Mechanics

BUICK CENTURY SPARK PROBLEM

1988 Buick Century

Engine Mechanical problem
1988 Buick Century 6 cyl Front Wheel Drive Automatic

2.8 liter engine will not start. Good compression good fuel pressure and spark through spark plugs it acts like it is not getting fuel through injectors since it will try to run on carb cleaner sprayed into intake. New computer installed yesterday and new crank/cam sensor also. Fuel pump does not pump during cranking is that normal? Power is good to injectors (tested with light)
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Jjtubs
June 9, 2008.




The 2.8 vin W doesn't have a cam sensor. Are you sure which engine you have? Sometimes when replace a computer, you have to use the prom out of the old computer. You have everything hooked-up ok? Are there any codes?

My info shows an oil pressure switch in the fuel pump circuit, once you crank it enough to bring up oil pressure, the switch closes and the pump gets voltage. The pump should run regardless of the pump relay or computer. The only problem is, if the computer doesn't see an rpm signal, it won't pulse the injectors. The voltage side of the injectors go hot when you turn the key on, the computer controls the injectors on the ground side. You can look for a pulse on the ground side of the injectors, with the engine cranking.

There should be a purple wire with white tracer, goes from the ignition module to the computer, that carries the rpm signal, without that signal, the computer won't pulse the injectors, the fuel pump relay won't work either, but, with the OP switch in the fuel pump circuit the pump should run anyway. 2.8 vin W
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JDL
Jun 9, 2008.
I do have the 2.8 and it was a crank position sensor that I replaced. I checked for pulse at one injector that I can get to and it was pulsing at crank. I replaced the computer only because I listened to the parts man. There was no codes showing. I did use the old prom also. Could it be the ignition module even though I have spark through the spark plugs? That was suggested by a mechanic but I hate to put more money into guessing. Thanks for all your help.

James

Tiny
Jjtubs
Jun 9, 2008.
You need to be sure about the injector pulse, I don't know how you checked for pulse? Because of the air plenum covering the injectors, they are hard to get at.

There may be a four wire injector connector on the backside of the air plenum, easier to get at. You can do some testing there. If your not sure of the connector, look at the wiring color. The solid pink wire is B+ for 1 bank, the ground for the same bank is light blue.

The B+ wire for the second bank is pink with black stripe, the ground for the same bank is light green.

If there is spark and no injector pulse, I would suspect the ignition module. If there is spark and injector pulse, then I don't suspect the module. You need to be sure about the injector pulse.

If you don't have a wiring diagram for your vehicle, the autozone site should have one. After you bring up the web page, click on (vehicle repair guides) and follow the links. I believe the wiring diagrams would be under (chassis electrical).

JDL
Jun 10, 2008.

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