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Discussion Starter #1
i bought my abandoned 79 Sprint Veloce about a year ago, and replaced the fuel pump to get it running again. i got a standard fuel pump from autozone after doing extensive research and it has been working quite well. however, my problem is i am getting a fuel smell in my oil, and my oil gets quite thin between changes. even after replacing my spica pump with a known-good one, im having this issue again. based on my "limited" knowledge of the spica system, the system is required to have 12-15 psi of fuel going into the (spica) pump. but as with any fuel system, the pump has a return fitting that allows excess fuel to leave the pump and go back to the tank. there is also a small fitting on the "in" line that limits fuel pressure as well. so is it really possible to over-feed the system with fuel, and then is it possible for that excess amount of fuel to somehow bleed into the oil system? or do i just simply have a bad spica pump?

thoughts?
thanks.
 

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Push hard and live
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I recommend you get the book published by Wes Ingram that will guide you through all diagnostic efforts. However, a few quick responses...

My understanding is that you want roughly 17 - 19psi at the fuel filter inlet in the engine bay. This pressure is maintained by a combination of the relief valve in a correctly-specified pump and the OUTLET orifice that is in the Spica pump. The rear fuel pump should have three ports - an inlet, an outlet, and a pressure overflow that returns fuel to the tank. If your pump has only an inlet and an outlet (common in modern replacement pumps) then you generally need to add a pressure relief valve back at the rear that returns the overpressure to the tank. The three-port pumps have a built-in pressure relief valve.

The outlet calibrated orifice on the Spica pump is sized to work with the original pump to maintain the desired Spica inlet pressure. It may be that the acceptable inlet pressure is 12 - 20 (my book is out in the shop). However, it is common that a non-original pump can provide too much pressure requiring a larger outlet orifice.

So - buy the book and go through the entire diagnostic process. Be very wary or relying upon "known good" as a diagnostic guarantee. Fuel in the oil quite often indicates an internally worn Spica pump with related bypass of fuel into the oil.
 

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What is you actual fuel pressure? Without that, it's hard to be very conclusive.

The fuel pressure to the injection pump should be between 7 psi (low pressure light) and about 17 psi (pressure relief, if fitted). On battery only, you still need to be getting at least 7 psi. With the engine running (alternator running), I like to see 10-15 psi since the voltage is 14v instead of 12v.

I believe that the small fitting you mentioned is a one-way check valve, not a pressure regulating valve. Most of those have long been removed. Look for the arrow engraved on the valve.

That said, if you're getting fuel in the engine sump, you almost certainly have a bad injection pump.
 

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The Spica pump will take in what it needs, the rest of the gas just flows back to the tank. Never had an issue using various pumps to feed the Spica system. It seems your running too rich. You must adjust the fuel mixture in the Spica pump itself. Be careful!
Get the Wes info or from John(RoadTrip), and read it.
 

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Trained (ex)Professional, , 1953-2018 RIP,
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It seems your running too rich.
This is another reason for fuel in the sump. I personally will not condemn a Spica pump until all pump parameters/adjustments are correct and the car driven for a time after an oil change.
 

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Discussion Starter #6
there are a few books that came with the car, including Wes' book. the issue with tuning my car is that it needs a Thermostatic actuator before i can properly get it to that stage. however, the advice is positive - i may not have a bad pump.
 

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I'd have to run pretty darn rich to wash down the cylinder walls, and to dilute the oil to the degree you describe. What color are the spark plugs? Smoky, rich smelling exhaust?
 
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