Possible cause | Remedy/test |
Filter bowl at fuel prefilter/manual fuel feed pump leaky | Clean or replace sealing ring/parts and tighten filter bowl |
Fuel heat exchanger leaky (is drawing air) | Replace fuel heat exchanger |
Fuel feed lines and connectors leaky (are drawing air) | Replace sealing ring and retighten threaded connections |
Eliminate cause and repeat test | If the value is still too low |
Fuel, power steering pump unit is worn or protective valve in the fuel feed pump is clamping in open position | Replace fuel, power steering pump unit |