Air entering fuel lines but only on rough trails (1 Viewer)

[WideAngleWandering]

I joined the local 4x4 club here in Guatemala for a ride up to Cerro Las Minas north of Guatemala City. The trails were pretty rough - steep, rutted, rocky good stuff.

About 10km in, my engine started to stumble and then died. It wouldn't start back up, just cranking.

We cracked the bleeder by the fuel filter and found quite a bit of air in the line. Checked the bleeder on the IP and it was fine. Once bled, it started and ran fine for about 1km. This process repeated itself 5 more times until I made it to camp. Today, it started acting up within a few minutes of setting out. I was going more like 100-500 meters before having to stop and bleed the air out.

Unfortunately I had to abort and took a side-trail to the highway, leaving the rest of the group to their day of awesomeness. I was pulled most of the way out by a diesel 80 series (wow - very impressed with the 1HZ motor. I don't think I could have pulled him out.)

Back on the highway, it ran like a dream. I drove 150km from near sea level in Rancho to Guatemala City, up to 2000 meters around San Lucas and then descended sharply to Antigua. No issues.


It happens when I'm inclined.
It happens when I'm level.
It happens when I'm crawling or accelerating or idling.
It happens when ambient temps are low or high.
It happens when I'm on trails but not paved roads.

It seems that it only occurs after I've jostled and sloshed the fuel around on a really rough patch of the trail.

That said, with the tank near empty, I tried to recreate the problem on a rough trail near my house. I sloshed the fuel around and ran up and down that trail fast and slow but couldn't get it to die.

I had to get towed out. The only other vehicle to fail the trail was a Suzuki Samurai. I need to redeem myself. Ideas?

 

[WideAngleWandering]

Cerro Las Minas Fail by WideAngleWandering, on Flickr

 

[roscoFJ73]

Have you tried removing the fuel filter and replacing them carefully to make sure you have a good seal?

 

[WideAngleWandering]

Gave it a twist to see that it was tight but I didn't remove & reinstall.

Will do. Problem is, right now I don't have a good way to recreate the problem to know if I've fixed it.

In any event, suggestions like this are what I'm after.

 

[lostmarbles]

If you get air in your fuel only when travelling in rough terrain it sounds to me like you may have a fracture in a metal fuel line that's letting it in (with the fracture/crack opening sufficiently to let air in only with the heavier vibrations).

 

[WideAngleWandering]

If that's the case, I imagine it would be tough to spot.

Pre-emptive replacement of fuel lines - good or bad idea? I am sometimes suspicious of the quality of replacement parts and I hate to swap out a good Toyota bit for whatever i can find locally.

 

[lostmarbles]

If that's the case, I imagine it would be tough to spot.

Pre-emptive replacement of fuel lines - good or bad idea? I am sometimes suspicious of the quality of replacement parts and I hate to swap out a good Toyota bit for whatever i can find locally.

I had a troublesome leak. It didn't open up only on rough roads like yours but instead it constantly prevented my BJ40 from starting (without first priming/purging) whenever it was left parked overnight.

I found the leak's location by mildly pressurising my fuel tank and placing facial tissues around areas where I thought the leak may be.

Finding tissues wet with diesel identified my leak which was in an area where there was vacuum rather than pressure (and that's why the leak location was revealed only when the tank was pressurised).

I used a motorcycle handgrip and air gun to pressurise my tank:


And here's where one of my lines had fractured from engine vibrations:


And this little hose is another "below-atmospheric-pressure" area where leaks are likely on my BJ40:


If it is from fuel sloshing around in your tank, perhaps you have a fracture in the pickup tube inside you tank .... but hopefully the leak's in a more accessible place because that one would be impossible to check without removing the pickup tube...

 

[WideAngleWandering]

Ok, good thoughts. I will undergo a search. Have a shop here in town that I work with and I bet they can pressurize the tank.

The attachments aren't visible to me. Are they part of another thread you could link me to?

 

[lostmarbles]

...
The attachments aren't visible to me. Are they part of another thread you could link me to?

I stuffed up.

Fixed now..

 

[Tapage]

if you still have the factory water separator ( frame pass side ) check on that too .. oooh 2H what a delicate engine for air in the line ..

 

[snowboardonsnow]

is it only when under a good amount of load or throttle? I found a air leak in my priming pump but I would only feel it under close to full load for over 30 seconds. I would pump your tank up with a air hose and find the leak if no leak then it is either A at the priming pump/lift pump or B in the hard line that is inside the tank itself, I have seen those go.

 

[roscoFJ73]

Ok, good thoughts. I will undergo a search. Have a shop here in town that I work with and I bet they can pressurize the tank.

The attachments aren't visible to me. Are they part of another thread you could link me to?

What kind of clamps do you have on the fuel lines? If you still have the original finger clamps ,they have probably lost their tension.
Diesels often suck in air without leaking fuel,thats been a recurring problem for owners especially around the primer pumps and in my case,around the finger clamps on my 1HZ

 

[WideAngleWandering]

is it only when under a good amount of load or throttle?

It only seems to happen when the chassis flexes, regardless of load. It died on me at one point while I was idling (to keep the power brakes/steering alive) and being being towed.

Thanks for the suggestions. I'll check those.

What kind of clamps do you have on the fuel lines? If you still have the original finger clamps ,they have probably lost their tension.

There are still some finger clamps. The only ones I remember seeing were on the rubber (return?) line near the lift pump but I'll check.

Gracias all.

 

[samwise]

Someone already mentioned this but check your fuel pickup at the tank. Mine had somehow fractured in the metal hardline, and would occas take in air, I made it worse when I replaced the fuel lines etc by pulling on it, when I was trying to find the problem, but didnt know as you cant see it.
After it was worse I found it by reaching up and could feel where it was partly broken. Had to drop the tank (what a pain) and replaced with a new pickup, from a fj60 I think, was cheap at least, about $30.
Best wishes with your search.

 

[WideAngleWandering]

if you still have the factory water separator ( frame pass side ) check on that too .. oooh 2H what a delicate engine for air in the line ..

And we have a winner. The leak was on one of the rubber lines going to the fuel separator. It had a very small but clean slice that just barely went all the way through. It took some flex to get it to open up.

On the plus side, I now have a shiny clean tank, water separator and all new rubber fuel lines from the tank all the way to the fuel pump.

 

[lostmarbles]

And we have a winner. The leak was on one of the rubber lines going to the fuel separator. It had a very small but clean slice that just barely went all the way through. It took some flex to get it to open up.

On the plus side, I now have a shiny clean tank, water separator and all new rubber fuel lines from the tank all the way to the fuel pump.

Glad you got it sorted..

 

[hj 60]

Obviously the Suzuki guy used his knive

tankstuff:

77242 TUBE, FUEL MAIN, NO.2
77252-60050 HJ60, W/SEDIMENTER (08/1980 - 10/1984)
77252-60051 HJ60, W/SEDIMENTER (11/1984 - 07/1987)
77242A HOSE, FUEL, NO.1 (FOR MAIN TUBE, NO.2)
95332-08020 HJ60, *H, L=200, ID=8
95332-08030 HJ60, *H, L=300, ID=8
77242B HOSE, FUEL, NO.2 (FOR MAIN TUBE, NO.2)
95332-08020 BJ60, HJ6*, *H, L=130, ID=8, W/SEDIMENTER
77243 TUBE, FUEL MAIN, NO.3
77251-60191HJ60..EUR, GEN (07/1983 - 10/1984)
77251-60192 HJ60..EUR, GEN (11/1984 - 07/1987)
77251-60211 BJ60, HJ60, W/SEDIMENTER (07/1983 - 10/1984)
77251-60212 BJ60, HJ60, W/SEDIMENTER (11/1984 - 01/1987)
77243A HOSE, FUEL, NO.1 (FOR MAIN TUBE, NO.3)
95332-08020 BJ60, HJ6*, *H, L=130, ID=8, W/SEDIMENTER
95332-08030 HJ60..EUR, GEN, *H, L=280, ID=8
77243B HOSE, FUEL, NO.2 (FOR MAIN TUBE, NO.3)
77256 TUBE, FUEL EMISSION, NO.3
77256B HOSE, FUEL, NO.2 (FOR EMISSION TUBE, NO.3)
95332-06030 BJ60, FJ60, HJ60, *H, L=240

Click and open to zoom the picture in picture:

77256 TUBE, FUEL EMISSION, NO.3 if this one leaks no problem, I replaced with rubber hose.
The double U-shape is if for if the vehicle is on its side and then it should not empty.

 

[WideAngleWandering]

Obviously the Suzuki guy used his knive

Hah, I hope not. There were two suzukis - the other one lost his transfer case and I happened to have the right bolts to get him back on the road. Couldn't help the first one though - failed clutch.

Thanks for the tank info.

 

[jzilla]

Obviously the Suzuki guy used his knive

tankstuff:

77242 TUBE, FUEL MAIN, NO.2
77252-60050 HJ60, W/SEDIMENTER (08/1980 - 10/1984)
77252-60051 HJ60, W/SEDIMENTER (11/1984 - 07/1987)
77242A HOSE, FUEL, NO.1 (FOR MAIN TUBE, NO.2)
95332-08020 HJ60, *H, L=200, ID=8
95332-08030 HJ60, *H, L=300, ID=8
77242B HOSE, FUEL, NO.2 (FOR MAIN TUBE, NO.2)
95332-08020 BJ60, HJ6*, *H, L=130, ID=8, W/SEDIMENTER
77243 TUBE, FUEL MAIN, NO.3
77251-60191HJ60..EUR, GEN (07/1983 - 10/1984)
77251-60192 HJ60..EUR, GEN (11/1984 - 07/1987)
77251-60211 BJ60, HJ60, W/SEDIMENTER (07/1983 - 10/1984)
77251-60212 BJ60, HJ60, W/SEDIMENTER (11/1984 - 01/1987)
77243A HOSE, FUEL, NO.1 (FOR MAIN TUBE, NO.3)
95332-08020 BJ60, HJ6*, *H, L=130, ID=8, W/SEDIMENTER
95332-08030 HJ60..EUR, GEN, *H, L=280, ID=8
77243B HOSE, FUEL, NO.2 (FOR MAIN TUBE, NO.3)
77256 TUBE, FUEL EMISSION, NO.3
77256B HOSE, FUEL, NO.2 (FOR EMISSION TUBE, NO.3)
95332-06030 BJ60, FJ60, HJ60, *H, L=240

Click and open to zoom the picture in picture:

77256 TUBE, FUEL EMISSION, NO.3 if this one leaks no problem, I replaced with rubber hose.
The double U-shape is if for if the vehicle is on its side and then it should not empty.

Where does each end of number 3 connect? Photo?