Thread: lumina apv needs help

Auto-tech Challenge
If you think you can fix anything and up for a challenge, read on. I want this car back on the road.
12/20/09
Vehicle:
1995 Chevrolet Lumina APV; 3.1L
History:
September: I returned from a 400 mile trip, parked the vehicle. The following morning it did not start. It had absolutely no spark at the plug wire. After a few test with a volts meter (as per Chilton manual), pickup coil replacement was indicated. I replace the entire distributor with a rebuilt. Car ran fine. Problem solved.
November: I filled my fuel tank with barely a gallon remaining. Within 10 miles, the vehicle began to miss and buck. I discovered that if I accelerated I could move more smoothly. The trouble got worse. After consulting my Chilton, I changed the fuel filter, and added fuel treatments to the tank, suspecting it was the last refueling that spurred the incident. The condition got better, and the vehicle was drivable, but not normal.
I drove to another town about 50 miles away, and it began to buck again. I drove it home using the same accelerate-decelerate cycle to maintain a highway speed. Eventually that system began fail. First, I was only able to maintain a speed of 20 mph, by holding the accelerator to the floor -- could hear the engine suck air. Finally, I finished the last 5 miles at a 10 mph maximum – pedal to the floor.
Next day: Woke to a no-start condition. Checked fuel pressure (10psi-OK), and found no codes (initially).
Tested MAP, TPS, based on Chilton trouble shooting section. I replaced the MAP sensor. Tried cranking the engine--During cranking, the engine would fire but not run. Eventually, once it had warmed from partial-start under cranking , the engine would idle. Engine would buck and die when accelerator was pressed.
I tested the voltage at the TPS. No change when rotated, so I replaced the TPS-- Condition unchanged.
Computer threw VSS code, which can happen with a fault in the engine temperature circuit. OK, it’s off to the experts (?).
Off to Mr. GoodWrench: I took it a local GM garage. After $170.00 worth of testing, including catalytic converter removal, EGR, etc, they determined there was “nothing mechanically wrong” and suggested changing the ECU. They recommended an ECU change because Timing was jumping around, suggesting the electronic spark timer was defective. ECU was replaced – No Change.
Could the new distributor have failed? Is there a short in the system? Cure this car, if you can.

WOULD LIKE MOR INFO; if your car is OBD2, fuel injected and witch injection system used. motor size ect... if you have an injected car 10 psi is no where nere what it needs to be .will the car accelerate at idle or is your problem only when the motor has a load on it NOTE; mid 90s chevy products had a lot of fuel pump problems . write back with more info

Hightechredneck is corect in saying 10psi is not enough. Do a fuel preasure test and unhook the vacuum to fuel preasure regulator. This should increase fuel preasure by 5psi. If so, purge your preasure tester, does it kill your engine ? If so ... Replace fuel pump.

The car is OBD1. The engine is fuel injected and the spec is 9-13psi. You are a little low on pressure but still in spec. A VSS (vehicle speed sensor) won't have any effect on the starting of the vehicle. I would get the car running. With a can of brake clean I would rev the engine and when it starts to bog out hit it with the brake clean and see if it revs. If it does than you have a fuel problem. I would lean towards the pump because you only need a little bit of flow to make 10psi. So you may have a pressure thats in spec but you just don't have the flow. With a fuel injection system that requires a higher pressure like some gm's that need 60psi will be hard to achieve that spec with low flow. Is the engine missing when it is running, because if it is that would explain the timing jumping around. Let me know how you make out on the fuel test.

They are all right...Do a fuel pressure test and unhook the vacuum to fuel pressure regulator.