Hyundai Repair: Fuel pump or Fuel relay problems, fuel pressure regulator, hyundai excel

Question
Hi,

Just after a bit of help we have a 94 Hyundai Excel that has recently had problems starting and cutting out on us while driving. The car will start but not kick over but if we leave it for around half an hour it will start and work for the next couple of days then have the same problem again. We have been advised that it may be the fuel pump but on searching on the net that it could be the fuel relay. I guess I'd like to eliminate the cheaper option first instead of buying a new pump. Are the symptoms for the fuel relay problem the same as a fuel pump problem?

Answer
Either of these components could be the issue, but there are many other components that could be the issue as well.  Anything that will cause a lack of spark, air, or fuel could cause the issue.  

Prior to guessing at what the problem may be, it's a good idea to try to narrow down the potential causes.  

Is your check engine lamp coming on indicating a fault?  If so, start with reading the trouble codes.  There's a good chance the trouble code will be related to the problem you're having.

When the problem occurs, will the check engine lamp illuminate for five seconds when the key is turned to the "on" position?  If not, the engine control module (ECM) is likely not powering up properly.

Do you have spark when the problem occurs?  If not, suspect an ignition coil problem or a problem with the sensors in the distributor.  You can check for spark by carrying a spare spark plug with you.  When the problem occurs, pull the #4 wire off the #4 plug, insert the spare plug into the wire, and lay the plug on the intake manifold.  Have an assistant attempt to start the car and observe whether the plug sparks.

Do you have fuel pressure when the problem occurs?  If not, you should suspect the fuel pump.  You can make a rudimentary check by removing the return line from the fuel pressure regulator, disconnecting the ignition coil connector (preventing spark and a potential fire) and just momentarily turning the key to the start position and releasing.  If fuel runs out, that tells you that the fuel pump is operating (but not necessarily that it's providing sufficient fuel pressure).