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Rochester quadrajet 4 barrel flooding

C

contender31

Regular Contributor
My carburater was flooding and pouring gas out the top of the carb - I took it out and*bench tested it with a portable gas tank and fuel pressure ball*to see what the problem was. I noticed fuel continuing to pour into the bowl and overflowing. The float appeared to be set to high and the needle not seating as designed. I took apart the carb, cleaned it thoroughly and rebuilt it with a new kit*- before reinstalling it, I bench tested as before and the problem went away - the float rose as designed and the needle stopped the flow of fuel. I reinstalled the rebuilt carb and when I tried to start the boat the same conditions appreared again. Fyi this time I had a certified mechanic look at it and he has no answer either.
*
Any ideas what may be creating the problem?
 
Where did you get the "new kit"? Who made the kit? What was in the kit? What is the float made of? What does "bench tested as before" mean?
 
makomark said:
Where did you get the "new kit"? Who made the kit? What was in the kit? What is the float made of? What does "bench tested as before" mean?
Click to expand...

Thanks to answer your questions

1. Generic kit no name
2. Kit contents - all gaskets, needle and diapfram assembly, plunger
3. Float is plastic
4. bench test meaning - I took a outboard style tank and pressure ball and hooked it up to the gas inline of my carb and shot gas into the carb with the float in view and when the carb was all put back together. note : I tested the same way before dimantling the carb and gas came out the top of the carb - this is what led me to believe it was the float and needle. Once I put the new needle and diaphram, adjusted the float I retested it on the bench the same way and re installed it on the motor. I finally got it started but gas continues to be evident out the exhaust by smell and white exhaust. This is the same problem that persisted prior to my taking the carb out and redoing it. The next step would be perhaps to install the other motors carb on this engine and see if the problem still exists. If not then it is not the carb but perhaps the fuel pump.

What do you think after having said all this?
 
The generic "no name" kits usually have components that are low grade for auto use, let alone marine use. Ethanol will usually degrade cheaper material (the "rubber" parts in particular) in hours not days.

I think you need to cycle the inlet system more than once to pronounce it functional. The most reliable test I've found is to see if the needle and seat will maintain a vacuum and several cycles can be done in short order.

Float is plastic - guessing the normal black colored stock stuff. Any idea how old it is or any knowledge of when it was last replaced? The service life of those plastics floats averages about 5 years. Brass ones can function much longer. The only method given by rochester to 'test' the plastic float is to weigh it - most savvy rebuilders just replace them as the scaled required to do that kind of measuring isn't used for much else and the cost is trivial compared to a "come back".

Doesn't have anything to do with the flooding but did you make sure the gaskets in the kit had all the holes required and that they were of the proper sizes and in the correct locations?
 
Update - I switched the carbs from one engine to the other and the rebuilt carb ran perfect on the other engine. The carb that was working on the other engine ran poorly when switched. Now that I have established that both carbs are working fine could it be the fuel pump? If so what am I looking for?

Thanks
 
Thought I would let everyone know - the problem was the fuel pump, I took off the bleeder hose (not sure of the terminolgy) and it was full of fuel. Ran the engine with it off for 2 seconds and fuel gushed out of it.

Thanks for all your help
 
check the new needle and seat, the seat opening comes in 4 or 5 different sizes from .125" to .145" hope you saved the old one
 
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