kill switch stopped engine, now no restart? Penta 5.8FL with carb

NwBoatDad

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Sep 2, 2019
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Hi all, hoping to get an idea of what could have happened. My son was driving boat home for 2.5 hours and about 300 yards from shore we went to trade places and I tried to stop him from moving since kill switch was on his loop. We were moving about 5-10mph and the boat started to try and keep going with kill switch out. I even tried to push it to keep it going, but we were too slow to get the lock in place. After engine wouldnt start at all and got a tow in after some hard paddling. Any ideas? I noted that the tachometer is stuck around 4500 and wont move from attempted turn overs. I checked all fuses and removed one spark plug thinking it might be fouled. I appreciate the help. im pretty new to boat mechanics. Thanks!
 

alldodge

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boat started to try and keep going with kill switch out. I even tried to push it to keep it going, but we were too slow to get the lock in place

Not understanding this comment fully

The kill switch when pulled, most can be flipped back on easy. If the switch broke then it can be replaced.

Can you post a pic of your switch?
 

NwBoatDad

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Thank you for the reply. Sorry for the vague post. The switch just did what it was supposed to do by shutting down the boat but the engine was trying to keep going and before I could get it off his loop I was trying to hold the button down to keep the engine going until we could get it off his belt loop. Then I realized that was going to happen fast and just let the engine stop. I will post a pic of the kill switch later. I did try and push the button in also by finger while starting it to make sure the plastic clip wasnt warped and loose. Thanks for the reply, I appreciate it. I will get very comfortable with this engine over the winter :) thanks!
 

alldodge

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The kill switch should kill the motor quick, and if it sounded like it was struggling to run it may have been dieseling (run on). If it did do this then it could suck water into the motor

If the motor will crank over but not start then you could be safe in this regard
 

Saline Marina

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Sep 9, 2014
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I don't know Ford well at all, but in concept the kill switch should be wired in series as a normally-closed contact that removes power from the ignition coil when the clip is removed (the other series contact is the maintained 2nd position of the ignition switch in RUN position)

I would start by verifying spark, easiest is to use an additional spark plug or a "visualization tool" (Lisle 20700 or similar). Spark should easily jump a 3/4" gap at atmospheric pressure.

Be careful of doing this where raw fuel is present...use fans and/or the bilge blower if at all possible. Don't hold any HEI components in your hands while checking spark.

If there's no spark it would be good to verify 12vdc is reaching the coil with the ignition switch in 2nd position and the kill switch clip installed. If you don't get 12vdc then there's likely an electrical issue with the kill switch itself.
 

Saline Marina

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Haha. I go by the GM HEI system which I'm well-versed in, this will do the 3/4" no problem, try it sometime if you don't believe me. I figure Ford is on the same track. It seems like overkill but when you get to ~500psi cylinder pressure at the time when the spark should jump the gap, the charge is a lot more dense and tougher to ionize, and the charge is also moving, as mixture motion correlates to torque.

The old 6 volt breaker point tractor ignitions developed in the late 30s will jump a 1/4" gap at atmospheric, so its not a far stretch that the HEI can go 3x that distance. Its a powerful burst of energy and that "overkill" leads to reliable running.

I do believe that the spark plug gap in the cylinder could be more than the .020- .045" typical but then it becomes an issue of the longer exterior electrode becomes a hot spot which can initiate spark knock running fast speeds and high loads, and I think there's an "arc blowout" to the side due to the mixture motion if the plug gap becomes greater. Its sort of a sweet spot between competing objectives.
 

Scott Danforth

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The kill switch should kill the motor quick, and if it sounded like it was struggling to run it may have been dieseling (run on). If it did do this then it could suck water into the motor

If the motor will crank over but not start then you could be safe in this regard

Im in agreement with AD on this.

if the motor cranks, your good to go
if the motor doesnt crank, your cylinders sucked in water when the motor death-rattled

if that is the case, pull the plugs, crank the motor over a few dozen times, install new plugs and get it running.
 

NwBoatDad

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Awesome, thanks you guys, will take me a while to reply to this, but when done I will. Thanks again!
 

NwBoatDad

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Thank you thank you thank you! Your guys advice helped and it did the trick. I removed and broke in the process all my spark plugs. They were old and looked to have never been replaced. Heads up and lazy hard way to replace these plugs on a volvo penta 5.8fl engine (I couldn't believe an engineer would design something where you couldnt easily access the spark plugs) perhaps because the engine was first designed for an automobile? It was a drag to replace them. I had to create a nub that dropped into my spark plug socket to avoid removing the manifold. This made it so I could drop a 3/8 wrench on the top of the socket. (and work with a flashlight and a mirror and work in reverse) I would have bought a ratchet wrench insert, but I was trying to be inventive, cheap, and lazy. Seriously, I might recommend removing the manifold to anyone attempting this themselves. Anyways, i really appreciate the help. very cool of you guys to take a minute/hours to help people. Thanks!
 

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kenny nunez

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I used to use a 5/8” box wrench to loosen and tighten the spark plugs to keep from breaking them. I also use a piece of 3/8” fuel line to start them back in their bore if the clearance is too tight.
 

ChrisinPHX

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Jun 9, 2013
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That's odd. I've got a 5.8L (FSi) and I just use the typical spark plug socket. Mine has GT40 heads though, so I guess that could be a bit different from the standard heads. Still, that's interesting to hear.
 
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