Fuel line clogged

[9Ball]

The fuel pickup tube inside the fuel tank has a small screen in it. And this is what I found

Todd

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[Scott]

Wow I'm going to check mine. Which hole did you go thru to get to it?

[No1hedberg]

Is that a mouse?

[9Ball]

I'll take some pictures tonight when I get home!

Its some trash that was in the fuel tank! Here's what was going on:

Cruising along at 3K RPM for about 30 min, eng started sputtering, Pulled back to 2500RPM and it would stop, Push back up to 3K rpm and it would sputter again, Headed back home at 2K rpm. Thinking that it was a fuel filter. I checked but nothing in the filter, so I checked the Fuel Pickup tube in the Fuel tank and found it was clogged. It was letting just enough fuel thru to run at lower RPM's but not at higher rpm's. I have a Clear inline Filter coming out of the Fuel tank. I cleaned the Screen in the pickup tube, installed a Inline Fuel Filter and a new Water/Fuel Filter. I will also change the Carb Filter this weekend. I also removed the Fuel level sending unit so I could inspect inside the Fuel tank but I didn't see any trash.

Todd

[9Ball]

Here's the Pictures!

Todd

[9Ball]

Well.... That didn't fix the problem. went on a test run this weekend and the same issue, eng spits and sputters at 3K rpm, Pull it back to 2000 and it runs fine! so next is to pull the Carb and check the Float adjustment!

I'll take pic's if I find anything!

Todd

[ss3964spd]

What carb is on it Todd?, Has the carb ever been apart? My guess would be the fuel lines or maybe even a weak fuel pump, before the carb float. Does it have a filter in carb inlet housing?

[9Ball]

It’s a quadrajet, and as far as I know it has never been apart. This Carb doesn't have a Filter in the inlet. I replaced the inline filter and the Water/fuel filter, cleaned out the Fuel pickup tube in the Tank.

I rebuilt this eng last fall and did run it for 2.5 hours before winterizing it. But I didn't run it at 3K rpm for longer than 5 min and didn't have a problem. I was thinking some gunk in the Carb or the Float was stuck or set too low.




Todd

[ss3964spd]

Judging from the first picture, I'm thinking if you re-connect them spark plug wires it might rev past 3K.

Joking aside, the second picture shows that the carb is not a QJ. Looks to me like it might be an Edlebrock Performer 1405 - or something close. Def not a QJ though. I don't know if the 1405's have an internal fuel filter.

I'm sure you've got the timing set right. Regardless, I still think I'd pull/inspect/replace all the rubber fuel lines before I opened the carb. You might also verify that the secondarys are working correctly; 3K ish is probably about where they should start opening up.

I don't crack a carb open until I've checked everything else. However, if that is a 1405 they are pretty easy to work on.

Dan

[9Ball]

Ok so now I am really confused, Here's the number on the carb 9661S 3203. Is this a Carter?

Todd

[ss3964spd]

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

[mcoffey]

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

[9Ball]

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

[9Ball]

Originally Posted by ss3964spd

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

[9Ball]

Originally Posted by ss3964spd

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

[ss3964spd]

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

[9Ball]

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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[ss3964spd]

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.

[9Ball]

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

Note to Mother Nature: If I leave a Box of chocolate and Flowers next to the Old Oak Tree for you, Can I have a nice boating weekend!

[Ken Kwasniak]

That is a Weber carburetor and you do have a fuel filter on it.