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ffejsimek

5.7L Mercruiser Will not fire

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ffejsimek

Hello All. I have 1995 Malibu Echelon with 150 hours on it. 5.7L Mercruiser Carb with thunderbolt electronic ignition. Boat ran great last year. Pulled it out of storage and can't get the engine to fire at all in the driveway. I have spark. Just checked a couple of plugs tho the spark looks a little weak. Battery checked fine at the auto store. Gas is pumping into the top of the carb when i stoke the hammer. It appears to be getting to most cylinders except #1 so i sprayed starter fluid in that cylinder.. I've change distributor cap, rotar and plugs. I'm a little stumped. All wires on the engine appear to be fine. I did have to tighten the main ground a little. Thoughts on this?? I know it's about time for me to get a new starter as it is now disengaging from fly wheel every so often..

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ffejsimek

Also.. this has the thunderbolt IV ignition module? on it and meant to ask if anyone has had trouble with that before. i took it off and it looks find inside.. nothing burned up or anything. i'm getting spark so i'm thinking it's fine..

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eyepeeler

Check for spiders in the killswitch. Gall durn varmints! :guns:

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Wayne

If it was the kill switch I would assume no spark. Since it's carburated, you really can't "turn off" the fuel and you kind of checked that by seeing the accelerator pump shoot a little fuel into the carb.

Are you sure you have the spark plug wires fully seated and in the correct order? With a new cap and rotor, that rules out any corosion build up on the contacts preventing spark. Double check the firing order and if possible stick a timing light on it to make sure the timing isn't way off.

If that all checks out, a slow turning starter can cause starting problems, but it should be easy to tell the engine is turning over slower.

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JasonK

Paper between your points? Keeps them from corroding over winter.

Did u do the winterizing and recommission?

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Woodski

You indicate you are getting spark. You also indicated that you changed plug wires and cap, so check the firing order and plug wire orientation. You might have clocked the plug wires off and thus it is now trying to fire in the wrong cylinder. There should be markings to help you identify the firing order and a marking on the distributor. You can set the engine at TDC or jsut slightly before and check to make sure that #1 is aligned with the rotor (you have to remember it has to be on the correct rotation as it does 2 revs for each firing stroke, so it can also be correct 180 off on the rotor).

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fastjohnny

You can still get spark with a bad TBIV. Ask me how I know. ;)

Did you replace the ignition pickup sensor? If not, is it rusty?

The ignition module is a spark amplifier, and when going out, can be finicky.

Somewhere on the 'net, there are good diagnosics, try iboat forum.

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rodman

Don't make this any more complicated than it has to be. 3 simple things to remember if you have fuel, spark and air it will start. Like Wayne said earlier check your firing order 18436572. Your rotor and cap will only fit one way so you can eliminate that. The only way you could be 180 out is if you pulled the distributor. Even if you are out 180 degrees out will still fire some with lots of back fire. If your battery is fully charged your, starter is spinning fast enough. All you need is gas, spark and air. You

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