Air in the fuel system: the diesel won't start
Diesel won't start, or starts and dies, after a filter change or running the tank dry? It is almost always air. Top up, bleed with the hand pump until the diesel comes through without bubbles and look for leaks on the suction side.
Manuals
Check step by step
Select your engine on its model page to see the relevant steps and part numbers.
- DIY
Look in the tank and make sure the fuel valve is open.
Volvo Penta gives fuel shortage as a cause both when the engine won't start and when it starts but stops again. A tank that has been run dry leaves air in the system.
Action: Top up and open the valve. If the tank has run dry, the system must be bled before you start (next step).
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Has the filter or the pre-filter element just been changed, or has the boat been laid up for a long time? Bleed the system with the hand pump.
Volvo Penta states that the fuel system must be bled after a filter change, after the tank has run dry and after long periods of non-use. Air in the fuel system is listed in the troubleshooting table as a cause of the engine not starting or stalling again.
Action: On the D1/D2, open the bleed screw on the filter bracket about three turns. Pump with the hand pump until the diesel comes out without bubbles, and tighten the screw while you pump. Start the engine and check for leaks. Other engines have the screw and pump in other places, so follow your owner's manual. Don't run the starter motor for long periods. On the D1/D2 the starter circuit cuts out after 30 seconds, and the starter motor then needs to cool for at least five minutes.
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Drain the prefilter or water separator and check the bowl for water and dirt.
Water or contaminants in the fuel is a separate cause in Volvo Penta's troubleshooting table, with the same symptoms as air: the engine does not start, starts and stops, or runs unevenly.
Action: Wait a few hours after the engine has been stopped. Place a container under the filter and drain water and dirt using the tap or plug at the bottom of the bowl. If the element is clogged: close the fuel valve at the tank, replace the element, open the valve and bleed the system again.
pre-filterwater separator - DIY
Check the suction side for leaks: hose clamps, filter gaskets, the bleed screw and the connections between tank, pre-filter and engine.
Volvo Penta states that the engine must be started and checked for leaks after every filter change and bleeding. A fuel leak must be investigated and fixed before the engine is started.
Action: Tighten loose clamps and screws, and fit the filter correctly with an intact gasket. If air bubbles return after bleeding, or diesel leaks, find the leak before starting again. If you can't find it: hand it over to the workshop.
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Replace the engine fuel filter if the water or dirt in the pre-filter suggests it has also been contaminated.
Volvo Penta replaces the fuel filter according to the service schedule and requires bleeding afterwards. A filter containing water or dirt causes the same fuel starvation as air.
Action: Wipe clean around the filter bracket, put a bag around the filter to catch spills, change the filter and bleed the system according to the owner's manual. Start the engine and check for leaks. Take the old filter to recycling.
fuel filter - Workshop
Is the diesel coming out bubble-free at the bleed screw but the engine still won't start? Check the stop control and the glow plugs.
Volvo Penta's table lists more causes of failure to start than fuel: stop control pulled out, insufficient preheating and a stuck stop solenoid.
Action: Push in the stop control and preheat for as long as the manual says. If that does not help, it is a job for a workshop. Do not loosen the injection lines yourself.
When to call a workshop
Call the workshop if the engine still won't start or stops again even though you have bled the system and the fuel flows without bubbles. Also call if diesel is leaking from a part you cannot seal yourself, or if the fault is in the injection pump or stop solenoid.
Frequently asked questions
How do you bleed a diesel engine in a boat?
On the Volvo Penta D1/D2, open the bleed screw on the filter bracket about three turns. Pump with the hand pump until the diesel flows without bubbles and tighten the screw while you pump. Start the engine and check for leaks. Other engines have the screw and pump in different places, so get out the instruction book for your specific engine.
Why won't the diesel start after a fuel filter change?
Usually there's still air in the system. Volvo Penta requires bleeding after every filter change, and air in the fuel is listed as a cause in the troubleshooting table. Bleed again and check for leaks at the new filter and seal.
Do I need to bleed the diesel after running the tank dry?
Yes. Volvo Penta requires bleeding when the tank has run dry, after a filter change and after long periods of inactivity. Fill the tank first, then bleed with the hand pump.
Where are the fuel filter and water separator located on a Volvo Penta?
On the D1/D2, the fuel filter is mounted on the engine, on a bracket with a bleed screw and with the hand pump next to it. The pre-filter with water separator is optional equipment fitted between the tank and the engine. It has a tap or plug at the bottom of the bowl where water is drained off.
Related troubleshooting
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