engine dies at full speed

[satman]

posted question a week ago about engine dying at full speed,only response was to buy manuel, i did. also went ahead took it to wrech.did complete tuneup, cleaned carbs, did timing,compresson,spark,test,changed spark plugs,changed fuel line from gas can to engine. $260. still dies when i put throddle to full speed. joe reeves if your out there i need some help on what the problem could be, ive seen you fix problems over and over on line,,please, or any other inputs would be nice. almost want to set fire to boat and sink it,,, thanks for any inputs.....

 

[BF]

Re: engine dies at full speed

Hiya,<br /><br />some background might help. What engine? year/model? Are you running from a portable tank or fixed? Is the motor new to you? Was it running good before, and then started dying?<br /><br />My first guess is a fuel problem.. maybe a clogged tank vent or a bad fuel pump. If you try and pump the bulb as it dies can you keep it going? Or if you bump the choke? Does it die suddenly? If you loosen the cap on the tank to let air in does it still do this?<br /><br />Your fuel line is new (and I guess primer bulb too) so I guess it's not a problem there. Sometimes they can come apart inside and restrict fuel flow.<br /><br />If it's not fuel, then it'd be electrical... Maybe there's a problem in your remote throttle. A cracked wire somehow killing the ignition only at full throttle?? (or are we talking about a 2 hp??)<br /><br />that's my first thoughts anyway...

 

[OBJ]

Re: engine dies at full speed

Good reply by BF satman. Knowing how the engine dies does help. If it just sorta spits and sputters while slowing down, usually fuel related. If it just quits, usually ignition related.<br /><br />Not overheating or anything? Do check the gas tank/can vent.

 

[satman]

Re: engine dies at full speed

HI BF THANKS FO REPLIYING LIKE I SAID I DIDNT REALLY GET A RESPONSE LAST TIME AT LEAST I KNOW PEOPLE ARE TRYING TO HELP. WELL ITS A 150 JOHNSON FASTSRIKE. I MADE THE MISTAKE OF BUYING IT WITHOUT TESTING IT, BUT I THINK I GOT LUCKY, I THINK ITS SOMETHING SIMPLE BUT WHAT.AT FIRST THATS WHAT I THOUGHT A FUEL PROBLEM SO I MYSELF CHANGED THE FUEL LINE AND YES BULB, SOMEONE SAID THE BULB SHOULD STAY TIGHT THATS WHY I REPLACED IT CAUSE IT DIDNT.AND YES IT DID THIS FROM DAY ONE.IT DIDNT GRADULLY START.I WISH I COULD TRY TO PUMP THE BULB AS IT DIES TO SEE IF IT WOULDNT CUT OFF BUT IT DIES SO FAST ITS LIKE WHEN I PUSH THE GAS THRODDLE TO THAT POINT BAM IT DIES JUST LIKE THAT. KNOW WHEN I GET IT TO GO DONT GET ME WRONG IT RUNS LIKE A CHAMP UNTIL I STOP IT AND FISH FOR A WHILE IS WHEN I HAVE THE PROBLEM. IT WILL CRANK RIGHT UP AND START DRIVING SLOW BUT GO TO FULL THRODDLE,,,DIES JUST LIKE THAT. IT WILL DO THIS FOR ABOUT 15 TIMES AND THEN IT WILL GET UP AND GO, ALMOST LIKE SOMETHING NOT ENGAGING??? IF THAT DOESNT SOUND WEIRD.SOME TOLD ME IF I HAD A ELEC. FUEL PUMP AND IF ITS SUCKING IN AIR THAT IT IS TAKING SOME THIME TO SUCK ALL THE AIR OUT AND THATS WHEN IT WILL GET UP AND GO COULD THAT BE? NOW AS FAR AS THE THRODDLE CABLE BEING BAD I DONT THINK SO CAUSE THIS BOAT HAS HAD A GAS PEDLE PUT IN IT. I THOUHT MAYBE THAT COULD BE IT TOO BF, SO I HOOKED THE OLD THRODDLE CABLE UP AND STILL DOES IT. AND THATS WHEN I GOT FEED UP AND TOOK IT TO WRENCH AND LIKE SAID STILL NO FIX. WHAT WOULD CRACKING THE CAP LOOSE ON THE TANK DO, DIDNT THINK OF TRYIND THAT. ANYWAY SORRY SO LONG THANKS FOR YOUR INPUT AND HOPEFULLY YOU WILL HAVE SOME MORE IDEAS. THANKS

 

[satman]

Re: engine dies at full speed

I FORGOT TO SAY OBJ NO IT DOSENT SPIT OR SPUTTER IT JUST DIES. AND AFTER I RUN IT WHEN I PUMP THE BULB IT DOES FELL LOOSE .I HAVE TO SQUESE 2 OR 3 TIMES ,BUT ALL CLAMPS ARE ON TIGHT..THANKS

 

[Joe DeNardo]

Re: engine dies at full speed

Hi I heard of this problem before. I think you need to see if your engine is overheating, or may have a faulty temp sensor. Low oil or no oil will kick in the slow mode until overheat which does a quick shutdown as not to damage the engine. good luck

 

[Walker]

Re: engine dies at full speed

Very hard to read all caps. I'd say you need to overhaul the carbs.

 

[BF]

Re: engine dies at full speed

He just paid a wrench to overhaul carbs, same problem. What loosening the gas cap would do is allow the tank to draw air in. If your tank vent is clogged, it would build vacuum up in the tank, which at some point, the fuel pump would not be able to overcome... with cap off/loose, no vacuum would build up and that would exclude a problem with the gas tank vent.<br /><br />The bulb going soft may or may not point to a problem with the fuel pump... they usually don't stay really firm, but when you pump it, you should feel it start to get firm immediately (ya, that sounds bad, I know! )... If you can squeeze the bulb several times and feel the gas getting pushed as you do it, then it means that the fuel line (and probably carbs) are empty. Could be bad pump, could be that there's an air leak in your fuel system, or it could be that the pump is drawing against a closed, non-vented tank. Maybe at the pickup line in the tank (?). When it gets like this (you said it'll die 15 times in a row), if you pump the primer will it run then, or still die?? Can you try running it off a different (portable) tank?<br /><br />If it dies quick, it does sound more like it could be an ignition problem rather than it running out of gas... I don't know anything about SLOW mode, so I dunno if that could be the problem. <br /><br />Heat related is another possiblity... something electrical (stator?) warming up and then starting to fail (?) That's why folks have asked about whether it's overheating. (and could be knocked into SLOW mode).<br /><br />Seems like you've still got some troubleshooting to do....<br /><br />And typing in CAPS is considered YELLING... funny how the internet has its own little culture eh?<br /><br />Good luck<br /><br />Brent

 

[satman]

Re: engine dies at full speed

sorry for the caps, didnt know. yea i know i still need to trouble shoot more,i didnt think about trying to use a portable tank cant get the boat out to water till this weekend, will try that. but it seems as if its 2 or 3 things..bad fuel pump,bad heat sensor,stator, or fuel line.but yes i did try to pump the bulb before i cranked up and tryed to drive boat, but no good it would still do it. as joebass was talking about the oil, i disconneted the vro, heard too many bad things obout it, i mix my own oil with gas 50:1, could that possibly elimiate the slow mode kicking in cause i know i have oil in there, then i could have to worry about two things,, fuel pump or stator oh and fuel line which ill know about that this weekend when i try the portable gas tank i feel dumb, i should've known to try that already, so i could've letting you guys know about that already, well i cant do nothing till this weekend as i will let you know about the portable tank trick just as soon as i can. thanks for all your replys so much.....

 

[marops]

Re: engine dies at full speed

Not sure with the 150, but there is a way to check the fuel pump pressure with a vacuum guage. This procedure tests the air-tight integrity of your fuel system (from gas can, through fuel pump, ending at the carbs). If you've got a break somewhere and there's air getting into the system this will point it out. Sorry I can't elaborate on what to do, I don't have a tech manual in front of me, but most manuals have it. Basically, you connect a vacuum guage before the fuel pump, test, then connect it after fuel pump and test.<br /><br />If the ventilation system is clogged, you'll get a few minutes of full throttle, then a pretty quick slowdown and cut but it's not instantaneous; you can definitely tell it's laboring for more fuel before it dies. It doesn't sound like that's your problem.<br /><br />I remember hearing a similar symptom that was caused by contaminated gasoline from dirty fuel tanks; supposedly they got good clean fuel until boat planed out (at full throttle), then somehow the contaminated stuff (probably water) got into the system and cut the engine out. I don't remember specifics other then it was one hell of a mystery to troubleshoot...since everything pointed to the engine at full throttle instead of what else happens when boat is at speed...<br /><br />Good luck and keep us informed!

 

[Oceanpro1]

Re: engine dies at full speed

just a quick suggestion you might need a new power pack and also check the fuel filter if the seal is not perfect it will cause the pressure to release and it will not hold fuel inside it for more then a minute or two especially a full throttle