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#1
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560 SEL - Hard to Start
1991 560 SEL, 150 K miles - over the past two months the engine has become increasingly difficult to start, most noticeably when at operating temperature... engine can be running, shutoff and then a restart attempted... but the accelerator pedal has to be depressed fully and the engine cranked for several seconds before it will start. Once running, the vehicle's performance was a bit sluggish, with a noticeable stumble when moderate acceleration was required. Occasionally, when hot, or frequently, when cold, the engine would start immediately without any need for depressing the accelerator pedal. Inspection of spark plugs reveals a rich mixture. Plugs, distributor cap, rotor and air filter are new. Cam and crank timing is correct, engine vacuum lines and connectors are intact and free of leaks. Check engine light is not illuminated and on-board diagnosis with pulse counter reveals no fault codes. Oxygen sensor appears to be the factory original.
Replaced the fuel pressure regulator, both fuel pump check valves and fuel filter. Performance is significantly improved but difficulty in starting still remains. Installed an EHA of known quality, with no noticeable improvement. Can a faulty fuel accumulator result in a difficult hot restart attempt? Any suggestions as to the source of this starting difficulty? |
#2
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A bad fuel accumulator will cause hard hot restart. But not for immediatly restart or after engine cools off.
What happens the bad accumulator will bleed the fuel back into the tank, than you can have vapor lock. |
#3
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And that's the problem - difficult immediate hot restarts. And cycling the pumps several times before attempting the hot restart makes no difference.
Pulled the cold start valve and checked for leaks - valve is dry regardless of engine operating temperature. Perhaps leaking injectors? |
#4
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Fuel Accum.
I recommend you check the fuel lines and if no leak is found, replace the fuel accumulator.
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1989 420 SEL |
#5
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Have you checked the position of the air flow flap? If it's sitting too high or low it will give a hard starting fault.
Push it down gently, it should have some freeplay. While holding the air flow flap down clean the air flow meter housing near where the flap is at it's rest position. Check that where the flap sits is where it has the least clearance between the flap and the housing. If there is a big difference between the flap rest position and where it should be resting then you'll need to adjust it.
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Alex. MB Tech Sydney, Australia Volvo 122S W201 190D 2.5 manual W202 C240 W203 C32 |
#6
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leaking injectors and a leaky fuel distributor will also cause hard hot starts. sounds like if you give it enough air with the throttle wide open, it finally matches the fuel in the engine. good luck, chuck.
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#7
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2 things I just thought of.
Have you checked the fuel mixture/lambda? After engine is upto temp shut it down and let it sit for 2-3mins. Press down the air flow sensor and smell inside the fuel distributor. If there is a very strong fuel smell the the fuel distributor might be leaking directly into the manifold through the fuel distributor plunger..........just a thought
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Alex. MB Tech Sydney, Australia Volvo 122S W201 190D 2.5 manual W202 C240 W203 C32 |
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