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Engine only runs with oil sensor unplugged.

T

Trebuchet06

New member
This is a project boat that I've been handed down from the guy who was hired to fix it and then gave up on it. It used to have a 5.0 that was swapped for a 5.7. It is using the Thunderbolt V ignition. The last guy put the engine in and since he broke a starter bolt he gave up.

I finally got everything hooked back up and it wouldn't start. Found the ignition coil was not giving any spark. Replaced the coil and it fired right up, then instantly died. Kept doing the same thing. Tried shorting the oil pressure sensor with a jumper wire and still didn't start, but the jumper wire was warm to the touch. Tried it with the sensor unplugged completely and it started and ran perfect. I didn't let it run for long, because I realized now that it was running, the impellor wasn't pushing water.

I'm going to replace the water pump before trying to get it running again, but confused by the engine only running with the sensor unplugged and a little concerned the the jumper was getting warm.

Anyone have advice on where to start troubleshooting? I'm going to get a mechanical oil pressure gauge to make sure this new engine is actually creating oil pressure.

Thanks I'm advance everyone!
 
do you have a serial nuber for the engine?? a 350CID with a TBV ignition really isn't enough to define the specifics...

"...Tried shorting the oil pressure sensor with a jumper wire..." - what exactly are you shorting and how
 
assuming you are jumping the OIL PRESSURE SWITCH, not a SENSOR, the warmth could be due to a bad connection.

That the engine runs which requires the fuel pump to run, with the oil pressure switch disconnected suggests something isn't wired correctly...
 
Tried to attach a picture, but it's giving an error.

I've unplugged the one with two wires and a waterproof connector, and not the little can with just the one wire. I tried shorting the connector with a small jumper wire between the terminals at the plug.

https://imgur.com/a/iBWz0cs
 
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