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350 MAG starts nice dies in 23 seconds

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captn_jack_1

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Starts cold nice then dies 2-3

Starts cold nice then dies 2-3 seconds later. Pump throttle and I see fuel jetted into primary side of webber 4 barrel. Starts again and dies 2-3 seconds later again. It will not idle more than a few seconds ??? Help please.
 
"electrical? put a voltmeter o

"electrical? put a voltmeter on the purple side of the coil to check system voltage. If 12V is there when it quits, then suspect ign. coil or module. Just finished one that did that after 20 seconds,tried a coil ,no change, was the module on (not in) the dist."
 
"Can you post more specifics a

"Can you post more specifics as to what engine, year etc.? As Doc said, look towards secondary ignition failure. Different years use different components therefore diagnosing becomes also different. Al W."
 
"Al, Iput the voltmeter on the

"Al, Iput the voltmeter on the + of the coil and a good ground, turned on the ignition key and got a 8+ volt reading. I then started the engine and when it quit it still had the 8+ reading.Is that an indication the system is ok and I should go back to my fuel delivery ???? Jack"
 
"John, Guy is pretty sharp on

"John, Guy is pretty sharp on this stuff. I'd also say 12V required. Hopefully one of our Pro Mechs. is more familiar with your system and will chime in. Until then I think you need to check your Battery, groundings, and Alternator output when it finally runs. Get yourself a Digital Volt Meter to diagnose all things electrical. Radio Shack, Sears etc. is just fine. Should cost you under $30. Please keep us posted. Al W."
 
"If it`s anything like the one

"If it`s anything like the one i just worked on, my moneys on the ign module.starpped to the dist.
you could try a jumper from the +12v to the + side of the coil.if it runs then ,suspect corrosion lowering the voltage enough to not fire the module.also test with a spare coil, then look at the module"
 
"John,

you need to start fr

"John,

you need to start from the begining.

1. with nothing on,check battery voltage across the pos and neg terminal. ( fully charged battery!!)

Is it 12.6 volts dc +/-.2 volts?

If is is less than 12 volts you have a dead cell.

2.2 volts per cell x 6 = 12.6

2. You need a test light because a volt meter does not always show what is needed to be seen when checking voltage.

If your battery is good, put test light across battery and look at light intesity. Very important!!

Next put key in the ON position and check the pos side of coil with test light and confirm = or less intensity and if so now we can trouble shoot.

Pull large connector apart, the one that connects all the engine wiring to the rest of the boat.

Look at the pins and sockets and make sure they are not corroded.

Reinsert the connector and use a slight twisting motion when reseating it.
Now recheck 12 volts at coil.

If still low go to dash and check for the 12 volts at the key switch. A bad switch could give you a voltage drop like you are seeing.

The key switch should have a red +12 v and a purple (ignition on 12 volts with key in the on positon) check for voltage there and see if you have a good 12 volts or not.

Let us know some answers..."
 
"A 1993 engine won't have

"A 1993 engine won't have an electric fuel pump, so it's not an oil pressure switch failure. I don't think it's fuel related at all. My money would be on an ignition sensor (not module) failure.

Get a service manual an go through the T-Bolt IV troubleshooting procedure and you will find the problem."
 
"Dave N, I installed the elec

"Dave N, I installed the elec. fuel pump on the 1993 BAJA myself. Yhe boat ran great with the pump . This trouble I'm having occured after. Yes my Clymer manual says it may be the ig. sensor as you suggest. I may just spring for a sensor $60.00 and hope for the best. I think the Module is more costly but I was hoping to be absolutely sure before spending anymore "green". Thanks jack"
 
"Ignition sensor failure is fa

"Ignition sensor failure is far more common than module failure, and as you guessed, the module is far more expensive. So if you're not sure, bet on the sensor.

I'm not sure what the troubleshooting procedure is in the Clymer manual, but the Merc manual procedure will pin it down so there is no question, so you don't risk wasting any money. The Merc manual can be downloaded at no cost by the way."
 
"I might be missing something

"I might be missing something but did you test for spark when the engine dies??? You could pull of one plug wire, run it on 7 cylinders, stick an old spark plug in it and see if the sparking stops when the engine is dying"
 
"Give this a try.

<center><

"Give this a try.

<center><table border=1><tr><td>http://www.marineengine.com/discus/icons/attachment_icon.gif""" align=left alt=""application/vnd.openxmlformats-officedocument.wordprocessingml.document"">Thunderbolt Ign. tests
[url=""][b]Tests for Thunderbolt Ignition.docx[/b][/url] (10.6 k)</td></tr></table></center>"
 
You guys forget we just had a

You guys forget we just had a customer on here who had a bad electrical connection in the 12 volt ingition circut.

Not to say it may be as descibed but he should start at the begining and give us his results.
He is running a electrical fuel pump he installed himself and one would hope he installed a oil pressure/igintion on switch also????

If he is running with a weak battery it could cause issues.
 
"Tests for Thunderbolt Ignitio

"Tests for Thunderbolt Ignition:


Tests for Thunderbolt Ignition:
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."
 
"Thank you all for your ideas

"Thank you all for your ideas re my 350 MAG. The problem was dirty and corroded terminals in the ignition amplifier to coil harness. A thorough cleaning of the terminals and other items made the engine run like a clock !!! thanks again, Captn Jack 1"
 
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