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Low Oil Pressure starts

fa35jsf

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OKC, OK
So I've had my 802 for about a month. I've noticed that if I let it sit for 5-7 days and then go to start it, the starter will get the engine started and just as the engine tries to pick up speed it shuts down and illuminates the low oil pressure fault light. If I try and start it right away it will start successfully and run just fine.

Operating conditions:
Ambient temp = 60F
Oil Px after start (cold) = 65psi
Oil Px after start (warm) = 30-40psi


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lindsey97

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wynnewood, oklahoma
Your oil pressure readings are spot on. Read the large metal tag on the inside of the control panel cover. When starting the 802a, hold the start switch in the crank position until the oil pressure comes up to 30-40 lbs. on the gauge.
 

Daybreak

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So I've had my 802 for about a month. I've noticed that if I let it sit for 5-7 days and then go to start it, the starter will get the engine started and just as the engine tries to pick up speed it shuts down and illuminates the low oil pressure fault light. If I try and start it right away it will start successfully and run just fine.

Operating conditions:
Ambient temp = 60F
Oil Px after start (cold) = 65psi
Oil Px after start (warm) = 30-40psi


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Howdy,

The MEP-8xx generators start different than what people are used to. Holding the switch to start longer then starting is fine with a MEP-8xx. It will not grind the starter. (if things are good) After the engine starts, the starter disengages. It actually is the correct starting procedure. It flashes the field, it holds the fault system from being employed and shutting down like you experienced.

MEP-80x startup routine
 

fa35jsf

Active member
135
32
28
Location
OKC, OK
I've read the instructions and I could have sworn that's what I have been doing but I guess I've been releasing it too early. I'll give it a try again in a few days. At what pressure does the low oil Px light come on?


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Guyfang

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8. Protective Devices:Low Oil Pressure Switch:Trip Temperature 15 ±3 psi (103.4 ±20.7 kPa)

This kind of information can be found in the TM 9-6115-641-10 manual.
 

fa35jsf

Active member
135
32
28
Location
OKC, OK
Just an update. It may have been my starting procedures originally causing this issue, however, last night after connecting it to my house and running it for several hours I shut it down. Then I attempted a restart that failed for low oil Px. I went to go check the oil and found that the common wire on the low oil pressure sensor had pulled out of the butt splice. Apparently this sensor had been replaced before and someone made a poor connection. After putting on a new butt splice it worked perfectly. The shaking of the motor on starts may also have been contributing to my issues.


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Guyfang

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Thanks for closing the loop. Such problems are indeed hard to find. Loose connection or an almost broken wire are the hardest problems. Good job!
 

lindsey97

Member
738
16
18
Location
wynnewood, oklahoma
Vibration.

I forget which wire it was on my 802a, either an alternator wire or coolant temp sensor wire that did the same thing. I repaired it, extended the wire a couple inches and zip tied it off. Good job on self diagnosing.
 

mciikurzroot

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wimberley texas
Yes indeed, this starting condition it very normal, more instinct really, from the times when you were taught to not keep the starter engaged once the engine had started. The real cause is and has been stated before and recently OIL pressure is simply not reaching the Oil Pressure switch from a not used state the oil journals drain back from the block into the oil pan and when you are starting the set it just takes a few seconds longer that what your normal sense of engine starting is more used to.
When in fact the starter has already dropped out of being engaged as determined by K-14 i think it is. K-14 is a VOLTAGE provider, it is driven from the MAG pick-up or sending unit as it might be called, but none the less, the MPU counts the flywheel teeth as it spins and make a very slight voltage out of the chopped square wave pattern of the MPU generating as a voltage, this MPU signal is converted into a small voltage and then applied across one of the small chipset devices mounted onto the circuit board as can be seen when you pull or look into the K-14 relay device. thus when the flywheel spins faster from a dead stop to rated speed the small chopped signal is converted into voltage and the ckt board thro and to the small 8 pin chip set, so the starter has dropped out, by your continuing to hold the S-1 switch in "START" position you are also sending a signal the the injection pump to keep the fuel solenoid open and distributing fuel to the engine respective injectors .. Then in this same sequence of starting events oil has finally reached the OP switch and has forced the switch closed thereby completing the ckt and your set will keep running just fine and you can release the S-1 back to its normal run position and all is well.

As a side bit of information when i converted my sets to full auto start just when a signal is called for i had deep reservations the set would respond to being able to Auto Start and stay running. But it does and has every time. I use these 10kw [mep-803a] sets as prime back-up power sources for a local FM low power radio station and a MEP-802a 5kw set at the Transmitter site as well..The 5 and 10 kw sets use identical control schemes and control cabinets, just running a 4 cyl engine V. a 2 cyl engine ..I forget the frequency of the MPU signal at 1800 rpm but it is near 2800Hz .. As an FYI I have about 15 extra K-14 relay units and am pleased to offer them at $60.00 shipped.
Good luck man and these are great little sets to have and use .. best mac/mc
 
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