Wondering why this type of car is losing pressure

A NON USA CAR, where is it what country? (engines and EFI vary by, countries sold to) (2 engines in 2001) near same but....what/?
1.3 L M13A I4 (petrol) with VVT
1.5 L M15A I4 (petrol) with VVT (VVT can fail and lose power too)


well, you did not do the right tests.
not using a scan tool first is #1 cause of going astray, do that first.
Fuel consumption low tell me it, the ECU is in limp mode. and the ECU has lots of DTC errors you are ignoring.
low power has many causes. not just one #10 filter. inside the tank
let me list them to you , in no order, and is ASE class 101 basics, all the way,

1. low fuel pressure, bad filter,bad pump bad FPR fuel pressure regulator. we use a hand tool gage to find that.
2. bad MAF sensor has this, NO ENGINE STATED BY YOU!
3. bad spark if misfiring, ever do a tune up in 60,000 miles.????
4. Bad fuel ,
5. clogged or leaking fuel injectors.
6. bad engine, is compression at spec? (more tools)
7. CAT Melted, (ignoring those DTC error caused this)

that is about it, can go more, but you have no tools to test, so find a shop , to fix this car, as they SURE DO HAVE all tools to do that job right and fast.

No what you are describing is lack of air through the intake.
Rich means lack of air or too much fuel. Fuel pressure remains constant and drops when the accelerator is pressed down if the pump is bad, the fuel filter is plugged or there is an injector problem or a fuel pressure regulator issue (if one is present) and this results in lean running engines.

Many things to check. Wonder if this work was done to alleviate problem or problem was from doing the work.

Putting gas fumes in a 21:1 compression cylinder is sure way to ruin engine.

2 possible problems are losing your diesel fuel draw from an air leak in the fuel lines and an inoperative glow plug timer.

When you change a fuel filter you lose the vacuum lock that is in the fuel lines. Some mechanics add fuel to the new filter to remove some of the air and promote fuel draw. The O rings on the injector lines are a special type which resists petroleum products. Using cheap O rings will cause problems.

Glow plug timer-there is a power Relay to the timer and the timer itself is a type of Relay. You should hear clicking noise and lights should dim as timer provides power to the glow plugs.

Other things to check would be the Vacuum pump as Diesels work differently than gas engines and require a pump to supply Vacuum. Covering the intake suggests engine needs a Vacuum draw.

Weak fuel pump. Too weak to pressurize or draw fuel. Can be measured with pressure gauges.

Really bad rings could also cause symptoms.

Would be interested knowing what proved to be wrong.

Has the feul filter ever been changed ? loss of fuel Pressure will cause problems similar to what you listed. I would need to know more about the truck to go further on this. Millage ? Honest maintenence record ? Way its driven ? By the way, hate saying this but, if the fuel filter has never been changed it could possibly put such a strain on the pump that when you change the filter the pump could possibly go out soon after from Exhaustion of it's new freedom. Weird but true. Not saying it "Will Happen" it is just common in this situation.

Yes, it can be the relay. What I do is unplug the relay and swap it gor yhe horn relay. If this doesn't work, I use a volt/ohmmeter to probe the relay socket. Doing this, I can usually find the problem. With the key on , there should be two terminals in the socket that have battery voltage and one that is grounded. The last terminal goes to the pump and should show low ohms to ground. In your truck, the relay coil is connected to ground and turned on by the ecm with a positive signal. It also seems to depend on the oil pressure switch, so you might want to temporarily bypass the switch with a paper clip in the connector to see if that is keeeping the pump from running.

Your ford should have a schrader valve in the fuel rail for testing fuel pressure. You shouldn't need to remove a fuel line. On the left inner fender there are two, maybe three relays, usually encased insome type of enclosure. The relay with the green plug is the fuel pump relay, the relay with the brown plug is the EEC relay. Unplug both of these relays and inspect for corrosion, broken pins, and corrosion. A problem with either relay will cause the fuel pump not to run as the EEC relay controls the fuel pump relay. Corrosion at these connections has been very common at my shop.

I dont know the year so it is difficult to be specific.Is there enough feul in the tank for the feul pump to pick up.Some feul filters have the same connections on both sides and can be installed backwards, this will cause a restriction because feul will only flow one direction.Can you open the feul cap and hear feul pump turn on for 3 seconds when the ignition switch is cycled.Let me know if i can help?

Sounds like bad fuel pressure. Check fuel pump and fuel pressure off the rail. Also a severely clogged fuel filter can cause that.

start checking fuel pressure easier then changing pump re check that all is plugged in by air cleaner

change the feul filter first. if that does not do it change the feul pump module with the new wire harness for the pump. do not put in a new pump with the old harness.