Engine starts and dies, oil pressure warning light on - *** Resolved ***

[Jeff Pettit]

Help! Went out to move our coach, it started right up as usual but died about 30 seconds after starting. Tried starting again and it died again, I noticed the low oil pressure light is on but the gauge reads 75psi. Also checked the oil and it is full. Has anyone else had this problem before? Any suggestions? I am thinking it's a wiring issue I was messing around in the engine compartment.

It's 1995 Marquis with a Cummins 8.3

Things I have done since the last time it started and ran without any issues
- Flip the engine start switch in the engine comparment to see if it works, started, and ran fine, flipped switch back to normal mode. Noticed the oil pressure gauge in the engine compartment is stuck on 60 psi
- I wiped down engine hoses with rubber dressing to clean and protect them.
- Washed coach
- Started refrigerator   

Any help will be greatly appreciated!! 

[Jeff Pettit]

Still trying to resolve this issue . We were planning a trip but canceled until we can resolve this since it will only run for about 30 seconds. Called the PO he said it did this before and he just kept trying to start it and finally started and didn't happen again so he didn't follow up with getting it fixed.  I am pretty sure it is an electrical issue, when I get off work today going to see what I can do, not really sure where to start. I checked all the connections in the engine bay last night, will check again today in the sunlight.  Reached out to a few friends in the area trying to get a recommendation for a mobile diesel mechanic that knows what he is doing and not just going to start replacing parts.

Note: The house batteries were almost dry (added 10.5 bottles of water) but were showing 12 volts not sure if this would cause any issues with the engine. 

[Jeff Pettit]

One additional note, the Low-pressure light was NOT on this morning but it still would only run about 30 seconds cut itself off.

[Steve Huber Co-Admin]

Jeff,
Check the battery voltage when the engine shuts down. The ECU may be shutting down due to low battery voltage. If you've only got 12v at the batteries the ECU is probably seeing less due to the connections between it and the batteries. One way to check is to see if it runs normally when the geni is running or plugged into shore power.
Steve

[Dave Atherton]

Jeff, on your Cummins 8.3 engine just behind the injection pump and under the secondary fuel
filter there is a mechanical fuel lift pump. My suggestion remove the discharge line going to the injection of the fuel filter and push the primer pump to see if your getting any fuel fuel while pumping
hand pump. Your problem is on the outside of engine and buy starting at hand primer pump will
take you to a bad primer pump or leak in primary fuel filter or plugged fuel filter. Once you get a stream of fuel going out of hose to injection pump reconnect fuel line and open all injectors lines and
Spin engine over and tighten each injector nut as fuel starts to come out and not air bubbles.
Dave Atherton Retired Cat Mechanic

[Jeff Pettit]

Thank for the tips I will give them a try tomorrow, it was raining buckets here when I got home from work this evening.  One other thing I noticed this afternoon is if I turn on the key but do not start the engine in roughly 30 seconds I hear the "kill relay" kick in.

[Jeff Pettit]

FIXED!!! After 8 stressful hot days of troubleshooting, we believe we found and eliminated the start die issues. In the engine bay, someone had run a wire from the trailer light plug through the door opening of the rear engine start control panel and it was grounding out to the box. The wire was run to the back of the oil pressure gauge inside the box.   

All the time and trouble for one little wire. Just glad we finally found it! It was getting really frustrating. But did find a way to add a theft kill switch if ever needed.