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Solex downdraft carbs on AQ 130C Question

M

macleod

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Hi, silly question, can anyone tell me?:confused: Should there be a continuous stream of fuel from the acceleration pump when you open up? I was out today and ended up have to pump the throttle to get home, a pump of course gives a spray as you would get for a cold start but when in gear and under load should there not be constant stream of fuel from the acceleration pump nozzle?. Any ideas then why i can not get the boat to rev without pumping?

Regards

MacLeod
 
macleod said:
Hi, silly question, can anyone tell me?:confused: Should there be a continuous stream of fuel from the acceleration pump when you open up? I was out today and ended up have to pump the throttle to get home, a pump of course gives a spray as you would get for a cold start but when in gear and under load should there not be constant stream of fuel from the acceleration pump nozzle?. Any ideas then why i can not get the boat to rev without pumping?

Regards

MacLeod
Click to expand...

I could easily be wrong because I've never looked at my carbs while running fast, but based upon the fact that gas does not keep streaming out of the nozzle when you give it full throttle while the engine is stopped tells me that the answer is no.
 
Thanks am_dew! There's a diaphragm pump on the carb for the acceleration jet which would only give a burst when the throttle is pumped so I don't think there should be a steady flow of fuel from it. Must have a blockage in one of the other jets? It's a nice day for stripping carbs...
 
The accelerator pump is a spring loaded diaphram. One pump = one squirt. It doesn't free flow. If you look at the linkage, you'll see that the stroke is maxed out before you get the throttle half open. The concept is, when you accelerate, it supplies additional fuel until engine vacuum builds up enough to draw more air/fuel into the venturi. So no, it shouldn't be squirting fuel out of the bent nozzle continuously.

Dirt and varnish can and does build up in the carbs so a good cleaning is necessary every few years. You're right, time for a good soaking in carb cleaner. It's best to also use pressurized air to blow out all of the passages. Nice thing on these is that you've got two so if you forget how it goes back together, you can look at the other one:). Kits are on ebay for around $30 each.
 
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Hey Joe, thanks for the explanation on the accelerator pump! I think that's what I thought. I have just followed the manual when servicing them previously, without thinking about how they actually work. It made sense - when I had them in pieces today - that as there was a diaphragm there which would only work with the throttle that it would just be a single burst of fuel. Anyway am just back in from a burst in the boat. I stripped down the carbs, blew them through and all back to normal now. Embarrassingly when I was taking them off, I noticed that one of the jet screws was missing(that could explain some fuel issues!) I found it in the sediment under my bilge pump, along with some other interesting archaeological finds! That particular carb was the most gunked up....

The lesson learned here (again) is to be methodical, and don't just go onto the internet and harass folk for help before you've looked closely at your engine:rolleyes:....
 
Hi kimcrwb1, thanks for the reply. I chucked the old fuel filter a few years ago and got a wee see through one - I replace this now and again, my old tank seems to have an eco system of its own judging by what ends up in that filter......
 
LOL-I have personal experience with finding a carb jet in the bilge so know what you mean!

I highly recommend putting in new gaskets and replacing the banjo bolt washers. Those washers are really only a one use thing since they compress against the fuel line fitting and carb body to provide a seal. Fuel dripping on a hot exhaust manifold kinda wigs me out!

The rebuild kits don't have those washers in them so you need to buy them separate from an online VP store. I tried finding the right size at automotive stores with no luck. I allways order extras since you're paying for the postage anyway.

Edit - just noticed what you wrote about the clear fuel filter. If it's one of those plastic inline ones, they're really not recommended for IO use. Your best bet is to install a newer spin on cartridge type of separator/filter combination. Especially with an older boat where you suspect there might be a little junk in the tank.
 
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Hey, I have a pile of them! I live on island so handy to keep a supply of spares :)

Honestly, there was handfuls of sediment down there, I did find something that must have been there for years. It is a clear glass ball full of what looks like oil in a chrome casing which has snapped off something when it was a posh boat, any ideas? The only other noteworthy finds included a stainless steel jubilee clip, a fire extinguisher, a fork (the eating kind), a selection of stainless steel screws and a a roll of insulating tape that fell out of my breast pocket in 2008. The other stuff I'm awaiting lab results on.....
 
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