Yes, Am familiar with the starting sequence as I've had Merc outboard for years with no problem. When if fires from the prime you have to kick it up a notch to keep the RPM up, if not you go thru the whole thing again. Son talked to other owners and they say they have to either cycle the lever a number of times, AKA prime or crank forever. Just doesn't seem you should have to do that. Always an easy start w/ outboard.

 

[Another retired guy]

Re: Hard Start

You don't mention the choke- is it closing properly when engine is cold?
A wide open choke on a cold engine will result in similar symptoms.

 

[Another retired guy]

Re: Hard Start

Sorry , ignore last post I missed the comment re the choke!

 

[Don S]

Re: Hard Start

Yes, Am familiar with the starting sequence as I've had Merc outboard for years with no problem. When if fires from the prime you have to kick it up a notch to keep the RPM up, if not you go thru the whole thing again. Son talked to other owners and they say they have to either cycle the lever a number of times, AKA prime or crank forever. Just doesn't seem you should have to do that. Always an easy start w/ outboard.

It's not an outboard!
Pumping the throttle a time or two pumps fuel from the carbs accelerator pump and allows the choke to set. That's how they work, and the process is even described in the owners manual.

 

[captk]

Re: Hard Start

Outboards and stern drives are not the same animal, and starting procedures differ. Outboards do not have an accelerator pump in the carb as do IO's. You must pump the throttle once or twice to set the choke and throw a slug of fuel into the carb, body. Conversely pumping the throttle on an OB does nothing more than exercise your arm, as they have no pump in the carb. Also check your choke to insure it is set right and works. If you still have problems the carb needs rebuild as it is allowing the fuel to run out and evaporate between outings. good luck Bill

 

[captk]

Re: Hard Start

It's not an outboard!
Pumping the throttle a time or two pumps fuel from the carbs accelerator pump and allows the choke to set. That's how they work, and the process is even described in the owners manual.

Sorry Don we were replying at the same time, I guess Great minds think alike. Bill

 

[Don S]

Re: Hard Start

Outboards and stern drives are not the same animal, and starting procedures differ..................

Not a problem, may help him understand the differences.

 

[generator12]

Re: Hard Start

I just corrected the same kind of problem on a 470 with a mechanical fuel pump. First start of the day required manual priming - all was good afterward. The correction was a new fuel pump. The original did everything right except draw a prime from the tank.

 

[0ldog]

Re: Hard Start

First of all, thanks everyone for the suggestions. I should have mentioned I?ve read what seems like a hundred posts on no start fuel problems and many have excluded your suggestions. Trying to keep the post short I probably eliminated some information. Being by myself it was difficult to view the choke operation so I set up my digital camera and video taped it. On a cold start. once the throttle button is depressed and the lever moved forward, the idle screw releases pressure on the cam and the choke closes almost completely. There is a slight gap maybe the thickness of a dime. (I have had an extra hand once and they held the choke shut completely to no avail) So I?m assuming the choke is operating properly. I have installed a new separator. Removed the fuel line and checked the screen in the carb and it?s spotless. I was told that the gas had stabilizer in it last fall. Numerous activations of the throttle doesn?t help, which leads me to agree with Bill about the absence of gas in the carb. I?m just trying to eliminate as many things as I can before going out and spending the $75 my dealer wants for a carb kit, I replaced the anti syphon valve with a clear thru fitting to see it this would help a weak fuel pump. But wouldn?t I have a fuel problem at high speed if the pump was bad? That was my first question, that no one answered, I assume the valve is also a protection to keep the line full to help the pump. My second question, that no one answered, am I going to do any damage by jumping the oil pressure switch? I realize the reason it?s there and the issues it brings up if faulted. I just want to know if I?m going to do damage. Like most of us I?ve spent needles $$ replacing good parts at times, so this is my reason. I?m just frustrated at this point......... John

 

[0ldog]

Re: Hard Start

included....

 

[achris]

Re: Hard Start

Jumping out the oil pressure switch as a TEMPORARY diagnostic test will not hurt anything...
One more test worth doing is to disconnect the throttle cable, hold the choke open with your finger and give the throttle a couple of full strokes. You should see a couple of squirts of fuel from the accelerator pump... If you don't see those, start with that being you main problem...

Chris...

 

[Cal195]

Re: Hard Start

I have about the same problem "oldog". Re-built the carb, could not replace the pump though... one in kit was not the same. It did help, but trouble has not been resolved completly. i did replace the choke and that seemed to help also, but i am having problems restarting after it is shut off for awhile, i have to treat it as though its flooded ang keep the throttle wide open to start it....runs rough for a bit and then straightens itself out. I ended up disabling the choke so its not a factor, helps but issue is not solved completly, gets frustrating....a lot of good info from some of the people here though, they can be very helpful....good luck. I will keep checking back to your post, maybe I can figure this out by reading some of the posts here.

 

[Eric 3.7LX Alpha 1]

Re: Hard Start

If you do as Chris mentioned and you don't have squirts of fuel from the pump, there is a good possibility that the fuel bowl is empty. Rochesters have internal welch plugs which can slowly leak fuel down into the intake after a long period of "off" time and make cold starts difficult until the bowl is refilled back up by the fuel pump.

 

[0ldog]

Re: Hard Start

If you do as Chris mentioned and you don't have squirts of fuel from the pump, there is a good possibility that the fuel bowl is empty. Rochesters have internal welch plugs which can slowly leak fuel down into the intake after a long period of "off" time and make cold starts difficult until the bowl is refilled back up by the fuel pump.

This is what I'm seems to fit most of my symptoms, my son is here now and we will try the suggestions............. Thanks for the TEMPORY answer......... Chris

 

[0ldog]

Re: Hard Start

Update........ Attempted normal start. Choke lever looked okay, spray from jets several times. Turned over, caught and ran out gas in bowl and stopped. Removed leads from pressure switch and jumped. Pulled fuel pump connector and had 12 volts at harness pins. Plugged into FP no noise, no fuel from line entering carb.

Went back and installed pressure switch leads normally, hooked fuel line back up and started by spray prime in carb. As in the past after several attempts engine runs longer than on just the prime. Once that is achieved it will start and run normally until you let it sit and get cold.

Best guess is something intermittent in the fuel pump. When things get hot and expand or whatever it works.

So it?s fuel pump pricing time unless someone sees something else. Oh and back to one of my original questions, The anti syphon valve should also keep the line full between the tank and the pump, correct?

Thank you all........... John

 

[generator12]

Re: Hard Start

John, I repeat, I had the same thing with my 470 - needed a prime for the first start of the day - started and ran fine for the rest of the day. Fuel Pump, my man.

It can have difficulty establishing prime - essentially drawing a vacuum on the incoming line - and still not show a problem on the outlet side once running.

 

[0ldog]

Re: Hard Start

Thank you all for your help. I just installed a new Fuel pump and and it started beautifully............ well after I put the plug on. I had tucked out of the way after testing the new pump prior to install and forgot about it. Oh well, all is good ............ John