You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to start new topics, reply to conversations, privately message other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, join Chevrolet forum today!
I'm having similar issue right now. It back fires as it attempts to start. Getting spark and fuel pressure okay. I am thinking fuel injectors might be clogged, leaking or might be ignition coil as i replaced spark plug wires, distributor cap and rotor so far.
Register today for free or log-in if already registered to remove this ad!
I get some backfiring as well as it diesels. I am going to test my fuel injectors in the next couple days but I'm not sure what to expect. The van drives perfectly fine when it runs at all. That's why I feel like its something electrical, like a sensor.
I might go pick up an ignition coil for the hell of it since they are cheap. That is the only electrical component I havent replaced (besides the ignition control unit). plugs,cap,rotor, cam sensor, crank sensor and harness are all new.
Really though. I can't believe I haven't figured this out yet!! it cranks, it gets spark, it gets fuel!!!
Last edited by Chillin014; 11-03-2009 at 08:03 PM.
I may have different problem then yours. I also have spark and fuel pressure is okay (slightly above 60psi). I tested it test light but i may have weak spark. I almost started the van with starter fluid. You have want to try odb reader and see. if it gives you a code then you might have a easy solution. Mine gave me none. I either have timing is off, sensor or ecu is causing weak spark, or fuel injector issues. i am trackling this one by one but it is really puzzling. i did change ignition coil and no help.
I have an OBD-II reader but there are no codes so its no help. Most of the tests in this stupid ALLDATA manual I have require the scan tool that only the dealership has, so thats not of much help either. Unless the EGR is this cylinder mounted right on the front of the intake manifold with no exhaust hosing going to it...there doesn't seem to be one.
All I really have left to check is the injectors but according to the manual I'm not sure that you can get a reading from them individually without the scan tool.
The van starts if I bump the key. It will choke to life on its own the first try and start perfectly after that. My guess is that the injectors are flooding it or something. If that isn't it...then I give up.
I may just have to take it to the dealership and see if they can diagnose it.
Yours does sound like fuel injector problems. You supposed to take it out and test the injectors with noid light tester (i think that's what it is called) to check and see if there is pulse. Then tackle the clogged fuel injectors if any. Of course, you may damage it or might have to replace one or two if you mess with it. However, if you are careful i think you will be alright. At least you will find out if it's clogged out not and getting the correct pulse.
In my case, I do believe there is some sort of problem with fuel injectors but i am leaning more toward ignition module which might be a problem. i think i want to check igition control module, crank and cam sensor first then go into fuel injectors. i seem to have weak spark so i may have a failing ignition control module.
I'm going to check my spark strength as well since I bought a tester for it a week ago. As far as testing the injectors, how do I get to them? do I have to remove the intake manifold? And where is the cold start injector?
If the dealership can test all these with a scan tool it might be easier to do that rather than rip it all apart.
I would follow haynes manual and take it out slowly and carefully. It is pretty delicate stuff since you can brake parts easily. According to haynes manual, you should be able to test each injector on 4.8L, 5.3L, 6.0L, 7.4L v8 engines by listening and taking measurement of resistence on each injector. I am not sure how to test the fuel injector regulator.
Oh I dont have a Haynes manual, I have an ALL DATA worthless POS manual. I used to have a haynes but returned it because the instructions were too generic and it didnt seem like my specific vehicle was covered.
I've got a 5.7 liter SFI V8. I may glance at the haynes in the autostore anyway but if i can just figure out where the main harness connector is for the injectors I think I will be able to probe and get some readings.
If you take the intake and engine cover off, then you should be able to see everything. ALLDATA was a waste of money I agree. Only information that I got out of it was fuel pressure specification.
