Fuel Leaking In Engine Compartment

[mberry]

I have fuel leaking somewhere in the engine compartment. It didn't do this until it got really cold here last Sunday. Anyway, the fuel is near the front of the engine on the drivers' side. It has coated the steering components, and inside of both wheel wells. Drivers side getting the bulk of the fuel. I checked the fuel drain and it's ok and not leaking.

From my visual inspection, there is liquid fuel on the line running from the CP3 to the fuel rail next to the valve cover. That is the only location I could actually see liquid fuel sitting anywhere. I couldn't see anything leaking while the engine idled or while it was shut down. It does drip onto the ground while sitting. Just a few small drop is all I have been able to see but I can smell it while at idle or parked and off. I have not touched anything on the pump, fuel rail, sensors, or anything else related to the mechanical stuff on this truck on this side of the engine. The truck runs fine. No loss of power. No loss of MPG other than the winter fuel.

Please help me try and figure out where this may be coming from and how I may be able to fix it. Thank you.

 

[BHanna]

Just a guess but there's been a problem with the #4 injector line breaking. Also check all the connections to see if one's obviously loose.

 

[RBridenbaugh]

Seems like it is time to get out some cardboard and put it under your fuel lines and test the connectors as recommended below. Read the caution about working near high pressure lines. High velocity, injection of diesel through the skin is not good.



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[mpaulson]

I've got the same problem on my 6. 7. It leaked last winter, and it is leaking again this winter. I did smell some in the summer from time to time. I'm going to get the dealer to look at it again as I had a different one look at it last winter.

Mine drips onto the front dif cover.

 

[mberry]

Thanks for the help. After i posted that yesterday I went out and started the truck for the drive home. I saw that it was coating pretty much everything on that side of the block. I even saw fuel mist coming out of the wheel well. I wish it was warmer so I could spend some time looking at it before I run inside to get warm. Anyway, I will check the lines in the diagram posted and anywhere else I can stick a piece of cardboard in there.

As far as the pressures go I'm a former aircraft mechanic with Uncle Sam's Moving Company and worked on airframes/hydraulic systems. Definitely not sticking my hands in there while it's running!

 

[flyby night]

I have noticed that mine looks as if it has started to leak. Only mine looks as if it is coming from the lower rear of the fuel pump. I can't see anything leaking above the pump, mostly only the underside of it. It kind of ticks me off though, I only have 64,800 miles!!! I need to take a closer look, but I hope I don't have to eat the fuel pump.

 

[DWBauer]

At about 60K I had #5 high pressure line develop a crack and had to be replaced. It was spraying so hard though that I was painting the cars behind me with diesel fuel as I was traveling down the road. Yours might be a loose fitting that's leaking under pressure.

 

[flyby night]

Has anyone ever tried UV dye in the fuel to narrow down the source of a fuel leak? I have used UV dye in just about everything else, and have had great success finding some leaks that were very difficult to find where they were coming from.

 

[Wingate]

There are easier ways to find a high pressure fuel leak. One of the easiest is to use electrical component cleaner (aerosol spray) on the affected area to wash the fuel/residue from the engine. (Note, do this with the engine cool, then allow it 10 minutes to evaporate off. ) Personally, I would NOT use brake cleaner for this, use only electrical component cleaner, LPS makes a good product.

Now that everything is degreased and dry, start the engine and watch for the wet spot to appear. If it doesn't, you will need to load the engine to get the rail pressure up. (some high pressure leaks only happen when the pressure is at or near max)

IMHO, just wiping the drips off really doesn't help... due to the vehicle being in motion, and the cooling fan(S) blowing under the hood. Atleast this way, you can eliminate the vehicle motion and the cooling fan really doesn't blow it around with the hood up.

 

[JJPage]

This type of leak has been discussed in the past, usually the gearcase pump on the back of the CP3. Some of them leak in cold weather, if you follow the thread below(Relentless Diesel), you will see where an 0-ring gasket, (that looks like a "O" with 2 small "o"s on either end) sits between the gearcase pump and the main body of the CP3.



You may be able to tighten the 4 torx screws that hold the two assemblies together, or you may need a new o-ring gasket, be careful not to strip out or twist off the torx screws. torque specs are most likely inch pounds. Follow the thread down to the pictures.



Relentless Diesel • View topic - DIY CP3 Mods

 

[pullya]

I had to replace a #4 injector line also. Fuel all over the engine and the cars behind me till the truck stopped running. Truck smelled really good for about 2-3 weeks after . Last time I checked the fuel lines were on nation wide back order and some people were brazing their old ones just to get back on the road.

Jay

 

[JRMora]

Twice I have had a leak develop eventually leading to fuel spraying all over the engine compartment. One time it was a crack on the fitting where the fuel line return from the rail connects to the back of the CP3. New line, banjo and washers fixed this. Next time is what at the other end of the same line where the rubber line and hard line meet. I just pulled everything apart and reseated everything and reinstalled the clamp on the hose. No leaks. I don't know why these fail and leak so often.

 

[mberry]

Thank you JRMora. After a thorough cleaning of the lines and hoses I finally took a look this weekend. I wasn't able to see the source of the leak itself, but it is coming from somewhere behind whatever the sensor is on the CP3 as you are looking at it from the drivers side fender. It is dripping, once driven and up to operating temperature, about 20-30 drops per minute onto the ground. It didn't leak that I could tell while idling and cold. Does this sound like the plumbing, or the CP3 itself?

I do not have room to put in in my garage and turn the heat on, and laying in the snow and ice getting covered with fuel doesn't sound appealing right now. Someone really needs to take a couple of Scouts home for Christmas.

 

[Diesel Power]

This is mostlikly a fuel line that is cracked #6 is very bad for this. though the lines that come from the rail to the cp3 can also leak. on rare occasions the cp3 itself will leak too.

 

[JRMora]

Thank you JRMora. After a thorough cleaning of the lines and hoses I finally took a look this weekend. I wasn't able to see the source of the leak itself, but it is coming from somewhere behind whatever the sensor is on the CP3 as you are looking at it from the drivers side fender. It is dripping, once driven and up to operating temperature, about 20-30 drops per minute onto the ground. It didn't leak that I could tell while idling and cold. Does this sound like the plumbing, or the CP3 itself?

Mine started as a drip then became a spray at failure. When it went, it went pretty bad. You may just try reseating all your clamps and seeing it all the banjo bolts are tight.

I do not have room to put in in my garage and turn the heat on, and laying in the snow and ice getting covered with fuel doesn't sound appealing right now.

Fortunately you can get to all these by standing, not laying in the snow. Not that either is appealing, though...



Juan

 

[mwilson]

Mine did exactly the same thing when it had only 25,000 miles on it. It was the FCA on the back of the pump. Changed under warranty and hasn't leaked since. Your fan was picking up the fuel drip and blowing it all over the place.

Mike

 

[mberry]

As far as I can see, it is not leaking from any lines. Banjo bolts are not loose and it appears to be leaking fuel from some kind of plug just below and to the left of the FCA as you're looking at it from underneath. It only starts leaking fuel when the RPM comes up then it leaks constantly and consistently. What is that plug for? Does it have an O ring that may be bad? The plug is a star pattern and looks to be around 3/4" diameter.

 

[JJPage]

As far as I can see, it is not leaking from any lines. Banjo bolts are not loose and it appears to be leaking fuel from some kind of plug just below and to the left of the FCA as you're looking at it from underneath. It only starts leaking fuel when the RPM comes up then it leaks constantly and consistently. What is that plug for? Does it have an O ring that may be bad? The plug is a star pattern and looks to be around 3/4" diameter.

The case of the CP3 has a couple torx head plugs, that's all they are, I'm pretty sure. Find the proper size torx bit and tighten it, or back it out enough to get some loctite on the threads and re-tighten.



If you go back to my post on the first page, and click on the Relentless thread, then scroll down to the pictures, is the plug you are talking about just to the right of the FCA in the picture of the CP3?



If you remove your inner fender liner, the CP3 is more accessible, there are like 8 screws and 1 plastic punch plug holding a sensor wire, and it drops right out.

 

[mberry]

The case of the CP3 has a couple torx head plugs, that's all they are, I'm pretty sure. Find the proper size torx bit and tighten it, or back it out enough to get some loctite on the threads and re-tighten.

If you go back to my post on the first page, and click on the Relentless thread, then scroll down to the pictures, is the plug you are talking about just to the right of the FCA in the picture of the CP3?

If you remove your inner fender liner, the CP3 is more accessible, there are like 8 screws and 1 plastic punch plug holding a sensor wire, and it drops right out.

I'm sorry JJ I couldn't find your post you were talking about. My wife was in the hospital last week and this is the first chance I've had to get back on TDR since then.

 

[JJPage]

It's the 10th reply to your post on the 1st page of this thread... .



Hope your Wife is ok.