need TBI help-can only drive in reverse!!!!

[no_doz]

my friend's 89 chevy 1500 with 5.7l & 4 speed auto/4x4 truck (the one that was having the full throttle issue a while ago) is once again having problems, it truck runs great if in reverse or park, but in the forward gears (all of them) if you give it more than light cruising throttle (which is to say -not much-) it sounds like the fuel is cut & it dies.

-runs fine in reverse & park & can be full throttled then
-dies with any more than light throttle in forward gears
-there seems to be a very light (but present) miss at idle

we had the ignition control module tested at several places & its fine as well as replaced the plugs/wires/dis cap/rotor. it runs GREAT in reverse...LOL

any ideas guys?

[robertisaar]

well if its not spark related, and compression wouldn't make much sense, how about fuel?

[no_doz]

its been checked, the fuel pressure is fine, and it runs like a champ in park or reverse, but for some reason when you put it in the forward gears it just cant be given nearly any throttle or it like hiccups (not backfires) and dies.

tonight we're going to look around & see it a linkage is pinching a wire or something, i also went & pulled every fuse but what was absolutely needed to run to see if it would run normally but no change, so it doesnt appear to be grounding out on any of that wiring.

the previous owner was a moron that told us he rebuilt the engine & when we asked what all he did he said it was a year ago so he couldnt remember (he couldnt tell me 1 single thing he did to the engine other than "rebuilt it").

he had a tach & speakers wired up with the pos & negative together & wired to a one positive on the fuse panel & hooked to no ground, & wondered why everything was acting goofy & not working right, i figure some of his other wiring had to provide a ground through the fuse panel or something-it shouldnt have worked at all...

could this problem be ecu related? because those "US Fidelis Auto Warranty" commercials claim that putting a new one in costs $2200 LOL (id do it for him for nothin, i just love how much of a joke those commercials are :P)-also a new alternator installed is $1500.

[robertisaar]

89 5.7TBI: should be a 1227747 ECU. from the way this guy decided to wire his awesome sound system, i wouldn't be surprised, if his general fucktardery is the reason behind this....

any codes?

[asylummotorsports]

89 5.7TBI: should be a 1227747 ECU. from the way this guy decided to wire his awesome sound system, i wouldn't be surprised, if his general fucktardery is the reason behind this....

any codes?

Oh great! ANOTHER new word to use at the bar this afternoon!! Fucktardery!

But yes!! See if you can find another ECU. Sounds messed up.

However you should check out ALL the wiring to ensure you aren't doing this regularly!

[double00bu]

Hey,i had a very similar problem with a 88 chevy truck,took forever to figure it out
i had a parts truck and swapped everything i could think of including the dist module and, computer
last thing i changed was the whole dist and,it took care of it
turns out after talking to a few people its a very common problem with those yrs of tbi v8
not saying i am right,it was just the problem in my case

good luck

[no_doz]

thanks for the help guys, i doubt thats the problem though because my buddy had a new engine put in it (new to him) & it ran great until he took it mud running & now its doing this crap again.

he blew a headgasket on the other motor

[no_doz]

well we tinkered around, checked all the linkages & wiring & nothing appears to be getting hit or grounding out in the forward gears, but there are half a dozen wires disconnected, possibly due to the engine being slightly new.

we determined that anything 1/4 throttle & above in the forward gears cuts the fuel or doesnt allow it to get enough, & if he lets off right as it begins to die it acts normally but if he doesnt it dies, so what could cause this?

[bszopi]

Bad or incorrect fuel pump possibly.

[LeftVentricle]

Does it have a throttle position sensor?

[pocket-rocket]

Bad or incorrect fuel pump possibly.

I was going to mention this. Maybe a broken baffle in the tank allowing the fuel to surge forward (the same concept behind driving a tanker and learning your gear changes really fast and avoiding sudden stops).

http://www.patentstorm.us/patents/4775070/description.html

The transport of various types of fluids, including fluid hydrocarbons, and other volumes of fluids, it is most commonly undertaken in a transport vehicle of the type which would include a single or double elongated tank portion horizontally disposed on a frame, the entire transport portion being pulled by the truck. These "tankers" are used often to transport vast quantities of fluid material, i.e., between 20 to 50 thousand gallons or more so that the liquid, contained in the fluid portion of the vehicle, which creates an enormous amount of inertial mass as the vehicle is attempting to accelerate or to decelerate in stopping the vehicle, or attempting to undertake sharp turns of the vehicle during transport.

Although the total weight or inertial mass of the fluid is the problem during transport, one of the more common and perhaps more dangerous problems is the situation where the fluid contained in the transport portion of the vehicle is not fully loaded with fluid. In that event, when the vehicle must attempt to stop sharply or to undertake sharp turns, the inertial force created by movement of the fluid causes a surge wave within the transport section thus causing an enormous shift of weight in the vehicle, which, depending on the type of maneuver being undertaking, may cause the vehicle to continue moving rather than stop, or in the worse case, may cause such a lateral shift in the weight of the fluid that the vehicle will be tipped over on its side and upended.

One of the more common methods that have been attempted to be utilized in this type of event, is the use of a baffling system on the floor of the transport section, which would normally comprise a series of walls along the bottom portion of the vehicle which would tend to separate the fluid in the vehicle into a lesser quantity of fluid and would attempt to avoid fluid surge within the vehicle. This baffling system for the most part has met with limited success, but has not solved the problem of fluid surges when the fluid contained in the vehicle does have space within the fluid section to surge vis-a-vis the movement of the vehicle.

There have been attempts to suggest placing panel type members to act as baffles against tank surges, which, however, have left flow spaces between the tank portions wherein fluid would be allowed to move between the portions of the tank. Therefore, in those instances when a transport vehicle is undertaking a rather lengthy curve or a steep climb, during the time period that the curve or climb is being undertaken, the fluid is surging due to the centrifugal force or gravity on the fluid, through the holes in the baffles, which could cause a problem of uneven distribution fluid during the turn or climb. Therefore, the fluid is not separated or isolated into separate compartments within the transport vehicle.

[no_doz]

im not sure about the tps-ill have to take a look tomorrow. also if it was the wrong fuel pump wouldnt it have problems running in general, not just in forward gears?

also it doesnt care how nicely you ease on the throttle, once you hit 1/4 throttle it dies (unless in park neutral or reverse). and it can do reverse burnouts quite nicely, so would that rule out the whole gas tank baffle thing?

he said it ran perfect until he took it through a mud hole & shortly after getting out (on its own power with no help) it started having this problem.

[robertisaar]

possible tranny/drivetrain issue?

[no_doz]

no way, its a fuel-cut issue for sure, we just arent sure why

[no_doz]

it was a short caused by the mechanic who put the engine in, he didnt bolt up the heat shield & a bunch of wires were laying on the header, we fixed that & bracketed it & now it runs like a champ.

thanks for your help though guys