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· Registered
19 Posts
Discussion Starter · #1 ·
I have a problem with the fuel supply in my project.

Brief description of the project:
1975er Lincoln mark IV with Ford 460 with megasquirt fuel injection. Fuel supply with return line to the tank. Pump is a Bosch 044 fuel pump, tank and pickup are original.
Supply line has 8mm inside and return has 6mm inside diameter.
I installed a 30 macron bat motorsport filter after the pump and the fuel pressure regulator sits at the end of the rail and is set at about 3.2bar.

The problem:
The pump starts after a few minutes of driving to get loud and pumps air, the pressure breaks down to 1.5bar and the engine is logically lean.
No matter in what driving situation, pump does not recover even at idle.

I've checked:

Tank is full
opening the tank cap has no influence
pump, filter and pressure regulator are new

Problem can be solved by turning off the engine and wait 5 minutes, then continue.
I suspect the original fuel pickup, maybe the diameter is too thin? It looks like this:

Any tipps or suggestions?



· Registered
203 Posts
The symptoms indicate pump cavitation. Cavitation is obviously bad, but can also damage the pump. Cavitation is caused by pump intake restriction of any type. Restricted filters, pickup socks, pickup diameter, fitting restrictions, lift head (height), etc.

Those pumps suck at sucking. :LOL: The pump feed circuit is commonly tested by gravity flow-testing for pump flow rating, ensuring no restriction. This is difficult, and Ford used a low-pressure in-tank pump to feed that same Bosch-type HP pump for many years and models, as their choice of solution. They also used a fuel surge tank (accumulator) to ensure the HP pump never ingested air, thereby ensuring the injectors always received full pressure without bubbles, to the bottom of the tank. With their solution, no tank mods, baffles or sumps are required. You may consider one or both of these options.

Here is a diagram I made to depict the general features of the Ford system and similar conversion options, also used by many other OEMs and a favorite in racing for positive fuel feed:
Green Rectangle Yellow Font Line
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