I have a 89 silerado 350 efi and it back fires like when u give it gas timing how do i set the timing?

we changed rotor cap plugs cap wires but still back fires is there a special way to time it? something i have to uhook or something because we moved the distibuter and it did nothingI have a 89 silerado 350 efi and it back fires like when u give it gas timing how do i set the timing?
Sound like you crossed wires.Check Firing order again.



1-8-4-3-6-5-7-2 rotor turning clockwise.I have a 89 silerado 350 efi and it back fires like when u give it gas timing how do i set the timing?
Was it Backfiring before you worked on it? If so, it sounds like it's jumped Timing.Does it still have the original Factory Nylon Sprocket on the Camshaft ? If so, one or more of the %26quot;Teeth%26quot; may have stripped off.One way to determine this is to remove the Valve Cover on the Driver's side of the Engine, remove the Spark Plug to the 1 Cylinder, which is in the front of the Engine on the Driver's side, and bump the Engine over, without starting it. Put your Thumb over the Spark Plug Hole, and you'll feel the Compression build up when the Piston comes to the Top. With the Piston at the very Top, and the Distributor Rotor Button pointing at the 1 Spark Plug Wire,[You'll have to remove the Distributor Cap to see that], and both Rocker Arms for 1 in the closed Position, look at the Timing Mark on the Harmonic Balancer on the bottom pulley of the Engine. It should be pointing somewhere close to the Timing Mark where you see the Timing Adjustment Settings. If it's not, and it's way off, then chances are that it's jumped Timing, and you're going to need a full Timing Kit, which consists of a Timing Chain, Camshaft Sprocket, Crankshaft Sprocket, and a Timing Cover Gasket. Everything on the front of the Engine has to come off to replace the Timing Set, so you want to make sure that's what it is before proceeding. I've done it, and I can tell you, it's a lot of work ! Make sure you have a Haynes Manual, and read it thoroughly before you start.That'll cost about $15, and will tell you exactly how to set the Timing, and replace the Timing Set. If you do it yourself, it'll cost about $50, maybe less, and it'll take several Hours, maybe a couple of evenings, if you're doing it by the Shadetree. If you pay a Repair Shop, it's going to cost around $250 to $350 easy, but make sure you know what you're doing before you attempt it.Try polkan47's Answer first.I hope he's right, cause it'll save you a lot of Hasle ! Hope this helps !I have a 89 silerado 350 efi and it back fires like when u give it gas timing how do i set the timing?
i agree with polkan47.their is a olds rocket 350 with a different fireing order but in your case it is 18436572 in clockwise rotation.I have a 89 silerado 350 efi and it back fires like when u give it gas timing how do i set the timing?
Yes, you have to dis-connect the brown wire behind the plastic cover on the firewall underneath the hood. Before timing it to ZERO timing provided the ECM computer is still hooked-up. Once you have the timing set on ZERO, re-connect the brown wire and you should be good to go.



Below is a search I did over @ fullsizechevy.com on setting the timing. See if, this can help you w/ your issue.



Good luck!I have a 89 silerado 350 efi and it back fires like when u give it gas timing how do i set the timing?
I own a shop, and since yours is this old, you probably have a worn out camshaft. The symptoms are: It runs fine until you give it gas %26amp; get it under a pull, and then it backfires through the intake (most common) or the exhaust. Remember; timing doesn't get off by itself, and one that jumps on the gears will ( 99% of the time) not run at all, and/or will backfire all the time, not just when you give it gas. The best way to diagnose this problem is to use a vacuum gage attached to manifold vacuum source. You are on the right track by thinking its in the ignition timing, and it could be if you changed the plug wires, and then the problem showed up. Other suggestions on how to set the timing is correct, but you will more than likely find the timing is dead on. The most common causes are: EGR system not functioning properly, Vacuum leak, Damaged valve springs or sticking valves, and the Intake gasket leaking. To properly diagnose the problem, I would suggest running a vacuum test, a compression test, and a leak down test. It will more than likely show up on the vacuum test, and you will need a chart to interpute the needle readings. Since you have replaced the plugs %26amp; wires, and cap %26amp; rotor, then if the engine has a lot of miles on it, then you more than likely have a worn camshaft.

One final thing that is not so common on these vehicles is; The distributor may be worn out. Remove the cap, grab hold of the rotor, and see if you can move it from side to side. There should be no, or very tiny amount of movement. When the bushing (in the top of the distributor) gets worn, the shaft will flop around, which opens %26amp; closes the air gap between the reluctor %26amp; magnetic pick-up. This will cause the ignition timing to be all over the place, and when you give it gas it will move to one side from the torque on it from the camshaft %26amp; oil pump. This will also (sometimes) wear the gear on the distributor that runs on the camshaft. If this happens, then its just like a rearend that has too much backlash in it, and it prematurely wears out the gear due to improper mesh between the two. The camshaft gear is much harder than the distributor gear, thus it doesn't wear it. This can be a serious problem as it will cause metal from the gear to be introduced into the oiling system. Any metal in the oil will wreak havoc on the bearings, cam %26amp; lifters, and rings. It can also severely damage the oil pump. I would pull the distributor out, and replace it with another one. If you use one that has been used before, then you must replace the distributor gear with a new one, or it will wear out pretty fast. This sometimes is the case with an engine that has a roller cam, and the cam is walking inside the block too much due to the thrust button/bearing wear. This will also cause the cam to walk enough for the timing chain to hit the block, and in some cases wear a hole in the block behind the chain %26amp; gear.

Glad to help out, Good Luck!!!I have a 89 silerado 350 efi and it back fires like when u give it gas timing how do i set the timing?
First thing to check is that you don't have your wires crossed either on the spark plugs or the cap. This can happen quite easily and engine will do exactly what you describe. Check these carefully before getting too carried away