Return Lines Leaking

[Mr_B]

I did a search on this and found a few things but nothing answering my exact question...

The truck recieved new injectors and return line kit about 1.5 years ago and has run fine ever since. However, a few months ago it started running a little rough and I replaced the fuel filter to no avail. Then when driving it down the interstate it died adn I towed it back home and have been trying to get it started. First the electrical stuff wouldn't work and I found a few ground wires under the hood that were burnt in half and I replaced these and now the electrical stuff works ok, ie the starter turns over, head lights work, and so on. However, it still will not start.

If I shoot a tiny bit of starter fluid down the intake it acts like its trying to start but doesn't. I have noticed that the return lines are leaking at the fuel filter and at the rear of the engine where the driverside bank of injectors tie into the line going to the tank.

So my question is where do I start on trying to track down what is causing the return lines to leak? Obviously, something is either clogged or causing it to pressure up. Could it be the fuel selector switch?

 

[Dsl_Dog_Treat]

First thing you need to do is replace the return lines.

Leaking, they will cause air to back up into the system and make it a total PITA to start.

Unless you have disabled the glow plug system, please for the sake of your motor, don't be squirting ether to aid in starting.

How much fuel was in the tank when the truck died?

More that 1/4 tank? IF not the fuel pickup assembly may have rotted off in the tank. ( A common problem due to the age of these trucks)

Once the return lines have been replaced, check to see if fuel is being delivered to the filter by way of the schrader valve on the filter head.
If so, then check to see if the fuel shutoff solenoid is activating by unplugging the most forward line on the top of the IP.

From there crack the injector lines to see if fuel is being delivered to the injectors and the air is bled off.

A few more things to help ya if ya haven't found them searching yet.

 

[f-two-fiddy]

Peeps go to the FSS waaaay to early in Their diagnostics. They fail very rarely.

Try this, get someone to crank the engine, while You hold the air bleed on the fuel filter header. If You get air, You need to find out where it's leaking down. I think You already know the returns are allowing air.

Address the return lines, and try again.

 

[lotzagoodstuff]

+1 on how much fuel was in the tank when it died.

It's pretty easy to starve these things for fuel and have a tough time getting them to fire again. Put down the ether as that's the last resort (maybe not even a resort).

I would start with verifying that you have fuel at the lift pump, then at your filter head, then your injector pump, then the injectors. At the point when you have verified all that, look at your glow plug circuit and make sure they are all in good working order.

Keep at it, you'll get it to run if it ran before.

Good luck and keep asking questions, lots of help/support/experience on here.

 

[Mr_B]

The tank i was on had about 3/4 when it died on the interstate. I've tried to bleed any air from the filter to the injectors and I get fuel coming out at each point I crack open. however, I'm not sure I understand how having air on that side of the fuel supply will pressure up the return lines and make them leak. Now in the past I have run it out of fuel and I just put more in the tank, filled up the filter with AT fluid and cranked it a few times and it would start right up. Right now it acts like its not even trying and the obvious place to start is where I see fuel coming out where it shouldn't: the return lines...

 

[JPR]

Don't rule out a bad fuel pick up. I would fill the tank up and then try to start it.

The rear tank on my truck starts pulling air with 11-12 gallons still in the tank due to a bad pick up.

 

[Mr_B]

My local diesel guy told me to take the hard lines completely off the injectors (not just crack them to see if fuel is coming out) and have some one crank the motor over and watch to see if any of the injectors are spewing fuel out the top of the injector. i.e. the injector is stuck and wont close completely and thus PRESSURING UP the return lines. Well, low and behold i found one and replaced it. Now, all the others are working fine. So I buttoned things back up to start it and the returns lines are still pressuring up!!

So i took all the hard lines back off to verify that none of the injectors are getting stuck open. Not one of them are stuck open... My question is: what on earth is there that can be pressuring up the return lines?

Note: by pressuring up I mean that once the motor has stopped cranking and I stand there scratching my head I can watch fuel pushing past the joint of a hose and fitting even though its clamped. Then after a few moments the fuel stops coming out, ie the pressure has bleed off...

 

[international]

Take the hose off the rear return cap and see how she runs. sure you'll dump your return fuel down the back of your motor but it may tell you that the line to the tank is bad....and it'll kill weeds and clean the oil off.

 

[icanfixall]

Fuel tank changeover valve..... Time to replace it or hit it with a small hammer to knock it loose internally.