There are some unusual occurrences with the W124 300-24 when the whole fuel pump pack has been replaced.

[TechWhiz]

This is for the M104.980 engine.

The presence of a whining fuel pump and intermittent cut-outs, with the exception of one instance of stalling, led me to think that the fuel pump is deteriorating. However, the automobile was starting and operating flawlessly. Indeed, several individuals made remarks on the recently acquired vehicle with a mileage of almost half a million km. Therefore, we made the decision to completely replace all components, ranging from the tank strainer to the fuel conduit leading to the front.

The equipment used includes Pierburg pumps, Bosch accumulator, MB filter, and all new hoses from MB.

Following the visual inspection, we correctly positioned all the hoses, activated the ignition, and conducted a leak detection. There is no information available.

Next, the engine is turned on, followed by a few efforts to start it, and eventually it runs smoothly. There are no leaks.

Task completed.

However....

The automobile requires two efforts to start when it is chilly. On the second try, it is precisely the same as before, happening instantly.

Subsequently, the performance is as good as new. If anything, the acceleration is somewhat faster with the new pumps compared to the previous ones.

What may be occurring in this situation?

Furthermore, in the previous year, I successfully implemented a new fuel pressure regulator, which effectively resolved the issue of delayed ignition. Therefore, every component, ranging from the tank to the fuel distributor, has been replaced with new ones.

The metering head/fuel distributor and injectors were replaced in 2017, and have only been used for 80,000 km since then.

Perplexed!

Are there any intelligent males with ideas?

Additionally, we replaced the tank strainer with one from our inventory. However, this is the previous version, which is 33 years old, prior to my efforts to improve it:

[bvlenci]

Is the cold start injector functioning properly? Is the EHA misaligned?

[TechWhiz]

It is illogical. Everything was flawless, except for a malfunctioning pump. Currently, we have acquired new pumps and all the related equipment. However, it is necessary to attempt the cold start twice in order to successfully initiate the system.

Recalling that we installed a new cold start injector a few months back just because we had one available in our inventory. Everything was functioning well prior to the replacement of the fuel pump patch.

Thank you for your response.

[Mistral]

It is possible to excessively tighten the bolt/screw in the frame that attaches the pump/filter, resulting in the pump being unable to rotate correctly. It may be advisable to loosen it somewhat.

[CodeCrusader]

The poor electrical connections on the ignition switch result in an inadequate start signal being sent to the fuel pump, which is responsible for pressurising the system before the engine is turned on. This signal then switches to a signal indicating that the engine is running, although the specific origin of this signal may vary. Verify the consistent reception of electrical signals by the fuel pump relay.
During the first cold start, do you see the pumps engaging in the process of "priming" the system for a brief duration upon turning the ignition switch on, prior to starting the engine? Many individuals often attribute the fuel pump relay as a common cause, which is really true. However, it is important to note that even a well functioning fuel pump relay need consistent and dependable electrical signals in order to operate effectively. Apologies for the use of capital letters!

[SkippyTom]

I had a similar problem with a non-Mercedes-Benz vehicle, specifically related to difficulties starting the engine in cold conditions. A leaking injector would release gasoline into the engine overnight, causing the fuel rail to become empty and enabling air to enter the system.

The first effort was unsuccessful, but subsequent attempts, maybe the second or third, would prove successful since the air had been completely removed.

[AMG33D]

I am experiencing a similar issue, but specifically with an M103 engine following the installation of new pumps.Initially, the machine starts easily with the push of a button. However, with time, it becomes progressively more difficult to start each day. I have a new fuel filter and accumulator prepared for installation. If the engine fails to start initially, I suggest turning off the ignition and inspecting the gasoline distributor for any leakage via the plunger seal.Insufficient gasoline is always the reason why the automobile cannot be started for the first time after being parked.

[TechWhiz]

Thank you everyone.

However, it is peculiar since all functions were operating flawlessly prior to the replacement of the pump pack. I am referring to every single item.

The only reason for the alteration was an intermittent pump noise that indicated an impending breakdown.

Prior to the alteration, the initiation of the process was immediate and the operation, except for occasional interruptions caused by the pump's noise, was completely flawless, without any problems whatsoever.

All of your solutions are generally applicable, but I fail to see their applicability in my specific situation, since the whole system, including the ignition switch, is now brand new.

I am still perplexed, but appreciative of your attention.

Currently contemplating.

[AMG33D]

Did you provide your vehicle identification number (VIN) when you purchased the gasoline pumps? The pumps do not resemble authentic Mercedes components.