Loosing prime after 4 days gas

wakeup 19

wakeup 19

Member
Nov 14, 2008
676
(Medford)Boston Harbor to Cape Ann to Cape Cod and
Boat Info
1992 300 Sundancer, Quicksilver ding w/ 6hp merc 4 stroke, anchorlift windlass, extended swim platfo
Engines
t/ 350 merc's (carburated) alpha drives gen II
1992 300 Sundance one engine won’t start after 4 days of sitting unless I prime the carb. Rochester carbs. Had them rebuilt last season changed mechanical fuel pump no change.
Is there a check valve in the line on this engine? One tank feeds both engines.
I also heard Rochester cards have been known to drip down thru needle or alike in bowl over time.
 
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There are plugs in the bottom of the carbs that leak and will drain the float bowls of fuel.
When you say 'prime' what specifically are you doing?
 
My Monaco and 270 will only start their own way when cold after sitting a few days and not vice-versa. The Monaco wants fast pumping of the throttle and she starts right up. The 270 wants 3 pumps, then fire the ignition and crank while pumping slowly, takes like 7-10 pumps. Forget and pump fast like the other boat and she will never start. Both start right up when they are warm.

I had the same question as you and the answer for the 270 was figuring out how she wanted to start. FYI, that took a season and a half. LOL

MM
 
northshore said:
There are plugs in the bottom of the carbs that leak and will drain the float bowls of fuel.
When you say 'prime' what specifically are you doing?
Click to expand...
I have been shooting ether but try to stay away from that. Pump throttle and it cranks for a long time before it statrts. If I visit boat during week it will fire but 4 or more days gives me trouble.
I don’t no for sure if the plugs were changed during carb rebuild at Hobbs in New Hampshire
 
wakeup 19 said:
I have been shooting ether but try to stay away from that. Pump throttle and it cranks for a long time before it statrts. If I visit boat during week it will fire but 4 or more days gives me trouble.
I don’t no for sure if the plugs were changed during rebuild at Hobbs in New Hampshire
Click to expand...

I also did the starting fluid start. That is exactly what I fought and the slow pumping of the throttle and holding the key on until it fires worked every time.

MM
 
As stated above, there are plugs in the bottom of Rochester carbs that are notorious for leaking. When that happens there is no fuel in the bowl to allow the engine to start. And it won't start until the bowl fills. They need to be sealed.
 
sdarc said:
As stated above, there are plugs in the bottom of Rochester carbs that are notorious for leaking. When that happens there is no fuel in the bowl to allow the engine to start. And it won't start until the bowl fills. They need to be sealed.
Click to expand...
Thanks I will pull carb soon. Can you replace plugs or seal them if this found to be leaking?
 
Just take them out and seal them. Or you can thread new plugs in. There are are articles and YouTube videos galore.
 
sdarc said:
As stated above, there are plugs in the bottom of Rochester carbs that are notorious for leaking. When that happens there is no fuel in the bowl to allow the engine to start. And it won't start until the bowl fills. They need to be sealed.
Click to expand...

It was interesting that everyone thought that was the issue I had but it was not. Had two different top shelf mechanics look and attempt to diagnose the problem but nothing was found not working as expected.

MM
 
MonacoMike said:
Don't be afraid to crank it...

MM
Click to expand...
MonacoMike said:
It was interesting that everyone thought that was the issue I had but it was not. Had two different top shelf mechanics look and attempt to diagnose the problem but nothing was found not working as expected.MM
Click to expand...

So Mike you are still fighting this issue?
I had pulled rebuilt and reinstalled my carbs before the mechanic next door and the mechanic across the street both said "Did you seal the plugs". As of nearly 6 years later, I have not. I crank for 10 to 15 seconds, pump twice and 99 times out of 100, both engines start right up.
 
northshore said:
So Mike you are still fighting this issue?
I had pulled rebuilt and reinstalled my carbs before the mechanic next door and the mechanic across the street both said "Did you seal the plugs". As of nearly 6 years later, I have not. I crank for 10 to 15 seconds, pump twice and 99 times out of 100, both engines start right up.
Click to expand...

I do not consider it "fighting it", no, that fight is over. it varies how long it takes to start I believe based how long since it ran. Never longer than seconds though and I have never timed it so I may be guessing to long.

MM
 
the fuel evaporates from the bowels then you have to crank engine over till you get oil pressure as the electric fuel pumps won't work till you have oil pressure then the bowels fill and now you can pump the throttels and get fuel, standard practice with carbs. Boy EFI sure spoils people
 
atrick said:
the fuel evaporates from the bowels then you have to crank engine over till you get oil pressure as the electric fuel pumps won't work till you have oil pressure then the bowels fill and now you can pump the throttels and get fuel, standard practice with carbs. Boy EFI sure spoils people
Click to expand...

No electric fuel pump here. What now?

MM
 
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