hard starting

[barchetta95]

I have a problem starting my boat when it sits for a couple of days it's a 1995 4.3lx Mercruiser. I did notice no gas squirting in carb when moving throttle back and forth. have to crank engine numerous times and finally will start runs fine once started so I'am not sure if it's a bad fuel pump it's electric any ideas.

 

[Don S]

Re: hard starting

Probably not a bad fuel pump, more likely a bad accelerator pump or stuck checkball in the acc. pump circuit.
A carb rebuild could cure that problem.

 

[barchetta95]

Re: hard starting

thanks for your help

 

[farmboy]

Re: hard starting

My merc does this, always has. I blame it on the Holley carb. If the boat sits for over a week, the fuel in the carb evaps away. I saved my batteries and starter from the "extra" cranking need to re-fill the carb by installing a squeeze bulb between the fuel shut-off and the water separator. I also try to remember to close the fuel petcock and run the carb dry before pulling it home. I do not know if it helps, but I feel better with the fuel only in the tank while its on the trailer.

 

[barchetta95]

Re: hard starting

thanks farmboy have not noticed a fuel shutoff but squeeze bulb sounds like a good idea just had boat a couple months still finding myself around

 

[seamanben]

Re: hard starting

I've had the same problem:
Before I start the engine cold, I prime the engine by pushing the throttle forward three times, then turn the key and it runs fine. After I take it for a cruise (say 10 minutes) and turn it off, the engine still idles for 20 seconds or so (very roughly) then dies. When I then go to start it, I have to prime it agressively while turning it over. This process can take 45 seconds or so, and I killed a battery the other day doing it.

I have clean plugs, new dist cap, professionally rebuilt carb, clean fuel. Sprayed carb cleaner through the carb, and opened up the starter - looks fine.

Any ideas?

 

[f_inscreenname]

Re: hard starting

I think about everyone's boat does this. As long as it is not to excessive its probably a good thing. Giving the motor a couple revolutions by the starter before starting (and in most cases rev'ing up) helps the oil pump start flowing oil through the motor before the start and the rpm's hit it.

 

[seamanben]

Re: hard starting

I understand how it helps getting the oil moving when it's cold - (my 3L Merc starts fine when its cold) - But when it's HOT and I turn it off it diesels for a while, then when I try to start it it takes 30 seconds or so of trying, and pumping the throttle trying to get fuel to the engine. I would think when the motor's hot it would start up right away.

The fuel pump sight tube is clear of any gas, so I think the fuel pump is fine.. the plugs are fine, new distributor cap, starter looks fine, carb is rebuilt, gas is good.. I tried adjusting the idle speed screw and that didn't help the problem either.

The merc mechanic here is backed up for months, so any help from you guys is much appreciated!

 

[f_inscreenname]

Re: hard starting

Ahh now I see. Had a boat that did that also.
I found if turn the key and opened the throttle at a steady pace (from idle to WOT or start, what ever came first) it would start right up. It may work for you or you may have to fine how your motor wants to start. I rebuilt, replaced and upgraded everything I could but the boat just like to start that way.

 

[wallydc2]

Re: hard starting

When you say the engine is hot, how hot? If your engine is overheating you will have a hard time getting it started because the fuel is evaporating to quickly.

 

[cbear34]

Re: hard starting

Almost sounds like the carb is set to rich. When shutting down the carb might be "dumping" fuel causing the run on and hard starting. If you can, see if the carb is still dumping fuel when you shut down the engine. Also smell your engine oil to see if it had a gas odor. Sometimes if a carb is no good a rebuild may not fix a problem.

 

[seamanben]

Re: hard starting

I noticed that sometimes there is gas in the fuel pump sight tube (Not the gas line to the carb, but the see-through flexible tube that runs from the fuel pump to the carb). I heard that when gas is seen there it can mean the fuel pump is broken, and needs replacing. Perhaps this is causing the problem!?
Ideas? Thanks.

 

[cooter2506]

Re: hard starting

I believe the clear line is a safety for the fuel pump. If there is fuel in that line then the diaphram in the pump is blown.

 

[f_inscreenname]

Re: hard starting

Ya, what cooter said.

 

[180shabah]

Re: hard starting

Barchetta,

AS mentioned above, the fuel in your carb is evaporating when it sits for a while. Pumping the throttle helps very little because there is no gas for the accellerator pump to pump. Usually, after a couple of engine revolution, the fuel pump has run long enough to get some gas into the carb and you can pump it a couple more times and it should fire right up. However, if there is any trash in your antisiphon valve that prevents it from seating completely, then gravity will pull the fuel(very slowly) from your lines and pump back down into the tank. It takes your fuel pump 30-45 seconds to displace the air in the lines and get fuel into the carb, And it is very rare that someone actually cranks thier engine this long as it is bad for the starter.

Replace your AntiSiphon valve, and you can also do one more thing. I added a momentary switch that feeds 12v to the fuel pump, press for 5 seconds to fill the carb, pump the throttle, hit the starter, fires right up.

 

[barchetta95]

Re: hard starting

180shabah, were would I find the antisiphon valve, I followed the fuel line from the fuel/water seperater filter back to the fuel tank seen nothing that looked like a valve ecept brass fitting that screwed into fuel tank.

 

[180shabah]

Re: hard starting

AS valve doesn't look like a valve. It looks like a brass fitting screwed into the tank It is essentially an adapter(threaded on one side, barbed on the other) that has a checkball and spring inside of it.

 

[barchetta95]

Re: hard starting

Thanks for your help 180shabah, barchetta95

 

[180shabah]

Re: hard starting

no problem, did you get it resolved?

 

[barchetta95]

Re: hard starting

it will have to wait till spring time took boat out of water for winter the boat is in michigan I live Illinois thanks again