'88 5.7 inboard dies after running smooth, restarts after few minutes, smooth again

[nola mike]

1. Timing light on either the coil wire or any plug will give you an idea (obviously if it's on one plug wire it only shows that the module/distributer is firing that plug)
2. Wh/r wire is hot with ignition on
3. Just check the voltage at the end of the pigtails
4. If no spark with the timing light, electric is your issue. If there is a spark you'll need to run some confirmatory tests. In line spark tester is more accurate since it tells you if the voltage is strong enough to bridge the plug gap. Theoretically you need to check it at every plug.

 

[alldodge]

All test are with Key ON
Wht/Red only gets 12V with key ON

 

[kip2001]

Thanks all! I picked up an in line spark tester, I should have time tomorrow to do some testing so I'll report back.

 

[kip2001]

Success! (I hope)

First off, I cleaned up the ground contacts @ the engine and the voltage drop between the battery switch and battery went away. Still have a 0.3v drop between helm and engine but I don't think that's impacting anything.

Got engine running and after about 10 minutes it shut down. No Spark.
Key in run, I have 12v at positive terminal of coil and red/white wire. Now here I did screw a little, I then cranked the engine and no spark. I thought that meant bad coil but then I re-checked the chart and realized I was supposed to tap the white/green wire against ground 2-3 times a second. I did that and had spark. So I believe all that means I have a bad ignition sensor. After I hooked back up the white/green wire, the engine started when I cranked it a couple minutes later. I think even with me screwing up the test, that still means the ignition sensor is bad because it should have detected the starter spinning the rotor which basically is the same exact thing. Right?

New part should be here Friday, here's to hoping for happy boating this weekend! I'll report back either way.

Thanks again all!

 

[nola mike]

Yeah, tapping that wire simulates the switching function of the sensor. If it sparks it means everything up to there including coil and module is functioning. Hope you got a good quality sensor, many reports of Amazon junk not working correctly.

 

[kip2001]

Yeah, tapping that wire simulates the switching function of the sensor. If it sparks it means everything up to there including coil and module is functioning. Hope you got a good quality sensor, many reports of Amazon junk not working correctly.

Okay great.

Yeah, in general I trust sierra parts but I'm having second thoughts on that one. I'm going to order the OEM sensor, it's a pain to access this part of my motor and I don't want to think about it

 

[kip2001]

Brief update, in anticipation of the OEM sensor arriving today, I removed the distributor cap & old ignition sensor. Ignition sensor is relatively new, entire thing is encased in epoxy like the new OEM one. It is, however, the sierra aftermarket part so I guess it's a good thing I took the advice to go with the OEM part.

 

[Scott06]

Brief update, in anticipation of the OEM sensor arriving today, I removed the distributor cap & old ignition sensor. Ignition sensor is relatively new, entire thing is encased in epoxy like the new OEM one. It is, however, the sierra aftermarket part so I guess it's a good thing I took the advice to go with the OEM part.

Yeah Sierra is a better respected aftermarket supplier, but you never hear I bought the OEM part and it failed or was SOL in the box.. Also there are so many counterfeit parts suppliers online now. There is a toyota mechanic on you tube called Car Care Nut, he did a whole video on how to spot counterfeit Toyota parts. If you werent handling the originals every day you would have a hard time telling them apart

 

[kip2001]

Confirmed success! Ran the engine for about 2 hours and not a single hiccup! OEM sensor functioning perfectly, I only replaced the sensor, I see no reason to replace a working coil.

Thank all for your tips and help!