I need help with this engine. I bought the car a month ago. It has been sitting for a few years now not running ,but it did run well when it got parked. Anyway, It seems like it almost wants to start up. It will sputter a few times and backfire loud as hell occasionally. I replaced the fuel pump but I haven't checked my pressure yet. It does spray out of the valve at the fuel rails. I also checked the spark and it has very good spark. I washed the engine down when I bought the car because a rodent had packed it up with yard debris but it did not have a battery in it and did not get cranked over for week.... Of course that's before I knew not to spray down my engine.... but it still appears to get very good spark at the plug wire ends. Today I was messing around with it checking the spark and trying to get it to turn over ...but no luck... It sputters a few times like it wants to start.. then it will pop and backfire.... I noticed afterwards that both exhaust manifolds were warm/hot. Not bad enough to burn you but they were noticeably warm. I stumped..... Could it be not getting enough fuel pressure to pop open the injectors or something like that. I really don't smell gas at the exhaust. So I know it is getting spark and it is getting fuel... or some fuel... when I spray starting fluid in it .. it still will not start... Sometimes it will backfire through the intake with the starting fluid... Could a valve be sticking? Any help , idea, or anything would be greatly appreciated.

 

2 things I would check..

1. Check the wire that comes out the top of the opti spark. It is located right behind the waterpump. I had these exact same symptoms and turned out the wire wasnt connected properly.

2. Also check your coil as well. Could be bad..

Good Luck!

 

Ditto!
You can do the old 'hold this screwdriver close to the manifold while I turn it over' test, to be sure fire is making it to the plugs, too.
Also, CHECK/REPLACE THE PLUGS! I bought a Z24 from a guy several years ago, after it had sat less than 2 years. I had to drain the old gas (easy with an electric-pump!) and replace the spark-plugs. Then I drove it down off the trailer I picked it up with!
Seems plugs can foul with old gas, and then they won't start!
Good luck!

 

I did the old screwdriver test.... And it for sure is getting spark!! Next thing I'm gonna do is test the fuel pressure... If that's not the issue I'm gonna pull the injectors ..

 

Wait!
I realize that you have eliminated the coil, the icm, the ecm, the opti AND the wires, by locating spark at the plugs, but you haven't eliminated the possiblity of fouled PLUGS!

DO check the fuel pressure at the schrader-valve, but DON'T take anything else apart if it checks OK!

IMHO, I wouldn't go one step further without draining the gas-tank (pull the line before the filter and use a good battery to let the fuel-pump do it, if you haven't already!), replacing the fuel-filter, refilling it with GOOD gas, and replacing the spark plugs!
You will want to replace the filter and plugs anyway, after sitting for that long, so do it now, BEFORE you start taking parts off the engine!
THEN, you will have eliminated EVERY possible thing on the spark side of the equation BEFORE assuming it's a fuel-delivery issue!

Later, after you get it going, be sure and run some injector-cleaner thru the tank, to remove any varnish and deposits from the injectors, but maybe not on the first tankful, as it tends to cause them to run a little rough, and you will probably already have some of that going on...

 

Ok.... I have already cut a access hatch in the truck and drained the old fuel and replaced the fuel pump with a brand new pump. Gas tank was clean with no rust surprisingly...... At the time I didn't replace the filter which I know I need too.... I just couldn't get under the car at the time.... I'll check fuel pressure and change out the plugs too..... Which looks like a real pain in the ***.... If I still can't get it to start my next process of elimination would be to check the fuel injectors....

 

You should have already got any old fuel OUT. With fresh fuel in it, the first thing you should do when you have an engine that won't start is squirt fuel in the intake while someone cranks it over.

When it fires up and shuts down, you will be sure you have a fuel system issue.

The first thing you think of when a car has sat for a long time is the fuel system getting gunked up.

So the second thing you do is check pressure. When you see it's good, the third thing you do is pull the fuel rails and watch the injectors while someone cranks it over. You will see some squirt (albeit crappy) and some don't. More than likely the fuel rails have a gunk much like the consistency of molasses in them. They and the injectors would have to be removed and cleaned.

When you disconnect the fuel filter and the crap in the tank comes out, you will acquaint yourself with the foul odor of stale fuel. A smell you won't soon forget.

 

Oh yes.... The absolute first thing I did was remove the old fuel..... I also replaced the fuel pump... I did both of those before even turning the key.... If my fuel pressure checks out ok then I will pull the injectors.... It has a MSD ignition and the spark it very strong. I had thought I fried the optispark when I washed the engine but it definitely throws a flame and the pcm hasn't shut down off the fuel system yet. My bets are on the injectors.....but I'll be sure soon.

 

well..... I did a pressure check and it was above 40psi....so I tried squirting some gas into the throttle body..... I turned the engine over and got the same result... Just a few pops... It seems like the timing is off... I tried a few time with squirting the fuel and got nothing...It just pops and maybe a quick weak shudder.... that's about it.... Could the optispark be messed up and throwing the timing off??

 

Spark plugs...

 

It also backfires a little through the intake.... Nothing bad just little hiss and some smoke.... That's what makes me think its timing related..

 

Did you squirt enough? It takes a bunch.

 

Yea... I think so.... It doesn't want to fire off starting fluid either.... It backfired like a MFer outta the intake once with that stuff.... Gonna pull a spark plug out today and look at it...

 

If it wasnt the spark then it should have at least fired up for few seconds after squirting fuel into the intake (if u sprayed enuff) seeing as according to u the spark is very strong. Sounds like a spark issue. After setting so long how do u NOT change the plugs right from the jump? Do it so u can at very least eliminate that as posibility. It needs them anyways im sure.

 

Thank you!
IF I am wrong, then I'll eat these words, but I've had one do exactly what you are talking about, and it was the spark plugs! They are a pain in the *** to change in an LT1 Camaro, but it'll almost for sure fix your problem!