125 aq surging above idle

[the toy]

hi 1983 volvo 125 aq.engine starts ok first raise throttle or rev ,revs ok.then when try again engine surges no matter how high throttle pushed.stays around 1200 rpm.has new spark plugs cap and rotor ,wires all ok.replace every year.converted to electronic ignition timing at 6 degrees.new fuel pump old one worked put showerd fuel going up return line.note eng starts easy.acts up after high idle 2500 rpm for 5 minutes on trailer in neutral or after rev eng,or try after starting.will also rev ok if shut off wait a minute then restart and rev only once. thanks in advance for help .believe problem in carb,but not sure.also running temp at 170 alt shows 14.6 volts.

 

[cooter2506]

Re: 125 aq surging above idle

Check your fuel seperator(if so equipped). Also check your carb filter, tank pick up filter and antsiphon valve. I think your losing fuel. Or its time for a carb rebuild.

 

[the toy]

Re: 125 aq surging above idle

thanks for the advice.no fuel seperator.tried known good carb and anti siphon ,off my other boat.same thing .going to set up temporay fuel tank and feed hose to verify in tank. before removing fuel pick up to ck screen.just got laid off so ill do as soon as i can.any other advice greatly appreciated.thanks

 

[Don S]

Re: 125 aq surging above idle

Do a compression test, when was the last full tuneup? Plugs, points, condenser, cap, and rotor.
Have you checked the point dwell and timing to make sure they are in spec.?
Have you done a vacuum check while running?

 

[the toy]

Re: 125 aq surging above idle

cked compression showed ok.new plugs electronic ign.cleaned screen out of fuel be pick up ,replaced with in line filter.still only allows to rev up 3-4 times in neutral .then engine startsnping around as if trying to clear its self out.starts easy idles ok.also tried new fuel line pump to anti siphon valve.have tried just about every part of fuel system but gas tank its self.get same results everytime.any help greatly appriciated.laid off so cant take any where to have checked out.could bad ign coil be breaking down and causing this,has new one on it not neccesarly meaning its good.thankssorry for typo should say engine starts junping rpms around.

 

[warlock73]

Re: 125 aq surging above idle

I have an 82 aq125a/270. Mine is what they call an alternater driven ignition, it works with the starter coil. Just replaced my coil because it would nt start so I don t believe thats your problem. Temp runs at or about 170. It just sounds like your throttle sticks if I understand you correctly. I might suggest takeing the Dist. cap off, clean the contacts off and points contacts. It sounds electrical to me.

 

[warlock73]

Re: 125 aq surging above idle

http://www.4shared.com/file/89797330/b32e5bf9/AQ125145_AB_Service_Manual.html This might help.

 

[the toy]

Re: 125 aq surging above idle

put clear fuel lin e on to test/shows air in line.pipe doped all fuel fittings,made sure all were tightr.has new anti siphon valve.watched eng at idle try to slowly push air bubble up line at idle.when shut off devlops a 3inch airpocket up near the fuel pumpfitting.cked vent and vent line both clear.although with line attached to tank blew intothjen 30 seconds later felt air come back out at me.only thing engs 1983 volvo 125 aq .thanks in advance for any ideals and help.i havent tried that i know of is to try a test tank.but dont know what else other than internal problem in tank could cause this.prev.owner told me it all started after he drained fuel tank using a hand operated siphon pump to drain tank for winter.sorry fort ant typos fighting 2 yhr old neice for control of lap top.