Hard Starting?

So, I have a 4.3L Merc, 4bbl, and it fires right up cold, but when it's warm, it needs to crank for probably 30 seconds before it'll fire, and run mint....What do I need to check? I'm no good with carbs... Do I need to move the throttle a couple times to work the accelerator pump? there's gotta be a better way...It frightens my female passengers when the thing seems to crank forever...they think we're stuck!!! haha

Re: Hard Starting?

The 4.3's have been around since the mid 80's, the ones today don't even look like the old 4.3's.
Might be real handy if you at least gave a year of yours. A Merc SN would be even better because Merc doesn't go by year, only SN.

Re: Hard Starting?

PS94 said:

So, I have a 4.3L Merc, 4bbl, and it fires right up cold, but when it's warm, it needs to crank for probably 30 seconds before it'll fire, and run mint....What do I need to check? I'm no good with carbs... Do I need to move the throttle a couple times to work the accelerator pump? there's gotta be a better way...It frightens my female passengers when the thing seems to crank forever...they think we're stuck!!! haha

Click to expand...

As what Don said, we need to have the serial number, but it sounds like you have a Weber 4bbl and what you are experiencing is 'normal' for them. It's caused by capillary flow inside the drillings in the carb. Basically, they dribble after shutdown, causing a partial engine flood the next time you try to start. You can relieve the problem slightly by lowering the float level a couple of millimetres, but you will not eliminate it.....

Chris.......... (I solved my dribbly carb by putting an MPI engine in)

Re: Hard Starting?

My Bad. I thought the boat appeared in a sig...I'm unsure of the S#, as the boat is out at the lake, but it's a 1995 Sea Ray, 4.3LX, mated to an Alpha 1 Gen II



Achris - How hard was the MPI swap? did you do the motor swap, or just intake and wiring?

Re: Hard Starting?

Sounds like QuadraJet standard warm starting procedure needed. Crank 3-5 seconds and if no start then advance the throttle slowly to half throttle (slowly not to invoke more gas into the intake) and crank it should start within 10 seconds. I have had this problem ever since changing carbs two years ago and have not found a way to resolve it. My old carb 1705-9288which I'm going to rebuild very soon would have a hard time starting cold and would start within a second when warm. I later found out my cold starts were a combination of problems.

I was told you could run on idle for a few minutes after coming off plane and run the blower before turing off the engine to help reduce the dribbling into the intake and flooding it. Heat Soak of the carb.

Re: Hard Starting?

Do I need to move the throttle a couple times to work the accelerator pump? there's gotta be a better way...

Click to expand...

Ayuh,.... Advance it,... 1 time,... Leave it there til it Fires.....
No pumpin'...

Re: Hard Starting?

Hmm, You think there'd be a better way. IIRC the carb resembles the old pickup carbs, I always heard them called Rochester...

I guess I know why the idle speed was cranked way up....It started ok when it idled at 1000 rpm....but didn't go inot gear so well....

Re: Hard Starting?

1995 definitely makes it a Weber.

The MPI upgrade was a complete engine system, including leg, transom plates, instruments and controls. You can do it with just an engine, but, for me, financially it was better to sell the complete system. As it turned out a friend wanted it, even after I told him about the hard warm starting.

A change to a Rochester Quadrajet may help the problem. The other path I was looking at was a Edlebrock 1409.

An idle speed of 1000rpm will kill the gears in the leg...

Chris.......

PitchFork said:

I was told you could run on idle for a few minutes after coming off plane and run the blower before turing off the engine to help reduce the dribbling into the intake and flooding it. Heat Soak of the carb.

Click to expand...

Pitchfork,

You was told a crock of BS. The dribbling is caused by fuel running through the drilled passages inside the carb. Short of freezing the petrol, the blower isn't going to help one little bit, and neither is idling. The idle for a few minutes is to allow the combustion chambers to cool so the dribbling fuel doesn't cause run-on. Neither is the problem a carb heat-soak condition, I put a special heat insulating gasket under my carb and ran with the engine box open and it didn't change the problem one zot.

Chris (spent many weeks investigating a problem Mercruiser said didn't exist. A lot like my cracked timing covers. )

Here are some links to previous threads on this problem. Lots of reading, no fix to the problem.

http://forums.iboats.com/showthread.php?t=45705
http://forums.iboats.com/showthread.php?t=372208

Re: Hard Starting?

I also tried a special gasket same issue. I just do the procedure I listed above and half the time it starts on first crank other times it take 6-8 seconds of cranking. I wish I would have rebuilt my old Rochester Carb 1705-9288 as for some reason it would crank everytime within a half a second when warm just would not start cold well. I am going to rebuild this fall. I did notice this weekend the Port Verturi was dribbling fuel after shutdown and the Starboard was not that I could see.

The lovely world of carbs the next boat I have probably will not have a carb.