1986 Supra Stalls above 2500 RPM

I have an 86 Supra T6m. It has the 351 Pleasurecraft engine. It was stalling at low RPM's when it warmed up (vapor lock or something), so I ran some carbeurator cleaner through it. Now that issue is gone, but after about 30 seconds of running at 3000 RPM or so (when skiing), the boat completely cuts out on me. It seems to surge a bit before stalling. It's like it is starving for fuel. It does this on a full or a half tank. It only does it at higher RPM's. No problems at low RPM's.

Has anyone had this happen to them, or does anyone know what would be the first place for me to look/start replacing?

I have had the boat 2 seasons. I have not rebuilt the carb or replaced anything yet. Spark plugs are fine. All belts and hoses are fine. Would it be a fuel filter or just an old carb? Maybe a bad fuel pump?

Thanks for the help!!

Ian

I don't know if I'll be much help here but I think I'd start with the easy stuff. Replace the fuel filter cartridge and be absolutely sure that you have your fuel tank vented good - like no kinks or anything in the vent hose. It sounds to me like the problem is either related to a restriction in fuel flow at higher rpm's or it is somehow linked to temperature - running at higher rpm's under a load the engine is building heat and maybe something there is not liking the temps. Do you know what temp the motor is running at all this time?

Check the fuel filter for clogging also make sure there is no water in it. Check the fuel pump [pressure test,vacuum test, volume test] you must do at least 2 out of 3 of the tests. If all checks are good rebuild the carb it probubly needs freshening up anyway.

Hmm, I'm building my mechanical capabilities exponentially, but I am not really sure how to do a pressure test for the fuel pump. I've had a lot of the boat apart, but only as far back as the blower pump. Is the tank in the back, behind the rear seats, beneath the carpet? It's a Comp Ts6 model.

I had a problem with the stereo. My main accessory wire was shorting out the boat. Before I found it, I fried the solenoid, alternator and starter. After rebuilding/replacing those, I went out and the boat started hesitating at 3,000 RPM before stalling. If I let it set for a few seconds or a minute, it will start up. I wonder if this is the fuel pump priming itself or if I am getting air in the lines or if I simply fried the electrical components and now it's acting up on me.

Does anyone have a link to a way I could check the fuel pump/system? The pump is sort of expensive. I wanted to go out this weekend, and I couldn't have a pump until Tuesday, so I decided to take it apart. It was full of crud. I cleaned it out with WD-40 and it looked great. I put it all back together and then went out. Same thing.....it stalled on me once I was going 30 MPH for about 30 seconds. Then my battery was too dead to start the boat. Then I got towed back in.....how embarrassing.

Any links or ideas? I want to do my own work.

Thanks in advance,

Ian

ouch, that short doesn't help things.

have you tuned it up lately? also could be your distributor advance is rusted up. you can take the dist cap off and the plate under it to inspect the weights and springs.

why wouldn't the boat start? was the battery not fully charged? what was happening when it wouldn't start?...engine turning over slow? nothing but clicking sounds? did you happen to notice if the battery cables were hot?

I had this problem w/ my 351....I rebuilt the carb, did the ignition, still had the stalling problem...
12 bucks........ fuel filter.....
Especially if the pump was all gummed up...maybe even some fuel conditioner...

Another clue. Why was the battery dead? Check the alternator output.You must have at least 9.5 volts to supply the ignition. There are 3 ways to test a mechanical fuel pump. Pressure, connect a fuel pump gauge to the output side of the pump [ carb side] it should put out 5-7 lbs. Vacuum, connect a vacuum gauge to the suction [fuel tank side] it should pull at least a 10 inch vacuum and hold it. Volume, connect a rubber hose to the fuel line going to the carb put the other end in a clear bottle pump should push out a steady stream of fuel and fill at least 1 pint within a few seconds. All test are performed while cranking the engine.
The pump must pass two out of three tests.