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Update. Twice now I've let the pump run four about 4 seconds with the ignition in the on position and the engine does not hesitate to start afterward. I'm guessing I need a check valve -
Sorry I should have said that the car started perfectly prior to the pump being changed. FPR can be ruled out. It idles and runs fine.
If it was an intake leak large enough to hinder starting, wouldn't it idle like crap?
Should the cranking fuel pressure be the same as when running, ~38 psi?Leave a comment:
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If the pump is working properly and there are no other problems, normal rail pressure will be achieved in just a few turns of the engine even if the rail is empty. And you can check to see if that is happening by tee'ing a pressure gauge into the rail supply line.
The DME doesn't cut spark at any point in extended cranking. You have some other problem, quite possibly intake leaks. Which can be diagnosed by a smoke test.Leave a comment:
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Hard starting new Walbro 255 early model 2 to 1 pump conversion
As preventative maintenance, I just had a late model tank installed in my early model 325 along with a Walbro 255 Pump, and the high pressure pump deleted. The additional level sender was installed as well so my late model cluster would read correctly.
The car idles and runs great but I'm having problems with starting. It will crank forever and fire slightly in the process. If I stop and restart immediately it will start after a second of cranking. I was told that this is because the DME stops the ignition after so much cranking, so when I try again it is already primed and fires right up. Although this doesn't explain why it will keep firing slightly during the first attempt.
My mechanic believes that there may not be a check valve in the pump, and this is causing a loss of pressure in the fuel rail after the engine is shut off. Does this make sense for a Walbro 255? Does there need a be a check valve on the fuel return side as well?
Any input appreciated!
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