The Lotus engineers did not screw up. Typically you do not have a pump suck through a fine filter. The filters that are "pre pump" are just to keep the big junk out of the pump. Fine filtering is done after the pump where you can get a lot of pressure so when the filter loads up it can last longer with more dirt. Pumps are considered a wearable item so they are not intended to last forever. Even fuel tanks were not designed to last 30 years! And high alcohol content was not even considered in the fuel. If the tank is rusting eventually it will leak. The only fix is to remove the tank and have it cleaned and sealed. When I see that it is usually towards the top of the tank where all of the moisture precipitates out of the air. BTW when the filter on the suction side of the pump gets clogged the pump will run dry. That wears it out even faster so how is the filter "protecting" the pump?
Here is what my pre-filter/strainer (80 micron mesh) has caught. It prevented ingestion of major crud into expensive Bosch pumps. If you install pre-filter you must clean it at least once a year, though. Definitely, it is cheaper than new pumps!
A while ago, I read a technical article about a "Terne" coated steel (8% tin-led coating) used in construction of fuel tanks.
Oh, and by the way,
there never been any "factory" strainer on 86-88 Bosh injected cars! I checked it with a bore scope camera.
To prevent my aux. strainer filter from "loading up" with rust flakes, I'm going to mount it vertically and add a gravity/magnetic particle trap below. Gravity is free; use it to your advantage!
"Users of methanol blend fuels found an unsuspected cause of trouble in the gasoline tank, which traditionally has been made of "Terne” plated steel, a favorite roofing material of Victorian architects. It is steel sheet coated with lead, making it ideal for resisting rust from water in gas tanks. Methanol reacts with lead, slowly but surely, forming a flaky sludge that plugs filters in the fuel system. The easiest solution is to inspect and clean the filters every few days while using methanol fuel. The lead should all be eliminated within a couple of weeks of usage."
In the case of steel or aluminum tanks, both are conductive metals. Aluminum relies on an oxide layer for its corrosion protection properties. Steel relies on coatings for its corrosion protection. Low levels of ethanol, such as E10 (10%), are usually not a problem in aluminum tanks because the oxide layer provides a good measure of protection. What about steel? The problem occurs even with 10% ethanol content.
There are two mechanisms that occur with ethanol. Both mechanisms are a result of the hydroscopic property of ethanol, meaning it absorbs water. The more ethanol in the fuel, the more water there will be in the fuel tank. Water not only causes the tank to corrode, it also causes the corrosion particles to clog fuel filters, fuel systems, and damage engine components.
The second mechanism that can occur with the increased use of ethanol based fuel in aluminum or steel tanks is galvanic corrosion. Gasoline fuel is not conductive, but the presence of ethanol or ethanol and water will conduct electricity.
Boat builders are able to protect exterior aluminum boat equipment with sacrificial anodes known as zincs. Sacrificial anodes are not a feasible option for the interior of a fuel tank. In the long term, corrosion can perforate aluminum or steel to produce leaks that would cause fuel to spill into the bilge and end up in the environment. In the worse case it could cause a fire and/or explosion hazard. Boat fuel tanks are often located under the deck next to the engine where the operator might not be aware of a leak until it was too late.
High Strength-Low Alloy Steels.
High strength-low alloy steels show improved corrosion resistance over carbon steels in rural and mild industrial environments. In marine atmospheres and in immersion services, however, the difference in performance between carbon and low-alloy steels is minor (see Seawater Corrosion & Material Selection). The primary advantage of these materials is their higher strength. But remember that the same amount of material loss will usually have a greater impact on the load carrying capacity of a high strength material than on a low strength material. The high strength-low alloy steels should be protected when used in marine environments. They are somewhat more cathodic than carbon steels.
Steels with higher alloy content are more susceptible to pitting corrosion attack than steels with lower alloy content. Pitting is common in alloys with more than 5% total alloy content. Corrosion rates are similar to carbon and low alloy steels with pitting being only three to five times the corrosion rate calculated from weight loss.
Alloy steels are selected for their higher strength but can be susceptible to hydrogen embrittlement or stress corrosion cracking at yield strengths in excess 100 ksi. The alloy steels are somewhat more cathodic than carbon steels.