FUEL OR ELECTRICAL?? 150 VMAX DROPS RPM RUNS BOGGY. CARBS OR COIL?

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oonighttrain

Seaman
Joined
Jan 21, 2008
Messages
50
I HAVE A 2003 TLRB150 VMAX 150 CARB MOTOR THAT HAS RUN GREAT UNTIL A FEW WEEKS AGO.. IT STARTED TO DROP RPMS INTERMITTENTLY, RUN KINDOF BOGGY SO, A FRIEND OF MINE WHO IS A MARINE TECHNICIAN SAID IT PROBABLY NEEDED THE CRABS REBUILT SO, I TOOK THE CARBS OFF, GOT THE KITS AND HE REBUILT THE CARBS. I PUT THEM BACK ON LAST WEEK, IT RAN GREAT THE FIRST TIME OUT. TOOK IT OUT AGAIN YESTERDAY AND IT REAN GREAT FOR PROBABLY 15 PLUS MILES, THEN ALL THE SUDDEN IT WOULD DROP RPMS IN AND OUT, YOU COULD ACTUALLY HEAR AND FEEL THE MOTOR CHANGE TUNE, RUNNING CRISP AND CLEAN, THEN DROPPING RPM AND POWER. TOWARDS THE END OF THE DAY, IT WOULDNT REV OVER 4500 RPM AND WHILE TRYING TO GET UP ON PLANE, YOIU COULD FEEL LIKE IT WASNT HITTING CONSTATNTLY ON ALL CYLINDERS. I GOT IT HOME, DUMPED THE SEPERATOR (DIDNT SEE ANY WATER) AND ADDED FEUL ADDITIVE TO HOPEFULLY HELP WITH ANY WATER IN THE SYSTEM, TOOK IT FOR A QUICK SPIN TODAY TO SEE IF THERE WAS ANY DIFFERENCE.. THERE WASNT REALLY, IT DID REV TO 5-5100 BUT, NOT THE 55-5600 THAT WAS NORMAL. IMTHINKING THE CARBS ARENT TOTALLY CLEANED OUT OR IVE GOT A COIL BREAKING DOWN ON ME?
 
9

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
9,026
1st off, turn off the caps.

check fuel pumps to see if leaking into crankcase.

If there was anything hiding in the lines and pumps it very well could have hit the carbs and plugged thing up again.

check compression ,spark, and timing
Need to see if you can monitor spark to all plugs while it is messing up, Inductive Timing light or tach hooked to the individual plug wires should show if sprk is being lost on one or more plugs
Fuel pressure and vacuum also
 
O

oonighttrain

Seaman
Joined
Jan 21, 2008
Messages
50
sorry for the caps..

how do I check for fuel leaking into the crankcase? fuel pressure? and vacuum?
I have not checked the compression or timing but, I put a digital tach on the wires and they all seem to be fine(all read the same)..
thanks for any help!!
 
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