High pressure fuel pump timing

BoarX · **Joined:** Sun Mar 20, 2016 12:44 pm **Posts:** 127

Hi all,

I am in the process of the engine overhaul due to the blown head gasket. When I got to the timing belt and was getting ready to take it off, I noticed that with both cam shafts and crank shaft pinned, the mark on the high pressure fuel pump sprocket was not anywhere close to its corresponding witness mark on the back timing belt cover (belt still on and tensioned). It was not like a tooth off, but more like nowhere to be seen. Once the belt came off I found it of course. Any idea how critical is the proper timing of this pump? On one hand, the Jeep was running pretty well with the pump timing way off before the blown gasket, on the other hand this mark must be there for a reason, no?

Thanks in advance,
A.

APC9199 · **Posted:** Wed Sep 27, 2017 9:28 pm

The fuel pump pulley is only aligned every 6 rotations of the crankshaft, so it is actually not likely that it will be in time when you take the cover off. There has been some debate about whether or not it even needs to be timed when putting things back together and many have completely disregarded it and been fine. I would get it as close as you can during final assembly just for peace of mind, but it really isn't going to hurt anything having it off.

GordnadoCRD · **Posted:** Wed Sep 27, 2017 10:11 pm

From FSM:

NOTE: There are marks on the high pressure pump gear and both camshaft gears. These ARE NOT align-
ment marks and should be disregarded. (These gears are re-purposed from other applications and the marks have no significance to this application.)

1. With both camshaft alignment pins still installed and the engine locked at 90° after TDC, verify that the camshaft
gears are loose.

NOTE: DO NOT remove the timing belt from the
package until it’s ready to be installed. DO NOT
expose timing belt to oil, grease or water contam-
ination. DO NOT crimp belt at a sharp angle. DO
NOT clean belt, pulleys or tensioner with solvent.
Check that pulleys and bearings are not seized or
damage before installing belt.

BoarX · **Joined:** Sun Mar 20, 2016 12:44 pm **Posts:** 127

OK, great, thanks guys! One less thing to worry about

A.

WWDiesel · **Posted:** Fri Sep 29, 2017 12:22 pm

I aligned them when I did my timing belt job as they were aligned when I took it apart (OEM factory).
Only takes a few seconds to align marks before tensioning belt.

I remember reading way back several years ago a post on LOST something about how the fuel pump alignment marks put it in time with injector discharges or pulses or something to that end.
So I will always time it with marks aligned, it certainly does not hurt anything to do it!
But do as you please, its your vehicle.... :5SHOTS:

GordnadoCRD · **Posted:** Fri Sep 29, 2017 1:14 pm

WWDiesel wrote:

It certainly does not hurt anything to do it! But do as you please, its your vehicle.... :5SHOTS:

Yup.

GordnadoCRD · **Posted:** Sat Sep 30, 2017 1:09 am

kdlewis1975 · **Posted:** Sat Sep 30, 2017 2:13 pm

I think the guys from GDE chimed in once to say it makes like a 2% difference on horsepower. It was explained once, as mentioned above, that the pressure pulse from the pump was timed to coincide with the injection event. I would say it helps atomization a little bit.

Thing is, it can be a bit maddening to get that little sucker timed just right. I would have to get it 2 or 3 teeth short so that it would be lined update when I pulled the timing belt tight.

So, not mission critical, but probably in your interest to get it timed. Good luck.

Sent from my SM-G930V using Tapatalk

papaindigo · **Posted:** Sat Sep 30, 2017 2:41 pm

Assuming for the purpose of discussion, I don't know, that "I think the guys from GDE chimed in once to say it makes like a 2% difference on horsepower. It was explained once, as mentioned above, that the pressure pulse from the pump was timed to coincide with the injection event. I would say it helps atomization a little bit." is correct then it follows that one cannot simply randomly line the "supposed" fuel pump timing marks up and assume/presume that the pump is timed to any injection event. At best I see 2 options assuming the engine you are working on had the fuel pump timed from the factory AND that the fuel pump is still timed the same way:
1. rotate the engine enough times (Note - the fuel pump marks if used by the Factory won't line up until after XX revolutions) until the fuel pump marks line up AND the cam/flywheel pins go in/dimple on crank is at 3 o'clock or
2. assume the fuel pump was timed at the factory so mark it and install the new timing belt with the fuel pump in the same position.

As I recall when geordi and I did my 05 and my son's 06 we did #2.

PS method #1 appears to match the GDE suggestion posted by WWDiesel below and clearly would be the method to use if a) you want to "time" the pump and b) do not know if it is "timed" (ex. someone did a timing job after the factory and you do not know if they "timed" the pump)

kdlewis1975 · **Posted:** Sat Sep 30, 2017 8:14 pm

There is no need to guess. Just follow the instructions. https://drive.google.com/file/d/0BwRY3v ... dQVms/view

Scroll down and there is a picture explicitly showing the timing mark on the fuel pump.

I had missed of a couple teeth during one interval in the past because I gave up after three attempts to get it lined up. Life was okay. It depends on how much of a stickler you wish to be.

Sent from my SM-G930V using Tapatalk

WWDiesel · **Posted:** Sat Sep 30, 2017 8:28 pm

Agreed! Do it right the first time and never look back! :wink:

The marks are there for a very good reason.... :roll:

Posted by GDE back in 2011:
Based on the number teeth on the pulleys (24 for crank, 48 for cam and 36 for IP) the pump timing make will line of with the crank every 3 revolutions. However, to get the entire system in the correct timing position it will occur every 6 revolutions (where crank is 90 degrees after TDC, cam pins line up and IP is pointed at the timing mark).

A pump with the wrong timing can lead to lower power and higher noise as posted earlier in the discussion. This is due to the internal pressure wave in the rail. If the wave pulse is not timed with an injection event correctly, the pressure at the injector nozzle might be lower than desired when the injector is energized. This may lead to a lower pilot injection quantity or a missed pilot, thus leading to more combustion noise (typical pilot duration is 180-200 micro seconds). The main injection may have a lower actual injected quantity as well due to out of phase pressure wave (main injection pulse width can range from 200-1200 micro seconds depending on load). These pulse widths are for the Liberty CRD, other common rail applications can be different, depending on injector flowrate, solenoid actuation vs. piezo actuation, number of injections (two pilots, main and post), etc.

This is the original thread if you want to read through it all; it is long with lots of technical back and forth:
> viewtopic.php?f=5&t=58007&start=2

I rest my case..... :ALONE:

BoarX · **Joined:** Sun Mar 20, 2016 12:44 pm **Posts:** 127

Agreed, given the amount of effort it takes to swap the head gasket, it totally makes sense to spend some minutes to align the marks on the injection pump - even if it doesn't matter after all, it is going to be less one suspect if something doesn't work right when the engine is reassembled. Thanks for all the input! A.

GordnadoCRD · **Posted:** Sun Oct 01, 2017 2:55 am

AS you can see, Many people have many approaches for many reasons, and yet all of us have good running CRDs.

If theirs is producing 2% more horsepower than mine,, I'm good with that.

In two rotations of the crankshaft there are minimally 36 injection events, but only 4 pump events. That's a lot of injection events not being affected by pump events, and one pump event happening when no injection event is happening. Go figure.

But as said before, do what makes you feel at ease. Better to do, and feel good

, than not do, and worry :shock:

? I suppose... :roll:

I'll just be out here :JEEPIN:

when I can.

WWDiesel · **Posted:** Sun Oct 01, 2017 1:40 pm

I think this explains it best:
The pump timing mark will line up with the crank every 3 revolutions. However, to get the entire system in the correct timing position it will occur every 6 revolutions (where crank is 90 degrees after TDC, cam pins lined up and IP [injection pump] is pointed at its timing mark).

So,it is not necessary to worry about which cycle the pump was in when you took it apart, or its original position, just time/align it to the two marks with the crank 90 deg.s AFC and cam pins inserted, then it will always be correct and will put one of its 3 cycles right where it is supposed to be as long as it is aligned to its timed marks even if it is 1/3 or 2/3 rotations out from its original position it will still always be properly timed for the pulse cycles.

IP pulley is turning 75% slower than crank pulley! IP makes a fuel pulse 3 times per single complete pulley revolution @ 120, 240, 360, 120 degrees.
Injectors fire every 90 deg.s of crank rotation, so IP is making a pulse at every injector firing event @ 90, 180, 270, 360 degrees.

:dizzy:

This is the math:

Bottom line, time the dang thing!!!!! :banghead:

GordnadoCRD · **Posted:** Sun Oct 01, 2017 3:40 pm

You've forgotten the pre and post injection cycles, WWD. They are supposedly affected even more than the primary injection event.

WWDiesel · **Posted:** Sun Oct 01, 2017 8:48 pm

GordnadoCRD wrote:

You've forgotten the pre and post injection cycles, WWD. They are supposedly affected even more than the primary injection event.

Yea I know, I was trying to keep it simple! :lol:

You are more than welcome to figure out all the angles of pre and post injection by the CP3 rotation versus crankshaft rotation angles and post! :goink:

A mathematical nightmare!
I got a headache just figuring out the simple ones... :dizzy:

Again, the bottom line, time the darn thing and forget it!!!! We are beating a dead horse! :wink:

GordnadoCRD · **Posted:** Sun Oct 01, 2017 9:53 pm

WWDiesel wrote:

You are more than welcome to figure out all the angles of pre and post injection by the CP3 rotation versus crankshaft rotation angles and post! :goink:

Already done, multiple times just to be sure.

WWDiesel wrote:

We are beating a dead horse! :wink:

Exactly what I was trying to point out! We all have CRD's some timed some not timed some don't even know. If it's a factory or dealer job, you can be sure they aren't timed. (doesn't mean it's better) But they all run great, and I'm not going to quibble about 2% (or whatever it is in this case)

High pressure fuel pump timing

Who is online