Engine Miss, Electrical issue 1989 7.4 Chaparral

[stinger222]

After crusing for about 2 minutes last week, hit the trim tabs, engine misses, runs fine afterwards, starts up after stopping in a cove, however sometimes when i crank it pauses, then kicks over. Yesterday ran fine for 20 minutes, stop for awhile to let kids swim, then start back up no problem, but when accelerating to get on plane, sputters above 3300 rpm, backoff runs fine at fast idle...switch battery switch to "All", runs great, gets on plane normally, then after I get back to marina, volt gauges flutters, then it starts to miss at idle speed, coast into the slip.

Alternator looks original (nasty looking on the outside), batteries are 1 yr old and one is hooked up to trickle charger all the time. Checked all bat cable conn at bateries are tight and clean. Volt gauge reads 10 volt with key on, 12volt when boat is running. does this sound like weak alternator or bad ground cable?

 

[rbh]

Re: Engine Miss, Electrical issue 1989 7.4 Chaparral

with the boat running you should be charging between 13.5-14.5 vdc
rob

 

[stinger222]

Re: Engine Miss, Electrical issue 1989 7.4 Chaparral

Way too many varibles, your going to have to do some troublshooting.

Use a hydrometer to test batteries.

Make certain all grounds, battery connections and starter connections are shiny clean.

Take the alternator to a shop and have it LOAD tested.

hooked up voltmeter to each battery...12.5 volts on each one, 14.5 volts when motor running, so I think alternator is ok. Batteries seem ok too.. I cleaned all the connections with elec cleaner, wire brush, same with ground wires from each batt at the block, bolt as well. took the boat for a ride, symptons all gone, runs great, no miss when I hit the trim or trim tabs. Main pos cable at the starter had some white crap on it, and the stud that it attaches to on the solenoid was loose, so I tightened the nut.