What would cause hesitation at WOT?
 

So I've been enjoying the 3.73s the last 3 weeks, but i've noticed that when i put the pedal to the floor the car starts going like stink but then at random spots in the RPMs the car bogs and seems to lose a bunch of power and then it all comes back. It will do this like three times before i shift, usually around 3200rpm, 4300rpm and 5000rpm Doesnt matter what gear its in. What could could cause this?

Bad spark,or not enough fuel (bad,or clogged injector,dirty fuel filter).

^^^things to check for sure^^^

plugs, wires, rotor, cap, all new, new injectors and new fuel filter. How can i check the fuel delivery? For sure the pump runs, or at least it primes when i i put the ignition key to "accessories", what else?

Then i would check the fuel pump to make sure your getting the proper fuel pressure.How old is the pump?

she's the stocker from 87, ii hate playing with anything gas tank related. How can i check fuel pressure?

Just use the schrader valve with a fuel pressure gauge,then you remove the pressure regulator vacuum hose,then check the pressure.

so i don't know what the feck is happening but now hesitation is across the rpm band, feels like the car is severely down on power.

Is the timiing good,maybe your ignition modual is slowly going out the door?
You've pretty much covered everything!

I'm not sure when your car was built but TSB 06-9-9 deals with a bad fuel pump.
The correction was to replace it.

I had it done on my '05 that I had. This may be the problem and possibly the condition is getting worse as the pump gets older?

Just my 02 cents.

OK, I'm an idiot. For some reason I thought you had an '07 not an 87.:banghead:

LOL,it's all good,besides,it's the thought that counts!:tup

hehe and it still applies to, talking to my parts guy he said start with the Fuel pressure gauge and see if im getting the required PSI, he seems to think its the fuel pressure regulator, apparently they are know to go bad and i have a 23 year old stock pump and FPR

Well,get 'er done!!!:D:tup

Ok so here is an update, installed a BBK fuel pressure gauge. My research says that when the car is off but ignitiion is on acc. the gauge should read 30psi, which it does, when i start the car @ idle it should read 39psi, but it doesnt, it stays at 30psi. Pump or Regulator? Even giving it gas and pinning the throttle the gauge doesnt move from 30psi. It was actually dropping about 3 psi when i was giving it gas. Also something that comes to mind, when i removed teh shraeder valve from the fuel line there was no gas in the fuel line, which means the system is not staying pressurized.

I went through this exact same issue after I got a ton of parts put on. It went on, unexplained and was brutal. You would tromp on the gas and the car would launch, hesitate (as if someone flicked power off and on) and then go again. Generally for me it happened under heavy acceleration. That was when the car was completed at Nicks Automotive.

The following year I believe is when he closed his doors I went back to another local shop. Dropped some cash on a new dist, crank trigger and stand alone. Problem went away :) But truthfully, that is an overpriced solution.

hehehe yes it is.

Ok so update, for the fuel pressure, idiot me forgot to pull of the vacuum hose when i orignially checked it, pulled it and im getting 43psi, so good stuff. but before all that happened as i was letting the thread sealant dry i was looking at the back of the intake manifold for something and saw this:

http://img828.imageshack.us/img828/4...stang20004.jpg


Well to be honest is was still attached when i noticed, but as soon as i touched the hose it fell off. Followed the hose and it goes to a "T" fitting, fuel pressure regulator hose is attached to this fitting! Problem solved and the car is running great now, funny how one simple hose can so many things up. My new motto is look at the simple solution first.

Glad you figured it out.It's so true that sometimes it's those little things we don't think of that can cause a huge headache!!!

X2 on the Ignition module........

are you sure you have the right firing order, perhaps you mixed it up when doing the wires!

I also am having a similar problem!from standing start or on hard turns when tank is below half the car goes then coughs and then catches up to itself!!I have been told the baffle in the gas tank that keeps fuel pump encased in fuel mat have broke off!this would cause a starvation when fuel sloshes away from pump!I have not checked mine,to cold in garage, but I think you may have same problem!! My problem started all of a sudden, car didn't get worse gradually,one day great next day bad!!if lots of fuel doesn't do it!!

Good luck!!

try the fuel filter first,, about the easiest to do if it has not been done in a while