"B" motor with air intrusion. (1 Viewer)

[bblawless]

hey guys, new member as of today. Bought my first Toyota ever last year (1979 bj40) and I spent the winter replacing the rub and cutting/welding out all the rot etc. finally got the truck plated and was hoping to be driving it around but im having some significant issues with air in the fuel. I'm a little confused because when I first Brought the truck home, though the body was rough, the engine ran like a dream uninterrupted.

Now I've done a decent amount of research, scoured threads and im still at a loss here.

here's what I've done/replaced

- replaced ALL soft fuel lines, including the small 4" return at the firewall.
- replaced fuel filter
- replaced primer pump @ lift pump
- bypassed fuel tank to rule it out
- pressurized the fuel lines, sprayed down with dish soap water and found no evidence of leaks
- followed there bleeding procedure multiple times
- checked the particulate filter at the banjo nut feeding the lift pump


I spent a lot of time trying to bleed the air out of this thing, and I cant imagine there's so much air in the system that I haven't bled it long enough? I know this truck doesn't have a return to the tank itself, only back to the lift pump, so is there a chance im chasing a air pocket?

here's where its at now- I can prime the pump, glow up, starts immediately, runs great for a couple minutes then begins stumbling and eventually falls on its face. I can keep it alive by continuing to pump the primer, but once I let off eventually it dies again...I've had the return line from the injector rail capped and re-fed into a clear bottle of diesel, and can see air bubbles coming from the hose when immersed in the diesel.

any input would be greatly appreciated, I'm just looking for some direction on what to investigate next....and like I said, the truck ran great prior, had it driving around etc...

thanks guys.

 

[OTBT]

There is a bleeder screw at the top of the fuel filter housing sealed by an 'O' ring. I suspect that is the source of your issue. Alternatively, the priming pump itself may be the source of your air ... the seals around that priming pump are sometimes worn.

 

[duncanrm]

When you disturbed the banjo bolts did you use new crush washers either side of the banjos when reinstalling?

 

[bj70bc]

^^this
-any and all washers for the fuel filter lines (and elsewhere) oem rubber coated metal is best
-bleeder screw for sure (i capped mine off and thread sealed it when not in use)
-washer for the primer, maybe bad primer still too


soap and water wont show diesel leaks, they are in vacuum when letting air in..... unless you pressurized them like you said

 

[bblawless]

There is a bleeder screw at the top of the fuel filter housing sealed by an 'O' ring. I suspect that is the source of your issue. Alternatively, the priming pump itself may be the source of your air ... the seals around that priming pump are sometimes worn.

My engine is “B”, not a “3B”. Therefore lacking the bleed screw on the filter housing.

I did not replace the crush washers, maybe that’s my next step…I’ll pull a couple of them tonight and try and find the correct size locally.

 

[bj70bc]

You *can* re temper copper washers, so they arent work hardened anymore but the rubber coated ones are kinda foolproof

 

[bblawless]

Got pretty deep into it last night, decided to crack the banjo to the fuel filter while it was rubbing to see if there was air. And what I saw was nothing at all…. No air, no fuel whatsoever. Turns out the lift pump seized internally, so once I had it pulled I soaked it for a bit, got everything freed up.., runs like a champ now. Thanks for all the input guys

 

[bj70bc]

nice,