CRD quit, now just cranks but will not fire

Mountainman · **Posted:** Sat Dec 19, 2015 7:53 pm

I agree with Geordi, unless the CP3 suffered catastrophic failure. There should be some bad noises when you turn it over if the belt it busted as the rockers will be getting mashed, and pistons smacking valves. Might have to have your head under the hood when someone cranks it to hear this, but it should be pretty obvious since there's no noisy combustion going on.

very rare that they fail, but I've seen CP3's on ebay for as low as $250

rankom · **Posted:** Sat Dec 19, 2015 8:02 pm

ok guys i replaced motor mounts just routine maintenance for me. as you know i like spending money on this jeep , and i almost destroyed fuel pressure solenoid, harness and plug before realizing i should remove mounts bracket of engine block , lucky and surprised nobody said we need to do so

dhenderz · **Joined:** Fri Dec 11, 2015 9:26 am **Posts:** 164

geordi wrote:

Here's my problem with thinking that it's a sensor: every time I am putting one of these back together, I refill the fuel rail by manually spinning the high-pressure pump. I get a ton of fuel coming out. Nothing special, just turning the pump fast without the engine or the computer being on. If you had the number one injector high-pressure line disconnected, and you were not getting any fuel coming out of the rail while cranking the engine, then there is something wrong with the timing belt.

You don't have to disassemble the front of the jeep in order to get the timing cover off. Leave the radiator and bumper and grille exactly where they are. It will be a little difficult to remove the fan and the shroud together, but once you've done that, then you only have to remove the idlers, the alternator, and the power steering and crankshaft pulleys. Then the cover is fully exposed. I seriously think you have a problem with the timing belt. You're going to want to get a hold of a set of timing pins, but for a quick test, a couple of quarter inch drillbits will be sufficient. You will need to manually rotate the engine until the Divet in the crankshaft hub is at the 3 o'clock position, and then check to see whether the drill bits or pins will go in to the intake camshaft. If it does, check the exhaust camshaft.

Or, most likely you're going to find that your belt is not even attached. Seriously, I think you have a major mechanical failure going on, since you're not getting anything when manually spinning the pump by cranking the engine. You should be bathing in diesel fuel with that line unhooked.

geordi - is it possible to pull the timing cover screws off the upper half to be able to pull it back enough to peek in and confirm the belt is attached and rotating during crank?

dhenderz · **Joined:** Fri Dec 11, 2015 9:26 am **Posts:** 164

Mountainman wrote:

I agree with Geordi, unless the CP3 suffered catastrophic failure. There should be some bad noises when you turn it over if the belt it busted as the rockers will be getting mashed, and pistons smacking valves. Might have to have your head under the hood when someone cranks it to hear this, but it should be pretty obvious since there's no noisy combustion going on.

very rare that they fail, but I've seen CP3's on ebay for as low as $250

I have been under the hood during the cranking (looking for fuel coming out of the #1 injector pipe). There are no odd/strange/bad noises at all. Just a normal crank. That has me thinking nothing is wrong with the belt. But am wondering if it is possible to pull enough of the timing cover screws (along the top half) to be able to wedge it back enough and peek inside to confirm rotation of the belt during crank. Anyone tried this?

rankom · **Posted:** Sat Dec 19, 2015 9:00 pm

did you check harness above tranny you didn't pinch it when you re and re motor mounts?

flash7210 · **Posted:** Sat Dec 19, 2015 11:16 pm

dhenderz wrote:

Mountainman wrote:

I agree with Geordi, unless the CP3 suffered catastrophic failure. There should be some bad noises when you turn it over if the belt it busted as the rockers will be getting mashed, and pistons smacking valves. Might have to have your head under the hood when someone cranks it to hear this, but it should be pretty obvious since there's no noisy combustion going on.

very rare that they fail, but I've seen CP3's on ebay for as low as $250

I have been under the hood during the cranking (looking for fuel coming out of the #1 injector pipe). There are no odd/strange/bad noises at all. Just a normal crank. That has me thinking nothing is wrong with the belt. But am wondering if it is possible to pull enough of the timing cover screws (along the top half) to be able to wedge it back enough and peek inside to confirm rotation of the belt during crank. Anyone tried this?

You can pull off the front timing cover if you want, but you have a fuel system problem. There are some easy tests you should do first.

1. Verify that the rail pressure solenoid is properly connected. If so and still wont start, move to step two.

2. Disconnect the harness connector to the fuel quantity solenoid and try to start. If still no start, reconnect wires and move to step three.

3. Disconnect the fuel return hose from the fuel rail. Have someone crank the engine while you observe. Fuel should be coming out of the hose, or the fuel rail, or both. If no fuel, then the CP3 is definitely not pumping fuel. Problems could be:
a. Blockage in fuel lines/filter or a break in the fuel line
b. Broken timing belt
c. Bad CP3

rankom · **Posted:** Sun Dec 20, 2015 11:35 am

you can remove oil fill cap and look down just to check if camshaft turns (intake cam)

papaindigo · **Posted:** Sun Dec 20, 2015 11:42 am

Putting pieces together:
1. geordi says just manually spinning the fuel pump (CP3) will push fuel to the fuel rail with the ignition off
2. OP says while cranking there is no fuel in the fuel rail but there is fuel at the outlet side of the fuel filter head when that line is disconnected and the filter head primer is pushed.

Conclusions:
1. base problem of no fuel in the fuel rail cannot be a sensor if the CP3 is, in fact spinning.
2. the problem has to be somewhere between the fuel rail inlet and the outlet side of the fuel filter head as fuel is getting as far as that outlet side.

What to do:
1. yes if you pop the top few bolts on the timing belt cover you can pry it far enough forward to see if the timing belt is spinning while cranking. Won't tell you if the timing is correct but will tell you if belt is on and not broken and if spinning that the CP3 should be moving
2. undo fuel connection at the CP3 inlet and then pump fuel filter head primer. Does fuel come out? If not check for obstruction in line. If it does I don't recall if the line is a hose or hard line. If a hose carefully inspect for soft spot(s). I once dealt with a gasser that wouldn't run back in the day when most all vehicles had a "sucker" fuel pump on the engine block. Problem was a soft fuel hose back at the tank; as soon as fuel pump tried to suck fuel from the tank that hose slammed shut and no fuel was delivered to the engine.
3. if fuel is getting to the CP3 then check the outlet side of the CP3 to see if fuel is going thru it. If not check line from CP3 for obstruction.

Best I can suggest.

PS had not thought of looking down thru the oil filler hole but that's simpler than undoing timing belt cover screws as mentioned above. If cam is rotating then TB is not broken.

Mountainman · **Posted:** Sun Dec 20, 2015 12:01 pm

rankom wrote:

you can remove oil fill cap and look down just to check if camshaft turns (intake cam)

Good idea! :idea:

thermorex · **Posted:** Sun Dec 20, 2015 1:09 pm

This is the MPROP wire flash was talking about:

Disconnect it, the jeep should start and then die, since it can't monitor the fuel amount that is going through. If this happens, you'll need a new MPROP sensor for your cp3.

I doubt you have a rocker issue, but this can be. First see if your fuel delivery works fine.

dhenderz · **Joined:** Fri Dec 11, 2015 9:26 am **Posts:** 164

Status update.

1) Pulled the oil fill cap - confirmed cam is rotating. Timing belt is fine.

2) Checked the fuel rail solenoid valve connector - everything looks fine.

3) Pulled the connector off the CP3 fuel quantity solenoid - still no start.

4) Installed short section of clear tube from output of filter head feed to CP3. Primed and purged air - filled the clear tube. Try to start - no start, but all of the fuel was pulled from the clear tube, but oddly enough it did not (re)fill with fuel, refilled with air. Primed again, filled clear tube. Try to start, pump pulls in all of the visible fuel, but no fuel coming in from filter head to refill, only air.

I have tried priming and refilling the clear tube probably 50 times. Every time I try to start the fuel is drawn in, but only air is being pulled in behind it. Plus, I am wondering where is all the fuel going? Pulled the compression nut off main high pressure feed to the rail. Crank- only trickles coming out. Pulled the low pressure return hose off the back of the rail. Crank - only a trickle coming out. What the heck? Where is all of the fuel going. OK, pulled the low pressure return hose from the CP3 to the small manifold that combine the rail return with the CP3 return back to the tank. Reprime, crank - ah, now we've got fuel coming out. So it seems there are 2 problems -

1) The CP3 is dumping the fuel back to the tank, not up to the rail. What's up with that?

2) Why wouldn't the low pressure vacuum pump pull fuel through the filter after I've primed it and clearly removed all of the air? Is it possible I have a bad/clogged fuel filter? I just changed the filter 2 wks ago with a Hastings. I did pre-fill the filter with fuel from a 5gal can I had sitting in the shop. I have to admit the fuel was pretty old, probably sitting in the shop since I sold my skid steer. That was probably at least 7-8years ago. Maybe it was full of sediment and I promptly filled the new filter with crap and plugged it up.

And if the filter is bad/plugged, would the CP3 not getting a steady, solid flow of fuel cause it to simply bypass and dump the fuel/air mixture back to the tank?

Thoughts?

PS - assuming it is the fuel quantity solenoid that has possibly gone bad - is it possible to change it without pulling the CP3? Anf is this it?

Fuel Quantity Solenoid installs into high pressure pump, 2005, 2006 Jeep 5159962AA

papaindigo · **Posted:** Sun Dec 20, 2015 4:49 pm

"I have tried priming and refilling the clear tube probably 50 times. Every time I try to start the fuel is drawn in, but only air is being pulled in behind it"

You appear to have a massive air leak so that a teaspoon of fuel is sloshing around in the lines from the filter head to the fuel rail.
1. did you just change the fuel filter (FYI never ever dump anything but Power Service or fresh pumped diesel into a new filter prior to installing a) doing so is not needed-primer works fine and b) what you pour into the center of the filter goes straight into the engine with NO filtering). If so pull it off and see if you doubled up on the center gasket (the one that goes into the post the filter threads onto).
2. get a CLEAN container; dispense some fresh pumped diesel into that container; connect a line to the outflow hose from the filter and insert the other end of that hose into the fresh diesel; attempt firing up. If it fires look for source of air from the filter head outlet back to the tank. If it doesn't fire look for an issue between the filter head outlet and the fuel rail.

I could be wrong but I thought the only fuel bypass back to the tank was from the back of the fuel rail not direct from the CP3. If the CP3 does have a bypass and fuel is flowing from it rather than going to the rail then you may have a bad sensor on the CP3 causing it to just dump fuel without building pressure. However, given what appears to be a massive quantity of air it's likely impossible for the system to build pressure.

Mountainman · **Posted:** Sun Dec 20, 2015 5:08 pm

I wouldn't run any more air through that CP3 either. It's lubed by diesel. It should start when you bypass the air leak. But might take a 3-5, 8 second cycles with 30 seconds in between to protect the starter.

flash7210 · **Posted:** Sun Dec 20, 2015 5:11 pm

If all the fuel is being sent out the return and not up to the rail then there is a good chance that there is a problem with the fuel quantity solenoid (MPROP) on the CP3.

But first you need to fix the problem with air getting into the fuel lines. Either the problem is with the fuel head or you have a break in the fuel line somewhere.

The MPROP is just a solenoid, controlled by the computer.
When in the off position, all fuel gets sent up to the rail.
When in the on position, all fuel gets sent out the return line.
Its possible that the plunger is stuck in the on position.

dhenderz · **Joined:** Fri Dec 11, 2015 9:26 am **Posts:** 164

flash7210 wrote:

If all the fuel is being sent out the return and not up to the rail then there is a good chance that there is a problem with the fuel quantity solenoid (MPROP) on the CP3.

But first you need to fix the problem with air getting into the fuel lines. Either the problem is with the fuel head or you have a break in the fuel line somewhere.

The MPROP is just a solenoid, controlled by the computer.
When in the off position, all fuel gets sent up to the rail.
When in the on position, all fuel gets sent out the return line.
Its possible that the plunger is stuck in the on position.

Interesting. Wondering if in fact it is stuck in the on position (dump fuel). The engine quit after coming off the highway and stopping at the top of the ramp. So presumably the ECM would have commanded the MPROP to the open/dump position during the coast down off the highway and coming to the stop. From there the engine only ran about 1/2 block before going completely dead - maybe just running off the residual pressure in the rail.

How hard is it to changed the MPROP? Anyone done it?

Checked on the filter - no doubling up of rubber gaskets. Only single/new ones (inner & outer).

flash7210 · **Posted:** Sun Dec 20, 2015 8:35 pm

There are several places where air can get into the fuel lines.
There is a connection back at the tank.
The crimp connection at the fuel filter inlet hose.
Overheated/melted fuel heater in the filter head.

Adding a lift pump will help identify leaks. It easier to see fuel leak out than air leak in.
Some folks use the green MrGasket diesel pump found at local parts stores.
I use the Facet 40109.
No matter which one is used its easy to install at the fuel filter inlet.
Replacing the MPROP wont do any good when fuel cant get up to the CP3.

Replacing the MPROP can be done without removing the CP3 but its not easy.
You will need a long torx screwdriver to get to the 3 small screws. Be gentle, its easy to strip those screws.

dhenderz · **Joined:** Fri Dec 11, 2015 9:26 am **Posts:** 164

flash7210 wrote:

There are several places where air can get into the fuel lines.
There is a connection back at the tank.
The crimp connection at the fuel filter inlet hose.
Overheated/melted fuel heater in the filter head.

Adding a lift pump will help identify leaks. It easier to see fuel leak out than air leak in.
Some folks use the green MrGasket diesel pump found at local parts stores.
I use the Facet 40109.
No matter which one is used its easy to install at the fuel filter inlet.
Replacing the MPROP wont do any good when fuel cant get up to the CP3.

Replacing the MPROP can be done without removing the CP3 but its not easy.
You will need a long torx screwdriver to get to the 3 small screws. Be gentle, its easy to strip those screws.

The filter head appears to have been replaced. Looks like the new style. The inlet hose crimp is gone and the rubber hose has a worm clamp on it. As does the outlet hose.

dhenderz · **Joined:** Fri Dec 11, 2015 9:26 am **Posts:** 164

Here's an interesting one. Went out to take a photo of the filter head to post. And the clear tube is full of fuel. It was half empty when I left it a few hrs ago. Cranked it just for the heck of it. No start and again fuel dropped about half way down the clear tube. Still air back filling the fuel. Wondering if my clamp from clear tube to filter output isn't sealling. Plus interesting that it somehow filled itself sitting for a few hrs. Wonder if it is fuel running back from the rail seeking it's own level.

dhenderz · **Joined:** Fri Dec 11, 2015 9:26 am **Posts:** 164

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dhenderz · **Joined:** Fri Dec 11, 2015 9:26 am **Posts:** 164

Unfortunately I now away from the car for the next 7 days so I can't poke at it for awhile. Thinking about ordering a new fuel filter and a new fuel quantity solenoid.

CRD quit, now just cranks but will not fire

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