89 sea ray 5.7

Dbeam86

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Apr 13, 2013
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Need help I inherited this boat It's a 89 sea ray weekender with the 5.7 boat has been sitting for 7 years when I got the boat drained all the fuel out prime the oil pump squirt oil in the cylinders change plugs rotor cap Wires water pump did a compression test got 140 Psi in all cylinders took it out on the lake ran pretty good but once you try to open up the four barrel it fell right on its face no power if you kept it under 3000 rpms it was running great then all of sudden it backfired and would not run pull the carburetor off and got it rebuilt now when you give it gas I she will run great until 2000 rpms anything over that she doesn't have any power she almost stalls if you hold her wide open and once she gets about 3500 rpm struggling to get there she'll take off like a rocket had the carburetor Quadrajet 4 barrel rebuilt by a professional does it sound like it's still in the carburetor like I said if you hold her wide open as she runs great want you back the throttle off a little bit she says loses all power I also replaced all fuel line check valve in the tank clean the screen new fuel filterS did a fuel pressure check I got 6 pounds of fuel pressure what else can it be I would appreciate all the advice
 

Bondo

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Ayuh,..... Welcome Aboard,...... Definitely sounds like a Carb issue to me,....

Sounds like you've well covered the rest of the fuel system,......

What are the spark plug colors tellin' ya,..??
 

NHGuy

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It can't hurt to tell your carburetor guy that it's nutless from 2000 to 3500 RPM. At those RPMs your Rochester is feeding through it's primary main metering system. The way it works is you open the primary throttle blades with your throttle lever. This allows more air to be pulled through the carburetor. It also reduces the vacuum below the carburetor, which in turn allows a spring loaded piston that's vacuum controlled to rise against it's spring. That pulls up 2 metering rods allowing more fuel. Which creates more power. .
If my theory is right you have a hanging primary main spring or piston. But it could be other things too. Have you timed the ignition? How about did any one check the carb secondaries? They have a spring load that should be set 3/4 turn from slack. Some people loosen the secondary air doors in a mistaken attempt to allow them to open earlier. That only makes the fuel supply too rich.
Stay on here, others will come along soon. I tend to think up the most complicated possibilities. There are others on here who are way more practical!
There could be some easy checks I haven't mentioned.
 

Dbeam86

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Apr 13, 2013
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That 's what I was thinking just because it's kind of doing the total opposite of what it was doing Before I got it rebuilt I called the guy that rebuilt the carburetor he told me to run some seafoam through it over the weekend and let him know Tuesday But the plugs are on the white side so its running a little lean I think so I don't want to run it more then have to
 

NHGuy

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If you want to check it, look up how to take off the top section, the power piston is then visible.
I just took a look in my Qjet book in that area. It claims bent power piston arms are one of the most common reasons rebuilt quadrajets don't work as intended.
 
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Dbeam86

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Apr 13, 2013
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Really do appreciate all help Yes I have also checked the timing what would be the best solution going back to a new Quadrajet or going something different or taking my chances On taking it back to somebody else to take a second look at it
 

NHGuy

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i guess it depends on how the guy you used deals with things. Quadrajets are awesome, yet so complex. If you live near a good carb guy they all know how to do them. Only thing is most will want to re-overhaul, and for that money you might be better off just getting an Edelbrock 1409, which is the current replacement and a lot easier to work on.
 

NHGuy

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Here's how to pull air horn (top) to look.
You need a small punch to push in the accelerator pivot pin just far enough to get the pump arm free. Take off the external choke link with a teeny pick or pliers, undo the screws around the perimeter and 2 in the bore, lift & turn. You turn the section 90 degrees to get the choke link through it's opening.
The piston is in the middle, it should slide freely when you push it down and might even pop out when released, that's OK. If it binds straighten everything til they slide easy.
I know I am simplifying here, but that's really the gist of it.There are pics all over the internet.
The guys at hotrod.com will help you too. Quadrajets were on most GM V8's for eons.
 

Dbeam86

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Apr 13, 2013
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Ok got the carburetor apart found what you are talking about when you say push down on them and they should slide free mine are already down like there's no spring action there if I pull up on it then let it go it falls right back down is that normal
 

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Dbeam86

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Apr 13, 2013
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I see now it's missing that spring that pushes that thing up its not even in there Wtf
 

Dbeam86

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I gues my next question is I will find a spring for that is there 0 rings that go around that Or not
 
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