tbi issue

[BIG UG]

Alright fellas i need help fast, blazer bash is just around the corner and i just developed a problem. When i make right hand turns my truck acts like its run out of fuel. I am a pretty skilled mechanic but this is just wierd. Mind you i just did this tbi swap about 6 mths ago, and has ran fine until now. It is a 85 gmc k10 with 87 wiring harness inside and out, 454 tbi. Any help i gotta figure it out fast!!!

 

[Fordum]

At what speed?
If you are really honking it around a tight curve, you might be running out of gas.
Something could have come loose on the pump in the tank.

If it does it when you just turn the wheel, then more than likely something on the steering system is either hitting a wire, or moving something and breaking a connection.

Or, something is binding in the steering and loading down your engine when you turn right.

If it does it at moderate speed, then check to make sure your tank is tight. It might be shifting and causing the pump to lose its ground.

If it will do it sitting still, how far do you have to turn the wheel? You need to see if you can make it do it repeatably so you can watch to see what is moving or binding.

 

[BIG UG]

Seems to do it at rollin thru the turn, all until it striatens out then it is fine. I have to just idle thru the turn to get iit to run normal.

 

[70jimmy]

How much fuel is in the tank? The pump if using an internal and or fuel pickup is on the right side so if all the fuel is sloshing away from pickup maybe its starving momentarily?

 

[BIG UG]

Its a 40 gal suburban tank between the frame rails, and it will do it on a full tank or empty tank.

 

[Fordum]

Really sounds like gas sloshing in the tank with a bad pickup. But, it could be something moving when you get some G forces and either pinching a hose or moving a connection.

 

[BIG UG]

It runs fine straight down the road and thru left turns. It does kinda stumble when its cold but i think the map sensor is jacked

 

[Fordum]

I need to wait for the replies.......

If its not in the tank, then its something moving. If it won't do it just by turning the steering wheel, then its something shifting when you pull some G forces.

Make sure the engine mounts are good. You might be shifting the engine and breaking a connection or binding the throttle linkage.
If its an auto, have some one watch the engine with the truck in drive and your foot on the brake.
Give it a little gas and see if it moves a lot.
If its a manual, hold the brake and ease the clutch out a little to load the system.

If its the other engine mount, then you might not see anything that way, but you can try prising up on one side.

Remember, when you go right, everything in the truck wants to go left.

 

[BIG UG]

Thats why im stumped new motor mounts and fuels lines r clear. Truck has a 2 in body lift so plenty of clearance for all fuel lines and electrical.

 

[Fordum]

Well, something has to be shifting when you go around a right hand corner. Could be something as simple as a loose wire somewhere.
I would go out and shake every thing you can get your hand on to see if any wire or part moves or comes loose.

If you don't see anything obvious, then try it with it running to see if you can get it to skip.
Watch for moving parts, of course.
If that does not work, try driving sideways on a steep hill. Don't roll, but fairly steep left side down.

It could be a loose connection under the dash in the ignition switch or harness.

 

[BIG UG]

Checked all the wiring, all good. One guy said he had to replace his ignition module, but i dont understand that. I had one go out and truck wouldnt start period.

 

[MarineK5]

The best thing to do is jus throw that tbi and intake in the trash. They usually always run too rich and you cant really adjust them. Definately sounds like you need to drop the tank, could be something loose.

 

[Burbdood 74]

The best thing to do is jus throw that tbi and intake in the trash. They usually always run too rich and you cant really adjust them. Definately sounds like you need to drop the tank, could be something loose.

Yeah, but you can't beat a steady idle, instant cold weather start up, better mileage and the ability to run at any angle, something you can't do well with a carb.