Logo
FULL SITE MENU

Help! I need some ideas on what to check next Aq 130

S

SibetOR

New member
Hello. I need help on my 1977 AQ 130. I have had this boat since new. This spring I rebuilt the head, put in new rings, main bearings, rod bearings and rebuilt the carbs.

The boat runs great if I stay below 4500 rpms, it will go all day. It will pull a skier out of the water great running up to 5500 rpm and after about a minute it starts losing power and then backfires and will die. If I pull the throttle back down it will recover after a few seconds. (as long as I keep the speed down) It has consistantly done this each time I try. This happens just driving or pulling a skier.

I put in a new fuel pump. I checked all the fuel lines for blockage. I checked the fuel tank for blockage. I checked the carb bowl levels. New fuel filters. Changed the coil, new plug wires, new dist cap and points and rotor. Rechecked the valve clearances.

One thing that did happen is the engine overheated on the first day out (I had put in an "new but actually several years old" faulty impeller that disintegrated causing the overheating). This overheating happened after the engine dying thing happened a few times. I took the head off and replaced the head gasket which was affected by this. The next day out the same stalling thing happened. Compression is about 150 straight across.

I don't have any water in the oil or it isn't overheating, running about 160 at idle and 180 going higher speeds. After 35 years this hasn't happened before. The only similar thing that has happened is the carb jets getting some junk in them but when this happened, there was no power from the start.

To me it acts like fuel starvation but the other day the engine just died and investigating this I discovered the wire off the main fuse had fallen off. I tightened all the connections and it actually ran great for an afternoon. Now today I went to the lake and pretty much the same thing. Just won't stay at high rpm for more than about two minutes.I double checked the fuse and coil connections (those stupid push on connections) and even eliminated the fuse with no better results.

Can anyone give me some ideas what to check next or if I may be missing something. Sorry about the long post. Thanks for any help.
 
I would check for piston blow-by. Does the crankcase vent show more smoke at the high RPM's.
Does the crankcase vent into the carb intake?

What kind of end gap did the new rings have?
 
SibetOR said:
The boat runs great if I stay below 4500 rpms, it will go all day. It will pull a skier out of the water great running up to 5500 rpm and after about a minute it starts losing power and then backfires and will die.
Click to expand...

Sorry I don't have any troubleshooting tips, but I would like to point out that running this engine at 5500 rpms is not recommended. The WOT spec is 5100.
 
dennis461 said:
I would check for piston blow-by. Does the crankcase vent show more smoke at the high RPM's.
Does the crankcase vent into the carb intake?

What kind of end gap did the new rings have?


Thanks Dennis. I remember the end gap was in the specifications that were called for on the instructions for the new rings. I will check the blowby at high rpms, the hose goes into the carb intake cover. I was thinking of checking the voltage going to the distributor at higher speeds and see if that changes.
Click to expand...
 
Thanks, I forgot to add that my engine is an 1977 AQ 130D. I have the book that came with the engine and although I can't find it right now, I remember it specified something like up to 5500rpms not sustained. This engine will actually go up to 6,000 (depending on the altitude I am at and assuming that my tach is correct), but I try to keep it below 5500 after the skier gets up. I have had a valve spring break going faster than this before.
 
SibetOR said:
Thanks, I forgot to add that my engine is an 1977 AQ 130D. I have the book that came with the engine and although I can't find it right now, I remember it specified something like up to 5500rpms not sustained. This engine will actually go up to 6,000 (depending on the altitude I am at and assuming that my tach is correct), but I try to keep it below 5500 after the skier gets up. I have had a valve spring break going faster than this before.
Click to expand...

OK -- sorry, I was thinking you had an AQ130C for some reason.
 
Sounds like you have a fuel line leaking air in so at high revs there is not enough fuel, the engine will not stop but slow right down
then keep going but no problem at lower revs. I had the same problem, could not sustain high revs, I changed to the other tank and problem dissapeared. Another thing to check is the coil and ht lead.
 
Thanks for the ideas. I did put on another coil and got the same results. I am going to try basically hotwiring the distributor to see if there is some weird voltage drop going on. I do still suspect the fuel supply, maybe the vent on the tank, but I did try running it with the gas cap off to see if there was a vacuum in the tank with no difference. But the only time it ran better was when I tightened up the connections on the main fuse if only for an afternoon.
 
Valve seals melting and sticking the valves?

I've never experienced it but have heard of it in other engines.
 
Thanks for clarifying that. I am going to take off that fitting on the top of the tank and investigate what is going on in there.
 
i would run a seperate fuel line to a five gallon gas can, and see what happens. you could have a clog in a line or the fuel pickup sock in the tank has some crud on it. if you are running contact points in your distributor, another common problem where a weak spring tension on the points can bounce, (float)...causing the cut out you describe. relacing the contact set with the oem matching condensor will eliminate that.
......also having a buddy with a can of carb cleaner spray the carb intake in short bursts when it is cutting out will help determine wether it is a fuel or electrical problem. if it is cutting out, and a short burst of spray into the carb picks the rpm up....you have a fuel problem. pm me if you have any other questions on troubleshooting.
 
Thank You. Those sound like good ideas to go with some other things I want to try. Hopefully the weather will cooperate and I can go to the lake soon, to straighten out this problem before winter sets in.
 
once you try those suggestions, that will narrow down wether it is a fuel or electrical issue. don't worry, it is not as bad as you think it is.
 
Thanks for all the tips. I took the boat to the lake a couple of weeks ago and was at the engine ready to squirt some gas into the carbs when it started to die. What I saw was a small blue flame down below the carbs in the intake manifold. When the engine got to the quitting part, the flames came up to the carb, backfired and the engine dies.. I took the head off and we checked the valve stem clearances. Some were too tight (especially the intakes) so we reamed all of them out. I have it back together and can't wait to get back to the lake to see the results. So what we believe is happening is the valves are being pinched by the valve stems only when taking off on a hard pull at full throttle. We will know soon.
 
Back
Top