throttle body help

[jratliff]

what would cause my throttle body to release more gas than it should be ?
if you look at it, while idleing it is coming out pretty fast then on wot it is just gusshing out in there and almost flooding the engine
any help would be great

[xjs3667]

bad fuel pressure regulator, what is this on?? and is it running any different?

[HockeyGuy]

I had a mustang that did that 302. Was caused by the mass air flow sensor.  Unplug the sensor and see if it changes.

[xjs3667]

I had a mustang that did that 302. Was caused by the mass air flow sensor.  Unplug the sensor and see if it changes.

there is no mass air flow sensor on a t.b.i engine, that I know of at least not on any gm vehicles, only vehicles with m.p.i. or c.p.i have mass air flow sensors

[jratliff]

it's a 1994 sierra w/a 5.7 350
it aint running to bad unless i take off fast then it bog's out...

[xjs3667]

it's a 1994 sierra w/a 5.7 350
it aint running to bad unless i take off fast then it bog's out...

yea theres no maf sensor on that truck, it is rare that the pressure regulator will go out on the tbi's but it has happened, but I dont think thats your problem, check your fuel pressure before throttle body, your pump might be on the fritz, even tho it make look like its getting enough fuel or as you say to much, the way a tbi sprays can play tricks on ya, you might not be getting enough fuel, I had the same thing happen on my truck, also if fuel pressure is ok then check timing.

fuel psi should be around 55-62psi running, and no lower than 50 psi, if lower replace pump, as for the regulator there isnt really any way to check it, and for the cost to have it torn down (since the regulator is built inside the unit), it is way cheaper to just grab one at a scrap yard and swap em and then you know if the regulator was bad,

remember im just guessing here and giving you the most common problems, It would better if I was looking at it lol

ohh and also check the m.a.p. sensor that it is within specs, this controls the amount of fuel at wot

[01vortecpwr]

coolant temp sensor?

[Disturban]

it's a 1994 sierra w/a 5.7 350
it aint running to bad unless i take off fast then it bog's out...

yea theres no maf sensor on that truck, it is rare that the pressure regulator will go out on the tbi's but it has happened, but I dont think thats your problem, check your fuel pressure before throttle body, your pump might be on the fritz, even tho it make look like its getting enough fuel or as you say to much, the way a tbi sprays can play tricks on ya, you might not be getting enough fuel, I had the same thing happen on my truck, also if fuel pressure is ok then check timing.

fuel psi should be around 55-62psi running, and no lower than 50 psi, if lower replace pump, as for the regulator there isnt really any way to check it, and for the cost to have it torn down (since the regulator is built inside the unit), it is way cheaper to just grab one at a scrap yard and swap em and then you know if the regulator was bad,

remember im just guessing here and giving you the most common problems, It would better if I was looking at it lol

ohh and also check the m.a.p. sensor that it is within specs, this controls the amount of fuel at wot

Only the vortecs 1996 and newer have that much fuel pressure, his is a tbi 11 to 14 lbs is what is required for it to run. Pump could still be going bad though, you should have between 25 and 30 psi before the injectors. also the injectors could be clogged. Hook a timing light up to the motor and point the light at the fuel injectors while the truck is running and look at the spray pattern, it should have a nice cone shape to it comming out of the injectors, if not we will go from there, if one looks different than the other it is for sure a bad injector.

[jratliff]

injectors are spraying good (just a little to good)
just way to much fuel coming out

[reaper1986]

i would also suggest checking the pressure on your return line. if that's plugged up or block in some way, pressure's going to be way high. Had that issue with my own pickup for the longest.

[xjs3667]

it's a 1994 sierra w/a 5.7 350
it aint running to bad unless i take off fast then it bog's out...

yea theres no maf sensor on that truck, it is rare that the pressure regulator will go out on the tbi's but it has happened, but I dont think thats your problem, check your fuel pressure before throttle body, your pump might be on the fritz, even tho it make look like its getting enough fuel or as you say to much, the way a tbi sprays can play tricks on ya, you might not be getting enough fuel, I had the same thing happen on my truck, also if fuel pressure is ok then check timing.

fuel psi should be around 55-62psi running, and no lower than 50 psi, if lower replace pump, as for the regulator there isnt really any way to check it, and for the cost to have it torn down (since the regulator is built inside the unit), it is way cheaper to just grab one at a scrap yard and swap em and then you know if the regulator was bad,

remember im just guessing here and giving you the most common problems, It would better if I was looking at it lol

ohh and also check the m.a.p. sensor that it is within specs, this controls the amount of fuel at wot

Only the vortecs 1996 and newer have that much fuel pressure, his is a tbi 11 to 14 lbs is what is required for it to run. Pump could still be going bad though, you should have between 25 and 30 psi before the injectors. also the injectors could be clogged. Hook a timing light up to the motor and point the light at the fuel injectors while the truck is running and look at the spray pattern, it should have a nice cone shape to it comming out of the injectors, if not we will go from there, if one looks different than the other it is for sure a bad injector.

S#!^    your right about the 30 psi..... I got all confused lol,  thanks for the correction

[J.C.]

injectors are spraying good (just a little to good)
just way to much fuel coming out

we need to find out what "way to much coming out" is. are you sure its puttin extra fuel in, or could it be something else?

[jratliff]

injectors are spraying good (just a little to good)
just way to much fuel coming out

we need to find out what "way to much coming out" is. are you sure its puttin extra fuel in, or could it be something else?

yea way to much spraying out
on wot it just floods it out to almost stalling
i just bought a fuel regulator so ill see if that helps...
thanks again guys for the help