931 with 8.3 no start, no fuel out of injector pump

[camp9]

Went to start my 931 with the 8.3 two weeks ago and didn't want to start, figured it lost prime. Had it running last on the 4th of July. Went through all the procedures for priming. It has fuel coming out the banjo fuel return and also the priming screw on the engine side of the pump. No air at all coming through, only nice bubble free fuel. FSOV moves freely when soleniod pulls in. No smoke when cranking. Cracked a injector line, cranked with no fuel comming. Cracked all the injector line above the pump and no fuel coming from any of the lines. Are there anything internal that could of stuck? I've read the TM's that I could find, followed the procedures and I've been reading the many past posts for these trucks when they don't start. I farm for a living and have been around trucks and tractors all my life. To me it sounds like a bad IP. I just thought I'd see if anyone has any sugestions. Thanks.

 

[73m819]

The shut down solenoid took a dump, wire it up

 

[camp9]

The shut down solenoid took a dump, wire it up

It retracts when I turn the starter switch. I can only see it from the cab that it it retracting, but thought maybe it wasn't retracting all the way, so I did wire it back. No fuel comes out of any of the lines.

 

[MtnSnow]

While you have the solenoid wired in the retracted position make sure that the fuel lever is rotating into the start/run position and not sticking in the closed/off position.

 

[74M35A2]

There has been one case here where the fuel shut off lever itself on the pump was not grabbing the control rod that goes into the pump. So, the stop lever was rotating on the outside, everything looked correct, but it was found that the lever was not actually rotating the rod that goes into the pump. Check that connection between the two. I have not looked enough to know how it is setup, but think of how a kick starter or shift lever is on a dirt bike or street motorcycle, for example. I'm not sure if it is splined or whatever, but this was just to paint an image. It sounds like this is what could be occurring in your case. It sounds like you know what you are doing, the stop lever I think is plastic and looks like a dog's hind leg, has a large cam area that presses against the stop solenoid.

Do you have other indicators that show the accessory gear drive is working? Maybe easiest one is to try turning the steering wheel during cranking, you should be able to. Tach jump a bit when cranked?

Luckily the Bosch MW pump is only like $200 used on eBay, I just checked a day or so ago.

 

[camp9]

Yep, the top of the lever rotates twards the front of the engine, oposite direction of emergency shut off wire. And the shaft has splines on it and are rotating with the lever. My lever is not plastic and is metal. I'll check and see if the steering wheel turns while cranking, that's a good idea and will tell me if that gear in the housing is turning. Hopefully I won't be checking ebay, but good to know the price if I do.

 

[camp9]

Do you have other indicators that show the accessory gear drive is working? Maybe easiest one is to try turning the steering wheel during cranking, you should be able to. Tach jump a bit when cranked?

Accessory gear is working, front tires turn.

 

[WillWagner]

could be a failed overflow valve. can you remove the return line from the pump to see if fuel is just flowing out and back to the tank? It should normally be under 20-30 psi and spray out of the fitting.

 

[74M35A2]

Good call. Quick test is to pinch the return line shut with Vise-Grips and try a start. Don't let it run long if it fires. The pinch-and-release when running is a shade tree way of cleaning this OFV. It is located in the banjo bolt on the return line fitting at the pump.

 

[camp9]

Yep, that is something I didn't do. I just tried it and still no fuel coming out of the injector lines on top of the pump.

 

[camp9]

could be a failed overflow valve. can you remove the return line from the pump to see if fuel is just flowing out and back to the tank? It should normally be under 20-30 psi and spray out of the fitting.

I did disconect the rubber return line before trying the vise grip to pinch it off. Pumping by hand I did get fuel to flow past it.

 

[camp9]

Thanks everyone for the input. Unless there is something internal that is stuck I think my next step is to take the IP off and replace it.

 

[74M35A2]

My last ditch effort would be 2 items:

1. Remove one of the large plugs on the governor side case, and crank the engine, see if the pump is spinning at a rate you would expect it to be (1/2 engine speed). You should be able to see the governor springs rotating when doing so.

2. Pull the tach drive adapter and cover, check the IP driven gear nut for torque, and mark the IP drive gear and shaft with felt tip in alignment. Crank it. Check the marks again, see if the gear is spinning on the shaft. On a P7100, this is a tapered fit with no keyway. On an MW pump, I am not sure, but the eBay ones look like they have a keyway on the pump shaft. If this key is sheared, or the gear otherwise spinning on the shaft, it should be repairable through the tach drive adapter cover opening, without pulling IP.

 

[camp9]

My last ditch effort would be 2 items:

1. Remove one of the large plugs on the governor side case, and crank the engine, see if the pump is spinning at a rate you would expect it to be (1/2 engine speed). You should be able to see the governor springs rotating when doing so.

2. Pull the tach drive adapter and cover, check the IP driven gear nut for torque, and mark the IP drive gear and shaft with felt tip in alignment. Crank it. Check the marks again, see if the gear is spinning on the shaft. On a P7100, this is a tapered fit with no keyway. On an MW pump, I am not sure, but the eBay ones look like they have a keyway on the pump shaft. If this key is sheared, or the gear otherwise spinning on the shaft, it should be repairable through the tach drive adapter cover opening, without pulling IP.

Mine has a wire over the top of that big plug your talking about, I'll take a look and give that a try tomorrow if it's not raining or snowing. Not trying to get ahead of myself, but if it did slip on the shaft it'll have to be timed. Are there marks on the shaft and gear? If it did slip or I have to replace the IP, I have some reading to do in the TM.

 

[WillWagner]

I forget what gov these have on them. If you want to see if the pump is turning, there is a cap on the side of the gov housing that contains the timing pin. Take the plug and pin out and crank it while looking in the hole with a mirror. It is the plug that you time the pump to engine with IF it is an RQV/RQVK gov. I don't remember if the RSV has that plug/timing device.

Honestly, the only way to positively determine if it is a pump is to check pressures. If the FSOV is pulling up, you have the low pressure into the IP from the lift pump, (it takes about 15-20 psi for the pump to send the correct high pressure to the injectors and the normal running galley pressure is 25-35 at WOT. 20 at idle is acceptable, I lik 30 +), the only other possibility could be a stuck open nozzle.

You can remove the injector lines from pump to injectors and have someone crank it, these will need to come off anyway if the pump is failed. If you see fuel/air coming back out of the injector while cranking, that injector is putting compression back into the pump. The engine will never lite. Change that injector. If no air, the pump is failed.

The low pressure NEEDS to be verified before condemning the pump.

 

[WillWagner]

A stoopid question, did you try stepping on the gas while cranking? Shouldn't need to, but if the delivery valve rod and stop magnet have joblocked, this could also be a possibility.

Joblocking is when two flat, smooth surfaces get stuck together by a liquid....like cold, thick oil. It is a common issue in Jake Brake solenoids.

 

[74M35A2]

We are going through the IP timing right now on the performance thread for the 8.3. It does not look like anybody has messed or had to mess with it yet. You could be the first.

The Cummins Quickserve online service manual does not signify a difference between timing the 7100 or MW pump. These trucks are the MW pump, often found in agriculture apps. Timing is specified to be set by pulling the #1 injector line off, plugging the overflow vale, and then continuously pumping fuel into the IP at 300-375psi, then rotate the engine until the flow from #1 injector line slows to a drip. Then read the crank damper timing tape you put on.

If off from spec (8 degrees), then pull the IP driven gear, rotate engine to correct advance, and torque gear back down. This is the part I don't understand as the MW pumps on eBay seem to have a key in their shaft. There must be some type of adjustability though for build tolerances, and different timing settings for different applications (hp and RPM based decisions).

 

[WillWagner]

That procedure is spill port timing. That is used only to ts a performance issue...white black smoke, low power. I can tell you in almost 30 years, it has never had to be used, in my shops atleast, it is a grasping at straws thing. You just need to verify your pressures, If they are there, the pump is crap.

No key, there is a keyway cut into the shaft but no key is used on Cummins applications.

 

[74M35A2]

That procedure is spill port timing. That is used only to ts a performance issue...white black smoke, low power. I can tell you in almost 30 years, it has never had to be used, in my shops atleast, it is a grasping at straws thing. You just need to verify your pressures, If they are there, the pump is crap.

No key, there is a keyway cut into the shaft but no key is used on Cummins applications.

Thanks for explaining the keyway deal. It didn't make sense.

As a separate thread or PM, could you explain the procedure to check and adjust injection timing on the 6CTA8.3 with the MW pump? Quickserve only describes the method above. Myself and several others here are curious as to how to do this. Please and thanks.

 

[WillWagner]

From a Cummins POV, there is no other timing adjustment other than pinning the engine at tdc, pinning the pump and stabbing it. Any other "mod", anything other than the pump internal timing as per Bosch/Cummins spec and the pinning of the engine is all that is published. Nothing to change timing to something that runs mo better. It would violate the engine build as lined out with the feds...emissions ya know.

I can write up a timing procedure and make it a sticky.