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Old 04-16-2013, 04:38 PM   #11
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My bad, Todd, it's a Weber.

http://flyingfishcarburetors.com/lookuptable.htm
http://flyingfishcarburetors.com/Y43MercruiserOMC.htm

Can't quite tell but it looks like there is an aluminum spacer plate between the manifold and the carb. If so, my guess would be that the manifold is a QJ manifold and the spacer is actually an adapter plate to accommodate the Weber. You can verify by getting the manifold casting number and Googling it.

Dan
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Old 04-16-2013, 05:09 PM   #12
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Looks like the Weber 4bbl was an OE option in 1994. From looking at the diagram, it does seem to need a spacer/adapter. Maybe they decided to use the same QJ manifold for all 4bbl models and just adapt it to fit the Weber models?
http://www.mercruiserparts.com/Show_...2D+4+BARREL%29
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Old 04-16-2013, 05:59 PM   #13
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LOL Gezzzz, not sure now more than ever.... what ever it is, it doesn't have the filter in the Fuel inlet. Going to pickup the boat today drag it home and start looking.
Checking the fuel tank pickup tube, and remove the sending unit and checkout the inside of the tank in case I missed something. Then rig a Fuel pressure gauge and check that..... If all that is good then I'm back to removing the Carb and pop the top off of it and see if the "ethanol fuel" has done anything.

I'll keep posting till I fix this...

Todd
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Old 04-18-2013, 11:47 PM   #14
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Quote:
Originally Posted by ss3964spd View Post
My bad, Todd, it's a Weber.

http://flyingfishcarburetors.com/lookuptable.htm
http://flyingfishcarburetors.com/Y43MercruiserOMC.htm

Can't quite tell but it looks like there is an aluminum spacer plate between the manifold and the carb. If so, my guess would be that the manifold is a QJ manifold and the spacer is actually an adapter plate to accommodate the Weber. You can verify by getting the manifold casting number and Googling it.

Dan
Dan, you are right ,,,,, its a Weber, 3310-805484 (9661)... after typing my fingers to nubs, I looked in the Mercruiser Manual and there it was..LOL

Todd
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Old 04-19-2013, 01:55 PM   #15
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Quote:
Originally Posted by ss3964spd View Post
My bad, Todd, it's a Weber.

http://flyingfishcarburetors.com/lookuptable.htm
http://flyingfishcarburetors.com/Y43MercruiserOMC.htm

Can't quite tell but it looks like there is an aluminum spacer plate between the manifold and the carb. If so, my guess would be that the manifold is a QJ manifold and the spacer is actually an adapter plate to accommodate the Weber. You can verify by getting the manifold casting number and Googling it.

Dan
It has a spacer plate. I couldn't make out the intake casting number(old eyes), but it is defiantly a spread boar intake. I took out the tank pickup tube and sucked out some gas (from the bottom of the tank) I didn't see any water or contamination.


I think I'm down to Fuel Pressure or a bad Carb.


Its kinda puzzling. last fall I rebuilt the eng and ran her for 2.5 hours with no problems. All the filters have been replaced. New plugs, cap...etc. I am leaning towards replacing the Carb. But I want to check the Fuel pressure 1st.

I have always preferred Holly's. Not sure how good the Marine version is.


Back in the day..lol I had 3 or 4 carbs, intakes, heads maybe even a sm block or two,..etc....sitting around in the garage. Due to moving around in the Navy I had to sell off everything I had.


Todd
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Old 04-19-2013, 02:45 PM   #16
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Glad you're homing in on the problem, Todd.

I still believe the problem isn't the carb itself. If there is an issue with the needle/seat it usually shows up as a flooding condition because the needle/seat can't stop the flow of gas into the carb. Likewise, if the float itself is bad, it can't close the needle/seat so the carb floods. There could be a restriction before the needle/seat that is limiting the flow. I don't think there is crap in the carb because it idles fine - which means the carb idle circuit is clear, and since the engine will run under load to 2k or so it suggests the primary metering circuit is also clear.

I don't like taking carbs apart unless absolutely necessary. I'd be replacing the rubber fuel lines first, and verifying the pump (is it a mechanical pump?). Fuel pressure might be difficult to measure because it might read fine when the engine is idling. Only real way to check it is with the engine under load - right when it starts to stumble.

One other thought - did you check to see that the fuel tank vent is completely clear?

Dan
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Old 04-19-2013, 04:33 PM   #17
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I never thought about the fuel tank vent and that is easy to check..... I just got back from washburns boat yard.. they are an authorized Mercruiser dealer..
He seems to think that the ethanol has a messed up the fuel pump..

Todd
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Old 04-19-2013, 04:56 PM   #18
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Mechanical pumps have a rubber diaphram in them. I'd venture a guess that if ethanol has messed up the pump it may have also eaten up the inside of the rubber hoses.

You could always bypass the tank, vent, filter, and hoses by rigging a temp tank directly to the pump inlet. Would at least narrow down the suspects.
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Old 04-19-2013, 05:53 PM   #19
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I have a 5gl tank That I'm going to hookup just to test things. but the weather is going to be nasty Gust to 25kts. maybe get her out Monday for a test!

Todd

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Old 04-25-2013, 02:40 PM   #20
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That is a Weber carburetor and you do have a fuel filter on it. carb.jpg
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