Merc 5.7 - Won't fire up. Ideas?

[Jeff Quigley]

Firstly, sorry if this is a common topic. I've tried to search but for some reason the iboat search function isn't working on my Mac.

Sooo...

Yesterday I go down to the marina and open up the boat. I usually turn her over and let her run while I take the camper top down. Starts up no problem. After about 15 minutes the motor (Mercruiser 5.7 Alpha 1) just stops. I tried to restart it and I first though I may have flooded the engine as I could smell gas... so, it not restarding right away did not worry me. I went back down to the marina this morning with a spare battery just in case. The motor still won't fire up.

I'm thinking electrical/ignition... not getting a spark etc. Any trouble shooting suggestions are welcomed before I break out the wallet and have a mechanic come in and check it out.

Ideas?

Jeff

 

[Don S]

Re: Merc 5.7 - Won't fire up. Ideas?

Could be a lot of things, You will need to check spark first,
Did you look to see if the choke opens?
Pull the spark plugs and see if they are wet with fuel.
Being a carbed engine, did you just let it idle real slow, or do you give it some throttle to warm up?
When you tried to restart it after it flooded, did you open the throttle to the WOT position to see if would clear the flood condition?

 

[Jeff Quigley]

Re: Merc 5.7 - Won't fire up. Ideas?

Choke opens. I had it ideling around 1000-1500 rpms. I pulled off the flame retarter from the carb and held open the butterflies whith the throttle wide open while cranking. Still nothing.

Should I replace the plugs? How do I check to see if I'm getting a spark? And if I'm not getting a spark where do I go from there?

Arrggg... I just want to be on the water. :'(

Jeff

 

[lilmandavis]

Re: Merc 5.7 - Won't fire up. Ideas?

if you have a manual. it tells all the trouble shooting to do. pull the plugs, see if thier fouled. replce if they look bad. (thier cheap so why not just replace them.) get a spark tester or use a screwdriver to check spark. or just do it the old fashion way and hold a plug and crank it!!. if your getting spark, make sure that when you open the throttle, that fuel squirts out into the carb barrels.

 

[Don S]

Re: Merc 5.7 - Won't fire up. Ideas?

To check spark, just pull the center wire out of the distributor cap. Since it's a Thunderbolt ignition, you can't just hold the wire next to a ground, so just stick a #2 phillips screwdriver into the coil wire and hold the metal shank of the screwdrive next to a clean ground.
(NOTE: If you have a cracked screwdriver handle and the spark is good, you're gonna get Zapped!!)
Now have a helper crank the engine over while you hold the screwdriver about a 1/2" from a good ground. Should see a bright blue spark.
Hopefully you have already done a tuneup this spring and have new cap, rotor, and spark plugs, etc.
If no spark, check the chart below.

 

[bamadave]

Re: Merc 5.7 - Won't fire up. Ideas?

Just died, as in like the switch was turned off, or did it spit and sputter?

 

[Reel Poor]

Re: Merc 5.7 - Won't fire up. Ideas?

Does it have a kill switch???

 

[Jeff Quigley]

Re: Merc 5.7 - Won't fire up. Ideas?

don: thanks for the trouble shooting chart. will give it a go today.

bamadave: yep, just quit like I turned off the key

rick: not sure... you can see why I'm a mechanics dream customer!

 

[bamadave]

Re: Merc 5.7 - Won't fire up. Ideas?

Jeff, the kill switch Rick is referring to is a safty kill switch that is mounted near the ignition switch (if you have one, you didn't state the year model of the boat), might have been accidently pulled. Also, along the same track only different, and I will be corrected if wrong, I think if there is slack in the shift cable, the interupt switch may cause it not to fire. Is this correct Commander?
You not being familiar with mechanics of the boat, We need to know if it's an ignition problem, (no spark at the sparken plugs) or No fuel delivery.
Let us know what you find (hopefully something easy) !