My 88 Chevy 2500 with a 350 backfires through the throttle body when i try to start it i got every thing on mark with the timing and it's getting fuel and spark

SOURCE: wont start

Make sure that you're getting spark. A very common thing on these engines are coils going bad. If you can verify spark, check to make sure you have an injector pulse. As you rotate the engine, look inside of the throttle body and make sure that you see fuel pulsing into the engine. You can still have good pressure but you don't have an injector pulse, the fuel still cant get into the engine. You can use a test light as well to test for an injector pulse. One wire going to the injector will have constant power and the other will blink when the engie is rolled over. Does it start if you spray starting fluid into the throttle body? If it does, it's a fuel delivery problem. Again be sure you have spark from coil to distributor and plugs. You can remove the ignition module and take it to NAPA and they have a module tester. Have them test the module several times not just once. This will eliminate the possibilites of an intermitted problem. Let me know how it does. [email protected]

SOURCE: 88 Nissan z24i backfires through throttle body and loses power when in gear

Check your intake and exhaust modules. I have a 1987 D21 and had the same problem (if I understand your post). I replaced the modules located behind the driver side headlights and it fixed the problem. Good luck! I hope this helps.

SOURCE: Chevy 454 back fire

Ignition timing is set by the computer as long as the distributor pickup point is within reason.

It could be running too lean. One of the TBI injectors may be sticking or not working (wiring or computer problem), or fuel pressure could be low.

SOURCE: vaccum hose diagram for 88 chevy truck

it may not be a vacumn leak from a line,check the throttle shaft for movement,for example,i had a 89 1 ton 350 and my throttle shaft was moving around a lot and in order to keep it from idling high,i had to kick the throttle pedal.But also check the idle air control valve,which is the round sensor on the side of the throttle body.

SOURCE: 5.3 chevy hesitates when cold runs fine after warming up

I have same problem, Chevy told me it was probably a seal affecting fuel air ratio and when warm seal expanded to stop air leak. I forget which seal but they also said to check plastic case around seal because it will warp and may also need to be replaced. It was located near top center of engine. Please let me know if you figure it out.