The Car Care Clinic with the Dr John

88 Pontiac 6000 Sport - Fuel starting running problems

Arnold, Dagenham

Question

Help! Our '88 Pontiac 6000 just stopped dead three weeks ago, the problem seems to be it's not injecting petrol. I have replaced the ECM, MAP sensor, fuel injector,(it is a TBI model), checked the TPS and O2 sensor voltage and I've jiggled wires all over the car to see if it was shorting, no luck. Now I'm about to go bonkers!!!. The only thing left to replace is the ignition module, but we have spark. If I pour petrol down the bore it fires up straight away! What could it be ?

Answer

If the engine starts when you add fuel then you have to ask why no fuel? Is there good fuel pressure? The fuel pressure on your vehicle's injection system has to be in the area of 12 PSI. If fuel pressure is correct then you have to check to see if the fuel injector is being triggered by the computer.

If the computer is not triggering the injector you have to find out if it is receiving a signal from the ignition module. On your vehicle you can have spark with no signal to the computer to operate the injector. Without the right tools and information, diagnosing this problem is a hit or miss event. By what you tell me your check book has taken a few direct hits.

Take it into your dealer or a good garage that specialises in troubleshooting and have them run a scan on the system.

Good Luck!
Dr. John