1996 Dynasty - No Start - Help appreciated

[Paul Brown Jr]

I have a 1996 Monaco dynasty, I am trying to figure out why I can not start my diesel.  I just bought a new fuel separator to install but someone told me to check the lift pump, I am trying to find it and see how to check it, Help !!!

[klcdenver]

You need to list which engine you have. If you installed a new fuel separator & filter you need to fill the filter with diesel. Turn key on and off about 5 times so electric pump can re-prime the engine. Hopefully you just had air in the fuel line and it will start now.
Sign up on Cummins Quick Serve and then you can look at a diagram to locate the lift pump for your engine model.

[Benjamin]

As far as I can tell, you have a cummins engine, 8.3 but that doesn't matter to this question.  No electric fuel pump, a particularly NASTY transfer pump mounted low on the engine block and impossible to prime with the frame in the way.  It sticks out below and behind the injection pump, down inside the frame rail probably, and has a black rubber bellows about 1" diameter that you push in to prime, you should here squishing noise if it's pumping fluid.  If you can't hear the sound, easiest is to remove the small fuel return line from the top front of the injection pump and have somebody crank it over one turn and see if diesel comes out. 

Back up a little, when did the engine run last? did it run fine then? shut off normally? Is the tank full or low?  If the tank is full, and not parked facing downhill, then the next most likely thing is the fuel shut off solenoid, mounted on the injection pump but external so easy to see and tie open if needed. 

[Just Jim]

More info would be helpful as others have stated.  I had a 95 and it had the Winn Fuel water separator on it that you could just push the button and it would prime the system after a filter change.  I've attached pictures of it.  You have to turn the key on and I would let it go through its cycle a couple of times after a filter change, then start it with the rear start switch.

[Benjamin]

Yes, What Jim shows may have been standard on Dynasties.  I was talking about the engine as cummins built it, in 96 it should have an entirely mechanical inline injection pump, the bosch p7100, with a not particularly reliable external shut off solenoid, and a not particularly reliable transfer pump.  Both are cheap aftermarket if you want to carry a spare, the solenoid is easy to work around, the transfer pump is required unless there is an electric pump somewhere, and there may be on Monacos. 

[RoadTripper2084]

Just Jim's post is correct, you can use the automatic primer control in the rear engine bay to prime the fuel system after a filter change.

As Benjamin noted above, the Fuel Cutoff solenoid is a common failure point. This controls fuel to the engine, so it's down/closed when off, keeping fuel from flowing to the engine and shutting the engine down.  When the key is in the "on" position, the solenoid lifts the plunger and holds it lifted, allowing fuel to flow to the engine.

Over time the plunger can corrode and not slide easily, getting stuck in the down or up position, or something in the middle.  

You can test this by using your finger to make sure the bottom of the plunger is all the way "up" when the key is on. You can push it up if necessary and even use a zip tie to keep it up.  I have had success with mine cutting a very small hole in the rubber boot at the bottom and spraying white lithium grease into the solenoid/plunger area. This has worked for 3 years when mine started to stick.

You can also test for 12v power when the key is "on" at the plug connecting to the solenoid. If no 12v when on, you have electrical problem further up the line (see attached diagram).

Note: The Fuel Shutoff solenoid can be accessed via the bedroom, with the bed lifted, facing the rear of the coach, it's on your left side, near the middle/rear of the accessible area of the top of the engine.

Edited Tuesday at 02:02 PM by RoadTripper2084

[Craggar]

12 hours ago, Paul Brown Jr said:

I have a 1996 Monaco dynasty, I am trying to figure out why I can not start my diesel.  I just bought a new fuel separator to install but someone told me to check the lift pump, I am trying to find it and see how to check it, Help !!!

If it’s like my 98 mechanical 8.3 you should have a primer button under the fuel filter if that’s the issue. Also like mentioned the fuel shut off solenoid is a known problem. Maybe give us more info and tell us what happened before it didn’t start, sounds like it may have not started before you changed the filter which could mean something else.

[Paul Brown Jr]

It would not start and I had a friend helping me and he sprayed some stating fluid and it started but stop after the fluid was over so I bought a fuel separator system to replace the one on the motorhome ( waiting for it to come).   Any way I am told now it maybe the lift pump because nothing is priming the fuel.

Thanks, everyone, I will check everything tomorrow.

[Craggar]

1 hour ago, Paul Brown Jr said:

It would not start and I had a friend helping me and he sprayed some stating fluid and it started but stop after the fluid was over so I bought a fuel separator system to replace the one on the motorhome ( waiting for it to come).   Any way I am told now it maybe the lift pump because nothing is priming the fuel.

Thanks, everyone, I will check everything tomorrow.

 I'm not an expert on which motors came in what but I thought yours had the 8.3 mechanical like mine. If so there is no lift pump.

 

[RoadTripper2084]

1 hour ago, Paul Brown Jr said:

It would not start and I had a friend helping me and he sprayed some stating fluid and it started but stop after the fluid was over so I bought a fuel separator system to replace the one on the motorhome ( waiting for it to come).   Any way I am told now it maybe the lift pump because nothing is priming the fuel.

Thanks, everyone, I will check everything tomorrow.

Check the fuel shutoff solenoid. It's not difficult and is a very likely cause for your problem.

[jacwjames]

Should be able to see the solenoid actuate which allows fuel to flow.  Look at it with key off, then with key on.  If it hasn't moved it ain't working.

 

I have a Toro zero turn.  I mowed with it on Friday and all was good.  Went to start it on Saturday and it wouldn't start.  Checked stuff and made my way to the carburetor which has a fuel cut off solenoid.  Pulled the wires and it started right up, plugged back in and it still worked.  Not sure if it was the solenoid or plunger stuck,.  But at least I know what the problem is next time.

[Benjamin]

Yes, but you may need to hit the starter to "pull" the solenoid in.  The run wire will not pull the solenoid in, it needs the start signal to pull in, then the run will hold it in.  IF the run is interrupted, then it will not pull back in with the run, and need to be restarted to pull the solenoid in.

[RoadTripper2084]

Here's a video where the guy replaces a bad fuel shutoff solenoid on a C8.3 like yours for reference.

 

[Craggar]

You can turn the key on to the run position and go back and push the plunger on the solenoid to the up then start it. Mine started to fail while on the other side of the country and after a couple days of me going to the back to push the plunger up I did what Roadtripper suggested and it worked fine the rest of the way home.