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Discussion Starter · #1 ·
A friend of mine was up to the lake this weekend and was coming in and had no power. It is a 1998 sport craft with the 454 big block. We put a few cans of dry gas in it and finally got it started again seemed to help when idleing but took it out for a run and has no power wants to just act sluggish. Is there somthing easy to look for before calling a mechanic?
 

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Is it running on all 8 cylinders. To check it put the motor at 1500-2000 rpm's and pull one wire at a time. You will hear if one cylinder isn't firing. Do not pull the coil wire or you will feel like lightning hit ya followed by a few choice words. If thats the problem it's probably a wire. Time for a new cap rotor and wires and while your at it plugs too. Good luck but I would bet it to be a bad wire. Pm me if you need more help
 

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Discussion Starter · #4 ·
We did try changing the water seperator but that is the first time it has been changed this year. I checked a couple of plugs and they seemed to been firing but your right we might as well change them. it is fuel injection ,will check cap and wiring next. Thanks for the help I will let you know the outcome
 

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if it is Throttle body,,with the flash protector / Air cleaner off in a dark area take a flash lite shin it in the top and make sure there is a good even spray pattern one could be dribbling or not working they are easy to change,,,






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there are numerous things that need checked, what rpm does it stop advancing at? 2200-2600rpm suggests that the motor might be in SLOW mode.Is this s a volvo or merc? two things will affect slow mode water temp and oil pressure.Check the gauges on the dash-what do they say? the ones the computer sense are different than those on the dash.Try to unplug the sensors (water temp and oil pressure ) one at a time while under power and see what happens. I really need to know what rpm the motor stops at. Does the engine run rough when the throttle is advanced or does it stay smooth and just wont gain rpm? check fuel pressures static and running, a gauge can be purchased at auto zone. if it is electronic related like ignition it will most likely run very rough. How does the motor start and idle? Is there an alarm horn for overheating or low oil pressure? is it connected? make sure you didn't suck something up in the water pick up that will overheat and put it in the protective SLOW mode. Most of the time when you stop and shut the engine down it will clear itself, but not always.make sure the fuel/water separator is replaced, check for collapsed fuel lines causing starvation. You cna eliminate the fuel supply side by running a shop tank to the engine. If none of the obvious appear then you could begin to check timing and compression-how many hours are on the motor? checking the timing on the motor will most likely require you to short the diagnostic lead first. Answewr some of these questions and I will be able to give you more information to look for.Don't try the shop just yet and don't throw parts at it either.

You can also make sure that the prop shaft is turning freely, no binding, make sure the transmission is not bound up and not allowing the motor to reach peak rpm.
 

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apart from the obvios as everyone has stated, a long shot is a shifter cable. sounds like a fuel issue though.
 

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Discussion Starter · #8 ·
Well we had the mechanic out last week and he changed the oxygen sencer. We took the boat out and did the same thing. We called him back out this week and the computer said everything showed ok so he went to the old school basics. We found the cap and rotor to be really bad. We thought since it started and ran good at idle and up to 2500 rpm that was not the case. Well problem solved and thanks for all the help. There was a lot of good input I have the same motor in my boat so I have some things to look for when I have motor problems. Hope not for a long time out.

Thanks again LtDan
 

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I have had some years where I have changed cap and rotor as much as 4 times. Rainy humid years are the worst. Also if that boat is a Single Inboard you may have a little too much drip coming off the shaft leaving a little too much water below the hot oil pan and will make a lot more steam causing corrosion to the cap. Glad ya got it taken care of.
 
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