dw1998ls1

i have a 98 z28 and it has been cutting out and dying when i get in it all the way @ around 62-6500 rpm. put the car in neutral and it fires right back up with no problems also runs fine as long as i dont get in the gas pedal. anyone have any suggestions thanks.

Ironembraced

What mods have you done? Sounds like you might be running lean.

dw1998ls1

cam,full exhaust,lid,programed from texas speed, thats about it nothing major. it just started doing it recently.

dw1998ls1

cam,full exhaust,lid,programed from texas speed, thats about it nothing major. it just started doing it recently

Ironembraced

Is that when your WOT problems started? How long are you running at WOT before it dies?

What injectors are you running (and what duty cycle % are you running them at?) what size cam, how much estimated horsepower?

If I had to take a guess, I'd say it could possibly be dirty injectors or a dying fuel pump or clogged fuel system. But I am just completely guessing.

But we need alot more details to really be any help.

dw1998ls1

im not real mechanic savvy but when i get home this evening ill give you all the specs i have on the car it put up in a file at the house. the horsepower dyno was 385 done when they tuned the car at texas speed that was about 3 years ago and it just recently started acting up a few weeks ago. it runs fine as long as i stay out of the gas

dw1998ls1

also as soon as it hit around 62-6500 rpm it cuts and dies im wondering if it might be the fuel pump?

Ironembraced

It could be...but it could also be as simple as just needing a treatment of Seafoam.

dw1998ls1

Thanks ill give it a shot

Ironembraced

Just try to go easy on it until you find the issue. If you get detonation, that could ruin your day.

Camaropar

iTrader: (1)

Fuel pump, people should be saying this right away considering how bad the OE design is. Get yourself a walbro 255

Ironembraced

So you already ruled out the injectors without even looking at it?

But yeah I guess it is safer to just replace it now regardless.

mrmckeehan

sounds exactly like my problem I am having but mine does not cut off. mine throws the service engine light then bogs down. I have no clue what it is.

Ironembraced

Check your throttle position sensor and also check your fuel pressure.

Have you pulled your codes yet?

slowpoke96z28

iTrader: (2)

if you're gonna go the shotgun route, i'd do a fuel filter b4 i did a fuel pump. a dirty filter may very well manifest itself like this, and its the cheapest thing you can do. i'd probably pull a plug or two if you can do it right after it happens. the plugs can tell all...

myk

iTrader: (4)

Fuel system pressure test is the best thing to do. These pumps go out all of the time. Rent or buy a fuel pressure gauge and hook it up to the rails and see what you've got during start-up, idle, throttle and how it "leaks down" once the motor is off...

NVUSZ28

iTrader: (5)

If you don't have a upgraded FP, this was my suggestion.

Camaropar

iTrader: (1)

Yes, I did. Fuel injectors are not it as they'd be a problem at lower RPMs/loads.

I'm not saying blindly replace the fuel pump, obviously a fuel pressure test is in order but sure sounds like it.

dw1998ls1

fuel psi stays around 48-50 and holds when i kill the car. i pulled two codes they were p0135,&po155.

slowpoke96z28

iTrader: (2)

those are o2 codes. not gonna cause this symptom. fwiw, you need to see the fuel pressure when the problem occurs. whats THAT number?