Hey guys,

Well i am having a problem with my car. I just replaced my clutch, pressure plate, resurfaced flywheel, slave, and slave master cylinder a few weeks ago. I put in a Southbend clutch. While the car was down i also replaced the rear main seal and i pulled the crank position sensor off and changed out the little o ring on it ( had a slight oil leak). Dont believe any of these things are what is causing the problem???

After i put everything back together i began noticing a slight hesitation under 1/4 throttle (light acceleration) It seems as though it is getting starved for fuel or something. But once i acclerate faster the hesitation goes away. In full throttle it runs amazing no hesitation at all.

I put a fuel pressure gauge on it tonight and noticed.
-Without engine running (ign on) it has 42 psi.
-Once i start it it goes down to 32-34 psi
-I ease into the throttle and rev it up slowly it dips down to 30 psi or so and then starts climbing.

The problem seems to happen between 1500 and 3000 rpm.

The car is stock with stock injectors, with ps long tubes, egr!, !air, 255 walbro fuel pump, mail order tune, Mallory 685 ignition box (unhooked it and ran stock with blaster coil problem was still there), msd blaster coil, K&n filter in oem ram air box, taylor 8mm plug wires, csr electric water pump, previous owner replaced the fuel pressure regulator (over a year ago).

Would like your guys input as to the fuel pressure i dont believe that it is supposed to dip like that and then rise. Could it be a possible fuel pump going bad? Fuel Pressure Regulator? These are what first come to mind for me.

Any other suggustians as to where else to look for the source of this problem?

Thanks guys!!!
Devin

 

How old is the fuel filter? A dirty fuel filter can be ok at light throttle but then start to restrict at WOT.

 

Fuel filter is brand new. I change them religously at every oil change. Put a new one in earlier to day to be sure though. I use wix filters.

 

And it hesitates under light throttle not full throttle. Under full throttle it runs awesome. Its just under light ordinary city type driving that i am experiancing a problem with.

 

pump is shot change it

 

How is the best way to be sure though that the pump is shot and not the fuel pressure regulator? If the pump were to be shot i would think that no matter how i touched the throttle i would be experiancing the hesitation. Not only that i think that the wide open throttle would be effected more due to there being a higher demand for more fuel.

Not trying to argue or anything just trying to make some sence of things. And narrow it down further as to what the problem may be (dont wanna replace something that is good!).

Can somebody answer these Questions?
-What are possible symptoms of fuel pump failure?
-What are the possible symptoms of a fuel pressure regulator failure?

I appreciate your reply Rob!

Anybody else have any suggustions?

 

If you haven't already, hook the fuel gauge up with the vacuum line off the fuel pressure regulator. I would check the spark plugs and wires for good measure. A burnt wire or loose spark plug can also mess up low throttle response. Check the pump voltage and amperage if you want to look further into pump failure

 

wires look good. I didnt check to see if the plugs were loose though.

 

Anyone else?

 

???????????????

 

Have you tried my advice from the PM yet?