What type of ignition system do these have... I have a1987 gmc vandura 5.7 liter throttle body fuel injection? My problem is im getting spark and fuel but still will not start.

Place a spark plug tester in your number #1 ignition lead and confirm spark.- No spark = possible ignition module failure if spark from coil is present.

Test the fuel line pressure for 12 PSI.for throttle body fuel injection systems on 1987 to 1995 - If reading is low replace fuel pump. If reading is zero lbs check relay.

Compression test for acceptable compression.

If you have spark, fuel and compression, static time the engine and try again to start the vehicle.

PS: If your vehicle is a standard shift you have a clutch safety switch and a column mounted ignition switch that should also be considered.

Here is some more info that may help:


How to Test the Fuel Pump on GM TBI Fuel Systems How To Check Engine Compression GM 3 5L 4 2L

The throttle body injector are turned on by a cam position sensor this is located in the distributor,

If you vehicle is parked on a slant and the wheels are slightly turned, the pressure from the weight of the car may be forcing you steering wheel to bind. Try tweaking the steering wheel in the same direction that the wheels are turned using your left hand and at the same time try turning the key with your right hand. Tweaking the steering wheel takes the pressure off of the ignition switch. If that doesn't work, try a different key if you have one.

Look.
If you see a fuel rail or a short-throat throttle body, it is fuel injected.
If you see a carburetor... well, I think you get the point :)
From the year (unless it is a non-U.S. model), it is most likely FUEL INJECTED.

You probably need to adjust idle speed

100 psi per cylinder is way too low--should be in the vicinity of 150-165 per cylinder
back firing indicates wrong firing order and as you have replaced the plugs etc check that you have the leads on the correct plugs in the correct order
the timing for the engine should be around the 10 degree btdc and not tdc

Are you sure that you have spark?

If youare looking for fuel at the throttle body, you will not find any unless there is something TERRIBLY WRONG with your truck. Depending on which engine you have (there are 3 possible engines for the 1996 model year) your truck is equipped with Multiport Fuel Injection (MFI) or Sequential Multiport Fuel Injection (SMFI)
You need to test the fuel pressure by connecting a fuel pressure gauge to the service port on the fuel rail. If the pump is running, there is no need to mess with the relay because it is obviously working. If the pressure is OK, then there is no problem with your fuel delivery system. The next thing to check is the fuel injection system. Also, have you checked to see if you have spark at the spark plugs? It could be that your truck is not starting because of ignition system problems.

Please also review the following article:
What Else Could Be Wrong?

this is fuel injected it may look like a carb but its throttle body fuel injected,if you look down the throttle body while cranking you should see fuel squirting into the intake if not hold a piece of paper under the injector it should get wet with fuel.if this is happening then check for spark at the plugs,if you have no spark then you will have to check out the ignition system.if you have no fuel coming out of the injectors then you will have to check the injectors powers and grounds.if this is good then you will have to check for fuel pressure at the throttle body.it should be about 15-18lbs.also check to see if there are any codes in the pcm that could help in diagnosing.

Need more information. Has car been sitting? Is it getting fuel to the intake? ( injector or throttle body?) What engine does it have? What type of carb. does it have? fuel injection, carb., or throttle body? Pull off a plug wire, and check it for spark....does ignition spark? Check timing for jumping. could have jumped timing belt? you need someone to help you visualize and troubleshoot.