4 barrel Holley carb not idling/starting on '88 Ski Nautique

[sgivens]

Problem: The engine will start from cold, but once it's warmed up, the only way I can seem to get it to idle is to set the neutral idle speed to what seems higher than normal (~1000 rpm or so), otherwise it dies. When I put it in gear, it seems higher than the recommended in-gear idle (should be 6-700 rpm, right?)

Also, when I shut it off, it rarely will start back up again. I have to wait 5 min or so, like it's flooded, before it will start again.

History: The boat ran great back in April '04, but has sat since then. Before I shut the engine off in April, I dumped some fuel stabilizer in (Sta-bil) and let the engine run a few minutes to cycle it through. The engine was rebuilt roughly 150 hours ago.

Here's a list of things that I tried/checked/observed:

-drained the fuel tank, replaced with fresh 91 octane gas and some fuel system cleaner
-on the carb, I removed and cleaned the main body, both bowls, front metering block, and bottom plate where all the linkages attach
-replaced all gaskets, o-rings, etc associated with with above carb parts with new gaskets
-adjusted both fuel mixture screws by screwing in until engine starts to sputter, then backed off by a 1/4 turn. This puts the screws in the "1 1/2 - 2 turns out" range recommended by my local CC dealer
-fuel screen between front bowl and fuel line was clean upon inspection, cleaned again anyway
-carb and parts seemed clean to me, ie no build up of black junk, deposits, etc (I don't really know exactly what I'm looking for here or in what quantity, but it looked pretty darn clean to me)
-choke seems to be operating correctly
-haven't checked the fuel filter
-haven't checked the plugs
-engine seems to run fine at higher in-neutral speeds (~3000 rpm)
-oil has been changed
-when starting from cold or sitting for a couple weeks, a bit of black exhaust smoke is evident, but runs clean once the engine is warmed up

That's all I can think of for now. Any ideas? Help!!

[Nates78Ski]

RE: 4 barrel Holley carb not idling/starting on

The problem lies in the idle system of the carb. Cleaning the carb without the use of professional solvents or , don't cringe. a bead blasting machine. Dirt is lodged in the idle system and can only be removed with one or both of these methods. As a professional tech I suggest with an Edelbrrock marine unit(carter style). You carb problem & long term maintainance will be greatly reduced. Cost $300.00 for carb & the install is easy.

[83sn2001]

RE: 4 barrel Holley carb not idling/starting on

I would check the float level. It sounds as if the float may be saturated, allowing to much fuel in the bowl of the carb, thus creating a very rich fuel mixture. It will also cause gas to drip into the intake manifold after the engine has been shut down. Crank the boat and let it run until it gets warmed up,then shut it off and look into the top of the carb. If gas is dripping into the intake then the float is not sealing the bowl off, causing too much fuel in the bowl. If the boat runs good otherwise,you can get by with a new float and needle and seat assy. It is not that difficult to install them. If you are not comfortable doing that then you are better off with the new carb as it will cost you as much or more to have yours rebuilt

[sgivens]

RE: 4 barrel Holley carb not idling/starting on

Thanks for the replies. So with regards to the floats; the needle and seat assy is the mechanism that the float pushes up against as it rises, correct? I've noticed on the bowl cover that I have where you would normally do an external adjustment for the float, it's been sealed off with what looks like a grey cement of sorts. (From the manuals I've seen with this type of float, you adjust it by bending the little arm to the right level, which looked okay to me). Would I need to get to that sealed area to replace the needle and seat assy, or can you pull it from inside the bowl?

[sgivens]

RE: 4 barrel Holley carb not idling/starting on

Okay, so I figured out how to replace the seat and needle assembly, it's easy. Just as a quick check, (I'll run the boat tomorrow) I pulled the front float off and held it under water and didn't see any bubbles. However, is it possible for the plastic that the float is made out of to be saturated with fuel to where it doesn't float at the right level? Also, would the front float be the only contributor to the problem or could it be from both floats?

Thanks again........

[Nates78Ski]

RE: 4 barrel Holley carb not idling/starting on

If that float is a black hard foam material it is made fron nyril rubber.These floats can absorb fuel & become to heavy. If you have a brass float submercing it in a pan of very warm water for a minute or so should cause it to bubble revealing a leak. Replacing & resetting the level may work for the hard starting but the high idle problem sounds like that idle circiut problem. Also carbs do wear out to the point where rebuilding is not an option. Check those spark plugs for fouling. All that fuel leaking may have blackened those plugs causing poor idle quality

[sgivens]

RE: 4 barrel Holley carb not idling/starting on

Turns out it was a blown power valve, and excessive varnishing and crud buildup. I had a hard time finding parts for the carb, so I took it to my local CC dealer, and they re-built it. Idles like a champ, and starts (and re-starts) with ease.

[83sn2001]

RE: 4 barrel Holley carb not idling/starting on

In tghe future, skidim.com has all the parts you need to rebuild the carb. or for that matter any thing mechanical on the boat.

[Christopher-W.-Becker]

RE: 4 barrel Holley carb not idling/starting on

Blown Power Valves are caused by backfiring (amoung other reasons). There are replacement power valves available which basically have a ball check valve to prevent this. Not many rebuilders are aware of this unless they breath Holley. Marine parts can be hard to find. I found a shop in Illinois where the guys just luv holleys. They did the one on my older Commander a few year back and it NEVER ran better. Unfortunately when I sold the boat, I did not keep a copy of the parts list for the carb that they made for me.

However, I do know the name and number of the shop. Several CC friends of mine with Holleys on top have sent them carbs to rebuild.

If your rebuilding, I would seriously look at replacing the power valves or you will be back in this position again.