cumminsdriver635

My truck apparently has a fuel leak somewhere. It has been a little hard to start, and it is worse if the rear of the truck is pointed downhill. I guess it is getting air in the system. I have heard the return line can cause problems, but I absolutely can not see how the return line getting air in it would cause any problems since it runs directly into the tank. I can definately see how the supply line sucking air could cause problems though.

I havent had major problems yet because I have a carter on the frame rail. I just cycle the key about 3 times to let my lift pump prime the system, and it usually fires off with just a little sputtering. Im pretty sure if that pump wasnt there i probably couldnt get it started though.

So edumacate me. How can the return line cause problems? Supply is 3/8ths, and return is 5/16ths line correct?

Thanks for any help

Eric

somis13

you are correct on the line sizes. when the return line leaks, the engine is hard to start because the pressure bleeds off. I dont think air is getting in, its a pressure issue. my truck did the same thing. new 6" piece of 5/16 fuel line behind the pump fixed it. p.i.t.a. to change. good luck

j-fox

My 95 had a small crack in the return line at thwe rear of the head. It caused hard starting. I slid the hose on over the crack and all was well!!
It allows air into the line , which lets the fuel drain down. I had NO leakage on the truck!!!!

TIMMY22

Air bubbles work there way to the top and the injection pump is the highest point in the system.

97' CTD

Yep that pain right by the head if you just take the fuel filter canister and filter off and IC piping it ain't bad, I just deleted that stainless flex part between the cab and the motor also. I also had my sender up top of the tank rust and would suck air this way also.
Brandon

Fueling around

Start with the basics & trace the entire fuel delivery system (under the hood).
Fuel heater can burn out, and let air in the system.
Elbow to lift pump can leak.
Weak lift pump.
Loose/cracked fuel lines
Recently replace the fuel filter? Sometimes they leak.
Overflow valve?
Steel return line from pump is known to crack at the welded support bracket.
I've seen the rubber return line seep fuel as a sponge and not cause hard problems.

infidel

Think of it as picking up water with your finger over the end of straw.
Remove just a little bit of your finger and water comes and is replaced with air.

Easier and longer lasting fix is to abandon the stock line(s) and replace with diesel rated hose all the way from the tank to engine. The metal lines are also well known to eventually spring leaks.

cumminsdriver635

Thanks guys. I guess i might as well replace both supply and return lines while im there. It is still doing ok for now, but ill probably replace them pretty soon.

Eric

dieselman2300

Make sure you use diesel rated hose. I made the mistake to listen to the parts guy, a year and a half later the hoses were very spongy.
www.vulcanperformance.com has Parker diesel hose for probably the cheapest price, and the shipping is super fast.
Supply line is 3/8" and Return is 5/16"
Get about 15' of each if you have an extended/quad cab.

Fueling around

I'll probably do the swap this spring except use Synflex tube. I can get that a lot cheaper than rubber line.

somis13

I used the trident fuel line. a little harder to find if there isnt any marine shops in your area. but I was told its the best, so I went with it

96_12V

I first noticed my fuel return line leaking (air) when i returned to my truck in the parking lot it had been sitting in for three months while on an extended wilderness practicum trip. I had taken my car to our base camp, and ridden the train back to Chicago to pick up the truck for our break. I had to crank it several times, ending up with my foot pressing over halfway on the throttle pedal, to get it to start. (Looking back, I should have primed it thoroughly before I ever attempted cranking, being it was three months.) Amazingly, it held out until the last day of the break, two weeks later, when it completely refused to start at my parent's house. It was fully airlocked, my Dad and I traced fuel back to before the filter. It wound up getting sent in to our local dealer to have it all replaced alogn with the sender in the tank.

It's worked okay since - I had about two weeks of "borrowed time." I can't say how much you will have. Good luck

infidel

When the return line on my 3500 started leaking I had just a week of hard starts before it really cut loose and dumped a full tank of fuel in a matter of minutes in the middle of nowhere. Luckily I was able to buy a tank from a farmer out on his tractor pickup tank. I went from a full tank to almost empty in 50 miles.

dieselman2300

Sounds like fun.

96_12V

Re: Infidel - Wow - guess I was lucky. Not so great of mileage with fuel dumping out?