Cold start woes - please please help!

[LGRay]

95 220 BR Signature w/5.7L MERCRUISER 250 fuel injector not carb. My dad bought it brand new so we 've grown up with it and know it pretty well, but he passed away a couple of years ago and now we're struggling to figure out what's going on with these cold start problems.

Once the engine is warm, if we're out on the lake or something, never any problem whatsoever starting it over an over. Skiing it's on and off constantly and never an issue at all. However, doing a cold start at the beginning of the day more than 80% of the time it won't turn over. There doesn't seem to be any rhyme or reason to it, except for the fact that when we add gas sometimes that helps. Not like we're out of gas, we might still have half a tank but seems to correlate to it not turning over. We can't make heads or tails of that and the marina we use can't either, but I know you all are the expert so really hoping someone can poimt us in the right direction.

Other maybe helpful info: we use the boat only a couple of weeks a year, but pretty much every day during those weeks. And it doesn't seem to make any difference whether it's the first day or the last day when we're using it, it's always just a problem in the morning when we are first starting it up. Not super cold outside, probably 70 degrees. Does this make sense to anybody? Super super appreciate any advice,. More than once we've had the whole boat loaded up with kids and toys and everything and then had to sit on the dock for an hour while one of us tried over and over to get it to turn over. Pretty miserable.

THANK YOU FOR ANY ADVICE!

 

[JHornsby3]

Check to make sure your fuel pump is putting out the correct amount of pressure. And I would double check to see if you have a anti-syphon device inline. If so, make sure it is working.

 

[scoflaw]

Have you tried advancing the throttle about halfway?

 

[km1125]

When you write "it won't turn over", does that mean it won't crank at all, or it cranks and cranks but won't run?

 

[LGRay]

Check to make sure your fuel pump is putting out the correct amount of pressure. And I would double check to see if you have a anti-syphon device inline. If so, make sure it is working.

Thanks so much. That's definitely beyond our technical capabilities. Would next best thing be to ask the mechanic at the marina we store it at to check both of those things? Thanks again!

 

[LGRay]

Have you tried advancing the throttle about halfway?

Great question, I should have clarified. Our procedure is generally:

1) Blower for a minute or two
2) Push in the button at the base of throttle (to leave the boat in neutral but rev the engine), push the throttle all the way forward and back up twice, and then leave it in a position about 80% advanced
3) Turn the key

Would love any thoughts/suggestions on better process there, thank you!

 

[LGRay]

When you write "it won't turn over", does that mean it won't crank at all, or it cranks and cranks but won't run?

Sorry, should have clarified. It cranks - meaning it's making all the noises like it's about to start but then won't get the final VROOOOM to actually start. Does that make sense? Thank you for any advice!

 

[scoflaw]

That's not how you do it. Full advance on the throttle shuts fuel off. Don't touch the throttle at all and if that doesn't work advance it about half way. If it starts at half way it's your IAC motor.

 

[brewster16]

IDC= Idle Control Valve. It regulates how much air (oxygen) is allowed into the combustion chamber. No air = no start. Remember that fuel, spark and oxygen are each necessary to start the engine.

 

[Yendor]

I know this may be getting confusing given your inexperience with what we're talking about,
but I believe both the previous posters are referring to the same thing.
Not to add to your confusion, but the name for that part that I always used is an Idle Air Control Valve.

I was having similar issues with my 2000 7.4 and that was the definitive fix.
Given that MerCruiser is a little prouder of their parts than I think they need be, this is the one I recently bought for mine.
https://www.ebay.com/itm/175284787875 (ignore that description has yet another name, ha ha)
It appears that yours uses the same, but can't confirm. I'm sure someone will chime in about that.

I am willing to bet a (non-AB) beer that is the answer for your ailment.

 

[LGRay]

That's not how you do it. Full advance on the throttle shuts fuel off. Don't touch the throttle at all and if that doesn't work advance it about half way. If it starts at half way it's your IAC motor.

Thanks so much. So you're saying when I cold started in the morning I should not use the throttle at all. And if that doesn't work, then just advance the throttle halfway and try again?

Dad did it the other way for three decades but I'm totally open to the idea that that may be ass backwards wrong!

 

[LGRay]

IDC= Idle Control Valve. It regulates how much air (oxygen) is allowed into the combustion chamber. No air = no start. Remember that fuel, spark and oxygen are each necessary to start the engine.

This makes sense to me, but I'm still really confused about the fuel element. Does it make any sense to anyone why it would work when the fuel is full but not when it's a quarter tank?

 

[LGRay]

I know this may be getting confusing given your inexperience with what we're talking about,
but I believe both the previous posters are referring to the same thing.
Not to add to your confusion, but the name for that part that I always used is an Idle Air Control Valve.

I was having similar issues with my 2000 7.4 and that was the definitive fix.
Given that MerCruiser is a little prouder of their parts than I think they need be, this is the one I recently bought for mine.
https://www.ebay.com/itm/175284787875 (ignore that description has yet another name, ha ha)
It appears that yours uses the same, but can't confirm. I'm sure someone will chime in about that.

I am willing to bet a (non-AB) beer that is the answer for your ailment.

This is very helpful, I appreciate especially you clarifying the different terminology! And the link is great. When you say you were having similar issues, was it the same thing with cold start sometimes working and sometimes not? Did you have any similar experience with the amount of fuel having an impact on whether it worked? And, after replacing that part as the definitive fix, do you now longer need to use the throttle at all on a cold start? Is that the goal we should be aspiring to?

Again, thanks so much. Really appreciate the input!

 

[km1125]

Your start procedure would have been correct for older carb-based engines. Moving the throttle resets the choke and also squirts a little gas into the engine.

With an EFI engine you should have to do NONE of that. The ECU should detect whether the engine is warm or cold, and adjust the fuel appropriately. It will also use the IAC valve to give the engine enough air to start.

Try the newly-learned procedures. If you still have trouble getting it to start (cold or warm), then report back. There could be issues with the ECU not understanding it's cold or hot (due to sensor issue) or not being able to control the air or fuel (due to IAC or injector issue) that would cause issues, but I really wonder if just the new procedure would resolve your issue.

 

[LGRay]

Your start procedure would have been correct for older carb-based engines. Moving the throttle resets the choke and also squirts a little gas into the engine.

With an EFI engine you should have to do NONE of that. The ECU should detect whether the engine is warm or cold, and adjust the fuel appropriately. It will also use the IAC valve to give the engine enough air to start.

Try the newly-learned procedures. If you still have trouble getting it to start (cold or warm), then report back. There could be issues with the ECU not understanding it's cold or hot (due to sensor issue) or not being able to control the air or fuel (due to IAC or injector issue) that would cause issues, but I really wonder if just the new procedure would resolve your issue.

Ok, going to try out new procedure. THANK YOU! And so that we know, what is the throttle used for with an EFI engine? This makes sense that we were doing it wrong because my Dad learned everything he knew about boats from a 1970 Caravelle w/a Mercury OB! But now wondering when we *should* be using the throttle, if ever. And last question but anybody have a clue as to why the amount of fuel in the tank would have any bearing on it starting or not? That's still baffling us. Thank you all again, really appreciate all the help and will report back on how it goes with new starting procedure!!

 

[km1125]

Ok, going to try out new procedure. THANK YOU! And so that we know, what is the throttle used for with an EFI engine? This makes sense that we were doing it wrong because my Dad learned everything he knew about boats from a 1970 Caravelle w/a Mercury OB! But now wondering when we *should* be using the throttle, if ever. And last question but anybody have a clue as to why the amount of fuel in the tank would have any bearing on it starting or not? That's still baffling us. Thank you all again, really appreciate all the help and will report back on how it goes with new starting procedure!!

Once the engine is running and you've moved away from the dock, use the throttle controls to accelerate to cruise speed.



Ok, just having some fun. You really shouldn't need to use the throttle just for starting. If the engine is flooded for some reason, you can put the throttle to FULL and it will disable the fuel injection so you can crank the engine a couple times and clear it out, but make sure you're ready to pull the throttles down if the engine actually does start on the fuel that's already in there.

No clue on why the amount of fuel in the tank would make a difference. It could have just been a weird coincidence.

 

[LGRay]

Once the engine is running and you've moved away from the dock, use the throttle controls to accelerate to cruise speed.



Ok, just having some fun. You really shouldn't need to use the throttle just for starting. If the engine is flooded for some reason, you can put the throttle to FULL and it will disable the fuel injection so you can crank the engine a couple times and clear it out, but make sure you're ready to pull the throttles down if the engine actually does start on the fuel that's already in there.

No clue on why the amount of fuel in the tank would make a difference. It could have just been a weird coincidence.

Hahahaha, well deserved, well deserved. But educate us on more thing: what terminology should we be using for the version of the throttle where the button at the base is pressed and we're just "revving" the engine. As opposed to when the engine is running, the button is NOT pressed, and we're actually using the "throttle"?

So on my car, I'd say the first scenario is when it's in "neutral" and I'm just "revving the engine". But on the boat I'm not sure how to say that without sounding like a clown! It's not "choke", right? How would you describe when you have the button pressed in and are "revving" the engine?

Oh, and the fuel level thing has happened at least 5 times so I'm reluctant to believe it's a coincidence...but maybe that's a mystery for a different day.

Thank you again @km1125 and everybody else, this has been super helpful!!

 

[BillK2632]

The term is just Neutral, the "button" is usually referred to as the "Neutral Button". On my old carbureted boat, I used that button every cold start to pump the throttle, on my current fuel injected boat, only time I use that is when I am winterizing it and want to run at a fast idle. Day to day starting and running, just turn the key like a car.

The fuel level problem could be a couple of things you can try before maybe getting a mechanic involved:
1. Fuel vent line clogged. Next time it happens, take the gas cap off, if you hear a whoosh and or it then starts that means the vent line is clogged. Will need to clean it out.

2. Fuel pickup or line has developed a problem. Fuel pickup is like a straw that sticks into the tank and sucks the fuel out. Think of a drinking straw that has a hole half way down, you can drink fine until the hole starts sucking air. This can happen with your fuel pickup. Also the fuel line has several places where it connects to the fuel pump, fuel filter, carburetor, any of these connections can get loose and cause it to suck air - just check/tighten the clamps. The lower the fuel level in the tank, harder it has to "suck" to get fuel. Could also be debris in tank that collect around the pickup when the tank level get low. Also, the fuel pickup does not usually go to the bottom of the tank, so is it possible even though your gauge is reading 1/4 full, there really is not much gas in the tank? There is always a few gallons at the bottom of the tank that are not usable because of the pickup.

3. There is a thing called an Anti-siphon valve, it's the fitting where the fuel line connects to the pickup on the fuel tank. It's a check valve that keeps fuel from siphoning out of the tank if the fuel line were to rupture - a safety thing. This valve can get old and start sticking, causing strange fuel related problems. It's a $20 part that can wreak havoc when it goes bad. A couple of years ago I started having all kinds of strange problems, boat would start then immediately shut off, surging and sometimes shutting off while running. It all ended up being caused by this little $20 part that looked and seemed fine, but it wasn't.

I would try your new starting procedure, see how that works before you dig into any of the above -- a good rule with boat work - fix one thing at a time, make sure it's working before moving on the the next thing -- otherwise you do a bunch of things and have no idea which ones fixed something or broke something else!
Remember you have an old boat (nothing wrong with that) my SeaRay was a 1999 and my "new" boat is a 2014. Taken care of a boat can last decades, but a lot of little maintenance things start creeping in as they age. The sitting waiting for you to come back and run it is much harder on them than running it hard every week.

 

[km1125]

.... But educate us on more thing: what terminology should we be using for the version of the throttle where the button at the base is pressed and we're just "revving" the engine. As opposed to when the engine is running, the button is NOT pressed, and we're actually using the "throttle"? ..

You could just say you're "throttling up in neutral" or "revving up in neutral". That button disables the linkage to the shift mechanism. If you don't use it, then the control automatically shifts to fwd or rev when you move the control from the center position. Pushing the button "breaks" that linkage so the transmission stays in neutral.

 

[Yendor]

This is very helpful, I appreciate especially you clarifying the different terminology! And the link is great. When you say you were having similar issues, was it the same thing with cold start sometimes working and sometimes not? For the most part it was not an issue, only happened intermittently. However, when it DID happen, YES it was starting cold. Not any issue ever, once brought up to temperature. Did you have any similar experience with the amount of fuel having an impact on whether it worked? No, never made any correlation in that regard. I think that is an unrelated issue altogether. BillK did a good job of outlining those possibilities. If the IAC valve replacement doesn't address the issue, then and only then, I would pursue that list. And, after replacing that part as the definitive fix, do you now longer need to use the throttle at all on a cold start? Is that the goal we should be aspiring to? YES, it is. Other's information here is spot on: Never needed to advance the throttle, never did, still don't. This is almost guaranteed to be an unproductive effort. Again, thanks so much. Really appreciate the input!

Again, I will point out that I don't KNOW that yours will take the same part# as mine did. Research that before you get off your wallet. I didn't even stay at a Holiday Inn last night . . .

Typical lingo for that button you asked about is a neutral lockout, possibly born of antique outboard lingo where that button was actually a lever; no matter, same function involved. Maybe more current and proper lingo would be a "neutral safety switch", but again, same deal. Search "boat neutral lockout", you will see what I mean.