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88 Mercruiser 5.7 no fire from dist

J

jrwoodward

New member
1st time trying to start it this season. Ran fine when parked it out side covered all winter.

I did find I left my power switch on all winter so my batteries are shot. Put new batteries in and no start.
Tried starting fluid
Moved to checking for fire.
Pulled the distributor cap clean the contact points.

I did find a mouse/rat nest but I haven't found any chewed wires.

Any suggestions on what to check?
 
an 88 should have a thunderbolt IV ignition....there's a standard troubleshooting process if you are in a no-spark condition...its been posted here many times and is also on the www....
 
A corroded optical sensor wire under the distributor rotor will kill ignition. Rotor is locktited on. Follow troubleshooting procedure to prove it is defective.
 
What do you do if you follow the testing procedures but you're only getting 8.5 votes instead of 12?

"W/ignition key on AND BILGE WELL VENTILATED OF GAS FUMES!!!

#1 - Connect your voltmeter neg. lead to the engine ground and pos. lead to the white/red wire terminal at the dist. It should read 12 volts.

#2 - If 12 volts is present, remove the coil spark wire from the distributor and connect it to a spark gap tester to ground. Remove the white/green lead from the dist. terminal. Turn the ign. key to on and strike the white/green lead to ground. If there is spark, replace the ignition sensor in the dist.

#3 - If there is no spark, substitute a new coil and repeat test #2. Now if you get spark, install a new coil. NO SPARK, replace ign. amp.

#4 - In #2, if there is No voltage present, disconnect the white/red wire and check it again for 12 volts. If 12 volts is present, replace the ignition sensor inside the dist. cap. If no 12 volts present w/it disconnected--ignition amplifier is shot and must be replaced."
 
If you left the key on until battery went dead there is a chance you killed the coil. When the key is on battery voltage is applied to the coil and it can overheat.

Find Shift Interrupter switch and disconnect white with green stripe wire from small terminal block (do not allow this ring terminal to touch anything at this time, Best to cover in tape) this removes the interruptor switch from ignition circuit

A fully charged battery should be ~12.6-13.0 volts with no connections.

1. With Key OFF, Check battery voltage first, use volt meter to see what it is across battery terminals.
2. With key ON, check voltage at coil + with meter negative lead still connected to battery negative. Should be same as battery voltage measured at battery withing 1/2 volt!

3. The test for voltage at white with red stripe is at the screw terminals connection at base of ignition sensor at distributor. If a newer sensor has been installed then it has bullet connectors, Disconnect the white with red stripe and measure voltage at the side which goes to Timing module (also called ignition amplifier) this is the battery voltage that is supplied to the ignition sensor inside distributor from timing module. Unplugging it stops power to sensor.
The white with green is the output of the sensor which goes back to timing module. It also goes to the shift interrupter switch. Which when shifting out of gear is activated momentarily grounding Ignition allowing clutch dog to disengage from gear.

Do all the above and report back.
 
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8.5 volts sounds like it has the resistor wire....I pulled the manual and MOST production V-8 has the TB-IV system...the 5.7l SKI still used a mallory distributor...the initial post says clean contact points....so

first question is which distributor do you have? Quick check if you dont know definitively is mallory's cap has Sockets for the high tension leads, the TB-IV has posts (which look like the end unthreaded end of a spark plug)...

the 8.5 VDC is typical with the mallory (point's) at the + side of the coil with the key on....so the TB-IV troubleshooting procedure won't do you much good...and the wire colors called out shouldn't match either....
 
Thanks everyone for the help and suggestions, my issue has been resolved. Here is what fixed it.

1st, the kill switch was left on all winter and it wouldn't start or fire. (after installing hot batteries)

1st thing I did was replace the coil. Still no fire so I followed the Thunderbolt testing procedure and was only getting 8.5 volts, (early on in my testing I was getting 6 volts and tried cleaning connections and such and got it up to 8.5 ish)
Ordered a Sierra Marine Ignition Sensor Kit Item: 18-5116-1 from O'reilly which they had the following morning, installed it on my boat and voila!
the sierra part was an easy install, I didn't have to pull my distributer to install it.
 
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