Merc 888 hard start, backfires!

ccarson2

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Joined
Jul 9, 2006
Messages
12
Hi all,
My engine is hard to start w/o starter fluid and will occasionally backfire during this starting process. Also, I am not getting an accelerator pump shot.
It took me forever to get the timing even close and I think I fouled out the (new) plugs so I wire brushed them and put them back in. But that was two weeks ago and the boat has run several times since then although not since Saturday.
I rebuilt the 2bbl Rochester POS. The carb was previously full of water and really disgusting, so I let it soak in carb cleaner for a while and cleaned it up real good. The one alarming fact of the carb is that the little retainer that holds in the check ball under the main venturis is STUCK in the carb, and trying to remove it only makes it worse since little chunks of the retainer come off on my pliers. So, I figured what harm would it cause leaving it in there, at least the check ball hasn't been lost.
I had problems with gas coming out of the carb before, but just today I installed a new float and set it to 3/8". I haven't started it yet because the battery was dead and I just put it on the charger. Could this be a check ball problem?
I also apparently lost the check ball to the accelerator pump. I figure this why I'm not getting a pump shot. Where is this supposed to go, directly under the pump itself or one of the holes in the fuel bowl? I have some Quadrajets lying around, I'm going to see if the check ball can be used from that carb.
 

ccarson2

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Joined
Jul 9, 2006
Messages
12
Re: Merc 888 hard start, backfires!

BTW I did set the timing right, I believe at 15* advanced.
 

ccarson2

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Joined
Jul 9, 2006
Messages
12
Re: Merc 888 hard start, backfires!

OK, i reset it to 8* and it runs a little worse, still hard to start, and still backfires. Anyone have any ideas? it seems to be running really rich, and at idle it'll run slower and slower until it backfires and dies.
 

Bondo

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Re: Merc 888 hard start, backfires!

ccarson2 said:
I rebuilt the 2bbl Rochester POS. The carb was previously full of water and really disgusting, so I let it soak in carb cleaner for a while and cleaned it up real good. The one alarming fact of the carb is that the little retainer that holds in the check ball under the main venturis is STUCK in the carb, and trying to remove it only makes it worse since little chunks of the retainer come off on my pliers. So, I figured what harm would it cause leaving it in there, at least the check ball hasn't been lost.

I'd say you Need a NEW Carb before you're going to Get AnyWhere.......................
 

Limited-Time

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Mar 30, 2005
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5,820
Re: Merc 888 hard start, backfires!

Those check balls are there for a reason.........one stuck, thats bad...........one missing thats even worse.........oh yah and what bondo said.
 

ccarson2

Cadet
Joined
Jul 9, 2006
Messages
12
Re: Merc 888 hard start, backfires!

Does anyone have a carb they want to sell me?
What carbs will interchange with a jet swap from the old carb? I figure most all 2GCs are the same besides the jets.

As for the check ball for the accelerator pump, where does it go? No ball ever came out of the carb when I rebuilt it, so I didn't bother replacing it, but this seems to be what's causing the backfire on a holeshot - no pump shot makes the engine lean out when the throttle is slammed.

I let the engine warm to operating temperature and it runs a LOT better for some reason - I Think it had something to do with the choke. But I'm going to put it in the water tomorrow to test it out so we'll see if it can handle a load.

Chris
 

Limited-Time

Vice Admiral
Joined
Mar 30, 2005
Messages
5,820
Re: Merc 888 hard start, backfires!

There should have been an exploded view of the carb in the rebuild kit. that should tell you where the acc. pump chk ball belongs. Without a functional acc. pump you will experance a lean pop every time you try to increase the engine rpm. My guess is you'll be lucky to get the engine off idle once you put it in gear..........but good luck.
 
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