Electronic Fuel Injection Fuel Pressure Regulator Flow Rate

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Written by wolfems on September 10, 2009 – 9:28 am

Hi Guys.

We have come across this a couple of times lately, so I thought it would be worth while sharing it with you.

If you imagine a huge fuel pump. It pumps a huge volume of fuel. That fuel travels along a fuel line, some of it is used by the fuel injectors, and then it comes to the fuel pressure regulator. The only problem is that the fittings and internal galleries on this fuel pressure regulator are much smaller than the fuel line and fuel rail, and so the regulator cannot regulate the fuel pressure down to where it needs to be.

No matter what you do with the adjustment screw (if it is an adjustable regulator), the pressure remains higher than you want it to be.

This is a case where you have too much fuel flow from the pump for the regulator to handle.

The only course of action is to replace the fuel pressure regulator with one that is designed to cope with the fuel flow of your fuel system.

Funnily enough, it is far more common to have a fuel system that cannot deliver enough fuel, and the pump(s) needs to be upgraded.

This is just something to be aware of, as it is not as common as a lack of fuel flow is, and many people find it hard to understand what is going when they are trying to diagnose this curly issue.

Here a link to some info on fuel pressure and fuel pressure gauges.

PS: Measuring the fuel pressure requires a special fuel EFI pressure gauge. You cannot use a fuel pressure gauge designed for a carburetted engine as EFI fuel pressure is 6 or more times greater.

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