Starving for fuel

[iac27]

Posted this on patrol4x4 but haven't had any success yet.

I've been searching threads and inspecting parts in my system to find the problem but no luck...

So here goes: I run a dual tank setup with a fuel filter for each system. Symptoms were starving for fuel under normal driving conditions all of a sudden, so I switch to the aux tank and no problem. Fuel filter is changed. Try the main tank again which is good to drive at all rpms for approx 10 min and than starts to cut out at higher rpms, lighten the gas and still starving at low rpms. Turn on assist pump installed inline by tank which doesn't help much. Switch back to aux tank and instant power back.

I've inspected the fuel pick up by removing it from the tank and blowing compressed air through it. Blew compressed air through the lines to clean out potential junk. Inspected aux pump for blockages, nothing. Tightened up hose clamps and filter to ensure no air leaks. I bleed the system by loosening a hose near the solenoid that switched tanks (before ip) and turn on aux pump to prime the lines. Also checked the filter screen by ip which is clean. Breather on tank is also clear.

Is there a screen or filter in the fuel tank that's separate from the pickup that could be getting blocked with crud as more fuel is used eventually choking off the pickup?


Suggestions???

Thanks,

Ian

[4bye4]

Hi Ian. Does this happen on full tank, half tank or just anytime. Also does it happen anytime when driving or after an hour of driving or first thing in the day. Weather, hot cold wet or anytime?
Thinking maybe fuel pump unable to lift enough fuel somtimes when on full throttle and hot or somthing weird like that?

[iac27]

Happens consistently after driving for awhile. On half a tank right now and haven't tried filling the tank yet. It seems to be independent of weather. I have an aux lift pump to help with fuel flow and that doesn't make a difference.

[4bye4]

Way out of my league I think. If it happens after a while I would think maybe the fuel pump not working when its warmed up a bit, but you have an aux pump. I was also thinking of vacuum building up in the tank, but you say you have checked the breather OK. Where is the original lift pump, is it an in tank, in line or part of the injector pump? Is it a valve or diaphragm pump? If for example it is a valve or centrifugal type of pump and it is failing when warm/hot, the aux pump may not be able to push through it. Put it this way, if you have a door that will only open half way, putting another door in front or behind it won't help. Hope that makes sense, I know what I mean maybe someone else on the forum can explain it better.

Tony.

[threedogs]

have you tried it with the fuel cap off, or at least loose

[taslucas]

Which engine have you got mate?

[iac27]

Haven't tried it with he fuel cap off. Breather works though and no pressure when I take the fuel cap off.

Drained the tank the other day and blew compressed air through part of the fuel line to the pickup to make sure it was clear. Works much better now with only some hesitation/surging at speeds of 100 km/h up hills. The last thing to try is changing the filter again as may be plugged with something? I think I made the mistake of draining my fuel storage drums, to fill my tank, right to the bottom (which may have deposits)

It's a td42t