803A Hard to start

Guyfang

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Welllllllllllllllllllll, maybe we need to go back to the fuel cut off solenoid. As of yet, and I have read this thread 4 times now, this has not been checked, or has not been mentioned that it was checked.
 

quartermeter

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Welllllllllllllllllllll, maybe we need to go back to the fuel cut off solenoid. As of yet, and I have read this thread 4 times now, this has not been checked, or has not been mentioned that it was checked.
Yes the FCOS does move freely to the right. Checked it yesterday. When cranking/starting it moves all the way to right.
When cranking the engine sounds sluggish.
 

Light in the Dark

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You need to break the meter out for that. I have been talking with quartermeter for a couple days on this and actually am able to share the run video/issue he is having. See here:

 

Ray70

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In the video the batteries are not your problem, it's cranking fine. Although after so many failed starts you now may need to charge them again.
I think you idea of sluggish is not what Guy was thinking, he thought it was cranking slow, which its really not.
In the video each time it dies is it doing it on it's own or does it die as soon as you let go of the start switch?
Also, where is the throttle set? Is it pushed in or is the throttle knob pulled out.
 

Ray70

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I know you say you have had it running fine before, but have you load tested it? If so what were the results?
The motor has a slight sound of either low compression in 1 or more cylinders or possibly 1 or more dead injectors or otherwise dead cylinders.
I would imagine both of these conditions would result in the machine bogging down at less than 100% load.
 

Daybreak

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Howdy,
The fuel pump tick sound doesn't sound like it has gotten full.
Charge the batteries. Turn to prime and let it sit priming for a long time. Maybe 3 minutes or more.
Have you change any of the fuel filters?
 

Light in the Dark

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So this set was actually in my hands, before quartermeters. It did start rough, but it did start, and it made rated power before it left. That was 8 or so months ago.
 

Light in the Dark

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Quarter... try this. Get the machine priming and push in the fault light so everything is lit up... start cranking while holding this. Do not let go of the fault lights, if it starts to run, while still holding the fault lights, flip the battle short up (and let go of the fault light button). What happens?
 

Guyfang

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Howdy,
The fuel pump tick sound doesn't sound like it has gotten full.
Charge the batteries. Turn to prime and let it sit priming for a long time. Maybe 3 minutes or more.
Have you change any of the fuel filters?
Its not full. You can hear it. Its pumping air, or a little fuel, and air.
 

Daybreak

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Howdy,
Turn the S1 to prime and let it sit 3 minutes, then start.
 

zarathustra

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When cranking the engine, does it sound as if there is no or low compression?
If/ when it does or has started in the past, did it spew a lot of black smoke for a period before it began to run steady?
 

zarathustra

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I had a very similar problem with an Mep-802a a couple of weeks ago. The 803 & 802 have the same engine... one just has two more cylinders than the other.

My problem was much more severe... started initially, ran for 12 seconds and quit. Took around 5 minutes to get it to start again. One it was running on one cylinder I got a lot of smoke 'till the other one fired up. Once fully running and no black smoke, it would generate 105% of rated load.

But if it sat for a day the restart problem came back.

The problem was the oil pressure relief valve was stuck.... or more properly, it was mostly stuck closed. After a while of running on one cylinder it would finally "unstick" and it'd run just fine.

There is another thread on this site that addresses the valve. Basically it is a simple and minor repair. Just tedious.

First you need a new "door" gasket... the door is on the oil filler/dipstick panel. Gaskets are available on the large auction site or just google the part number and you can pick it up elsewhere.

You will need 10mm and 13mm wrenches, a 24mm wrench, a block of wood (2x4) about ten or so inches long, a dead blow hammer a torque wrench that'll measure in inch pounds and a chopstick.
The chopstick is the best part; cause that means you are compelled to get a great chinese dinner--- ask 'em for chopsticks and take 'em home. I recommend Mongolian Beef with steamed rice and a vodka martini straight up.
Remove the battery on the left (fuel solenoid side). I usually remove the cable on the + side of the other battery, but that's just me.
drain the engine oil--- the more oil you can get out the better. Remove oil filter.
remove the solenoid and solenoid mounting bracket. Remove the two studs that hold the bracket to the block
remove the oil pressure line that goes to the sender --
remove the nuts that are across the top of the door... there'll be four of them. Be sure to remove these nuts before the next step
Remove the bolts that hold the door to the block.
I took the 2x4 and after removing the oil filler cap and dipstick I put the 2x4 on the oil filler opening and gave it a good whack with the dead blow hammer.
That split the door from the gasket and I was able to wobble the door off.

Now, there will be four studs (that had the nuts on them) still sticking out of the block....... DON'T TAKE THEM OUT OR LOOSEN THEM
They are part of the fuel delivery system and should not be removed. this is more than just a little important.

you can see the valve coming down from the oil pump scavenge. It is about 5 inches long and has a squared off housing that goes part way down the valve.
The 24 mm wrench will grab that sucker and you can unscrew it from the scavenge. It's tight in there so getting it out is a slow process.

On the bottom of the valve is a "C" ring clip. remove the clip. Be careful as that end internal piece is under spring pressure. It may pop out or may not depending on how gunked up the valve is. Mine was so gunked up that removing the clip didn't cause anything to happen.
The whole valve is in five parts, clip, housing, spring, piston, and the piece that goes on the bottom held in place by the c clip
once the C clip is out you can put the chopstick in the valve on the threaded end and you should be able to get it out by tapping the chopstick with a hammer.
Clean it up and put some assembly lube grease on the innards and re-assemble valve. Make sure that, once assembled, you can push the piston down with the chopstick and it moves freely. BTW, you can buy new valves - google the part number.

cleaning off the old gasket is not fun. Be sure not to remove those four studs -- it is tempting to do so in order to get to the gasket, but deal with it and leave those studs alone.

Reassembly goes pretty much the reverse of the disassembly.

Regarding those four studs... before assembly make sure that they are finger tight snug in their seats before replacing the door. They might tend to wiggle out a little during this whole process. There is a sequence for tightening those screws and four nuts, but I would put the gasket/ door on and at least finger tighten those nuts on the studs first and then finger tighten the bolts and the two studs that hold the solenoid bracket. on. then I'd follow the manual on tightening sequence.

The manual has the torque rating and sequence in it. think of it as when torquing head bolts except you are dealing with inch pounds instead of foot pounds

If it sounds complicated, it isn't. As long as you have the right gasket and tools and a full belly of Mongolian beef and rice it is quite easy

My thanks to whomever wrote the initial description of this on Steel Soldiers.
 

Ray70

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Just to elaborate, in Zarathustra's case what is happening is the relief valve is stuck closed, causing oil pressure to go too high.
This pumps up the lifters to the max and floats the valves causing a loss of compression and then the motor dies.
If you are unable to even get the motor started, the OP's issue is probably slightly different only because you can not reach the excess pressure point just by cranking, it has to start and run for a few seconds.
However, you may have low compression due to carbon buildup on the valve sealing surface, something I have seen several times on wet stacked engines.
 

Guyfang

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I had a very similar problem with an Mep-802a a couple of weeks ago. The 803 & 802 have the same engine... one just has two more cylinders than the other.

My problem was much more severe... started initially, ran for 12 seconds and quit. Took around 5 minutes to get it to start again. One it was running on one cylinder I got a lot of smoke 'till the other one fired up. Once fully running and no black smoke, it would generate 105% of rated load.

But if it sat for a day the restart problem came back.

The problem was the oil pressure relief valve was stuck.... or more properly, it was mostly stuck closed. After a while of running on one cylinder it would finally "unstick" and it'd run just fine.

There is another thread on this site that addresses the valve. Basically it is a simple and minor repair. Just tedious.

First you need a new "door" gasket... the door is on the oil filler/dipstick panel. Gaskets are available on the large auction site or just google the part number and you can pick it up elsewhere.

You will need 10mm and 13mm wrenches, a 24mm wrench, a block of wood (2x4) about ten or so inches long, a dead blow hammer a torque wrench that'll measure in inch pounds and a chopstick.
The chopstick is the best part; cause that means you are compelled to get a great chinese dinner--- ask 'em for chopsticks and take 'em home. I recommend Mongolian Beef with steamed rice and a vodka martini straight up.
Remove the battery on the left (fuel solenoid side). I usually remove the cable on the + side of the other battery, but that's just me.
drain the engine oil--- the more oil you can get out the better. Remove oil filter.
remove the solenoid and solenoid mounting bracket. Remove the two studs that hold the bracket to the block
remove the oil pressure line that goes to the sender --
remove the nuts that are across the top of the door... there'll be four of them. Be sure to remove these nuts before the next step
Remove the bolts that hold the door to the block.
I took the 2x4 and after removing the oil filler cap and dipstick I put the 2x4 on the oil filler opening and gave it a good whack with the dead blow hammer.
That split the door from the gasket and I was able to wobble the door off.

Now, there will be four studs (that had the nuts on them) still sticking out of the block....... DON'T TAKE THEM OUT OR LOOSEN THEM
They are part of the fuel delivery system and should not be removed. this is more than just a little important.

you can see the valve coming down from the oil pump scavenge. It is about 5 inches long and has a squared off housing that goes part way down the valve.
The 24 mm wrench will grab that sucker and you can unscrew it from the scavenge. It's tight in there so getting it out is a slow process.

On the bottom of the valve is a "C" ring clip. remove the clip. Be careful as that end internal piece is under spring pressure. It may pop out or may not depending on how gunked up the valve is. Mine was so gunked up that removing the clip didn't cause anything to happen.
The whole valve is in five parts, clip, housing, spring, piston, and the piece that goes on the bottom held in place by the c clip
once the C clip is out you can put the chopstick in the valve on the threaded end and you should be able to get it out by tapping the chopstick with a hammer.
Clean it up and put some assembly lube grease on the innards and re-assemble valve. Make sure that, once assembled, you can push the piston down with the chopstick and it moves freely. BTW, you can buy new valves - google the part number.

cleaning off the old gasket is not fun. Be sure not to remove those four studs -- it is tempting to do so in order to get to the gasket, but deal with it and leave those studs alone.

Reassembly goes pretty much the reverse of the disassembly.

Regarding those four studs... before assembly make sure that they are finger tight snug in their seats before replacing the door. They might tend to wiggle out a little during this whole process. There is a sequence for tightening those screws and four nuts, but I would put the gasket/ door on and at least finger tighten those nuts on the studs first and then finger tighten the bolts and the two studs that hold the solenoid bracket. on. then I'd follow the manual on tightening sequence.

The manual has the torque rating and sequence in it. think of it as when torquing head bolts except you are dealing with inch pounds instead of foot pounds

If it sounds complicated, it isn't. As long as you have the right gasket and tools and a full belly of Mongolian beef and rice it is quite easy

My thanks to whomever wrote the initial description of this on Steel Soldiers.
A work around to going in and taking this all apart, and it works sometimes, and sometimes not, is to drain the oil and fill the crankcase up with ATF. Run the set 15-30 min, no load. Drain ATF and change oil. At least twice, if not three times. This was SOP for units coming back from Down Range. I would say it worked 90-95 percent of the time. Even units that did not have this problem profited from doing this. The dust/sand there took a big toll from the sets. Later, they went from Down Range to RESET.
 
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