Will not accelerate, restarting solves it

[wooshman]

Hello, I have an 87 GN that is stock minus injectors, fuel pump, regulator, actuator and chip. The car has recently started to give me problems. It will run great for a few miles and then when accelerating, it falls flat on it's face. It cuts out to the point that you can not accelerate. If I turn the ignition off and then back on, it will run fine again for a while. I have replaced the coilpack and module.
I am at a loss as what to do to fix this. It seems to be computer / electronic related but I am stumped. Any insight or help would be greatly appreciated.

Thanks in advance

- josh

 

[dank GN]

Check the grounds on the back of the pass. head

 

[Chuck Leeper]

What's the scan tool show when this happens??? You DO have 1, right??!Batt neg cable under the turbo tite?
Batt + cable not touching the DP when you accelerate? [As in a broken motor mount, allowing engine to rock over.]

 

[83ttypecooled]

Hi,
It seems like the system is going into closed loop,and then it loses power. That is my initial impression,anyway. I think it would be prudent to check the grounds the others have suggested. I guess the ECM could be going bad,but I never heard about this one before... More likely ,the computer is responding to a situation it can't handle. Treat it as such.

 

[bison]

First check for fuel pressure. If ok go clean the area around the crank sensor and be sure to remove all dirt and grease from the interrupter ring. If you still get the symptoms replace the crank sensor.

 

[wooshman]

Thanks for the replys. I will try all the suggestions and report back. Hopefully one will work
I do have a scan tool, TurboLink. Yeah, bought it a while back. It does not register any codes or seem to indicate anything abnormal. I did check fuel pressure but will do it again.
Thanks again for the help.

- josh

 

[DailyDrifter]

Hi,
More likely ,the computer is responding to a situation it can't handle. Treat it as such.

More likely its being told what to do, Input-Logic-Output :wink:. A bad input is going to cause a bad output. What chip do you have? Look at all your numbers on the Turbolink before you start the car, make sure they are all reading right. Will the car start right back up and run fine?

 

[wooshman]

I have the TurboTweak chip. It does start right back up and runs fine for a while and then it repeats. It is solved every time by turning the ignition off and restarting.

 

[wooshman]

Did some troubleshooting tonight. It is fuel related. It runs fine for a while and then the fuel pressure drops while accelerating. The strange thing is that when you turn the ignition off then on, it resets and runs fine again for a while. This is a new walboro pump and its hotwired. I did have an issue with the first replacement pump that I bought. It was sent back and this one installed. I am starting to think that whatever problem was there with the last pump is still present and maybe it was not the pump itself that was bad.

Any ideas? I am not sure what direction to go. What would cause the pump to do that?

Thanks

- josh

 

[Chuck Leeper]

Tank vented??

 

[wooshman]

Chuck,

It is a stock tank. What should I be looking for?

 

[Chuck Leeper]

Has the

Chuck,

It is a stock tank. What should I be looking for?

charcoal canister been removed?
If so, what was done w/ the lines? The tank is vented thru the canister. Plugging the lines will remove the vent....
Post the scantool results.....

 

[wooshman]

The canister is still there. The #s look normal until the fuel pressure drops off and then of course the o2 #s and knock get out of line. I have a fuel pressure gauge taped to the windshield and i can clearly see the fuel pressure drop as I accelerate. The thing that baffles me is that it is instantly solved by restarting the car. It then will do it a few minutes later.

I appreciate your help.

- Josh

 

[Chuck Leeper]

More ??'s

When U replaced the pump, did you see that the tank is the correct tank? W/o baffles, the pump comes uncovered and psi drops..
Does this happen w/ the tank full?
Does it happen only when you stand on it? Try to power brake it, and see if the same thing happens. [Don't let go of the brake.] This will eliminate the tank slosh theory.
When this happens, U see anything weird about batt volts?
Have you checked the volts at the pump?
Pos cable touching/close to the dp? [Under accel, the engine could rock over and short the cable]
When you installed the pump, did you get rid of the pulse dampener, and use the hose and clamps?
Any engine rocking ? Check the supply and return hoses at the alt for kinks...[Bad motor mounts]

 

[wooshman]

The tank is the correct, original tank. Once it starts to lose pressure it does it at any speed until I restart it. The voltage is normal on the TurboLink. I will check at the pump harness. The positive wire is not touching anywhere and the motor mounts are fine. I did not get rid of the pulse dampener. I did use the hose and clamps that came with the new pump. The pump is a Walboro.

Thanks

- josh

 

[TurboBuRick]

Did you put the sock filter on the pump?

 

[Just a Six??]

Why did you use the pulsator on the pump? Just curious as most discard them.

 

[wooshman]

I did put the sock on the pump. I do not know what the pulsator is. I did not remove anything from the stock set up when I swaped out the stock pump. The stock pump was fine and I only changed it as a precaution. The car only has 20k miles on it.

Is there something electrically that controls the pump that could be intermitently bad? A relay or such? The reason I ask is that turning it off then back on temporarily solves the problem.

Thanks

- josh

 

[Chuck Leeper]

FP relay is on the inner fender.
There is no way to put the pump on the hanger, use the pulsator and the hose /clamps..[Pulsator is between the pump outlet and the hanger line.
Check the FP relay bypass wiring at the oil psi block below the turbo...
I'm betting that the pump connection in the tank is leaking. At low power/idle, the volume requirements are low, and sufficient fuel is delivered.
Stand on it, the demand goes up, the psi goes down, and the engine quits.
Shutting off, and restarting just puts the pump demand back at a low level....
take the tank down, hanger out, and see what's going on.
Take the pump off, cut the necked down portion of the hanger tube off, install the hose and clamps. Discard the pulsator...

 

[Just a Six??]

Read this by Earl brown
How to install an intank fuel pump. - TurboBuicks.com