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bcclew

Regular Contributor
1992 mercruiser 454s rochester carb loading up i have done these and they seem to work fine. i went through this this one found no plugged holes new kit and new float i checked the float that was in there about 11/32inch seemed close to chart.set the new float about the same i was able too match gaskets as the kit i got fit a few carbs ck all holes seemed fine put carb back on still loading in front jets. also new needle and seat power valve seemed fine not sticking any ideas before i take it apart again i am going to hook up and out board can to it and see if it leaks on bench? or just when its running thanks bcclew
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bcclew said:
no leak with primer ball so its only leaking when running?
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Hmmm. Did you sand and fill the secondary jet plugs with JB Weld? Are the secondary metering rods seated, installed correctly. Have you verified the correct float height for this particular application? Do you have the correct gasket thickness between carb ans manifold?
 
plugs looked fine i thought when plugs leaked they dripped in the manifold not jets? rods were seated matched gaskets with old ones. base gasket was thin one.but thats usually hot perk this dosent run that long mabe 2 mins, this boat was just bought with little history on boat. but it looks like gaskets where fairly new this may of had this prob before? im thinking mad made some how.thanks for your imput
 
bcclew said:
1992 mercruiser 454s rochester carb loading up i have done these and they seem to work fine. i went through this this one found no plugged holes new kit and new float i checked the float that was in there about 11/32inch seemed close to chart.set the new float about the same i was able too match gaskets as the kit i got fit a few carbs ck all holes seemed fine put carb back on still loading in front jets. also new needle and seat power valve seemed fine not sticking any ideas before i take it apart again i am going to hook up and out board can to it and see if it leaks on bench? or just when its running thanks bcclew
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Just read your post again. When you installed the needle valve, did you install the clip into one of the holes in the float arm? It should not be in one of the holes, should be on the flat area of the arm. Also, re-verify your float adjustment. Are you sure the power piston which holds the primary needles is fully seated? And no, if the seconday jet plugs leaks, they should leak from below, into the throttle plate, not the main venturis.
 
you were reading my mind i spent a lot of time last night looking up some old posts and googled carb overhaul that clip could be prob not sure when i took it apart where clip was and didnt look this time;i am going to reinstall and try it thanks
 
Once carb is assembled I like to check metering rods/piston movement through vent port. When engine is idling make sure vacuum has pulled down this piston/rods assembly, thereby running full lean. just feel carefully down vent port with a small flat screwdriver.
 
wasnt thinking getting brain fog// this morning ck float clip and level again all good put carb back on same thing run 5 mins start too load out venturis also ck fuel pump pres. almost 10 lbs.went home primed bowl full again with primer ball no leak then i applied 10lbs pres. to line no leak. the prim jets should be in the up position would it not leak now? took carb apart again ?i held rods down sprayed choke cleaner with straw through the venturis backwards it seemed a lot can through the jets while holding them down.do these rods stop the fuel or just part way?also applied vac. to piston hole i can get piston move up and down but cant hold it to the bottom is this normal like i said getting brain fog thanks
 
This is your "power valve" and there is some flow when all the way down. If its operating freely, they should be completely bottom of travel when engine is idling and producing about 18" of vacuum. Have you checked the "installed height" following the carb overhaul specs for your engine?
 
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bcclew said:
how do you adjust the installed height?
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Timguy has given you good info....Kghost as well on the specs. The height is not supposed to be tampered with, not normally touched in a a normal "renew" of the carb. Did you try to adjust it during the renew ( rebuild )? I will have to look that up, please provide your actual carb number and I will get the info for you. Are you absolutely sure that the primary needles are in the main jets?
 
adjusted nothing rods are woring fine. i even put a coat of greese on them to see how far down they were going seems fine i am going too put it back on tomorow and ck with a small screw driver
 
also cant find a true spec on fuel pump pressure i found some replacement pumps on line they 5.8lbs a i stated before my is pumping 10lbs with gauge on thanks
 
bcclew said:
also cant find a true spec on fuel pump pressure i found some replacement pumps on line they 5.8lbs a i stated before my is pumping 10lbs with gauge on thanks
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If I am not mistaken NO carbed motor should be running 10psi of fuel pressure.

max should be no more than 6-8 psi

Here is Mercruiser specification,

Running ten psi of fuel pressure will overcome the needle/float pressure for sure!!

Sounds like a internal part in the pump is bad, possibly a check valve or what ever regulates it is stuck.......
 
OK guys here we go went through carb again last night every thing looked fine. went down to put it on. cked fuel pressure again now it was 8lbs put carb on started ran fine set adjustments idling 40 min at 800rpm so i am now thinking pump is the prob iam going to use it if starts to flood again i want to see where the pressure is if its high change the pump if good i will wait till fall and change pump. i want to thank all the help every seemed right on .thats what makes this fourm great thanks again bcclew
 
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