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96' Merc 454 hard starting

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Old 08-24-2009 | 05:09 PM
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How about doing a compression test. If the compression is low it will be a hard start, no matter what carb you have on it.
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Old 08-24-2009 | 06:00 PM
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Originally Posted by hamel01
Dogturd21 -
Blue thunder - I have tired it that way as well but I get the same outcome of the starter basicly trying to run the engine for a few seconds. It's just like it doesn't want to light and it dogs.
Ok, then next time no pumping but put the throttle to wide open and crank it over. Be ready to pull back the stick quick when it fires. Then buy a decent holley carb.
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Old 08-24-2009 | 07:23 PM
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Originally Posted by Throttle Fever
How about doing a compression test. If the compression is low it will be a hard start, no matter what carb you have on it.
Yep. Could be something other than a carb problem. Your cap and rotor could be the problem. How old are the plugs and wires? When was the last time timing was checked? How about the fuel water seperator? I'd get the obvious/cheap stuff out of the way 1st.

Last edited by Kidnova; 08-24-2009 at 07:30 PM.
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Old 08-24-2009 | 09:51 PM
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I never had a problem setting a choke up on any carb. The lack of experience is the only problem I see when people say they are a pain and disconnect them.
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Old 08-25-2009 | 09:59 AM
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I agree with Purple. Re-connect the damn choke. It's there for a reason. There's nothing inherently wrong with the Weber carb (Carter AFB) or the chokes they came with. They work very well and are very easy to tune, especially compared to a Holley.

On the 454 give it a pump or two and pull the throttle back to closed until the choke plate also closes (once you fix it) and the motor will start. Do not hold the throttle open.
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Old 08-25-2009 | 05:25 PM
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Originally Posted by PURPLE HORNET
I never had a problem setting a choke up on any carb. The lack of experience is the only problem I see when people say they are a pain and disconnect them.
My experience is with the Edelbrock marine 750, and it was a pain to get the choke correct. Looking at the parts diagrams (this is from memory back a few years) it appears that the Webers and Edelbrock are mechanically similar. IIRC the carb line was sold to Weber way back when and thats why Webers started showing up in the carbed Merc engines.

In fact I really dislike the Edelbrock carb as it has been a real challenge to tune. Actually swapping jets and needles is easy, even on the water, but getting it performing correctly has been nearly impossible. I decided to just rebuild my original Quadrajet 795 and put that back on, and the engine is night and day differenct- better power and better fuel economy. Following the formulas indicates I need 730 cfm so I felt the Edelbrock would be sufficient. Obviously the Rocheter is far more complicated and harder to tune, but it seems to work better over the entire rpm range. That said, I prefer EFI overall.
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Old 08-25-2009 | 05:49 PM
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Originally Posted by NightHawk
.

On the 454 give it a pump or two and pull the throttle back to closed until the choke plate also closes (once you fix it) and the motor will start. Do not hold the throttle open.
If the engine is flooded from the bowls leaking, you will only make things worse by pumpng the throttle.
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Old 08-26-2009 | 02:21 AM
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Originally Posted by blue thunder
If the engine is flooded from the bowls leaking, you will only make things worse by pumpng the throttle.

Of course it would. I simply assumed a hard start problem was most likely only to be the defeated choke. Lots of things could be wrong and there could be multiple problems.

I don't understand the problems people have with this carb. It's such a simple unit. Getting the main and secondary jets and metering rods exactly right have nothing to do with hard starts and the choke is so f'in simple.

Check that the float levels are correct and the needles are working.

One thing I found helpful was you can purchase spring-loaded needle and seat assemblies from Eldebrock. Designed for off-road apps in the 750 street carb they can cut down on minor flooding issues on performance boats as well. They are cheap and easy to install on the marine Weber.

Last edited by NightHawk; 08-26-2009 at 02:30 AM.
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Old 08-26-2009 | 11:30 AM
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Originally Posted by NightHawk
Of course it would. I simply assumed a hard start problem was most likely only to be the defeated choke. Lots of things could be wrong and there could be multiple problems.

I don't understand the problems people have with this carb. It's such a simple unit. Getting the main and secondary jets and metering rods exactly right have nothing to do with hard starts and the choke is so f'in simple.

Check that the float levels are correct and the needles are working.

One thing I found helpful was you can purchase spring-loaded needle and seat assemblies from Eldebrock. Designed for off-road apps in the 750 street carb they can cut down on minor flooding issues on performance boats as well. They are cheap and easy to install on the marine Weber.
So this kit is basically turning the Weber into the Edelbrock ? I agree that actually doing the needles / jets / springs on the Edelbrock is easy, and the full tuning kit gives you all the popular options. But mine never ran well - I guess you get what you pay for, as the Edelbrock and Webers are about the least expensive carbs you can get. The Edelbrock was running about 1/2 the price of a similar Quadrajet for a while.
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Old 08-26-2009 | 02:46 PM
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Originally Posted by dogturd21
So this kit is basically turning the Weber into the Edelbrock ?
They are basicly identical except for the exact setup (jets, metering rods and step-up springs).
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