1994 225hp v76 3.1ltr twins....misses wot and around 1700 rpm.

[regulator express]

remember me? rodbolt, I'm amazed at how much you know about these yams. I read and reread all I could find on this site.<br /><br />OK, port side engine runs great.<br />Starboard side starts and idles well. Has new impeller, water sep, gear oil, t-stats, poppet valve checked, primer bulb new, (crossed fuel lines with other engine and same situation).<br /><br />Symptoms: When trying to plane off and raising throttle, from 1400 rpm-2000 rpm, it runs out of fuel and either stalls or stays running at idle (I pull the throttle back). If I really gas it (to get "through" the range) it will make it up to 2200 rpm then run great above that and I can cruise all day in the 3s and 4s. My mechanic says the carbs are gummed up and need cleaning, that's it. He believes fuel pumps are fine, because it runs well in the upper rpms. Also, he thinks the tps is not likely the problem. He is 90% sure it's the carbs simply missing due to dirt and deposit. <br /><br />Also, this engine will not get past 4400 rpms. I always have to give this one more gas just keep up with the good engine's rpm. The good (port) engine will go right up to 5300+ without a problem. I have one throttle almost floored with the other where it should be in order the match my rpms.<br /><br />Do you think I should rebuild/clean the carbs simply to eliminate that as a reason? I might be able to do it myself....I already bought the rebuild kits. <br /><br />Rodbolt, can you paste/reply me the helpful hints to rebuild the carbs? I have the book, but they often lack the hints and clear wording.<br /><br />Thanks for all.

 

[rodbolt]

Re: 1994 225hp v76 3.1ltr twins....misses wot and around 1700 rpm.

motor is dying. fix it or it will. <br /> test compression. test spark. test the plug caps with an ohm meter. replace all three fuel pumps every 3rd season. the carbed 3.1's ate them. test the TPS with an analog meter. look for a needle skip or jerks when slowly opening and closeing the throttle. there were some stator issues with those motors. usually resulted in low speed to mid range miss. test the CDI output at the coil primaries with the engine at the problem RPM under load. if its not to spec it has to be fixed. if you decide to tacle the carbs you will have to have the TPS test harness. its cheap, a multimeter and patience. there are six carbs and each is different from the other.dont mix and match the carbs or the parts.carefully check the fuel enrichment solinoids. test the fuel pressure on the enrichment circuit. if the engine is not coming up to temp it may set a code 33 on the dianostic lamp. that system monitors engine temp and opens the enrichment circuit to compensate. if the ECU sees the head is cool and you run it at or near WOT the #6 fuel bowl runs dry and can smoke #6 piston. if you attach the diagnostic lamp and water test be aware that no automatic oil transfer can occur. all alarm functions will be normal.<br /> if the TPS sends the ecu a signal of rapid throttle opening the enrichment circuit is activated. if the knock sensor triggers timing is reduced and the enrichment system activated. if the sensor is dissconected it sets a code and locks timing at 7* BTDC. test the crank position sensor output. the CDI and CPS sensor outputs must be done with a peak reading multimeter.<br /> that should keep you busy for a bit anyway

 

[regulator express]

Re: 1994 225hp v76 3.1ltr twins....misses wot and around 1700 rpm.

holy sh#t!, rodbolt, you are a GOD to us DIYers.<br />I've read up on all details about these 3.1 yams, and I can't believe how you just summed up the diognostics for this engine in one fairly short paragraph. My mechanic and I will try to get this all wrapped up. I'll get started myself today. I will print this all out for him to use as a checklist more or less.<br /><br />Thanks a million. Have a beer on me. I'll give you the money next time!

 

[rodbolt]

Re: 1994 225hp v76 3.1ltr twins....misses wot and around 1700 rpm.

there is a lot more I just did not mention them. ya got enough for now. I would reccomend a fuel system vacum test. start between the pump inlet and the fuel line check valve. if your tech is not familiar with the V76 ign and fuel systems he will chase ghosts.