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1998 43L wonbt start

S

scewter

New member
"Newbie here with a particular

"Newbie here with a particularly difficult challenge.

My 98 4.3L Alpha w/TB IV ignition will not start. It cranks, but no spark from the coil. Here's what happened and what I've done so far: alternator (regulator) failed while running and voltage pegged in excess of 16.5v (limit of gauge). Throttled back to try and bring voltage under control, but even at idle voltage was between 15-16v. Boat has two batteries and switch to choose between 1,2,Both or Off. With voltage out of control I think I did a not-to-smart thing by selecting the Off position on the battery selector. It shut the engine down, but continued to diesel for another 20-30 sec. After that switched back to Both position on the battery selector and cranked the engine. Would not start, but now had electrical burning smell and smoke in the engine compartment. Shut everything off, got towed in, and have been working on it for the last month. The following is a list of new parts that have been installed in order:
Alternator, Ignition Sensor inside the distributor, Ignition Module bolted to exhaust elbow (expensive little box!), and finally the Ignition Coil.

Engine will crank, but will not start, and by hooking a spark tester from the coil to the distributor I see no spark. Spark tester ops checks okay on my car. Have followed the troubleshooting points printed on this forum as well as my repair manual about testing voltage at the coil, etc but now with all new parts, it appears that something else has burned up.

I have searched this forum for similar problems, but no luck.

Any suggestions would be greatly appreciated at this point.

Thanx in advance.
Scewter}}"
 
Is there 12 vdc at the coil?

Is there 12 vdc at the coil? Yes? Perform the ignition tests again. No? Trace the coil voltage.
 
"Guy, thnx so much for the rep

"Guy, thnx so much for the reply.

When testing the voltage at the coil there is 12vdc coming from the positive terminal of the coil.

In performing this test several days ago it lead me to the conclusion the coil was bad. After replacing the coil last nite, found I still have no spark coming off the coil to the distributor as evidenced by the spark tester hooked up between the coil and the distributor as well as the engine not starting (with the tester removed).

Is that what you mean by performing the ignition test again?

Thnx,
Scewter"
 
"Go back through these tests.

"Go back through these tests. Use a spark plug for testing spark if the spark tester fails to show a spark. If any more of them fail, check the wiring connections carefully. You may have fried a wire or two. Verify that you connected the dist. optic sensor correctly.

Tests for Thunderbolt Ignition:

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

Check the kill switch first!

#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 are 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."
 
Also disconnect the TACHOMETER

Also disconnect the TACHOMETER LEAD from the negitive side of the coil. (grey wire)

If the tach has a issue it will short out the coil.

Also check the interuptor switch to see if it is shorted closed. It is a normally open switch. I believe it also shorts the negative side of the coil to ground.
 
Kghost - thnx for the post. I

Kghost - thnx for the post. I will try that as well.

Where would I find/trace down the interuptor switch? Don't find that labeled as such on the schematics I have (Seloc repair manual).

thnx again.
 
"Where both the shict control

"Where both the shict control cable and short shift cable meet, a bracket will have all the parts and on it should be a micro type switch with two wires comming off it that sits in a V notch.

Also pull your main PLUG/CONNECTOR at engine ( about 1 to 1 1/2 inch diameter) apart and check all the pins and sockets for damage and possible burning."
 
"Great news – engine starts no

"Great news – engine starts now! Thnx to both Guy and Kghost for the great advice.

Kghost – the plug/connector pins and sockets appeared to be in good condition. Never got to searching for the Interuptor Switch, or other switch by the control cable/short shift cable bracket. Tried disconnecting the negative side of the coil for the tach lead but that didn’t appear to make any difference. All good recc but the problem turned out to be a defective ignition sensor in the distributor. That was the first item replaced weeks ago (after the alternator) and you wouldn’t think a brand new part would be defective, but I guess it happens.

Guy, here’s what I came across when performing the tests you outlined:
"#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." Result was 12.3 volts. So far so good.

"#2 - If 12 volts are 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." Wasn’t sure which end to strike to ground, so tried the end coming out of the distr terminal first – no spark. Tried the other end next which comes out of the ignition amplifier mounted to the exhaust elbow and that produced a spark! Okay, so that means the ignition sensor is bad. But it’s brand new!! So let me try the old ignition sensor that was removed weeks ago with the hope that it is still good and not burned up. Put that one back in, and the engine started right up. Go figure!

There is a lesson here, and I guess I had to learn it for a second time now – brand new parts are occasionally defective, so don’t assume anything!

Thnx again folks – you saved me a lot of time/money.

Hats off to ya"
 
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