93 mercruiser 4.3 alpha one gen 2 fuel problem (I think)

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donwatanabe

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I just bought this used 93 bayliner capri. It would start fine and run good but after a short time it hesitate and shut down and would be unable to start until waiting a while. As part of maintenance I replaced fuel filter fuel pump and anti siphon valve. It starts up right away in beginning but still shuts down and won't start again until I waited till the next day. The carburetor is getting fuel but I noticed gas inside on the bottom. I haven't had a carburetor engine since the 70 and 80's so I know very little. It's a 4 barrel I'm not sure if carb is oem. Please any help
 

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Bondo

Bondo

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The carburetor is getting fuel but I noticed gas inside on the bottom.
Click to expand...
Ayuh,....... Welcome Aboard,........ On the bottom, Where,..??

If in the bilge, yer fuel tank is leaking, probably gas out, 'n water in,.....

When you changed the fuel filter, did you inspect it's contents for water,..??
 
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donwatanabe

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Bondo said:
Ayuh,....... Welcome Aboard,........ On the bottom, Where,..??

If in the bilge, yer fuel tank is leaking, probably gas out, 'n water in,.....

When you changed the fuel filter, did you inspect it's contents for water,..??
Click to expand...
I'm sorry I meant the bottom inside the carburetor. I forgot to inspect old fuel filter
 
nola mike

nola mike

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Is that an auto carb? Not familiar with it but it looks like a vacuum line there?
 
Bt Doctur

Bt Doctur

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a edelbrock 1409 or a carter AFB ,it is a marine one. seeing fuel in the bottom of the carb or intake may mean a float has been compromised and is flooding the motor
Same thing happened to mine
 
ESGWheel

ESGWheel

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Here are a couple of methods to check to see if engine is flooding possibly due to float compromised (too heavy) or other issue with the needle / seat / float adjustment.

Take off the spark arrestor and be prepared to pull a couple of spark plugs. Start it up and once is stalls out, smell at the carb. Smell heavy gas? Then pull two plugs. Do they appear wet and smell like gas? If yes, then it’s flooding out.

Another method is to remove and ground out the high tension wire fm coil to dist. So wire still in coil but grounded out on the other end. Again, with the spark arrestor removed, put the throttle fully open and have a helper turn over the engine while you hold open the choke and look down the carb throat with a flashlight. Do you see liquid gas pouring in or heavily dribbling in? Note it may take 30 seconds or more of cranking. If yes, then it’s flooding out.

How to fix? Rebuild carb and get a kit that as a new float.
 
Lou C

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Those Carter/Weber Edelbrock carbs actually have 2 float bowls on either side of the central venturis and so you have 2 floats, 2 needle valves. Could be something quite simple as the rubber needle valve tip deteriorates just due to time. My test for leaky floats is to unbolt carb & dump out all the gas. Then rig up a way to carefully blow thru the fuel inlet. Flip the carb upside down and try to blow thru the fuel inlet. If you can then the needle valves are leaking or the floats are hanging up on the inside of the bowl. With the carb empty of fuel & right side up you should be able to blow thru the fuel inlet….
 
ESGWheel

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Lou C said:
My test for leaky floats is to unbolt carb & dump out all the gas. Then rig up a way to carefully blow thru the fuel inlet. Flip the carb upside down and try to blow thru the fuel inlet. If you can then the needle valves are leaking or the floats are hanging up on the inside of the bowl. With the carb empty of fuel & right side up you should be able to blow thru the fuel inlet….
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Lou, this is a good way to check but how do you address if the floats are too heavy due to leaking or absorption? Thanks.
 
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svb165

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Could it be a weak coil? my 76 120 merc had that issue. and it seemed like a fuel thing, but,, it ran fine on the trailer for long periods testing but would stall shortly after launching..and re start after a lengthy wait. I cleaned everything over and over, carb, fuel pump, pick up... found out it was losing spark as it warmed up, put in a new coil and didn't slowly die. just a thought.
 
Lou C

Lou C

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Well you’d have to know how much the floats are supposed to weigh or buy a new set and compare new to the old. I haven’t had that problem with the Quadrajet in the boat but it can happen…I have heard of those floats in the Carter/Weber/Edelbrock 4 bbl rubbing against the side of the fuel bowl…..
 
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donwatanabe

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I took carburetor in for testing and rebuild. They were able to duplicate poor running after startup. He said a lot of build up and sticking. As part of rebuild i want to upgrade to electric choke. Where would I get 12v source for coil without having to run wire from fuse box. Can I come off fuel pump source since that's key on power
 
ESGWheel

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Before addressing how to power an electric choke, can you explain more about taking the carb in for a rebuild? Did you remove the carb and take it somewhere? Or took the boat somewhere and they experienced the same conditions as you did and said, “it’s got a lot of build up and sticking”? Build of what and what is sticking? The choke? Is the running issue now solved? If not, no reason IMO to jump to an enhancement. A sticking choke fix normally only involves a can of Carb Clean and 2 minutes.

Here is what I am getting at: I am assuming you took in the boat and got some advice on the issue that included ‘build up’ and ‘sticking’ as well as converting to an electric choke as a solution the shop was willing to do.

So what is going on?
 
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donwatanabe

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I took the carburetor in to a shop that had a engine set up to run my carburetor to be truthful once he could duplicate the poor running after startup I already knew I was going to rebuild. i didn't ask if the floats were sticking or what specifically was the problem . They didn't recommend electric choke. I was thinking about doing that after reading problems on different sites with manual choke. And the one time I had boat on water it took a few minutes of running for engine to start getting warm. Is electric choke better. I need to let him know before reassemble if I want to do conversion
 
ESGWheel

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It’s past my posting time so this may be a short answer
Warm up time of engine and type of choke are not related. It alway takes time to warm up based on lots of factors including intake water temp.

I would leave choke as stock (not convert) as it’s one less thing to worry about once you get carb back to get on water > bolt up and go have fun 😎
 
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