What kind of problems could i have if my fuel pump was installed upside down? could it cause any electrical problems?

How hot ? not to be able to touch it ? Resistance (high resistance) causes heat. Lose connections, corrosions, wiring that has been open for a while. which caused green crusty (corrosion)Fuse / relay box has corrosion inside . Looking at wiring diagrams an using a volt ohmmeter to test electrical circuits is the way to a fix. You don't know that ,take it to a qualified repair shop.

Did you check fuel pump electrical circuit ? Look at a wiring diagram to see what all is involved in making the fuel pump work. No , the knock sensor can't cause this ! Do you know how to do automotive electrical circuit testing using a DVOM - digital volt ohm meter ? How to read an use a wiring diagram to pin point areas for testing in a electrical circuit ! What do you think makes that fuel pump work ? AIR !!!! Looking at a wiring diagram I see a fuel pump relay that gets B+ voltage from the engine control relay. The engine computer energizes both, relays .There is a fuel pump resistor inline before the fuel pump.
Free wiring diagrams here http://www.bbbind.com/free_tsb.html Enter vehicle info. year , make , model and engine size. Under system click on engine then under subsystem click fuel controls ! Click the search button then the second blue link . The second diagram down shows the fuel pump electrical circuit .
Watch this videos from youtube .
Basic Electricity for Service Techs Ohm law Current Flow Opens Shorts
Electric Testing Techniques You Need to Know

How to Use Multimeter to Troubleshoot Common Problems

fuel filter inline some were

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Inside The Fuel Tank. If Yours Tests Bad, You Will Need To Drop The Tank And Replace It. Be Sure To Have Someone Test To Make Sure Yours Is Bad, This Is A Difficult Job And Expensive.

REMOVAL & INSTALLATION Fig. 1: Exploded view of the fuel sender, including the fuel pump

1. Properly relieve the fuel system pressure, as outlined earlier. CAUTION
   Fuel injection systems remain under pressure, even after the engine has been turned OFF. The fuel system pressure must be relieved before disconnecting any fuel lines. Failure to do so may result in fire and/or personal injury.
   
2. If not already done, disconnect the negative battery cable.
3. Raise and safely support the vehicle with jackstands.
4. Safely drain and remove the fuel tank assembly as outlined later in this section.
5. Detach the quick-connects from the fuel sender assembly and remove the fuel lines.
6. Using tool J 35731, or an equivalent spanner wrench, remove the fuel sender lockring.
7. Lift the sender assembly carefully out of the fuel tank.
8. Remove the sender O-ring from the top of the sender and discard. WARNING
   Do NOT run the fuel pump unless it is submerged in fuel. Running the pump dry will cause serious damage to the fuel pump and may cause the pump to explode due to the oxygen in the air.
   
9. Note the position of the fuel pump strainer on the fuel pump and, while supporting the pump assembly in one hand, twist the strainer off the pump and discard the strainer.
10. Detach the fuel pump electrical connector.
11. Remove the clamp from the fuel line at the top of the pump.
12. Hold the fuel sender upside down on a work bench and pull the fuel pump out of the lower mounting bracket. Once the pump is clear of the lower mounting bracket, tilt the pump outward and disconnect the pump from the sender assembly. To install:
    
13. Replace any attaching hoses or rubber sound insulators that show signs of deterioration.
14. Install the rubber bumper and insulator on the fuel pump.
15. Hold the fuel sender upside down and install the fuel pump between the fuel pulse dampener and mounting bracket.
16. Attach the fuel pump electrical connector.
17. Install the retaining clamp on the fuel line.
18. Install a new fuel pump strainer on the outer edge of the ferrule until fully seated. The strainer must be facing the same direction as it was before removal.
19. Position a new O-ring on the top of the fuel tank and install the sender assembly.
20. Install the lockring using J-35731, or an equivalent spanner wrench.
21. Install the fuel tank as outlined later in this section.
22. Refill the gas tank.
23. Connect the negative battery cable.
24. Turn the ignition switch to the ON position to pressurize the fuel system and check for leaks.

The fuel pump is designed to attach one way only. The wiring should be facing upward if you need to know, It is mounted on the sending float unit also in the tank

Removal & Installation


Exploded view of the fuel sender, including the fuel pump


Click to Enlarge

1. Properly relieve the fuel system pressure
   

1. If not already done, disconnect the negative battery cable.
   
2. Raise and safely support the vehicle with jackstands.
   
3. Safely drain and remove the fuel tank assembly as outlined later in this section.
   
4. Detach the quick-connects from the fuel sender assembly and remove the fuel lines.
   
5. Using tool J 35731, or an equivalent spanner wrench, remove the fuel sender lockring.
   
6. Lift the sender assembly carefully out of the fuel tank.
   
7. Remove the sender O-ring from the top of the sender and discard.
   

WARNING Do NOT run the fuel pump unless it is submerged in fuel. Running the pump dry will cause serious damage to the fuel pump and may cause the pump to explode due to the oxygen in the air.

1. Note the position of the fuel pump strainer on the fuel pump and, while supporting the pump assembly in one hand, twist the strainer off the pump and discard the strainer.
   
2. Detach the fuel pump electrical connector.
   
3. Remove the clamp from the fuel line at the top of the pump.
   
4. Hold the fuel sender upside down on a work bench and pull the fuel pump out of the lower mounting bracket. Once the pump is clear of the lower mounting bracket, tilt the pump outward and disconnect the pump from the sender assembly.
   

To install:

1. Replace any attaching hoses or rubber sound insulators that show signs of deterioration.
   
2. Install the rubber bumper and insulator on the fuel pump.
   
3. Hold the fuel sender upside down and install the fuel pump between the fuel pulse dampener and mounting bracket.
   
4. Attach the fuel pump electrical connector.
   
5. Install the retaining clamp on the fuel line.
   
6. Install a new fuel pump strainer on the outer edge of the ferrule until fully seated. The strainer must be facing the same direction as it was before removal.
   
7. Position a new O-ring on the top of the fuel tank and install the sender assembly.
   
8. Install the lockring using J-35731, or an equivalent spanner wrench.
   
9. Install the fuel tank as outlined later in this section.
   
10. Refill the gas tank.
    
11. Connect the negative battery cable.
    
12. Turn the ignition switch to the ON position to pressurize the fuel system and check for leaks.
    

The fuel pump relay is located on the fenderwell near the battery,it will be green. If that relay is sticking on, you should hear the fuel pump running (low wine or rumble) sometimes if someone has not put the relay back correctly it will sit upside down and water will get in it and cause the problem

REMOVAL & INSTALLATION
See Figure 1

1. Relieve fuel system pressure.
2. Disconnect the negative battery cable.
3. Raise the vehicle and safely support.
4. Drain the fuel tank.

Fig. 1: The electric fuel pump has an in-tank design

1. Disconnect wiring from the tank.
2. Remove the ground wire retaining screw from under the body.
3. Disconnect all hoses from the tank.
4. Support the tank on a jack and remove the retaining strap nuts.
5. Lower the tank and remove it.
6. Notice the position of the filter for replacement. Support the pump with one hand and grasp the filter with the other. Rotate the filter in one direction, then pull off of the pump. Discard the filter.
7. Disconnect the fuel pump connector, on wagons it will not be necessary.
8. On all models excluding wagons:
   1. Place the sending unit on a bench upside down, then pull the fuel pump downwards to remove from the mounting bracket. Tilt the pump outwards and remove from the pulsator.
9. On wagons proceed as follows:
   1. Disconnect the negative terminal nut and lead (black) from the pump.
   2. Disconnect the positive lead (gray) from the pump, then loosen the coupler clamps.

To install:

1. On all models excluding wagons:
   1. Assemble the rubber bumper and insulator onto the pump.
   2. Position the fuel sender assembly upside down and install the fuel pump between the pulsator and mounting bracket.
   3. Connect the pump electrical connector.
2. On all wagon models:
   1. Position the fuel sender assembly upside down and install the coupler and coupler clamps to the inlet tube, but do not tighten at this time.
   2. Install the pump between the coupler and the mounting bracket, then tighten the clamps so that 5-8 teeth are engaged.
   3. Attach the positive lead (gray) to its positive terminal with the nut, then attach the negative lead (black) to the negative terminal.Always install a new filter when installing a new pump.
3. Position the pump filter on the new pump and push the outer edge of the ferrule until it is fully seated.
4. Install the sending unit.
5. Install the gas tank and check for leaks.
6. Reconnect the battery cable.

Just a couple of guesses-

- Fuel pressure regulator - Located (normally) at one end of the fuel rail and controlled by a vacuum line which could be cracked or disintegrated inside.

- A shock sensor - One of the cars in our family, a Ford Escort, had a mechanical/electrical sensor in the trunk and concealed behind carpeting if I remember right.
Traveling over our rough private easement at speed would cause this thing to trip and it had to be manually reset to re-enable voltage to the fuel pump.
This thing was not well documented and a mechanic clued us in.
Since this ****** has a switch built-in, the switch could well fail intermittently causing the kind of problem you are having.

Also some theft prevention systems turn off the fuel pump to disable the vehicle; these would also have switches in them carrying the current for the fuel pump.

It would be helpful if you had a manual on your ride (Haynes or Chiltons) so you could study the electrical systems to see if there are these items present.