Ce matin, nous venons de remplir le réservoir parce qu’il n’y avait plus assez d’essence.

In French, venir de + infinitive is a very common way to express the recent past.

• nous venons de remplir = we have just filled
• literally: we come from filling, but that is not how it is translated in English

So here:

• nous venons de remplir le réservoir = we’ve just filled the tank

This structure is used a lot in everyday French:

• Je viens de manger. = I’ve just eaten.
• Ils viennent d’arriver. = They’ve just arrived.

Because in the expression venir de + infinitive, French uses the present tense of venir to mean have just done something.

So even though the filling happened in the past, French says:

• nous venons de remplir

rather than using a normal past tense.

This is simply how the recent past is formed in French.

Ce matin means this morning.

French often uses expressions like this without a preposition:

• ce matin = this morning
• ce soir = tonight / this evening
• cette semaine = this week
• ce mois-ci = this month

So you do not say dans ce matin or à ce matin here.

In French, nouns usually need an article much more often than in English.

So French says:

• le réservoir = the tank

Even when English might say fill up the tank or sometimes just fill up on gas, French naturally uses the article with the noun.

Here, le réservoir means the vehicle’s fuel tank.

Depending on context, réservoir can also mean:

• a tank
• a reservoir
• a container that holds liquid

In this sentence, because of essence, it clearly means the gas tank / fuel tank.

Parce que means because and introduces the reason.

• ...parce qu’il n’y avait plus assez d’essence.
• ...because there was no longer enough gasoline.

Here it explains why they just filled the tank.

You may also notice it becomes parce qu’il instead of parce que il. That is because que becomes qu’ before a vowel sound.

French avoids que directly before a vowel sound, so que contracts to qu’.

• que il → qu’il
• que elle → qu’elle
• que on → qu’on

So:

• parce qu’il n’y avait plus assez d’essence

is the normal and correct form.

Il y avait means there was or there were.

It is the imperfect form of il y a:

• il y a = there is / there are
• il y avait = there was / there were

So:

• il n’y avait plus assez d’essence = there was no longer enough gasoline

This expression is extremely common in French.

The imperfect is used here because it describes a state or situation in the background, not a single completed event.

• il n’y avait plus assez d’essence describes the condition: there wasn’t enough gas anymore

French often uses the imperfect for:

• background information
• ongoing situations
• states and conditions

Using a eu would sound more like a specific event of there was / there occurred, which is not the idea here.

Ne... plus means no longer or not anymore.

So:

• il y avait encore assez d’essence = there was still enough gas
• il n’y avait plus assez d’essence = there was no longer enough gas

In everyday spoken French, people often drop ne:

• y avait plus assez d’essence

But in standard written French, ne is normally kept:

• il n’y avait plus assez d’essence

After expressions of quantity, French usually uses de / d’ rather than a full article.

So:

• assez d’essence = enough gas
• beaucoup d’essence = a lot of gas
• peu d’essence = little gas

You do not normally say:

• assez de l’essence in this context

That is because assez is a quantity expression, and quantity expressions are generally followed by de.

No. In French, essence usually means gasoline / petrol.

So:

• de l’essence = gas / gasoline / petrol

This is a false friend for English speakers, because English essence usually means something like a concentrated extract or the essential nature of something.

In casual spoken French, people might simplify parts of it, especially the negation. For example:

• Ce matin, on vient de remplir le réservoir parce qu’y avait plus assez d’essence.

Changes you might hear:

• nous → on in casual speech
• il n’y avait → y avait because ne is often dropped
• parce qu’il y avait → parce qu’y avait in fast speech

But the original sentence is perfectly correct and more standard:

• Ce matin, nous venons de remplir le réservoir parce qu’il n’y avait plus assez d’essence.

A simple pronunciation guide is:

• nous venons de remplir ≈ noo vuh-NON duh rahn-PLEER

A few useful notes:

• venons has a nasal sound in -nons
• the final s of nous and venons is normally silent
• de often sounds like a light duh
• remplir ends with a clear -ir sound

And in connected speech:

• nous venons de flows together very smoothly

The sentence breaks down like this:

• Ce matin = time expression
• nous venons de remplir le réservoir = main clause
• parce qu’ = because
• il n’y avait plus assez d’essence = reason clause

So the overall pattern is:

Time + main action + reason

That makes it a very natural French sentence structure.