Engine cranks but won't fire, then LOUD backfire, help?

[race2win]

I did a search, but couldn't seem to find the same problem I am having. My car has been sitting for about 5-6 months, so yesterday I go to start it as I am starting to get it ready for autocrossing. I had to jump start it, but it fired off right away & idled great (I was impressed). I let it idle for a little bit, maybe 10 min, then went to drive it. Well, as soon as I started to feed any throttle to it, & just as the boost would start to build past 0 it would start coughing & sputtering. If I lifted, it would settle to a normal idle, but anytime I gave it more than say 20% throttle it would cut out (sounded like a 2 step set at like 2K RPM). I didn't have time to investigate things until today, so I put it back in the garage. This morning I go out to try & start it, it cranks & cranks, sputtered a couple times, but won't fire up. I try again, but this time it doesn't even sputter, it won't fire at all. But, as soon as I released the key & the engine quit turning, I get the loudest backfire I've ever heard out the exhaust! Any ideas what could cause this? Literally it ran yesterday, now this. I didn't even really drive it, the engine hasn't been above 2K RPM, I am at a loss. Before it was parked last year, this car ran awesome & for the most part always has through a few different set-ups. I checked the T-belt, all looks good. It definitely seems like the cylinders are filling with fuel, but like I'm not getting any spark while the starter is cranking. ECU?? CAS?? Coil pack?? Any help would be greatly appreciated, thanks in advance.

 

[robbo185]

how old is the gas?

did you check the timing?

 

[need2boostpsi]

Check your CAS, i would say you have it one backwards if its been off, take it off spin the key 180* and bolt it back on to test that theory, sounds like its firing when the valves are open.

 

[race2win]

Check your CAS, i would say you have it one backwards if its been off, take it off spin the key 180* and bolt it back on to test that theory, sounds like its firing when the valves are open.

Thanks for the ideas. Well, I will check that, but the CAS has not been off this car EVER. If the CAS failed, could it cause this? As I sit here & think things through, it's as if while the starter is engaged (or maybe when the ignition switch is in the start position) it has no spark. But, when the key is rotated back for some reason I do get spark & the unburned fuel lights off in the cylinder that happens to have the open valve. I am puzzled at how it's possible to get spark in an engine that is not turning though....any ideas on that? Sometimes the backfire is a couple seconds after the engine quits turning. The engine was dead cold (never got it started) & it was like 35 degrees out. I will try & confirm tomorrow if I am getting spark while the starter is cranking. Also, the bad fuel theory has merit I suppose. The fuel in the car is like a year old or more, but it is 100 octane unleaded, should the race gas last longer or have a shorter life? Thanks again everyone.

 

[91dsmgsx]

when was the last time you changed the fuel filter? if you have a hanyes manual or anyother service manual it will show you how to test the ignition coil. also check the power transistor i know that when those start to go bad the car acts really goofy.

 

[race2win]

OK, I figured a couple things out & I'm making some headway, but still can't get it to start. It's got spark while the engine is cranking, & it appears to be getting plenty of fuel. I pulled all the plugs & not only were they pretty black, but they were wet with fuel. I must admit though, I have not heard the pump humming with the key in the run position & the engine not running, should it be? I can't remember, I know I've heard it when the engine is running. There definitely seems to be fuel in the engine, so I would think it is working.... The backfire seems to be caused by a spark AFTER the key is released from the start position. I'm guessing it pops because the engine has stopped turning so the pressure is forced out the exhaust of whatever valve is open. Just my theory, but I definitely noticed a spark after the key was released as I was checking it. So, now as I try to start it, I make sure to rotate the ignition switch quickly to the off position rather than the run position. Since I have been doing that, no backfire. I did try spraying some starting fluid into the intake, & with the throttle wide open during cranking I did get a couple coughs & sputters like it was trying to fire. So, at this point I am really leaning toward bad fuel, so I think tomorrow I am going to try & drain the tank & put some fresh 100 unleaded in there & see what happens. But I am also going to test the coil & replace the power TR unit as well, those are good ideas. Thanks again for the help.

 

[scottiesoccer1]

I am also having about the same problem, so im interested in your findings.

Scott

 

[costas14]

ahhhh search it. I POSTED LIKE 100000 ENTRYS ON THIS. CHANGE THESE IN THIS ORDER

1.IGNITION CONTROL MODULE! (GET A BOSCH ONE)
2.COIL PACK (GET A BRAND SPANKING NEW ONE FROM THE DEALER)

dont do stupid things like oo check ## fuel filter. if your backfiring it that means u GOT MORE FUEL THEN YOU COULD POSSIBLY WANT. and u have little spark. change both of those and forget everything else.

 

[costas14]

also if u still cant get it started and u havent chagned what i told u take a monkey wrench to the coil pack, should get it fired up if its still got life left.

 

[97dsmowner]

I did a search, but couldn't seem to find the same problem I am having. My car has been sitting for about 5-6 months, so yesterday I go to start it as I am starting to get it ready for autocrossing. I had to jump start it, but it fired off right away & idled great (I was impressed). I let it idle for a little bit, maybe 10 min, then went to drive it. Well, as soon as I started to feed any throttle to it, & just as the boost would start to build past 0 it would start coughing & sputtering. If I lifted, it would settle to a normal idle, but anytime I gave it more than say 20% throttle it would cut out (sounded like a 2 step set at like 2K RPM). I didn't have time to investigate things until today, so I put it back in the garage. This morning I go out to try & start it, it cranks & cranks, sputtered a couple times, but won't fire up. I try again, but this time it doesn't even sputter, it won't fire at all. But, as soon as I released the key & the engine quit turning, I get the loudest backfire I've ever heard out the exhaust! Any ideas what could cause this? Literally it ran yesterday, now this. I didn't even really drive it, the engine hasn't been above 2K RPM, I am at a loss. Before it was parked last year, this car ran awesome & for the most part always has through a few different set-ups. I checked the T-belt, all looks good. It definitely seems like the cylinders are filling with fuel, but like I'm not getting any spark while the starter is cranking. ECU?? CAS?? Coil pack?? Any help would be greatly appreciated, thanks in advance.

Did you ever find the problem? I'm currently having the same issue.

 

[Joey Burger]

did you check your plugs? try taking a set of wires out of another vehicle you know is running and try that, i dont think a coil pack would go out instantly like that.. guessing its probably plugs or wires.. also check to see if your fuel pressure regulator is hooked into your vacuum lines, could be an issue.

 

[19gsx91]

Because I'm that guy.. Did you make sure your distributor isn't 180 out!? Also why are we reviving an 8 year old thread.. OP hasn't been on since 2010

 

[Nathan1993]

I had a similar issue. I ran the car really rich and fouled the plugs. Then I swapped wires when the car was missing. This solved all my problems.