1988 Audi Quattro

I have a 1988 audi quattro and i have changed the fuel pump and filter, but i have a problem with it when i try to accelerate. It seems that it starts to happen about twenty minutes into theride. Also the pump
sounds really loud. Does anybody have any suggestions?
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bush wrote:

Not really clear what your problem is and if you have the turbo or NA engine.
If your problem is in fuel delivery and it doesn't happen until you have driven for twenty minutes I would guess that you might have fuel tank lining in the tank that blocks the inlet screen to the fuel pump. The factory recommended correction for this is to cut off the fuel pump intake screen and change the fuel filter more often.
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Thank you tony. I will try that. Another question is where is the inlet screen is it on the pump or tank?? I look at my old pump and could not see it. The engine model is NA. I also did not know if it could be electrical?? Tony wrote:

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The pumps have a screen around the bottom where they fit into the bottom of the tank. The screen is part of the pump assy. just cut it out.
Your idea of an electrical fault is also possible. The most likely culprit is the fuel pump relay in the main relay box in front of the windshield and behind the brake master cylinder. They can get flaky. I used to carry one with me all the time.
There are other electrical possibilities: Differential fuel pressure regulator (on the front side of the fuel distributor), a sticky air flow plate that regulates fuel injectors (inside just above the air filter) and other things.
Be sure you do not have a vacuum leak. Vacuum leaks are very critical on the mechanical fuel injection of these engines.
There are a number of other possibilities but hopefully one of these is the problem.
bush wrote:

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One more idea. A very common problem is the MFTS (multi function temperature sensor) located where the upper radiator hose attaches to the block. These go bad very often and will cause poor start by not telling the ECU the correct engine temp. There are 3 or 4 wires attached to it. You can try checking the wires but replacing is almost surely required.
Tony wrote:

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