Failure in full march

Hello again, friends!

This time I'm reaching out for help with the following:

Recently, my 1998 Fiat Siena, while driving uphill in second gear, loses power and eventually stalls. This happens when the engine is warm and has been running for a while. I've already replaced the ignition coils, fuel filter, and cleaned the injectors. I've noticed that the fuel pump makes a rather loud whirring noise, even while driving.
A mechanic tested the pump pressure and says it's fine.

What could be wrong with the pump if it's indeed the problem? What else should I check before deciding to replace it?

I appreciate any help you can offer!

Thanks!

Did you check the pump regulator?

Hi friend, regarding your problem, it would be a good idea to install a fuel pressure gauge and test it while driving. If it were an electronic malfunction, the warning light on the dashboard would illuminate. It's more likely that the problem lies with the fuel pump or the electrical circuit that powers it.

Thanks, friends, for your comments.

The injector fault indicator sometimes comes on and then goes off.

When this happened a second time, I took it to have it scanned, but the mechanic found everything seemed fine.

The injectors were cleaned, and one was found to be faulty and replaced. This cleaning was done almost three months ago.

Recently, I've been in a mountainous area with very steep streets. I've seen 1998 Fiat Sienas driving around here, and they perform well for a 1.3L engine.

However, with four passengers, I can barely shift out of first gear to get uphill, and if I shift into second, I can't go faster than 20 km/h.

The fuel pump makes a constant humming noise that can be heard inside the car if you listen closely.

Before replacing the pump, I was advised to check the fuel pump pressure regulator. Where can I find it?

If I don't have a pressure gauge available, is there another way to test if the pressure is too low?

Thanks for your help! Best regards!

Hello friend. The fuel pressure regulator is located next to the fuel pressure pump (inside the fuel tank). It can also be tested with a pressure gauge. The pressure gauge is the only tool that can rule out a problem with the pump and the fuel pressure regulator. Good luck.