98 S70 T5 - no fuel pressure

Post by **scot850** » 22 Jan 2018, 16:22

Have you ever replaced the injector seals or the little filters in the top of the injectors? If you remove them I would recommend replacing the 'O' rings to prevent air leakage.

Neil.

shegarty · Post by **shegarty** » 22 Jan 2018, 16:38

I haven't ever serviced the injectors by replacing filters, do you know where I can find a kit to do this? I couldn't find anything on FCP or iPd.

Post by **jtp** » 22 Jan 2018, 18:29

https://www.ebay.com/i/172827990741?chn ... 2557542324

There is a tool for doing injectors, if I ever get a kit like that again I’m going to get the tool. In the past with these kits I was only able to replace the o-rings without the tool. But others could probably figure it out with normal tools

Post by **RickHaleParker** » 23 Jan 2018, 01:00

If there are no leaks in the injectors, fuel rail or fuel line from the fuel pressure regulator, there is only one other possibility. The pressure is back flowing through a defective fuel pressure regulator.

The fuel regulator is suppose to regulate the pressure at 43.511 psi (300 kPa) above the pressure of the intake manifold. You are coming up 5 psi (11.5%) short of that with the engine not running (intake manifold pressure = 0 psi, 0+43.5 = 43.5), which does indicate a defective fuel pressure regulator.

To locate the fuel pressure regulator, start at the fuel rail, trace the fuel inline back to the fuel pressure regulator, it will have four lines on it, One to the intake manifold, One to the fuel rail, Two to the fuel tank (Fuel and return).

When you have eliminated the impossible, whatever remains, however improbable, must be the truth -- Sherlock Holmes.

Post by **RickHaleParker** » 23 Jan 2018, 02:11

So if you have only 38 psi with a new pump you must have pressure leaking somewhere like you say.

Or being returned to the tank at 38 psi over intake manifold pressure by a defective fuel pressure regulator.
The fuel pressure regulator works by bleeding excess back to the tank.

shegarty · Post by **shegarty** » 23 Jan 2018, 05:47

Yep, my thoughts are exactly that ... faulty regulator. I have a small vacuum pump that I will test it with today. I was thinking that the best way to do that is to plug one line (there is one large line to the manifold and a small line to the snorkle just by the MAF) and then draw vacuum on the other, if it doesn't hold then I definitely have a faulty regulator?

Post by **RickHaleParker** » 23 Jan 2018, 07:22

I nave no idea what you mean by snorkle.

I would test the fuel regulator directly to remove any reasonable doubt.

I would pull the fuel rail line and the fuel return line off the fuel regulator. Connect the vacuum pump on the return port of the regulator and see if it leaks. If it does not, move to the fuel port then the manifold port.

shegarty · Post by **shegarty** » 23 Jan 2018, 11:01

Ok, so a vacuum test of the intake side of the pressure regulator (plugging one hose and drawing vacuum on the other) slowly leaks down from 20 inHg to about 18 inHg in the time it took me to write this (5 mins). There is no visible fuel in the line and also no vapours or smell of fuel. It is my understanding that when these fail there is a leak in the diaphragm through to the vacuum side, is this correct? My understanding is that the vacuum leak would allow air into the system thereby breaking the natural vacuum in the fuel line and allowing fuel to travel back down the return line to the tank. With what might appear to be a small leak on the vacuum side does this make it possible for fuel to leak through to the return line? Do I need to test the fuel side of the regulator with vacuum just to be sure?

shegarty · Post by **shegarty** » 23 Jan 2018, 11:24

Down to 15 inHg after about 25 mins

Post by **RickHaleParker** » 23 Jan 2018, 13:46

Take a picture of your "fuel pressure regulator" and post it.

98 S70 T5 - no fuel pressure

Re: no fuel pressure