1994 Mercruiser 3.0L Alpha 1 Gen II Hard Start when Hot

[Harritwo]

I purchased this boat about 6 years ago with less than 100 hours total time on it. Currently it has 210 hours total time, 20 hours since overhaul of the outdrive/transmission due to gimble bearing failure and water intrusion in the transmission. This engine will start with in two revolutions of the starter on a cold start. It has a merc carb and has been rebuilt. When it is hot, after running like skiing, tubing, etc... to restart the engine you have to advance the throttle to the half position and continue advancing to WOT while cranking. WHen it restarts, you immediately return to idle and the engine runs fine. The fuel system has been checked, all new fuel filters, no water, Carb rebuilt twice. The electric choke has been unhooked, and wired open. I think it might be a vapor lock condition but have been told by my local marine mech that on these engines a hard hot start is characteristic.

Is that info correct? What can be done to help it? The fuel lines are original and are not toucking anything. THe line from the pump to the crb sits about an inch off the moter running up the side, across the valve cover and into the carb.

Thanks for your help.

George

 

[Don S]

Re: 1994 Mercruiser 3.0L Alpha 1 Gen II Hard Start when Hot

Doesn't really sound like a vapor lock sounds more like a flooding condition when opening the throttle for more air makes it start.
When you shut the engine of, does it diesel a bit before stopping? That could suck some extra fuel into the cylinders and make it hard to start.

 

[dubs283]

Re: 1994 Mercruiser 3.0L Alpha 1 Gen II Hard Start when Hot

sure sounds like the engine is flooded upon a warm start-up

i would recommend a carb rebuild but you have done that

one thing to check is when you shut the engine off, check to see if fuel is running/dripping down the carb (maybe have a helper shut it off while you are looking) - if so, whoever is rebuilding your carb is doing something wrong

 

[timfives]

Re: 1994 Mercruiser 3.0L Alpha 1 Gen II Hard Start when Hot

Yeah, i would think it is carb / flooding related, mine did that as well and i had the carb gone through and it took care of the problem.. Also do you have a fuel separator? be sure to change that out as well..

t

 

[Harritwo]

Re: 1994 Mercruiser 3.0L Alpha 1 Gen II Hard Start when Hot

No it does not diesel. The timing has been checked and rechecked and is set by the book, with leads disconnectd at 1 deg BTDC. It has the factory carb and flame arrestor installed. The flame arrestor is cleaned monthly and i am unsure where to go with this any more. ANy suggestions are greatly appreciated.

 

[Don S]

Re: 1994 Mercruiser 3.0L Alpha 1 Gen II Hard Start when Hot

one thing to check is when you shut the engine off, check to see if fuel is running/dripping down the carb (maybe have a helper shut it off while you are looking) - if so, whoever is rebuilding your carb is doing something wrong

Right there is the best place to start.

Have you done a tuneup lately? Compression check, etc?

 

[Harritwo]

Re: 1994 Mercruiser 3.0L Alpha 1 Gen II Hard Start when Hot

All new A/C plugs, compression 115-120 across dry, 135 wet across. Fuel filter, water seperator, oil and filter changed annually. Using wix filter for fuel water, Fram for oil, fuel, and Pennzoil 10W30. WOT 4600. Timing 1 deg BTDC with leads disconnected and in water, no mouse ears. Cannot Locate marine plugs so am using auto equal in place. Marine is AC 10

 

[Don S]

Re: 1994 Mercruiser 3.0L Alpha 1 Gen II Hard Start when Hot

Don't think that just because a carb is rebuilt that it works correctly. Depending on what the insides look like, I find about 50% of them look good but don't work. Even the remans from Mercruiser. In my experience, they run about a 10% success rate. aka junk.

 

[Harritwo]

Re: 1994 Mercruiser 3.0L Alpha 1 Gen II Hard Start when Hot

Waht kind of carb would you recommend? Currently is factory MerCruiser Carb 2 bbl. ( Looks like a rochester) With current setup, My self and my son, (450 Lbs) plus gear, fuel, etc. top speed is 38 mph at 4600 rpm by GPS. It is running a 14-1/2 inch prop, 19 pitch. I usually trim up as high as i can without porpoising and get this speed. At this rate, my fuel consumption is between 5-6 GPH, if i throttle back to 4000 RPM 30 MPH and cruise, i can get fuel consumption down to about 3 to 3-1/2 GPH. I do not want to sacrifice pulling but would like to increase speed and get better economy if i change carbs. My WOT is within specs Mercury says 44-48oo at WOT so i am fairly confident the prop is right.

 

[Don S]

Re: 1994 Mercruiser 3.0L Alpha 1 Gen II Hard Start when Hot

You don't have a running problem, you have a starting problem. Props, rpm and speed have nothing to do with it.
Look at your carb as stated in post #3 and 6 and see if you have a problem. It may just be more carb repair, not replacement, but YOU have to actually LOOK and see what is happening. Then we can go from there. Throwing a $400 carb at something just to see if it cures the problem or not is silly.

 

[Harritwo]

Re: 1994 Mercruiser 3.0L Alpha 1 Gen II Hard Start when Hot

The first time it was rebuilt was by a marine mech at his shop. A year later i rebuilt it myself using merc parts. The inside is clean, all air passages blown out, carb was cleaned with carb cleaner and soaked for about 4 hours. The jet is stock, the float is set per the carb instructions. I do not remember the actual setting. With the engine running, when i shut it down i do not see any fuel leaking by, but there is a smell of fuel. Do you know the float setting or would you recommend changing it to where it shuts off sooner? Air mixture set by 1-1/2 turns out, then continue setting until engine smoothed out to highest smoothest RPM at idle w/ears. There is no vacuum port to set by vacuum gauge like i would on a car. My book, (A Clymers) does not fully address the setting of the carb.

 

[Don S]

Re: 1994 Mercruiser 3.0L Alpha 1 Gen II Hard Start when Hot

How did you set the float the first time? If you didn't and didn't do the other settings, then you just replaced parts not rebuild.
Here is the specs from the OEM manual.



Here is a link to the OEM manuals you can look at. #13 covers your engine. 14 for your drive.
http://boatinfo.no/lib/library.html

 

[Harritwo]

Re: 1994 Mercruiser 3.0L Alpha 1 Gen II Hard Start when Hot

I originally set the float based on the instructions in the rebuild kit. I just did not remember what the actual setting was. I will pull th etop of the carb this weekend and check the float setting again. The original carb problem was it would not take the throttle from idle. The accelerator pump o-ring was broke and when i went through the carb everything was fixed except the hard start when hot. The choke has been disconnected. In Florida i have never needed the choke to start. Everything else was originally set to specs but i will double check everything again. THanks for all your help and i will post results upon completion of checking everything else. I fully understand by your statement about parts changers. That is not me, i have been mechanicing for over 30 years, just not marine. I troubleshoot everything first, then do what is required. If at all possible, i will disassemble the offending item and see if i can repair it before i ever replace it. Been doing this the old school way all these years and been successful. With a marine engine, i know things are different than with an auto or truck. Thank you for all your help so far.

 

[ktbarrentine]

Re: 1994 Mercruiser 3.0L Alpha 1 Gen II Hard Start when Hot

Curious...does the 3.0L have an electric or mechanical fuel pump? Reason I ask is that my 1990 5.0L had the exact same symptoms. Turned out my 22 year old fuel pump (maybe 400 hours on the engine) diaphragm started cracking and it was flooding the carb via the sight tube. Changed the fuel pump and problem gone! Just watch out for the aftermarket fuel pumps! That's another thread....

 

[Harritwo]

Re: 1994 Mercruiser 3.0L Alpha 1 Gen II Hard Start when Hot

It still has the factory mechanical fuel pump. I have not run a Pressure test on it yet but i will. I have read several threads on aftermnarket parts and the one thing my marine mech friend has drilled into me is use only genuine merc parts. His exact words are Sierra is Crap.

 

[ktbarrentine]

Re: 1994 Mercruiser 3.0L Alpha 1 Gen II Hard Start when Hot

So have you checked the sight flow tube while the engine is running? Once I found out what to look at, it was obvious.

 

[Pete104]

Re: 1994 Mercruiser 3.0L Alpha 1 Gen II Hard Start when Hot

And did it act like this prior to replacing the accelerator pump?

 

[ktbarrentine]

Re: 1994 Mercruiser 3.0L Alpha 1 Gen II Hard Start when Hot

Cannot Locate marine plugs so am using auto equal in place. Marine is AC 10

Finding it hard to believe you cant find marine plugs.... They are all over the internet. crowleymarine.com, mercruiserparts.com, etc. Just sayin.

 

[Harritwo]

Re: 1994 Mercruiser 3.0L Alpha 1 Gen II Hard Start when Hot

Thanks, I got the A/C Marine Plugs coming, They are not available at my local dealer unless you bought a case of them. I did not think i would use a case anytime soon, but I have them coming from Crowley.

To Pete;

I do not know if it was hard to start before, the accelarator pump was not working when i bought it and i immediately went into the carb and rebuilt everything. I have not checked the fuel pump but that will be the first thing i pull after pulling the top and checking the float settigns.

 

[Don S]

Re: 1994 Mercruiser 3.0L Alpha 1 Gen II Hard Start when Hot

Here is all the carb info from the OEM manual.