Boat never starts without full throttle pumping, doesn't stay idle until 140F+

[Kronoss]

I have a 1999 Volvo Penta 3.0GS Carb and this is driving me nuts.

* My Spark plugs always get full of dark black carbon around the edges and sometimes inside of them.
* Never starts without full throttle + pumping motion
* Will never stay idle unless engine is warmed up to 140ish F, then it will idle just fine
* Even while warmed up, once in gear, and give it just a bit of gas, engine dies, if I go full throttle however, runs perfect.



What do you guys recommend ?

 

[Jeepster04]

Re: Boat never starts without full throttle pumping, doesn't stay idle until 140F+

Ever had the carb rebuilt?

Change the fuel filter often?

 

[Augoose]

Re: Boat never starts without full throttle pumping, doesn't stay idle until 140F+

X2 on the rebuild and inspection of fuel filter- especially if its a 1999 and the carb hasn't been rebuilt before.

The symptoms you describe point to a couple of things but in order to figure out exactly what the issue is, I think it would take more testing with you posting the results of what it did when you tried "x", etc.

Based on what you said, it sounds like its either running too rich since you have dark sooty carbon on the plugs, you are not getting sufficient spark to burn up all the fuel, or you are not getting enough air mixed in for good combustion. Does it smell like its running rich as well when its cold? What is the position of the butterfly in the choke when its cold? Open, closed or in the middle? Since it runs better after warm up I suspect the choke might have something to do with it.
When you say that after it has warmed up and you give it just a bit of gas, it dies...... is that under normal throttle for an easy take off? Just FYI, a blown power valve can result in the engine dying if you goose it vs gradually increasing throttle while an incorrectly adjusted accelerator pump can cause similar issues.

Has the engine ever run correctly? What has happened since the last time it ran correctly?
Do all plugs appear the same - all equally fouled?
What is the fuel level in the bowl?
What jets are you running?

 

[Don S]

Re: Boat never starts without full throttle pumping, doesn't stay idle until 140F+

It would also be a good idea to install a water separating fuel filter to your engine also. The 3.0L engines do not come with them as standard equipment, and with todays fuels, they are really needed to keep clean fuel in your carb.

 

[jeffnick]

Re: Boat never starts without full throttle pumping, doesn't stay idle until 140F+

I'd start with a fresh set of plugs.

 

[Don S]

Re: Boat never starts without full throttle pumping, doesn't stay idle until 140F+

Ever done any tuneup or other work on the engine? New plugs as mentioned, new cap, rotor, check timing with shunt, compression test, filters in the fuel pump etc? It all has to work together at the same time.

 

[John2037]

Re: Boat never starts without full throttle pumping, doesn't stay idle until 140F+

I've got a 98 3.0 and the fuel pump and carb were in bad shape causing similar issues. Cap and rotor a must, then after that check your timing. The fuel pump comes apart.

 

[hubbabubba]

Re: Boat never starts without full throttle pumping, doesn't stay idle until 140F+

Sounds like the carb needs adjusting,too rich.
Make sure the plugs are the right ones.
Change the rotor,cap,wires,plugs.
What's the idle set at? Don't go by the guage get a meter and test it again.
Not sure of the rpm;s in neutral, someone will chime in with the right answer.

 

[Mullin]

Re: Boat never starts without full throttle pumping, doesn't stay idle until 140F+

* Even while warmed up, once in gear, and give it just a bit of gas, engine dies, if I go full throttle however, runs perfect.

I'd repeat what has already been said but also add to adjust your carb really well. I mean idle, mixture, and accelerator pump all need to be adjusted just right. The last one, the accelerator pump, may me part of the problem with your last issue. It sounds like it could be out of adjustment to the point that a much bigger throttle movement is needed to get it to spray gas than if it was tuned correctly.

Of course don't even bother messing with the carb until you check the timing. Check it with the engine warm with a timing light. Check your manual for the proper degrees at what rpm.

 

[Don S]

Re: Boat never starts without full throttle pumping, doesn't stay idle until 140F+

Along with what Mullin mentioned, the idle mixture is really fussy on a 3.oL for some reason. To rich and it will hesitate on acceleration, to lean and you get the same thing.
When warmed up, if it's been idling for a while most will hesitate the first time, but work fine during normal running.

 

[vwbugman69]

Re: Boat never starts without full throttle pumping, doesn't stay idle until 140F+

It would also be a good idea to install a water separating fuel filter to your engine also. The 3.0L engines do not come with them as standard equipment, and with todays fuels, they are really needed to keep clean fuel in your carb.

Any particular filter you suggest? Any brands to stay away from?

 

[Don S]

Re: Boat never starts without full throttle pumping, doesn't stay idle until 140F+

Any kit works, just use a quality 10 mil filter element.

 

[Mullin]

Re: Boat never starts without full throttle pumping, doesn't stay idle until 140F+

This is the kit I installed on my boat: Fuel Water Separator Bonus Pack Kit for Johnson, Evinrude, Volvo Penta, Mercruiser 32-802893Q4 35-805269A4, OMC Sterndrive Cobra, Mercury, Mariner, Yamaha Outboard - Sierra 18-7852-2 - iboats

I thought it was a great deal because it came with the extra filter. It is really easy to install too.

Any kit works, just use a quality 10 mil filter element.

I don't know what the rating is on that kit I linked, it doesn't say. I see a different filter available that actually specifies the 10mil rating: Fuel Water Seperator Assembly - Sierra 18-7991-1 - iboats
The kit looks a little different.

 

[aerobat]

Re: Boat never starts without full throttle pumping, doesn't stay idle until 140F+

i installed a sierra marine fuel filter/water separator . it works just fine .

 

[vwbugman69]

Re: Boat never starts without full throttle pumping, doesn't stay idle until 140F+

So will this one work?


Invincible Marine Store - Fuel Water Separator and Filter Kit with Mercury 10 Micron Filter, Boat Engine Parts, Invincible Marine