defueling

[turf]

hey experts!

im having a bit of an issue with the bus. on the way to palooza, second day of driving, maybe my fourth or so tank of fuel after about a year of storage.

i would describe this as defueling..... when i am running all out.... 67 mph, all of a sudden it developed a noticeable "defueling". i was like taking your foot off the gas. then it slows down about 1 mph and starts rollling again.

i had a spare fuel filter and tossed it on at the first sign of this. it felt like a clogged .... something.
no change.
it seems to happen mostly at wot, foot on the floor. day 1, nothing. day 2, it started mid morning. seems worse when at half a tank or lower. symtom goes away with a full tank.
the first time i was experiencing it, it seemd to get worse the harder i try. over the course of the day.... if i ran 65, it wasnt a problem, back up at 67, and it would appear again.
Day 3 was off the interstate so only 55mph. no problems at all.

i've played with my afc....
so the thing is slid forward and the smoke screw turned all the way in. if i had to guess, the fuel thingy is falling of the end of the fuel thingy.

any advice appreciated and any fuel tips appreciated.

i took a video of my bus drive and the defueling, not sure you can hear the issue, but you sure can feel it. 3 or 4 times during the vid, i felt the fuel give up and roll down a bit slower.
my wife thinks it was the wind
maybe

https://www.youtube.com/watch?v=aho91aPNdNI

[Iceni John]

Do you have an electric fuel pump or fuel booster pump? If so, maybe it's failing intermittently, and if so, maybe it's nothing more than a bad electrical connection, maybe? Is a fuel line or hose pinched somewhere, restricting fuel flow enough to partially starve a WOT engine but allowing enough fuel at lower RPMs? If it was an old English car I would say it had vapor lock: can diesels also get vapor lock?

John

[mmoore6856]

anytime you suspect a fuel filter issue and you change it you should cut the old one open and see if it is the issue. it could be algae as it likes to grow in cheap fuel if it sits for a while. i use a additive that prevents it while sitting for a while

[Booyah45828]

Fuel tank pickup got a pin hole in it sucking air below half a tank? Failing lift pump possibly? Bad fuel from your last stop?

How'd the fuel in the filter look? If this sits a bunch less then full, water/algae might be an issue. That would typically remedy itself temporarily with a new fuel filter, but if it's bad bad the new filter might already be plugged.

I'm definitely leaning toward a fuel supply to the injection pump issue.

[joeblack5]

Morning turf, no expert by any means but I thought that some 5.9 IP had issues with the internal transfer pump..potential causing severe damage to the IP itself. Maybe different pump then you have. Nevertheless the easiest way to diagnose file problems is putting a pressure gauge on the pump to see if your symptom originates there.

Good luck
Johan

[TJones]

If it's worse with less fuel in the tank my vote would be failing lift pump or cracked fuel line.

Ted

[bus-bro]

Usually there are two filters in series, a primary then a secondary. The primary filter is before the fuel supply pump, closer to the fuel tank. A clogging primary filter could explain your symptoms.

YMMV! My experience is old school diesels.

[cadillackid]

the dirtier the fuel filters get on a diesel where the lift pump is in the injection pumpo, the more susceptible you asre to sucking air in fromt any fuel lines that are pump-side of the filters.. or if a filter's gasket isnt perfect etc.. you wont see a leak as its negaitve side, my vote is definitely to check and / or change filters.. and also insoect for possible leaks in the linesa coming into the lift pump.

[turf]

thanks for all the replies!!!! the support from peeps here is amazing. i wanted to pull over and chat up someone that knows diesels, and this forum rises to the occasion everytime.

i don't think i have an electric lift pump. i have run the motor more than once without a a battery or alternator. i think this is all mechanical.

ima crawl under today and get the filter number off that primary filter. and go pick up a new one. i had drained the water from it initially, the same time i changed the other filter, but failed to mention that in my post. if its paper filter and water separator, then for sure it could be clogged.

that leaves failing lift pump or air leak. can i get back home...1200 miles on a failing lift pump? is this going leave me stranded?

one step at a time.

[La Camioneta]

Originally Posted by turf

ima crawl under today and get the filter number off that primary filter. and go pick up a new one. i had drained the water from it initially, the same time i changed the other filter, but failed to mention that in my post. if its paper filter and water separator, then for sure it could be clogged.
.

How much water are we talking about and was it rusty or otherwise gross?

Try some 'Iso Heet' (red bottle) to help with any remaining water and probably get a couple more fuel filters to deal with any crud that passes.

Good luck and keep us posted.

[turf]

welp....

made it home, but the last day home was an adventure.

the bus made it into california fine, they have a 55 speed limit, which kept me off the pedal and the problem stayed at bay.

on the way out of cali, (after a tank of $7 diesel) the problem showed back up again. arizona roads suck. the problem reared itself both times heading into and thru arizona. arizona roads have lots of potholes, and rattled my teeth out of my head by the time we crossed the state.

i could go 65, but it would slow down to 58 and speed back up to 65. like the throttle was on a spring or something.

as i passed back by Albuquerque on the way home it got suddenly worse. it could only go 48, i pulled off the highway, lost most power and barely chugged into a parking lot.

i popped open the doghouse and diesel fuel was everywhere, just dripping off the inside doghouse and the engine. it took a few minutes to see the culprit, one of the fuel lines had rattled loose from the injection pump.

i bolted that back up and the truck started and seem to run normal again.

i got back on the highway, and started thinking about what had happened. i also started to hear some noise like windchimes coming from the vicinity of the fuel pump. i had neglected to bleed the injector and the windchime noise made me pull over at the next exit and go through and bleed all injectors and investigate the noise.
3 of 6 injectors bubbled air out, the last three seem to spray pretty solid.

underneath, is an bracket for something. nothing is attached now, but it looks like there was. the bracket curves around the air compressor and was barely hanging by a single bolt, making the wind chime noises i was hearing.

i'll post a picture of the bracket and maybe you all know what it was for.

after i bled the pump, the motor sounded like a sewing machine. noticeably smoother, my better half even commented how much better it sounds.

still the surging

ok we go a bit more, and the pedal snaps..... drive cable, but not the drive cable. a throttle connector ball joint with springs.... snaps free and no pedal.
that fix was right on the side of the road as you dont have time to move afterwards.

i had some zipties, and 3 ties later i had the cables reconnected pretty tight.
all is good for a bit. no surging, running like faster than usual (71-72mph).
then.... another snap.
this time it was not my zipties, the throttle cable had come loose from its holder bracket. got that re-attached and tightened.

i brokke the zip ties one more time and had to repair again to get home but i made it.

so, i think the throttle cable was lucy goosey and not giving me all it could. i think i was sucking air with the injection pump. i hope a new linkage to replace my zipties will fix it right up.
i still don't know what that bracket is for.
its 0 outside today at home. 2 days ago, i was on the beach, and got sunburned, today im shoveling snow out of my driveway

[turf]

this is my wind chime bracket. there is one bolt holding it on in the center, in 1 picture you can see the end of that bolt.

the bracket is j shaped, and goes around what i think is the air compressor.

views of either side (front or rear), from the bottom looking up.

the broken fuel rod is part #22 on the diagram.

[shortbus4x4]

That bracket looks like rear support for the compressor/power steering pump. I've seen the gear housing cover break from that bracket being MIA or the bolts being loose. Eventually the leverage of the compressor breaks the cover and it's not a cheap or easy fix. Loctite those bolts.