Fuel bleed down

[DVolk]

When my 92 sits for awhile the fuel seams to bleed down , im shure its a fuel supply line , any one know a easy way to track it down ? , knowing my luck its at the tank .



it runs fine but it can be a real SOB to start though !!!!



Any ideas ????

 

[HHhuntitall]

After checking and maybe replacing all the rubber fuel lines and O-rings in quick connects, and not finding a problem, an inline 3/8" check valve. I have some that open at 3-4psi and hold up to 250psi... ... I put it inline between the lift pump and fuel filter housing. http://www.oreillyauto.com/site/c/d...keyword=3!s!8+check++valve&pt=N0284&ppt=C0142

 

[PToombs]

I blow some air into the tank with a blowgun and a rag, they usually show up like that. Look 1st to make sure everything is dry so it's easy to spot.

 

[DVolk]

I have never looked at the fuel heater ive been wondering if its that ? i dont smell any hint of fuel any place either , when it does fire its kind of whitish blue smoke as well , and its getting to be a sob when warm as well , do i need to go to cummins to get everything to replace the gaskets for the fuel heater ?, afew years ago the pump backed off on me but it started fine but this is getting worse now

 

[DVolk]

How did you uinstall the check valve ? ive been thinking about a electric fuel pump as well , butit runs good , just bleeds down

 

[NIsaacs]

when it does fire its kind of whitish blue smoke as well , and its getting to be a sob when warm as well





How many miles on the injection pump? Sounds kind of suspect.



Nick

 

[HHhuntitall]

I replace the fuel line from the lift pump to the filter housing with rubber line, and add the check valve inline with hose barbs and clamps..... The lack of a fuel leak makes me think it's in a line, like one of the o-rings at the top of the tank, one of the plastic lines there, such as from dropping the tank, or maybe the plastic has begun to let loose from the steel part of the lines. Maybe an O-ring up by the lift pump as well... . Once primed, there is diesel in all the lines and injectors, so it wouldn't matter if it bled back to the tank, as it would pull diesel up. Air has to be getting in there somewhere. It could be an o-ring in the pump, but it's odd that it's not leaking at least a little when running, but it does happen..... If the pump is leaking air in, then the check valve keeps the fuel lifted up to the pump from the fuel tank from pulling vacuum on the fuel in the pump, which sucks air... . It's a cheater type fix. I've had VP pumps do the same thing, and it only buys a little time... .

 

[JLEONARD]

I have always used the air gun into the tank as Pete described. That has always made the leak show up for me. Having two people, one to use the air, the other to look makes it easy.

The one exception was when my one year old replacement lift pump crapped out. That was actually a "leak" but it was internal to the pump so it didn't show up.

 

[DVolk]

My truck has around 212K on it , the lift pump took a dump a few years back , it kind of did the hard to start thing then , but not like now though . Only time the tank has been lowerd was back in 96 when i bought it as the sending unit didnt work . If the fuel line o rings were bad wouldn't there be a fuel smell ? I hope its not the pump no $$ for that id like to get anouther 100 K on it that when the neighbors died at 300plus K

 

[HHhuntitall]

Orings could be just seeping enough air to allow it to lose prime. I'd suspect the ones up by the bellhousing. Could be several other things, too. The plastic lines can seperate at the place where they're bonded to the steel, they can crack from vibration, and if they've been replaced, typical rubber line will crack and start allowing air to get sucked in. Typically, for me, what I find are the O-rings on the quick connects or cracked lines... .

 

[DVolk]

I gues when i go get the o ring for the fuel heater ill get fuel line o rings as well, then ill find out
hopefully a simple fix , the lines look good but who knows ?

 

[HHhuntitall]

I suspect you will, before too long!! :-laf

 

[Diese-juice]

Yea... Run new fuel lines from the tank to the lift Pump/return. 3/8" and 1/4" IIRC. Get rid of all those quick connectors.
Handle the connectors on the fuel module/tankvery carefully. You don't want to snap those fittings off. Just rock your bed up to the passengers side to access the tank.

 

[DVolk]

OK, were do you get the fuel line O rings ? , yes id be better just tossing the plastic crap , but im trying to buy some time as i want to transplant whats there down the road she is getting beat up , I bought the fuel heater O ring , dodge dealer was actally cheaper than cummins and cummins is 40 miles away , but idot at the dealer says no listing for fuel line o rings any ideas for fuel grade O rings ??

 

[Diese-juice]

Get rid of those oringed fittings all together... Just go w/ the diesel rated 3/8 and 1/4 and use good ss clamps.

 

[HHhuntitall]

Good nitrile O-rings from the parts house will do, they should have a big box you can pick from, and maybe even help you match them up if they're worth a durn. While I agree they're not the best fitting around, they've run many a mile on many a truck. Look for cracks or weak spots in the plastic. If you do find anything, you can easily cut the end off and run some rubber line over it and double clamp it if you like.

 

[mysteryman]

Hi Don,

I would highly recommend leaving your stock pump as it is. Electric pumps that are not matched properly to the ve injection pump can cause a lot of problems. One of which is a locked up ve pump. Speaking of pumps . check the pressure on your lift pump . the diaphragms often crack and or the valves will get stuck allowing the fuel to drain back.

Also check where the fuel line connects to the sending unit on the tank. The o ring can shrink allowing a vacuum leak. DO NOT USE OLD STYLE NITRIL O RINGS! The new diesel fuel will cause it to shrink in short order.

I also noticed that you own a 69 Pete ? I own a 68 long nose wide tilt hood with air ride. it sports a 318 detroit with an RTO915 Road ranger . It is all stock as originally shipped. I have owned it since 1984. You are welcome to call me anytime wiht your truck truck problems... ///M/M 301-219-7399

How did you uinstall the check valve ? ive been thinking about a electric fuel pump as well , butit runs good , just bleeds down

 

[JLEONARD]

Nitrile (aka NBR/Bunan) and Viton are compatable with diesel fuel according the the chem compatability chart we use at work to design valve seals.

Our company has madeand continues to make thousands using Nitrile seals.

 

[HHhuntitall]

Hi Don,

I would highly recommend leaving your stock pump as it is. Electric pumps that are not matched properly to the ve injection pump can cause a lot of problems. One of which is a locked up ve pump. Speaking of pumps . check the pressure on your lift pump . the diaphragms often crack and or the valves will get stuck allowing the fuel to drain back.

Also check where the fuel line connects to the sending unit on the tank. The o ring can shrink allowing a vacuum leak. DO NOT USE OLD STYLE NITRIL O RINGS! The new diesel fuel will cause it to shrink in short order.

I also noticed that you own a 69 Pete ? I own a 68 long nose wide tilt hood with air ride. it sports a 318 detroit with an RTO915 Road ranger . It is all stock as originally shipped. I have owned it since 1984. You are welcome to call me anytime wiht your truck truck problems... ///M/M 301-219-7399

Hey MM, what are you calling "old style" nitrile? I was unaware of a chemical change... . I haven't had any malfunctions with any of the generic Nitrile rings I've used... . I keep a lot for A/C service, and the ones I have are supposed to be chemical resistant..... Don't want to start having any malfuntions, either!

 

[DVolk]

I think Im 99% shure of the problem , when i pulled the fuel filter off , guess what came with it ?, The fuel heater , of corase the o ring is paper flat . But stupid me , turned the wires out and the throttel linkage bracket hits . So i got to loosen it back up

and turn the fuel heater a 1/4 turn . I hate that stupid fitting with a screw driver slot , any buddy know of a better one or a scocket that fits it , i hope i don't mess it up takeing it off ???????, Wish me luck .



MM My old Pete runs like a raped ape puts over 525 to the ground with a 15 and 4 trans but pad suspention , 350 small cam



I got a 52 Autocar DC100 with a 220 Back Drop cummins ill trade for a newer 3 axel tractor