Tapping on fuel lines and trouble starting

IAmSuperTwinky

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Dec 14, 2018
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Not sure if this is in the right forum but my 1998 v6 mustang has a tapping noise coming from the fuel lines. Yes the noise is coming from somewhere inside the lines and if you place your hand over the lines themselves you can feel them pulsing. Has anyone had this problem and if you have has if been fixed? Also a little extra sometimes after the car has been driven a while my car needs to be primes a few times to start, is this solely a bad fuel pump or other things?
 
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It seems to me that your problem "might be":
  • bad fuel pump
  • bad fuel pump basket check valve
  • bad fuel pressure regulator.
  • bad fuel pressure damper (if equipped)
  • un-even intake vacuum reference to the fuel pressure regulator (weak cylinder).
  • bad fuel injector (clogged or other mechanical problem).
If a fuel injector issue is suspected I have had great luck with an injector cleaning and flow test service such as InjectorRX.com. Once cleaned and tested they are as good as new (but cheaper).

As for a possible fuel pump problem I would start with a fuel pressure test. See if removing the fuel pressure intake reference line changes the pulsating problem. This should also cause the fuel pressure to jump to 40 PSI.

Use a mechanics stethoscope to listen to each fuel injector. Are there any that sound much different than the others? This can also help narrow down which part is making the noise.
 
Its been a while and long since replaced fuel pump. It gave out on me one day thankfully not too far from home, had my dad tow me home lol. Upon replacement i did a full tune up and replaced other components. The tapping did in fact originate from the fuel pump no clue why but my guess was not enough fuel coming from the pump causing it to suck more than there was similar to emptying a capri sun. The pump was a junkyard pump put in by previous owners of the car. I put a walbro 255 and replaced fuel filter. Plugs, wires and distributor block. Running lean for too long pre maturely killed all of my spark plugs. Causing it to misfire when pump was replaced. I also replaced fuel pressure regulator and throttle position indicator thinking that was causing problems but hey those were cheap and it wouldnt hurt getting new parts lol
 

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