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Stalling past half throttle

R

randolf

New member
"Hoping someone can help with

"Hoping someone can help with this never ending project.
Im running an AQ120B, with a list of new parts, including pertronix ignition and coil, cap rotor etc.
The boat idles beautifully, accelerates fine, but once I go past half throttle, I have about 15 sec. before it stalls (maybe 5 at full throttle). To get it started again It takes alot of priming, and is a little rough till it idles fine.

Now if you want my opinion their is enough fuel in the bowl to keep the boat cruising low and running, and when the throttle is pinned it drains the bowl before it can keep up with the proper fuel level.
Leads me to the fuel pump (I think!!??) not pumping enough volume to keep up with the fast draw on higher throttle. Or something to do with a high speed needle on the carb if there is such a thing. I know little about carbs so this is out of my field, and their is NO info on my carb it seems anywhere, internet or Clymers. BTW the carb is a single barrel side draught Solex 44 PHN-3. I have pulled it apart, blown all the passages with comp. air, checked for cracks and so on, and it all looks good.
I also did a flow test on the fuel pump while cranking, but its sort of a crude measurement. Lots of gas comes out, how's that. Its also at low/no speed.
Again any help would be so appreciated from any you experts or quasi-experts out there."
 
"Glenn, I have a Solex carb an

"Glenn, I have a Solex carb and have had an issue like yours. Do you have a fuel filter/sea water strainer? If so, make sure the rubber o-ring is intact. I would even rub some oil on it like an oil filter to ensure a proper seal. also, check your fuel line to the fuel pump. Make sure no cracks or holes. I do want to ask, how did you check the bowl level while running? My advice is to put the boat in water or take a tub like the blue or green recycling bins like you see, tape the holes, put your out drive in it. Fill with water. This part is important. Disconnect your shift lever throttle cable from the solex carb arm. Should only be a cotter pin or so. Now you have the ability to run the motor @ any RPM. Remove the cover and spark screen from your carb. Crank the motor. (Make sure you keep e water running so you dont let the tub drain below the water intake of the out drive. It will start to drink a lot of water) Warm the motor a bit and the press the throttle arm on your carb. You SHOULD see a squirt of gas being dumped down into the carb. The more throttle the more pressure the fuel will spray. See if you can reproduce the problem under these conditions. If you see plenty of fuel being delivered and the problem dosent show, then the problem is only when the boat is under load. That may change things abit. This will show you if your carb is giving up the gas. I can take a pic of mine at WOT so you have something to go by if needed. Hope this helps."
 
"I have bypassed the filter an

"I have bypassed the filter and tank and am running from a jerry can as a test and have tested from the tank too. I will give your suggestion a try with my giant tupperware bin. The only gas I have seen coming out is from the little candy cane rod when I've had it running, where else should it come in (there are 3 small holes at the top of the carb (above the 3 brass rods, does it mix with air and come through there?
(The bowl draining suggestion was just a guess, seems logical that the pump doesnt seem to keep up with the draw, and when the bowl is empty it stalls, maybe not though)"
 
Have you taken the carb apart

Have you taken the carb apart and tried cleaning it?
 
"Make sure the accelerator pum

"Make sure the accelerator pump is working and not stuck. Remove the flame arrestor, then move the throttle lever: you should see fuel squirting into the carb. If this is not the case, you have a problem with the accelerator pump (seized, misadjusted, etc)."
 
"The accelerator pump seems to

"The accelerator pump seems to be working nicely, I put everything back together after blowing ever nook and cranny in the carb out. I could not get it to stall, but I did notice this time that there is gas coming from the bigger pipe in the middle of the carb throat (insert real name here). Im sure there wasnt any or much the last time I was at high rpm, and I know this is the main gas jet right??
Anyway I suppose I need to pay the 10 bucks to launch and try things out again."
 
"Well, took it out for a test

"Well, took it out for a test run after cleaning the carb, guess what, that's not it either.
Still seems like its starving for fuel past half throttle. I guess I'll try a new fuel line since the section from the motor to the filter seems more oval than round, maybe it's collapsing??

Any more suggestions?
It does seem that is is only stalling under load or while in gear though. Strange thing, I can go full throttle for a couple seconds, then trim back to under half and cruise without stalling."
 
"I have the exact problem on m

"I have the exact problem on my 120......
Just Dewinterized her, and she runs awesome. Til you put her under load.....Half throttle, and it seems like she starves for fuel, and dies out.
I put a new fuel pump on....I am thinking anti siphon valve, or timing......"
 
"Ijust bought a carb that was

"Ijust bought a carb that was in awesome shape on E-bay. I know I had a problem with the other one as the oil was gassed........Too much fuel, gave me a blow by problem...Got that taken care of with the carb, and now this....
WE can get this problem fixed if we alll stay in touch........Suggestions?"
 
"Gummed-up carb? I don't k

"Gummed-up carb? I don't know what kind of gas you are using, but the effects of bad gas can drive you nuts. Maybe you want to remove the carb bowl and see what's inside, it is a fairly easy job.

BTW, I am trying to understand how could too much gas possibly give you a blow-by problem. Blow-by happens due to worn cylinders or broken/worn/stuck piston rings, not because of too much gas."
 
"Ive eliminated the anti sypho

"Ive eliminated the anti syphon possibility with running off a jerry can. If timing was off, it would be rough at low speed and idle would it not?
Did your fuel pump make any difference??
How about something like prop pitch Let me know ? Wouldn't really explain the lack of gas on re starting though.
EL as far as the gas quality, I've used good mid grade, marine marked mid, and the left over in the tank when I bought it, it's all the same though."
 
"i had a similar problem with

"i had a similar problem with my aq 120b, turned out to be the float valve was sticking. switched it out and it runs fine"
 
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