4.3 Mercruiser cold start issues

MichaelBC

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Feb 28, 2020
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Hallo,

I wrote already that I will go back to the original setup and I will find another way to prefill the carb that is following the safety rules.
 

Lou C

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Interesting, I heard good things pretty much always about the Edelbrock carb but didn't really know this characteristic of it. Older Quadrajets had leaks from a welsh plug in the bottom of the bowl but I have not had that with mine. I also tried a Holley 4160 on mine for a while and that didn't have that problem either. I guess they all have their quirks.
 

achris

More fish than mountain goat
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May 19, 2004
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Interesting, I heard good things pretty much always about the Edelbrock carb but didn't really know this characteristic of it. Older Quadrajets had leaks from a welsh plug in the bottom of the bowl but I have not had that with mine. I also tried a Holley 4160 on mine for a while and that didn't have that problem either. I guess they all have their quirks.
Yeah, Merc stopped using Holleys after 1977... 'too many boat fires'.....
 

Scott06

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Interesting, I heard good things pretty much always about the Edelbrock carb but didn't really know this characteristic of it. Older Quadrajets had leaks from a welsh plug in the bottom of the bowl but I have not had that with mine. I also tried a Holley 4160 on mine for a while and that didn't have that problem either. I guess they all have their quirks.
In general the edlebrock is a good carb very easy to tune If needed. I have. Two one on the boat and one on my 65 GTO. I wouldn’t hesitate to by an other one.
 

nola mike

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So it does appear that my carb is affected. Tried today after a week sitting. Only 6 seconds of cranking, but feels like forever. Looks like I'll need to add a switch as well...

 

Lou C

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Yeah, Merc stopped using Holleys after 1977... 'too many boat fires'.....
I think that's a thing of the past Chris, if that were still an issue in the USA, you KNOW that Holley would have a pack of lawyers after them. Probably 80% of classic muscle cars and hot rods here are running Holley carbs, or their derivatives like Quick Fuel et al. Yet you never really hear about this being a problem.
 

achris

More fish than mountain goat
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.... Probably 80% of classic muscle cars and hot rods here are running Holley carbs, ....
One important word there, 'cars'. Leaking carbs in cars doesn't usually end with a swim in the sea.
 

MichaelBC

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Feb 28, 2020
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Just one more sentence about the time that is needed to fill the carb.
Only for testing I added some transparent fuel filter to my fuel hose to see what is going on. So I can say that it takes less than 5 seconds to fill the carb, it's rather only 3 seconds. You can see that the pump is pulling a remarkable amount of fuel from the tank very fast and then the flow stops immediately. I did this test only on land and the filter is replaced by a marine version made of metal already.
 

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achris

More fish than mountain goat
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May 19, 2004
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27,468
Just one more sentence about the time that is needed to fill the carb.
Only for testing I added some transparent fuel filter to my fuel hose to see what is going on. So I can say that it takes less than 5 seconds to fill the carb, it's rather only 3 seconds. You can see that the pump is pulling a remarkable amount of fuel from the tank very fast and then the flow stops immediately. I did this test only on land and the filter is replaced by a marine version made of metal already.
How long was that since the last start? (how long had the carb had time to dry out?) Often the line between the carb and the pump is also dry, and occasionally also the pump itself, and those pumps aren't great at self-priming.
 

MichaelBC

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Feb 28, 2020
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Time since last start on the test was about 3 months.
I do not know about the fuel line but it was at least partially dry on the part that I cut to put the tranparent filter in.

In about 4 weeks I hope that I will have all the resin and fiber work done on the boat and I can put the new motor in. Then I can do the test again with empty fuel lines, empty pump and empty carb. I will only prefill the original fuel filter cartridge. I will try to make a video then and post it here.
 

Lou C

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One important word there, 'cars'. Leaking carbs in cars doesn't usually end with a swim in the sea.
But this is the USA, anyone can sue anyone. If this was still happening we’d have heard about it. In fact even though Merc stopped using them OMC and Volvo used them from when Quadrajet production ended in 1989 or so until the change over to TBI. That means they were used approx 10 more years...
I think they improved the bowl gaskets and the rubber prints that seal the transfer tube.
 

Scott06

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But this is the USA, anyone can sue anyone. If this was still happening we’d have heard about it. In fact even though Merc stopped using them OMC and Volvo used them from when Quadrajet production ended in 1989 or so until the change over to TBI. That means they were used approx 10 more years...
I think they improved the bowl gaskets and the rubber prints that seal the transfer tube.
Pretty well known issue with hot rod folks here. My coworker has a holley on his 69 firebird, doesnt even try to start it in the spring without replacing the float bowl gaskets because of leaks. The one piece fuel bowl and no power valve blow out issues are two real advantages of the Edelebrock
 

nola mike

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So it does appear that my carb is affected. Tried today after a week sitting. Only 6 seconds of cranking, but feels like forever. Looks like I'll need to add a switch as well...

Well, hell, now I don't know. Didn't jump the switch today, 2 pumps of the throttle and it started first crank, no stumbling or anything once started. Had been sitting since my last post. So presumably the bowl was full.
 
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