New fuel pump in 2.0 Turbo - now won't start
 

Hi,

I just joined the forum so thank you in advance for helping a new member. I'm a decent amateur mechanic but have an issue that requires a little more knowledge.

My Volvo V40 2.0T (2001) recently went into the garage because there was a large puddle of fuel forming under the rear seat ie. on top of the fuel tank.

I bought a pump that was the same size as the old one, fits perfectly and connects fine with the plug and pipes but different model number (it was a good price). Before the new pump was the fitted, the car started fine (but was leaking fuel from the old pump). Just in case it matters, there is an after market LPG conversion but that never caused issues for running on petrol or starting. I have disconnected that system for now to eliminate it from the equation.

After further investigation, the fuel gauge works and the new pump appears to pumping fuel so it does not seem to be a connection issue. However, when I disconnected the fuel line in the engine and pointed it into a bottle instead to watch the flow, the following happened:

- A small amount of fuel went into the bottle at relaxed rate (less than you would expect) when the ignition was turned to the stage just before starting
- When the engine is started, it then starts to pump fuel again but seems a little weak and staggered

The above explains why the engine is not starting I think. There just isn't enough fuel coming through. However, I cannot figure out why the pump is doing that.

As I said, the pump fit but it is the wrong model. Could that be the cause? I thought something as simple as a fuel pump would either work or not at all. The two options I have now are 1. making the new pump work or 2. writing it off and getting the correct one. Option 1 would be cheaper but I don't know if it's possible!

The model my car should have is:

09751409900

The model fitted is:

09750409906

Thank you.

Check the fuel pressure at the Shraeder valve on the fuel rail.
it should be around 44psi.

Thank you. I will pass that information onto the mechanic as he has the car. I suspect the reading is going to be too low based on what I saw coming through that pipe.

Bearing in mind that he has fitted a pump with the wrong model number (under instruction from me), is it common for Volvos (or any car really) to have this issue with a pump that has the wrong model number even if it physically fits and connects?

Unsure on whether the same applies to the 2.0t, but I have seen t4 discussions in the past where it was mentioned how imperative it is to ensure that the exact correct pump is used.

I suspect it'll be the same then. It's weird with a pump being such a simple device! Thanks for the advice.

Regarding the previous comment, it's nowhere near that pressure level so definitely not working properly.

It's not a simple device. It needs to be able to self-prime when dry, achieve pressure, not fall apart with contact with petrol, not catch fire, not wear out through friction, not leak ... it's quite a lot to ask. It's no simple impeller!

I get that and was not underestimating the great engineering of any car part. However, it ultimately has a very basic purpose which is to pump fuel from a tank in through one pipe and back out through another to the engine. I don't understand how any of what you mentioned would affect the basic purpose of a pump. It was not sending enough fuel to power a 50cc moped. The fire protection etc shouldn't make any difference.

Anyway, I bought a secondhand one with the correct code based on advice above so will have to sell the new pump on to someone who has the correct car! Either that or if it sounds to anyone like I have been sent a dodgy pump, I'll just send it back.