1982 aq125 surging and dieing after 3/4 throtle for 30 min

Hi all been reading all the past post for weeks. I bought this 1982 20' Trophy about a month ago and have been chasing down this issue. I run 4400 rpm for 30-60min then the engine surges and rpm drop and then it dies even if you bring the throtle down. Try to restart and it will start then die pump the throtle and starts then dies. Let it sit for 45min then start right up runs great sounds great then the prosses repeats.

I've rebuilt the Solex down draft carb and replace fuel pump, plugs, wires, converted to pertronics electronic ignition, replace water fuel seperator timed it to 10deg under a load @ 1000rpm in the water. Temp runs between 185-195. Alternator out put good @ 13-14vdc. water pump rebuilt.

But the last time out with a freind and his son we pulled the spark arester off and check to see if fuel was flowing and noticed that the over flow return tube from the carb had air blowing thru from the fuel pump?

It runs great in the morning then after the first surge and sit prosses it does it all day and your lucky to get it to run for more than 15min in bettween sit times.

Any help in regaurds to this would be greatly appriciated.

Re: 1982 aq125 surging and dieing after 3/4 throtle for 30 min

check is the accelerator pump is pumping make sure the fine screen filter for the accelerator pump is clean. the filter is above the check valve is atached under the accelerator pump. I am pretty sure what you think is the over flow return tube, is the accelerator pump, and fuel is supposed to come out of there.

Re: 1982 aq125 surging and dieing after 3/4 throtle for 30 min

Sounds like the fuel tank vent is plugged up and after running for a while creates a vacuum in the tank the pump can't over come.
Next time it does that, remove the gas cap and see if you hear air enter the tank and it starts running better.
You can also preform these tests (best way to go) http://forums.iboats.com/showthread.php?t=167561

Re: 1982 aq125 surging and dieing after 3/4 throtle for 30 min

The accelerator pump is pumping good. The tube I'm refuring to is Yellow clear tube connected to the top base plate to the spark arrester and when the problem occures I get alot of air being pushed though what I belive should be the over flow return due to the tube goes back to the top of the fuel pump.

Re: 1982 aq125 surging and dieing after 3/4 throtle for 30 min

I'll have to give that a try next time I'm out. Is that the reason I'm getting the air coming though the retune line from the fuel pump at the base of the carberator? Cazy huh!

Re: 1982 aq125 surging and dieing after 3/4 throtle for 30 min

sorry, that is an air vent.

Re: 1982 aq125 surging and dieing after 3/4 throtle for 30 min

I thought you were looking into the carb my mistake.

Re: 1982 aq125 surging and dieing after 3/4 throtle for 30 min

82Trophy said:

I'll have to give that a try next time I'm out. Is that the reason I'm getting the air coming though the retune line from the fuel pump at the base of the carberator? Cazy huh!

Click to expand...

No, not even close.

Re: 1982 aq125 surging and dieing after 3/4 throtle for 30 min

bump

Re: 1982 aq125 surging and dieing after 3/4 throtle for 30 min

Well we were out again today and it happened again so when it started to surge and hesitate we tolk off the fuel cap and it still died a the prosses repeated as above. We tryed to bypas the full filter and all is the same. Its just weired that the fuel overflow line that ties into the carb make a loud ticking sound with air that pulsates and sound like a lifter tic only when the surging starts. Please HELP anyone?

Re: 1982 aq125 surging and dieing after 3/4 throtle for 30 min

Well seeing that its rare that people post what fixs the issues. I will post mine. Found that the pickup tube from the fuel tank and the anti siphon valve at the fuel tank were the issue. Cleaned the filter screen in side the pick up tube that was clogged and got ride of the anti siphoning valve. and ran great tonight for hours.

Re: 1982 aq125 surging and dieing after 3/4 throtle for 30 min

Until all the crud is removed from the tank, the pickup will most likely get clogged again. Like it or not, the real solution is to clean out the tank. The anti-syphon valve serves an important function so should be replaced, not just removed.

If you don't allready have one, a spin-on type fuel/water filter is a good idea. Older fuel systems tend to degrade over time. It's just the nature of the beast. Many of us with older boats have decided to bite the bullet and replace everything so we don't have to live with problems like you're experiencing.

Thanks for letting us know how you solved the problem .