Quote:
Originally Posted by barry12345
More likely the valves in the lift pump are not sealing at all. The primer pump uses the valves in the lift pump to get fuel on the upstroke and seal on the downstroke.
A good preliminary test is the primer pump should get harder and harder to use until the relief valve on the injection pump opens. This usually makes a kind of squeeling noise.
If this is not happening and the pressure of the strokes is remaining constant. I would rekit the lift pump.
If This car used waste vegetable oil for fuel the odds of a problem in the lift pump existing also increases .
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If the bypass spring is broken, you can not build pressure, and it is difficult to bleed the system.
The valve kit most common to fail is MB# 0000900210
http://www.peachparts.com/shopforum/mercedes-parts-reference-library/327357-0000900210-om615-616-617-lift-pump-valve-kit.html
If these valves do not seal, the primer pump is useless.
If the primer pump is mis-installed = two copper seal rings, one ring not seated or no seal ring = it will suck/pump air, usually failing to prime.
Fuel injection pump starvation with a good lift pump
Fuel injection pump starvation with a good lift pump - PeachParts Mercedes ShopForum
Fuel pressure relief valve adjustment
Fuel pressure relief valve adjustment - PeachParts Mercedes ShopForum
lift pump test
1979 300td -- Can anybody walk me through a lift pump test? - PeachParts Mercedes ShopForum
fuel pressure
fuel pressure - PeachParts Mercedes ShopForum
http://www.peachparts.com/shopforum/diesel-discussion/249082-fuel-pressure.html
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