If the fuel pressure is 95 and the air pressure is 110, that is a big problem.
Prior to your first post in this thread... when was the last time (month) that you used the boat and it ran correctly?
If the fuel pressure is 95 and the air pressure is 110, that is a big problem.
Prior to your first post in this thread... when was the last time (month) that you used the boat and it ran correctly?
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
The fuel pressure was 110 and air pressure was 95 (sorry) It ran correct loaded on the first run of the morning in the tournament, Then after fishing for a couple of hours it wouldnt fire, then third try started, hasnt had loaded holeshot since, Running light it will finally get on plane and runs great on top end, However with water in the livewells it will try to get up, will turn about 3800 rpms and hang there, Suddenly the rpm's will come up and it runs fine on top end. The boat had sat approx a month between tournaments
Last edited by boatman00; 09-20-2017 at 08:12 PM. Reason: added to post
Let's look at this differently... no presumptions (at least for a few minutes). What PROP are you running, and what is the HONEST condition of the prop (condition report you would want if you were buying it from someone)?
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
25 Tempest Plus, Probably 9.5 out of 10. No dings,nicks or scratches. Have been running this same prop for a couple of years,
Last edited by boatman00; 09-25-2017 at 06:25 PM. Reason: added
Nice speaking with you a couple times, Reed. Good to hear the reeds are in good condition (and all screws are present, accounted for, and tight).
Be sure to report back after you've tried a known-good MAP sensor (and spark plug on #6).
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
Thanks Don. Tested with the known good map sensor and plug, Same problem.
My dad just experienced a similar issue with his 2005 250XS, EVERYTHING checked out normal, only problem we and the mechanic ever found was one plug that was incorrectly gapped (they were brand new plugs btw)....it has run fine every trip since all the plugs were re-gapped.
1999 Bullet 21XDC
2016 Mercury 300xs
2020 Ford Powerstroke FX4
I bet I know who he was tooT C M
.................................................. ...the scariest thing in life is the unknown ...................................
Hey Joe, didnt know you were on here!Originally Posted by JOE54
I bet I know who he was too
1999 Bullet 21XDC
2016 Mercury 300xs
2020 Ford Powerstroke FX4
Any updates? Curious on what is causing such a odd problem
Still trying to work through it, have swapped out about everything external and pulled both heads for internal inspection, same problem as originally, going to swap out Pcm for testing next week.
Just curious if a prop could cause such a odd scenario - I've expierence problems that were prop related I never would have imagined would have affected anything - I'm sure you have tried a different prop with no chance?
Reed: Refresh my memory on something (not sure if we looked at this): Where the fuel RETURN line (form the port rail) connects at the back of the VST, there is a black collar/grommet that fits between the line and the rear of the VST, correct?
Just want to make sure that piece is not missing...
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
I have already changed he engine back to the Xb, just went out and checked tho and the grommet is in place.
Thanks
So what did you find out was wrong? I don't have anything better to do than read these forums and I get quite curious - getting old is rough
We never found a problem of any kind, Just struggled on hole-shot,It ran great on top end. Had the ProXb that i had removed from the boat, so i put it back on.
Check the diaphragm pump. Ethanol chews em up and if a diaphragm is ruptured, or one of the springs broke and poked a hole in a diaphragm, you would be flooding the bottom 2 cylinders until you burn all the fuel off.
Good suggestion- and simple to check. This engine still has the STOCK exhaust (no modifications, tuner not cut, no aftermarket tuner, etc), correct?
Sure would like to know what was going on with it!
Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor
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