Air building up in fuel???

[airmech3839]

Ok here goes.....My deuce is starting to act up...I keep having to bleed air out of the fuel system... first it started after I changed the fuel filters then went away after purging lines well..... then about every other day it would need a little bit drained right after start up... yesterday it needed it at startup cause I was out of ton for 2 weeks and didnt drive it any...but it drove fine all the way to work and home...then today she needed it again at startup this time it had alot of air....once it was cleared I drove it to work with no problems....then tonight I go to leave work and she starts up fine and idles fine ( I would normally get a little loppin in the idle that would tell me air was present) so i go to leave and as soon as I get it in second gear she nearly chokes out so I stop and get out and purg the air and this time I have a ton of air in there....5 min later its clear and I drive down the road....I dont get 5 miles before sje starts hesitating.....so I pull over and purge again....get going and so here I am riding along and about 15 miles later and not more than 2 miles from home she starts up again....so I limp home and park her...

I have no visible signs of aggressive leaking or heavy seepage...

I am running WMO and all filters are new less than 100miles and new air cleaner at same time... It is a daily driver so she usually runs alot...round trip is about 37-40 miles...the only time I get oil on the pavement is when purging air out...

I will have to see tomorrow in the daylight if I can see any other explination...

 

[WillWagner]

Sounds like the issue started after a service. You mght have a can seal that pooched out of the groove. I'd start by dropping the fliters and looking at the seal rings.

 

[Earth]

...or the washer on top of the can

 

[airmech3839]

Ok I will investigate today..

 

[airmech3839]

Ok...got distracted and finally got back to work on the deuce....here is what I have found... I am certian it is not the filters now...dropped them and checked...they looked ok...and reinstalled and leak checked...well while trying that she got so much air in her that she would cutoff right after start...not even enough time to get out of truck and make it to the bleed port on top of secondary filters.....well now she will run but I have to pull out throttle cable and idle her at 1200-1500 and I dont like doing that...I tried bleeding air and it just keeps pumping out air while its running...she finally cut out again and I heard some gurgilling by the fuel control but could not isolatelocation....tried cranking and running some more and checking it out but could not find location....maybe I was hearing oil in filters cause the oil filters are right there...maybe? I am at a loss...the fuel control is damp all over so looking for a leak is almost pointless unless I clean it really good... maybe that is where I will go next...

 

[doghead]

You bleed the primary and secondary filters with the truck off and the "ignition" switch on.(not with the engine running)

 

[LanceRobson]

DH has it right. The tank pump pushes fuel and the injector pump tends to pull it. If you have air in the system without a visible fuel leak you likely have a non functioning fuel pump and a leak at the filter gaskets.

Turn the master power switch on without the engine running and you should hear the in tank pump. You may need to dismount and walk to the tank if the air pressure buzzer is sounding.

To bleed the system, turn the master switch on and open the bleed screw on the final filter. When fuel comes out you are done.

Some trucks run fine without the in tank pump, some die. I suspect a combination of a filter gasket and a weak or dead tank pump. You could have a cut or twisted filter gasket and see no leak if the tank pump is inop; the dead tank pump won't push fuel out and the injector pump is sucking air. When installing the filter cans it is imperative that you NEVER let the can rotate even a few degrees. Also, don't let the can tighten up without being level at all times. Push the can tight and square into the gasket before tightening. Sometimes, especially with the primary fuel filter, you need three hands.

Under the cover where the electrical connections are on the tank is a 2(?) amp fuse, check it first.

Lance

 

[airmech3839]

ok thanks for schooling me...in tank pump is running at least making a sound in the tank cause tank is vibrating too, and I found a slow leak at the primary bolt on top.....didnt notice it on initial leak check last time cause it was under the bracket and alt and I was looking from below... I degreassed the IP and it looksgood and clean...I dropped bowl and cleaned up and inspected seal...I think I didnt have it tight enough but bowl seral looks good and bolt seal is intact...didnt think leak at primary could be bad enough to cause that much air to be in the system....

now that my pee-pee has been oficially slapped I will discontinue the purging of air in previously said manor

 

[LanceRobson]

If the in tank pump pushes fuel out of the bleeder screw on the final filter at a high rate then it's working. If the air leak problem continues I'd keep looking at all the gaskets since they are the only thing changed from back before the air leak started.

I've got a sister who has lived in Hephzibah for over 30 years since her late husband retired out of Fort Gordon. Her two kids have raised their families in the area. Nancy and I looked at the area as possible retirement area but visiting in August convinced us that we didn't want that big a temperature change. Could you help with a pick up at Gordon if it was needed?

Lance

 

[airmech3839]

If the in tank pump pushes fuel out of the bleeder screw on the final filter at a high rate then it's working. If the air leak problem continues I'd keep looking at all the gaskets since they are the only thing changed from back before the air leak started.

I've got a sister who has lived in Hephzibah for over 30 years since her late husband retired out of Fort Gordon. Her two kids have raised their families in the area. Nancy and I looked at the area as possible retirement area but visiting in August convinced us that we didn't want that big a temperature change. Could you help with a pick up at Gordon if it was needed?

Lance

You bet!!

I understand the temprature thing!! I am from north GA and if I could work in the mountians I would in a heart beat... Allergy season is here too!! This is the worst Allergian city in the Southeast!

Got the deuce fixed it seems took it out for a 30 min road test..took the neighbor and his kids on a ride around the block once with each of his kids stopping and going and some slight cruise on I-20.... She sems to be responding after reseating the filters and cleaning up... she even seemed to have a little more spunk in her than I remember too....maybe thats the seafoam I put in this last tank!!

I let her idle a good 10-15 min before road test and then about 5-8min after done!

 

[rosco]

As mentioned, the "in tank fuel pump" should push fuel out the bleed port, on the secondary filters, with the master switch ON/engine off. i recently changed fuel filters, only to find the that there was no fuel at the bleed port at the secondary filters. The short story is that my in-tank pump runs, but doesn't pump. I have had it out, but can't see how the pump part is serviced. Is there a solution to this problem, short of complete pump assembly replacement? Thanks

Lee

 

[LanceRobson]

Lee, I've never messed with one because mine have never given trouble but a buddy has repaired several for himself and others. He's not on this site but if you search for the info, there should be a lot. I know I've seen threads about it. If that fails, try a thread title asking to be pointed in the right direction.

airmech, if it's going to idle for more than the time to warm up or cool down the turbo, use the hand throttle to run the RPMs up to 1,100 or higher (I go to about1,400). A curb idle the engine will never warm up enough for the rings to seat fully and you'll get a lot of blow by and fuel washing down the cylinder walls into the crankcase. You'll also get a lot of slobber in the exhaust which will christen everything near the truck when you hit the throttle hard. Also, in a cold engine the unseated rings allow the pistons to slap around more and the engine wears faster than when run warmer.

Lance

 

[airmech3839]

Interesting......I will remember that..


Lee I would wait a little bit before pulling the in-tank pump....It may take a while to bleed off the air with just the intank pump...it took a minute or two for mine....I left the bleed port closed for a minute and then opened it and it hissed and gurgled a little then stopped then I closed it and repeated the process about two more times till it didnt stop gurgling then opened it wide up....till the fuel came out... It seemed like forever... Just my 2 cents

 

[airmech3839]

Ok did a long road test today to work and to run some errands... Got to work and let her cool down then shut her down...she ran great.... then I get out and chock her and do a quick walk around....Did I mention I degreased the engine after getting her running....not while she was hot of course did it Sunday morning so any leaks would be obvious....no leaks noticed yesterday evening during my 30-40 min run.....but today I was walking around and saw a small fresh puddle under the IP on the ground and one about where the last secondary filter bowl is....hmmm....open side door....and sure enough the top of IP at the base of all the pressure line distributor are leaking and the last bowl has a leak.... I guess she got real warm and opened up....but I have never touched the IP leads before....Can that be fixed....is it just an O-ring or seal? I reseated the last filter bowl and I have a set of spin on filter kits in my future cause this sucks... any advice?

Tracy----now aka(drippy)

 

[airmech3839]

she drove fine home and only leaked a little from the IP head while parked after getting home... I will clean it off tomorrow and try andget a picture of what I have so it will be easier to guide me!!

 

[chevkeith]

I have been having trouble starting my 6.2 lately. The truck will start up fine and run for about 5 sec and then shut off. I can crank and crank the engine but it will not start.

I put air on the tank thru the breather tube until fuel comes out the top of the filter, and then close the filter.

I can then crank the engine a few times and it will start right up and run perfect - for a day or so. I

I have replaced the fuel filter and don't see any noticeable leaks. I would assume that the pressue in the lines would be higher than the air going in, so I would be able to notice a leak..?

Any suggestions as to where the common air entry points are? The truck is an 86 with 7500 miles on the engine.

Thanks

 

[rlwm211]

The lift pump in the tank pushes the fuel to a pump AHEAD of the Injector pump. If there is a leak in the line between the in tank pump ane the second fuel pump, you can get air accumulation and also a leak when you shut the truck off. If it were leaking fuel while it was running you would probably smell it, and see evidence of this all over the engine and underneath the truck. You may, or may not, have a fuel density compensator which can also leak and cause problems.

I would download the unit maintainence manuals for the deuce and look carefully through the portion regarding the fuel system.

RL

 

[Heavysteven]

I agree could be pump problems. If i open my drain valve on the primary fuel is literaly shoting out. Last time it did not take more than 20 seconds to fill my filters and purge the air.

I run 100% diesel with an additive

Good luck.