MEP-802A Starter problem?

[rcamacho]

I'm getting into seasonal maintenance a tad late.
MEP-802A is acting up a tad. The starter will kick in briefly and then stop when the switch is engaged. Dead crank has no problem engaging the starter continuously. I presume this is a bad solenoid or start relay somewhere. Where do I start in the TM for diagnosis on this?

 

[Farmitall]

I'd start with the schematic on the door of the unit.

Identify the parts involved in cranking the engine and check the wiring for accuracy and soundness of connections.

If the dead crank switch will engage the starter without the starter dropping out, your problem is not the starter or starter solenoid, it is more likely a switch or relay further back in the circuit.

 

[Light in the Dark]

As Farmitall said, if DC kicks it over without issue its in the other circuitry. I would take the top off and inspect/clean the crank relay. A very simple assembly you can hit with some deoxidizing cleaner when you take the small plastic/ceramic top off it.

 

[Jetred]

That happens when you have a fault light as well. Make sure none of the little red lights come on while your cranking. (Ex. Low fuel)

 

[Ray70]

In addition, verify your batteries are fully charged.... , despite being able to crank from the dead crank switch, low batteries can still cause this same problem.
The starter pulls so much amperage that it can cause the cranking relay / starter disconnect relay inside the control cube to open almost instantly if the batteries are low due to the starter motor drawing down the available voltage.

The dead crank switch bypasses the relays sending power to the start solenoid through a different path.

 

[Daybreak]

Don't over think it.
Charge your batteries.

 

[kloppk]

In addition, verify your batteries are fully charged.... , despite being able to crank from the dead crank switch, low batteries can still cause this same problem.
The starter pulls so much amperage that it can cause the cranking relay / starter disconnect relay inside the control cube to open almost instantly if the batteries are low due to the starter motor drawing down the available voltage.

The dead crank switch bypasses the relays sending power to the start solenoid through a different path.

Attempting to start via S1 also engages the Preheaters which draw a lot of power. When dead cranking the preheaters are not powered.

 

[kloppk]

After you verify your batteries are good and fully charged...

To help isolate the cause of the starter dropping out you could measure the DC voltage at relay K16 terminals 6 & 9 with respect to chassis ground.
Both terminals should have about 24 volts DC on them when cranking.
If both have 24 volts on them and them when the starter stops then issue may be with the K2 starter relay.
If you only have 24 volts on terminal 9 when the starter stops then issue may be with S14 or the MPU.
If you don't have any DC voltage on either terminal when the starter stops then issue may be with a fault being generated by the fault monitor.

Here are the terminal locations on all the relay sockets.

Here are the relay locations

 

[rcamacho]

Charged both batteries. One was low.
Malfunction Indicator Panel is inop.


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[CallMeColt]

Charged both batteries. One was low.
Malfunction Indicator Panel is inop.


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Sounds like toy have a gremlin. Those are not fun!

 

[rcamacho]

Disregard,
MIP is functional and starter is no longer dropping out. Why? Not sure. All I did was look at FU1, and circuit breakers for MIP and DC.
Going through PMCS now. Replacing fuel filters and oil service. Air filter is fresh/clean.

 

[Light in the Dark]

I've got a MIP on the shelf if you find the intermittent issues lies within it.

 

[rcamacho]

Fuel filter and oil PMCS completed.
Waiting on water separator part.

Generator is acting like it has no gel fuel delivery.

Fuel shut off solenoid is pulsing position off of stop on cranking. Tried running the fuel rail by hand during cranking-no difference.

Next up is checking low pressure feed to the injectors then output on the high pressure side.


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[Ray70]

No Gel delivery and your fuel shut off solenoid is pulsing....?? Gotta love speech to Text!
So is the shut off solenoid pulling back and holding steady when cranking or are you seeing an issue with it bouncing ( pulsing ) back and forth?
Hard to tell what you said Vs. what your phone thinks you said!

Check fuel delivery to the metering pumps.
TM gives a fuel delivery / time spec. but if you have the cube style fuel pump they typically die ( but still sound like they are working ) and deliver no fuel.
This is assuming your primary pump is in fact making noise? ( you should hear the primary pump when in the prime / run position on the start switch.

 

[rcamacho]

Lovely job Siri...
Fuel stop solenoid is pulsing off of stop when cranking, not holding steady.

Verified fuel pump is operational and delivering plenty of pressure to injector pump low side feed. Validated fuel pressure/feed at the filter output line.
I was not able to get any high pressure output from the injector pumps even manipulating the solenoid/rail manually.

 

[Ray70]

Ok, sounds like a potential fuel rail / stuck Metering pump pin issue as far as no fuel out of the metering pumps
However it sounds like you still have some kind of DC voltage issue going on if you fuel stop solenoid is bouncing around.
CallMeColt just posted a fantastic video the other day showing how the fuel rack works as seen from inside the block.
Can you put a volt meter on your batteries or other 24V location and tell us what the voltage drops to while cranking?
I suspect you have at least 1 battery that is marginal at best, causing you to loose voltage while cranking.
Or better yet, do you happen to have a battery load tester? they are like $19 for a cheap one at Harbor Freight.

 

[CallMeColt]

Ok, sounds like a potential fuel rail / stuck Metering pump pin issue as far as no fuel out of the metering pumps
However it sounds like you still have some kind of DC voltage issue going on if you fuel stop solenoid is bouncing around.
CallMeColt just posted a fantastic video the other day showing how the fuel rack works as seen from inside the block.
Can you put a volt meter on your batteries or other 24V location and tell us what the voltage drops to while cranking?
I suspect you have at least 1 battery that is marginal at best, causing you to loose voltage while cranking.
Or better yet, do you happen to have a battery load tester? they are like $19 for a cheap one at Harbor Freight.

I just got this tester a few weeks ago and am happy with it for the cost. It does a few extra things over the $20 Harbor Freight one.
https://amzn.to/3Y3Mmyi

 

[rcamacho]

Saw your video on the IP rail. Very helpful
I doubt the rail/governor is at fault as the assembly moves freely at the throttle and solenoid arms.

Thinking my next step is to remove and clean/inspect IP’s. Good opportunity to replace a seeping low pressure hose assembly.

DC is definitely low asI’ve been using the batteries a lot. I’ll recharge and see if the solenoid still acts up.


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[CallMeColt]

Saw your video on the IP rail. Very helpful
I doubt the rail/governor is at fault as the assembly moves freely at the throttle and solenoid arms.

Thinking my next step is to remove and clean/inspect IP’s. Good opportunity to replace a seeping low pressure hose assembly.

DC is definitely low asI’ve been using the batteries a lot. I’ll recharge and see if the solenoid still acts up.


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It may move freely because it is not moving the pump levers at it should. They may have "missed" the hole when installing. Have seen this the other way where the pumps "missed" the hole but were way beyond full throttle and you'd go to start it & it would scream until it died out of fuel in 20-30 seconds or so.

Inspect your injection pumps by removing them completely and going through the process of installing them as the TM says too. It will take an extra 5 minuets to check the rail inside with a light and mirror to be sure it is okay.

Then, once they are installed, try to start it for a while and look for fuel coming out of the top of the pumps before putting the lines back on to the injectors. This will purge your air out of the pumps as well.

Really sounds like your injection pumps are not installed properly and simply are not delivering fuel because of it. But, just reading and not being there isn't the whole story either.

 

[Billy2642]

After you verify your batteries are good and fully charged...

To help isolate the cause of the starter dropping out you could measure the DC voltage at relay K16 terminals 6 & 9 with respect to chassis ground.
Both terminals should have about 24 volts DC on them when cranking.
If both have 24 volts on them and them when the starter stops then issue may be with the K2 starter relay.
If you only have 24 volts on terminal 9 when the starter stops then issue may be with S14 or the MPU.
If you don't have any DC voltage on either terminal when the starter stops then issue may be with a fault being generated by the fault monitor.

Here are the terminal locations on all the relay sockets.
View attachment 885213
Here are the relay locations
View attachment 885214

off topic but do you have a similar picture of what each relay is for for the 804/5/6?