Must pump the gas several times to start

[callbay]

1998 Mercruiser 350 CID V/8 260 HP with a 4 barrel Rochester Quadrajet carb. It's all stock. It's in a 19 foot runabout boat.

To cold start I must pump gas five to seven times and then it still won't start. If I pump it a couple of more times it starts.

When the engine is warmed up it starts fine.

What would cause this and how do I fix it?

Thanks guys!

 

[eljefino]

Your choke's dead. Pumping the gas squirts fuel through the accellerator pump which substitutes, poorly.

Look down the air cleaner, should be a flap that's supposed to move, which is gummed up and not moving "for whatever reason."

 

[kc8adu]

time to rebuild.
get a brass float and pay particular attention to the leakdown fix.
i wirewheel the plugs with a dremel and coat area with jbweld in addition to the stuff in the kit.
the leaking plugs empty the bowl after it sits a while.
try cranking about 20 seconds then give the accelerator 1 pump to set the choke and give it a squirt. bet it starts right up.

 

[BrocLuno]

Also check valve in the fuel pump is maybe leaking a bit so that the pump can't fill the float bowl immediately when the engine turns... The carb is warm when you shut down, it will evaporate some fuel. More may go when it sits between uses.

So you go to start and it takes a bit to get full. Between the choke not setting and the lower fuel level you are having to manually "prime" it.

But there is nothing wrong with doing that for a while. Start cranking and row the lever. It'll light

 

[abycat]

seems to me like your choke needs Repair or adjustment. You are essentially choking your engine with the accelerator pump nozzles. Some chokes are adjustable. loosen a screw and turn the choke then tighten the screw up. next time you start it cold slowly floor it before starting for about 10 seconds and then let the throttle up all the way then try to start it. the mechanism might be operating slow because of wear or sticky parts. but I do think a full carb rebuild by a pro would be a great investment for your car and sanity

 

[splinter]

Originally Posted By: kc8adu
...the leaking plugs empty the bowl after it sits a while...

Quadajet troubleshooting flowchart often leads to...

...leaking main well plugs. Now sealed with epoxy.

 

[Donald]

If it's never been rebuilt get the carb rebuilt by a pro. It's been in service 18 yrs. Tredwell Carb in Tredwell NY is very good with any type of carb.

 

[supton]

Sounds like leaky plugs, like splinter says. You could try just cranking w/o pumping, a bit of a crank to pump gas back into the carb; and then the routine pump or two before starting.

When I had a dead choke vehicle it used be, pump and it'd fire but sputter right out. So I would have to keep pumping it while it was running, so that the accelerator pump would add the extra gas. After a minute or so (longer in cold weather, not that long in warm) I could then hold a high idle and/or take off.

 

[philipp10]

Originally Posted By: kc8adu
time to rebuild.
get a brass float and pay particular attention to the leakdown fix.
i wirewheel the plugs with a dremel and coat area with jbweld in addition to the stuff in the kit.
the leaking plugs empty the bowl after it sits a while.
try cranking about 20 seconds then give the accelerator 1 pump to set the choke and give it a squirt. bet it starts right up.


Check the choke FIRST....rebuild if choke adjustment DOES NOT HELP. With mechanical things, always start with the simple things before total rebuilds. Use some commen sense!!