96 5.7lx 4-bl carb slow to fire- Where do i start looking

[shawnmd]

I have a 96 mercruiser 5.7lx 4 bl weber carb (non vortec) with bravo 3 in my 96 Chap. When it's cold the starter turns over the engine strong (not a battery issue), but the engine won't fire for about 5-6 secs. That is understandable when its cold, with the choke coming on and so forth. However, if I run the boat to operating temperature, shut it down for more than 20 mins, it will do the same thing, and take 5-6 secs before it fires.

That being said, if I were to bring the engine up to temperature, shut it down, then immediately start it, it starts right up instantly. Could this be a carb or fuel pump issue? maybe the float is set wrong in carb and fuel is draining back. Could the fuel be draining back to the tank from the fuel pump causing the fuel pump to have to pump fuel for those 4-5 secs before it starts?

 

[Bondo]

Re: 96 5.7lx 4-bl carb slow to fire- Where do i start looking

I have a 96 mercruiser 5.7lx 4 bl weber carb (non vortec) with bravo 3 in my 96 Chap. When it's cold the starter turns over the engine strong (not a battery issue), but the engine won't fire for about 5-6 secs. That is understandable when its cold, with the choke coming on and so forth. However, if I run the boat to operating temperature, shut it down for more than 20 mins, it will do the same thing, and take 5-6 secs before it fires.

That being said, if I were to bring the engine up to temperature, shut it down, then immediately start it, it starts right up instantly. Could this be a carb or fuel pump issue? maybe the float is set wrong in carb and fuel is draining back. Could the fuel be draining back to the tank from the fuel pump causing the fuel pump to have to pump fuel for those 4-5 secs before it starts?

Ayuh,... Welcome Aboard,... That's Impossible,...

But,.... Yer carb is noted for leakin' off into the intake,...

At 5/ 6 Seconds, I don't see a problem,... Are ya Advancin' the Throttle when ya start it,..??

 

[shawnmd]

Re: 96 5.7lx 4-bl carb slow to fire- Where do i start looking

Ayuh,... Welcome Aboard,... That's Impossible,...

But,.... Yer carb is noted for leakin' off into the intake,...

At 5/ 6 Seconds, I don't see a problem,... Are ya Advancin' the Throttle when ya start it,..??

Thanks...5 to 6 seconds doesn't sound that long, but think about an engine cranking, and count to 6---- that is quite long for an engine to be cranking over. How far should I advance the throttle when starting it? In the morning I do give it 3-4 full throttle pumps then leave the throttle just out of the neutral zone...

 

[Bondo]

Re: 96 5.7lx 4-bl carb slow to fire- Where do i start looking

Thanks...5 to 6 seconds doesn't sound that long, but think about an engine cranking, and count to 6---- that is quite long for an engine to be cranking over. How far should I advance the throttle when starting it? In the morning I do give it 3-4 full throttle pumps then leave the throttle just out of the neutral zone...

Ayuh,... I've got the same carb on a 4.3l,...
Cold, in the mornin' start, Mine cranks 5/ 10 seconds to reprime the carb,...
Then after a short wait, I pump the throttle to Wot a couple of times, 'n haul it back to 1/2 - 3/4s, 'n hit the key,...
When it fires off(which is Quickly), pull back the throttle,...
(Jumperin' the fuel pump eliminates the 1st crank over, 'n carb primin')

After it been runnin', 'n shut-down, Crank it on a Full Wot Throttle,...
It's flooded from the leakin', 'n goin' Wot helps clear it,...
Of course, again, be ready to pull it back when it fires,...