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Vapor Lock

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wickeral

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"Here's the history. We&#3

"Here's the history. We've owned this boat for 5 years without the current problem. It's a 97 SeaRay Dancer, powered by a stout 7.4/300HP, TBI,Electronic Ignition engine. This season our boat will start and Die after maybe 2/3 seconds.This happens after short duration stops such as lunch. First start of the day, no problem. Let it cool for a few hours and there is no problem. I've rebuilt the Distributor, replaced the IAC, Temp Sender for the ECM changed out, installed a new Ign.Cap, Rotor and Coil. The Fuel Filter is new. I've added StarTron and an appropriate amount of Marvel Mystery oil. The gas is from last Sept./07 so I added a few gallons of Aviation Gas to freshen it up.
When the engine refuses to start there is Ejection from the Injectors for the 2/3 seconds it runs and then nothing. I'm inclined to think it's Vapor Lock due to the old fuel. When started she runs very strong.
I'm going to put a 160 Degree Therm. in and try to open the Hatch when stopped to see if it helps. BTW, it's a closed cooling system. I may add Water Wetter also. All opinions are appreciated. Thanks! Al W."
 
"TBI been rebuilt? Problem se

"TBI been rebuilt? Problem seems to be temp/fuel/electric related. Any spark when it dies? Get two cans of canned air for PCs and before you start it after lunch, empty one can on the fuel line, injectors and throttle body to chill them. If it starts you may need injectors since they were saturated w/heat while you ate lunch.

If there is no spark then empty the other can on the ignition amplifier since it also heated up thru lunch. Make sure the ground is clean and tight for the amplifier; it was the solution for others w/a similar problem.

Above no help? Check, clean and tighten elec. grounds. Disconnect each elec. plug and inspect for loose and dirty/corroded wires and pins; clean M/F receptacles as needed w/tuner cleaner from electronics shop."
 
"Thanks for the reply,Guy! Int

"Thanks for the reply,Guy! Interesting to say the least. The Injectors do work temporarily with a healthy pulse, then nothing. So, the soak thought is doubtful? I will give the PC can a go. I'll run her hard and then shut it down and start to cool the Fuel Line after a half hour or so. I don't know if your familiar with my boats Ignition but everything reports to an Electronic Control Module. I believe the Module is what you refer to as an Amplifier. I haven't checked for spark when the engine fails but certainly will next time. If no spark I'll cool that also. Thanks for your input and I welcome your thoughts. I'll post the results as I find out things. Al W."
 
"Thoroughly familier w/Thunder

"Thoroughly familier w/Thunderbolt Ignition. You can try the amplifier "module" test when it won't start.

<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>"
 
"Tests for Thunderbolt Ignitio

"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."
 
Year old fuel is really old un

Year old fuel is really old unless you have added stabilizer to it. Mixing new fuel doesn't really help. I would try and replace it with newer fuel. I have had lots of equipment that sits for a long time and you get similar results if the fuel is bad.
 
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