odd TBI problem

[dusterbd13]

i have begun to open track my TBI project. it really does quite well, but im having a problem that i cant figure out. coming out of hard right hand turns, like out of turn 14 onto the front straight at CMP, the thing lays down. just no power, no throttle response, no acceleration. will so it more or less depending on the turn sharpness, and also on left hand turns. will not do it on the street.

as far as eliminating variables, i have tried a new fuel pump and filter, rebuilt the TBI, and tund it up. full tank or empty does not make a difference. does not do it in the rain, only after the track dries out and i can drive it harder. it gets worse the further into the session i get. im stumped on this, to be homest. i left this thing injected so i wouldnt have to worry about these kinds of things.

the vehicke is an 87 s10, five speed, 2.8 TBI. stock 92 ECM, stock PROM, stock motor. the motor has had th EGR removed, the air pump removed, timing bumped to 12 degrees initial, no cat, and 2/25 exhausts. no CEL happens to light, and no backfiring. seems like it is running lean at these points. i have not verified fuel pressure, nor do i belive i can do so safely.

if you have any ideas, let me know.
thanks
Michael

[IsaacHayes]

It's got to be a wire/connector or something that is getting pinched or stretched... Possibly the wiring going to the fuel pump.

[Raffaelli]

Do you have a tach? Does it freak out? Like an ignition problem?

First thought is that its uncovering the fuel pickup in the tank, but that depends on fuel level

Figure a fuel pressure test somehow.

[dusterbd13]

no tach, but the volt auge isnt flickering. may still be ignition though, as it is session duration related.

im still trying to figure out how i can do a fuel pressure gauge that is safe enough to be on track and readable by my instructor without spending a ton of money.

michael

[geoffinbc]

visit turbocity.com for a fuel pressure guage kit. You could extend the guage to mount in the truck or perhaps install an electric guage.

But if you just check the pressure that should suffice. It does not change with engine vacuum. Several sources suggest increasing the pressure to 12.5 to 13.5 on any TBI system. You can do this with shims under the regulator spring. A datalog would be a big help but its not easy to do without the right tools. But you may be able to rent some prefessional time.

My guess would be lean from low pressure, dwindling ignition performance from and old flakey coil, ignition module or pickup. Or poor injectors that let the engine performance sag under demanding conditions.