7.4 L mercruiser 4 barrel won't kick in
06-29-2015, 10:47 AM
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7.4 L mercruiser 4 barrel won't kick in
New here! I have a 1994 Bayliner 2858. It has a weber 4 barrel carb and I can't get the 4 barrel to kick in. I can push down on a lever on the left hand side and it will open up, but the throttle has no effect on the carb. Can't get on plane without it!! Anyone ever had this issue? Thanks! Jeff
06-29-2015, 11:21 AM
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The secondaries are air activated. The air door over them is weighted.
It is not intake vacuum operated, nor is it 'mechanical'.
Therefore, the only way to see if they open, is to actually see them when out in the boat and you open throttle to wide open.
They won't open when on the trailer :ie neutral gear.
It is not intake vacuum operated, nor is it 'mechanical'.
Therefore, the only way to see if they open, is to actually see them when out in the boat and you open throttle to wide open.
They won't open when on the trailer :ie neutral gear.
06-29-2015, 12:56 PM
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Thanks guys, I had her out yesterday with two guys that know engines. I could push the throttle wide open and the secondaries never opened. I didn't think boat engines used vacuum because they don't "coast" like a car. So, what I am hearing is that it IS a hose leaking vacuum. I am going out on Thursday for a three day trip. I'll have plenty of time to tinker especially without secondaries!! Thanks, Jeff
06-30-2015, 08:06 AM
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The weber doesn't use a vac hose to open the upper blades (ie, air door) on the secondaries. The secondary throttle blades open and then the air flow opens the air door as it pulls more air. The air door is counterbalanced and can jam or stick. Check to make sure the secondary throttle blades are opening (mechanical linkage, should open around 60% or so of primary opening). Check that air door moves freely.
These are the same design as the Edelbrock carbs, so look for information and resources for those for a description of operation & trouble shooting. Heck, you can even use the Edelbrock rebuild kit & parts on them.
These are the same design as the Edelbrock carbs, so look for information and resources for those for a description of operation & trouble shooting. Heck, you can even use the Edelbrock rebuild kit & parts on them.
06-30-2015, 08:08 AM
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See page 6 - Edelbrock calls the air door and air valve.
http://www.edelbrock.com/automotive/...404_manual.pdf
http://www.edelbrock.com/automotive/...404_manual.pdf
06-30-2015, 08:21 AM
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Thanks, I'll get my neighbor to take a look at it. He rebuilds old chevys etc. I'll be out on her Thursday for three nights. The carb was just rebuilt because that's what I thought was the problem. It started doing this intermittently, sometimes it would open up and not others, now not at all, so I thought a rebuild would do it. It's got to be something simple, that's why it drives me nuts! Thanks for your help!!
