Hesitation

[jazzman]

Well the new engine is runnin fine but i get a hesitation when i want to accelerate. So kalvin was sellin his parts so i bought the afpr and ffp pulley. I'm hoping that if I bump up the fuel pressure a little bit it will take care of my hesitation. What does everyone think?

Derek

By the way if you want to see my car click here (www.n-body.net/registry/jazzman/)

[Red99GAGT]

Are you using the computer from your original motor or from the 3400? I'm not a guru when it comes to this....thats why I ask.

Also, my old car ('91 Grand Prix, 3.1L V6) developed a hesitation. It was caused by a bad fuel pump. Once I replaced that it was fine.

Are you sure the hesitation is coming from the motor? I ask this because your tranny might be "slipping" which could feel like its hesitating. Hope I could help...

[jazzman]

yes its the motor because it will bog down in rpms when it hesitates. and after the cars warmed up a little and has been run the car is fine

Derek

[93GASE3300]

If you think it may be fuel related just pick up a fuel pressure gauge and attach it to the service port on your fuel rail and see what your reading. What kind of mods are you running by the way?

[jazzman]

Well i installed the afpr tonight and also picked up a pressure gauge. I tested it with the stock and was running at like 40 psi at WOT. So i bumped it up to 48 at WOT, and that has seemed to solve the problem, but time will tell.

Thanks for the advice.

Derek

[93GASE3300]

well you have to look at root cause also. Hopefully the fuel pressure regulator was the problem. however you might have a restriction some where in your fuel lines or a weak fuel pump. Just out of curiousity, what is your fuel pressure when you disconnect the vacuum hose from your pressure regulator?

[jazzman]

That is how i test wot, it was at around 39-40 and now its at 40-50.

I also added a bottle of stp and that seemed to help as well.

Derek

[93GASE3300]

oh ok just checking you dont want your pressure to be to high but yours seems reasonable

[Gimli]

Aclogged fuel filter will also cause irregular pressure drop and hesitation.

If you get hesitation at 40psi worth of fuel pressure I suspect there is something else wrong and augmenting the fuel pressure would only be a band-aid solution.

[jazzman]

no the 40 was at wot. It stood at around 34 at idle with the stock so i bumped it to 40 and 48 WOT. And this is not a band aid solution. I'm thinkin that with the motor swap the stock fuel system needed a boost to help itself keep up.

Derek

[93GASE3300]

Well good luck I hope you dont have any trouble with aftermarket equipment. Keep an eye on your plugs because you might be runnin a little rich now and excess carbon can buildup on your intake valves and create problems in the future.