Thank you in advance for any and all help in regards to helping me diagnose my 1998 5.0 TBI Searay 240DA. I purchased the boat in April of 2008 it has 200 hours on it.
I have a reasonable level of electrical and mechanical ability so don’t hold back with the tech talk. I am New to boating power plants and control systems but not new to V-8’s and ecm troubleshooting etc. Again thanks for your help in advance and here’s my boating problem.
I purchased the 240DA in say April of 2008 the boat seemed a little doggy, a neighboring sea ray owner with a 1986 350ci carbureted 240 DA (nice boat) confirmed my boat performance was a dog at best.
I performed a tune up, cap-rotor-wires-plugs-spin on fuel filter. I was told by the previous owners mechanic that the high volume fuel pump was replaced (maybe it’s not the right pump) and the boat WOKE UP from 32 mph to 42/43mph @ 4300rpm but....
From standing to top speed of 42/43 @ 4300 the boat pulls hard, boat goes fantastic, But when I open it up for a few miles I get a very pronounced "lean pop - small backfires - decrease in power" until I back it down to say 35mph 3200 rpm (all rpm’s are approximate as memory serves me from last season).
At the same time the tach reflects the same sort of anomaly, the tack jumps wildly it even seems to climb in rpm while the motor is lean popping. (Sort of like the tach is shorting out ??) or ignition is shorting out or rev limiter or neutral switch.
As the boat is one month away from hitting the water I wanted to get an early start on trouble shooting.
So far here is the list of items I am planning to test not necessarily in order. Please let me know which test if any could be performed while on land.
• Disconnect tach in case of internal shorting – verify no other wires on motor are touching ground
• Batter terminal connections will be removed and cleaned and reinstalled and greased.
• Fuel Pressure (new spin on filter installed last year)
• Check for ecm codes
• Neutral or forward reverse switch jumper “test” deep water test only not with anyone near prop
• Pull plugs test for compression and or water coming in via risers etc.
• Routing of plug wires
• Replace pickup coil
• Inspect fuel system including VENTS – not to mention FRESH GAS.
• Verify correct gph fuel pump as this was replaced (should show up on fuel pressure test)
• I have the mercruiser manuals (thank you to whomever posted the links)
• Could I have a rev limiter problem? prop is the correct S.S. per Sea Ray web site
The boat was owned by a non mechanical person who seemed to take slow rides I don’t feel it saw allot of WOT.
Please feel free to cut and paste links which you feel may be of help as this might limit wasting your guy’s time. I am really open to any suggestions. Thanks again. Ed