Fuel Leak

[Emcemv]

Hi all, getting the bus ready for a trip and have discovered a bad problem.  I have a fuel leak on the drivers side rear of the engine, at first look, I thought it was between the head and the block but further investigation makes me think it is running down the seam between the head and the block from above.  I see the fuel pump is above this area but I can't see any obvious leak up there.  Running at fast idle, the leak is pretty bad, dripping steadily and the fan blows it on the exhaust manifold and the muffler so I'm not going anywhere until this is solved!
In the pictures, the area that is wet with fuel is where the "92" is in the center of the picture, just above the engine nameplate.  One question I have is could this be leaking from the Head/block seam? are there fuel passages in this area of the head?  I see the fuel line from the filter outlet goes into the head but no leak at that fitting.  I don't see any obvious leaks from the base of the fuel pump but I can't see much more without tearing into it. Really tough location to see.

This is a 8V92T reliabilt reman from 2000 (non DDEC)

Any ideas on where I should start?

[wg4t50]

Looks like the fuel pump located above that area is where I would be snooping closely.
Dave M

[luvrbus]

There is a line that comes from the secondary filter then a line that ties the 2 heads together try tightening those if that doesn't stop it the fitting is broke or the hose is bad lot's of fun to be had in that small @$# area   you have to remove the thermostat housings from the heads to get enough room to work on the silly fittings and 1 bolt on T housing is a bitch but you just loosen it as it does not require removing. If the fuel pump is leaking it has weep holes you can see it leaking easy "got crows foot wrench"

good luck

[Emcemv]

Guys, thanks a lot for your quick reply! So it sounds like you guys agree it is up by the fuel pump somewhere?  I don't have to worry about the head gasket?  Tearing into this does not look like fun, it looks like I have to take off the coolant crossover pipe to get at this area and that means draining everything.....I think Clifford said it all in his reply

[bevans6]

The fuel system is simple yet complex on these engines, but it's all at the top of the head.  The fuel gets pumped into the heads on each side on an input drilling, goes along a drilling from front to back to all the stand pipes and into the injectors, and out on a return line drilling.  One head may be tied to the other head, and there will be a restriction orifice at the end of the return line that sets up the fuel pressure to the injectors.  Where it can get complex is in tracing the actual flow path of the fuel, on my MCI engine it goes in at the front and out at the front of the left head, the return from the left head is piped to the input of the right head along with an input from the fuel filter, then the final return is at the back of the right head.  What can leak are the pipe plugs that plug up all of the optional places to put your plumbing connections, there are a number at the front and back of each head.  If the haven't been disturbed try not to touch them unless they look very suspect.  Also the plumbing fittings are often what is called a reverse flare fitting, not all that common except on old DD two strokes I have found.  The hose end fittings are tubular steel and are somewhat prone to cracking.  I had a cracked hose end last year on a fuel line, spent an afternoon going all about the town I was in looking for one, when I found it the guy looked at my hose and said this is perfectly fine, you don't need a new one.  I said it leaks, I'm replacing it and I want you to make me a new hose...  $100 later I had a new hose and no leak...  Mind you we had a great time exploring the town by driving from tractor place to auto place to hydraulic place to truck place...  Each place asked where we'd been already and sent us on to the next place!  It was great small town stuff.

Brian

[Emcemv]

Thanks Brian, I was checking out how my hoses are run and they all look to be in good condition, this motor is only 14 years old.  I'm thinking it might be the fuel pump itself leaking.  Can't see anything down in there very well, it's got to come apart.  I'll be diving into it this week, will let you know what I find.

Thanks for all the advice!

[luvrbus]

The fuel pump should be easy to remove unless a person installed the water cross over pipe in the wrong direction I hate that when it happens that is the purpose of the ark in the pipe

[Emcemv]

Got things apart today. I can see the weep hole in the fuel pump and it is dirty and dry so no leak there.  The block below the right angle fitting in the photo is nice and clean so I think that fitting is leaking.  I would sure love to see it leak to be sure.  I was thinking of giving the engine a quick start but then I remembered that It won't shut off until it builds up some air so am not sure I should run it that long with no coolant in it.  Is there a way to start it and shut it right off again?

[sparkplug188]

Yes,  the fuel shut off lever is on top of the governor housing, next to the throttle lever.  You will see an air actuated cylinder lined up with the fuel shutoff lever.   You can push the fuel shutoff lever closed by hand instead of waiting for air pressure to build and actuate the air cylinder.  You will also see another air actuated cylinder for the high idle.  It will be pointed at the throttle lever. Don't let that one confuse you.

[luvrbus]

If you have a electric priming pump turn it on 

[wg4t50]

Just a thought, might want to take a few pictures of the fuel line positioning, don't laff, but have seen hoses connected wrong, they removed all the hoses, went to the hose shop, made new hoses, and when reinstalling, just put a hose where it would reach,  WRONG answer.
As mentioned, just a thought.
Now for a little funny about the fuel lines, a newer mechanic rebuilt his 8V-71, looked great, had very little power, got to checking, found his fuel pressure was about 15 psi  OPPS, should be 60-65 psi, he had failed to reinstall the orfice  fitting for fuel return in head, used a standard fitting.
As said, little funny.
Dave M

[Emcemv]

As Brian has said in this thread, the fuel system is simple but complex!  I think I will make a drawing of all my fuel lines so I know where they go.  I know about the orifice  fitting, that one seems dry, no leak there.  I really want to see this leak, I don't want to "think" I've fixed it! I'm going to try and run it for a few seconds tomorrow as spark plug describes.

No electric fuel pump Clifford....

[luvrbus]

On the head behind the fitting is a plug make sure it is tight looks like the one in the photo but is on the same galley as the fitting some time those are left lose and takes time before good leaks start

[bevans6]

Last year I had one of the inverse flare hose end fittings to the head develop a nice steady leak.  Fitting looked perfect but must have had a crack, it showed signs of having been over-tightened in the past (a little bit rounded off hex).  I had a new hose made and that solved the problem.  So it's possible to just have a micro-crack in a fitting.

Brian

[luvrbus]

Diffidently a high pressure leak or it would stumble on start up with a low pressure leak cracked fitting are what I find most of the time fwiw