fuel problem

well guys ive a problem with my jap truck (UD) it seems to either get air into the fuel sysytem or the fuel pump isnt always working ,,usually i can get fuel pressure up by using the primer(lift) pump..then the motor will start but often "run out of fuel" again ..first it done it a couple of months ago & has been fine since ..now the past couple of days has been playing up again .. what do you guys think? .. also im thinking of wiring in a electric fuel pump to see if that helps ..but im not sure if a electric pump would have enough pressure?
thanks in advance

Some time's I've found Kenny the lift/primer pump is the problem or the 1 way valve in fuel line is problem, or the pick up in tank is cracked, only some idea's

cool .. ive fitted a new lift pump..i never thought of a 1 way valve in the fuel line ..keep the ideas coming guys .. im supposed to load up for my trip to N qld 2moz im stressed lol

I'd start looking at the lift pump those jap style push/pull ones do tend to wear out easily.

Haha looks like you beat me to it.

OK second thought cracked fuel line (steel) or rubbing on the chassis somewhere. it doesn't have to leak out and make a mess for it to suck air in.

Check the fuel filter between the tank and lift pump you might have picked up some doodgy fuel.

thanks guys ..ive checked every thing visually . . do the fuel pumps wear out much ? .. im thinking maybe to bypass it with a electric pump but ive no idea if a car type electric pump would have enough pressure etc

Hey, kenny - the Jap truck won't go? .. is it over 10 yrs old? It must be time to forget about fixin' it! .. and take it straight to Sims, for smelting down into new Toyotas!! ..

Seriously .. what kind of fuel system are we talking? Japanese Bosch or rotary? Have you checked the fuel line for rust pinholes, that could be sucking air? Any fuel line mesh filter screens that might be hidden? (got caught with one in the top of the glass-bowl fuel filter on a Jerkins .. :'( )

Trash in the tank blocking the fuel outlet? (not the first time someone's dropped a rag in the tank, and it's disintegrated over a period of time).

Blocked vent in the fuel tank or cap? Loose fuel line fitting? Partly-crushed fuel line? Leaking seals in the lift pump?
Might it be time to light an "accidental" fire under it, and buy a new one?? .. LOL ..

its 25 years old ..
japanese bosch system
fuel line seems good ..(im thinking tomorrow ill look for a mesh filter(most likely at one of the connection points?)
have previously drained the tanks after dirty fuel/filters a few months ago .. has a new lift pump
.. if i cant fix it tomorrow ill swap the Ud for a neuss powered acco a perkins or neuss is a excellent choice of motor if you work on hourly rate . . just dont forget to tell the missus you will be late for dinner



.. just thinking if there is a dirty mesh screen/filter somewhere the lift pump probably would suck the fuel past it anyway?

LOL - Re those mesh screens, they hide them everywhere. Sometimes they are inside banjo fittings. The Jerkins in the ACCO gave me grief for months with a similar problem. Pump up the lift pump and it would go. It would run for quite a while, then start dying in the ar$e. Stop and pump, go again .. repeat, ad inifinitum.

One day, I had the lift pump fuel bowl off, cleaning it for the dozenth time .. and just happened to look up inside the lift pump body, and - voila! - there was this little flat brass mesh screen, stuck underneath the seal washer for the glass bowl.
Even when I'd pulled the seal washer out, the screen stayed in there. Had to prise it out, then wash all the congealed fluff out of it .. and then, when I put it back, it was like I'd fitted a 454 Chevy V8 ...... well, nearly ....

Check fuel line elbows for gunk blocking them, too. Often crap will go right through a line, then it gets stuck, right in the middle of an elbow .. :'(

hi Kenny the mesh screen you will be looking for from memory is screwed inside the banjo fitting on the inlet side of the lift pump. its about the only thing that will stop a ud. while your at it i would pull every banjo fitting out from the tank to the filters and check them and blow out the lines. go to your diesel injection shop and buy a fistfull of the proper copper washers that fit and replace them while your at it.
as ron said too make sure your fuel tank breather is clear . if you break down in rocky i could rescue you