Electric fuel pumps are far more reliable now than in the oId Days. I can think of many reasons to stay with the original mechanical pump though.

Also if I were to bypass the original pump. I would remove the constant pressure spring and piston. When not processing fuel The piston will be driven from one extreme of movement to the other until it perhaps seizes up in the bore. The lubrication for that piston is the fuel in process. Normally it does not have to move much I suspect in comparison when it is processing fuel.

Last but not least perhaps ninety percent of them or better will respond to a cheap renewal kit. The valves are usually the issue and replacements come in the kit. The exception might be if the fuel used was recycled vegetable oil.

I will add that for those rebuilding the 240d lift pumps. If you can get the pressure spring out of an old turbo 617 lift pump. It to me is a sensible upgrade. This slight modification may even be beneficial to the non turbo 617s as well. I am not sure though but think they might also put out less pressure than the turbo lift pumps by design.

These pumps also in my opinion fail very slowly over time usually. There are simple tests to establish if they are still providing proper pressure and in a general tuneup should be perhaps checked.

When we aquire an old example of these cars to me it is important to check out the fuel system even if it is still running decently. Best of all this is very cheap to do yourself and not really complicated.

A breakdown on the road can e very expensive and frustrating as a result of not considering it. Remember that now I am just an old guy perhaps even around the bend as well.

I am driven by the thought that nobody has produced a car so simple for a very long time now. Plus an average individual can handle most of the repairs and maintenance. Plus with all the support from the members is also a major factor to consider.

The original lift pumps were a very clever very long lasting reliable design. The pre filter is there in my opinion to prevent large particle contamination of the valve seats in the lift pump from dirt in the fuel. The valves also serve as check valves to prevent fuel draining back down in the fuel system with the car sitting around.

For example my diesels in decent temperatures start almost instantly the next morning. So I know at least one of those two valves is sealing well. So if you do go electric pump remember to incorporate a check valve. That's if the electric pump does not have one. You do not want to pump a shot of air through the system at startup if the system back leaks overnight.

Many people probably do not like the length of some of my posts. I am just too simple minded to condense them.