3.1 Won't Start - Third Generation F-Body Message Boards

dragon574444 · 04-29-2012, 01:00 AM

Hey all,

I just picked up a 1991 Firebird with a 3.1 V6. I snagged it for 500 bucks, but unfortunately it won't start! The previous owner bought a new ignition coil and a new distributor. My dad and I figured that the timing was off...and it was. We pulled out the dizzy and dropped it in at TDC, still no start. We tried to get it a bit closer to 10* BTDC, but the car just wouldn't start. It tries to start, you can hear some popping.

We know we have spark, and we know we have fuel. What are some common issues for this car/year? I'm a Ford guy, so I'm not familiar with GM engines at all...I've read a lot of people mentioning leaky fuel injectors, would this cause a no start condition? Does this car have a crank angle sensor? Is there a way to test the fuel injectors? I tried to pull codes, but I only got code 12 infinitely. Would it be a good idea to get a fuel pressure gauge and test pressure while cranking?

Thanks in advance!

KrisW · 04-29-2012, 02:42 AM

You absolutely need to test the fuel pressure. Pump failure is common due to age and mileage. You need to get 41-47 when you first key it on and then it should hold for 20 minutes or so when you key it back off. It should not drop very low when cranking.

Take your ignition module out of the distributor and take it to the auto parts store and have it tested. Whether you get a new one or not, make sure you put plenty of paste on the back of it when you install it.

I thought I had plenty of spark once, too, because I could pull a plug and hook it to the coil wire and watch it fire on the intake. I was wrong, because at night when it was dark, I could see the coil actually let some spark out through the side of the housing to ground at the same time! It completely wrecked the spark timing and when I put another coil on it I was good to go. Make sure the coil is mounted well and grounded well.

Next you need a noid light tester. You can get those at the auto parts store too. You can plug it in to the injector plug and it will flash just like an injector is firing when you are cranking the car over. No light means that the ECM is not letting the injectors fire. That can be caused by the ECM not seeing the cranking (from the harness at the ignition module) or by the VATS system malfunctioning (the computer chip ignition key.)

If it turns out to be VATS, if you search the forums here you will see how to bypass it to get your car going and how to repair it as well.

Welcome aboard!

Base91 · 04-29-2012, 10:52 AM

You need to get at least a Chilton type manual and do some reading. There's a bunch of info on what needs to be tested/cleaned etc. Plus search this board. There is a good chance the injectors and fuel pressure regulator need to be replaced. Southbayfuel injectors (search TGO) has a good set. Once those things are done you're in good shape to start on all the other stuff. Check back in soon.

dragon574444 · 05-07-2012, 06:26 PM

Update:

So I got good news and bad news. I picked up a Chiltons manual that covers our cars, and with a little elbow grease and new spark plugs, I got her running fairly smooth. And that's where the bad news comes in. HEAD GASKET. As soon as the engine got running, I noticed a lot of coolant leaking onto the passenger side exhaust manifold. I'm hoping the head isn't cracked. There were puddles of coolant under both tail pipes. I checked spark plug 1, looked fine. A little soot. Checked number 3, same thing. Checked plug 5. Soaked and way too clean, looked like it was never installed. That was all I really needed to see, didn't bother checking plugs 2 4 and 6. After the car stalled, I couldn't get it going again...

Not really looking forward to the head gasket job, I haven't done one before. What's is the BEST head gasket that you would recommend me use? I don't want to do this job twice.

Oh yeah, are the head bolts on the 3.1 Torque to Yield? As in, you can only use them once?
Thanks!

project89 · 05-07-2012, 07:06 PM

Quote:

Originally Posted by dragon574444

Update:

So I got good news and bad news. I picked up a Chiltons manual that covers our cars, and with a little elbow grease and new spark plugs, I got her running fairly smooth. And that's where the bad news comes in. HEAD GASKET. As soon as the engine got running, I noticed a lot of coolant leaking onto the passenger side exhaust manifold. I'm hoping the head isn't cracked. There were puddles of coolant under both tail pipes. I checked spark plug 1, looked fine. A little soot. Checked number 3, same thing. Checked plug 5. Soaked and way too clean, looked like it was never installed. That was all I really needed to see, didn't bother checking plugs 2 4 and 6. After the car stalled, I couldn't get it going again...

Not really looking forward to the head gasket job, I haven't done one before. What's is the BEST head gasket that you would recommend me use? I don't want to do this job twice.

Oh yeah, are the head bolts on the 3.1 Torque to Yield? As in, you can only use them once?
Thanks!

cheap felpro or victor rienz head gaskets will be just fine, same gaskets i use on my turbo motors

yes the head bolts are tty ur not supposed to reuse them, i have though very carefully but i dont recomend it, if u look on ebay u can get brand new head bolts for about 15 bucks, i forgoet how much they are at the parts stores but i want to say somewere around 50 bucks

fasteddi · 05-07-2012, 09:36 PM

I got my felpro head bolts from advanced autoparts for 26 bucks

http://shop.advanceautoparts.com/web...5_R%7CGRP60012_____