Fuel Filter light but clean filter!

[matt v]

My son's 79 series fuel filter light comes on but upon inspection the filter is only slightly dirty. This has happened a number of times. He changes the filter and before long (approx 100 km) the light re appears. Any ideas? The tank has been drained a few times and all fuel samples ok.

 

[Grimbo]

Is it a "blocked filter" warning light ? or more likely a "water in fuel" warning light ?
The latter is often the sensor itself or the wiring too it . The sensor works by measuring the resistance through the fuel and as water is a better conductor than diesel it will set off the warning light.... try a known good or new WIF sensor

 

[matt v]

Is it a "blocked filter" warning light ? or more likely a "water in fuel" warning light ?
The latter is often the sensor itself or the wiring too it . The sensor works by measuring the resistance through the fuel and as water is a better conductor than diesel it will set off the warning light.... try a known good or new WIF sensor

Thanks for your reply Grimbo. It is a Fuel Filter light. My son clears the code and it comes on again before long, 100ks? Filter is clean as he checks or replaces.

 

[Brett]

I'm pretty sure the sensor works on detection of a pressure drop. I can't find the info now, but it can't detect a dirty filter, as long as the fuel pressure is correct the light is off. If it detects a drop due to clogged filter or water in the filter bowl, it causes the warning lamp to illuminate.

 

[Russ1968]

Thanks for your reply Grimbo. It is a Fuel Filter light. My son clears the code and it comes on again before long, 100ks? Filter is clean as he checks or replaces.

Hi, did you find the problem in your sons landcruiser, I have the same problem, light comes on after approx 80km

 

[Shayne]

Filter not tight enough to seal ? filter housing failed which is a maddening hard to diagnose because it lets air in but doesn't leak fuel ?

Suspected primer pump failure on my 80 I wrapped tape around it and filled the makeshift cup with spray silicone oil and left it overnight . Its never been a problem since . Silicone replenishes rubber .

 

[Towpack]

On the 1HD-FT in the 80 series, the fuel filter warning light is operated by a float switch screwed into the base of the filter.

 

[Russ1968]

Filter not tight enough to seal ? filter housing failed which is a maddening hard to diagnose because it lets air in but doesn't leak fuel ?

Suspected primer pump failure on my 80 I wrapped tape around it and filled the makeshift cup with spray silicone oil and left it overnight . Its never been a problem since . Silicone replenishes rubber .

Looks like I found my problem, the light always came on after approx 80kms, fuel tank vents blocked, found the tank has collapsed from the suction of the fuel pump. New tank tomorrow, flush and clean vents, fingers crossed we can get back on the road with out issues.

 

[Shayne]

I just figured water has been ruled out by fuel testing but air would cause similar problems .