Wiggles

Picked up a 91 Camaro RS 3.1L MPFI with a T5 this last Saturday...
When I turn the key, it doesn't want to start; a click can be heard but no starter engagement. I can hear the fuel pump whirring sound for a few seconds every time I make the attempt. All the lights on the dash turn on as well, if that helps any. It may take 5-20 attempts before it fires up.

Some back story to help with this problem:
PO told me "sometimes it starts and sometimes nothing happens when you turn the key". It started up fine for me and drove fine during our initial 10 mile test drive. Drove back to our initial meeting place and turned it off. He wanted to show me the problem and attempted to turn it on, the starter sounded very sluggish as if it wasn't receiving the full voltage. A few more attempts and no starter sounds at all. After 10 attempts, it started up. I figured it was the starter. I decided to pick it up regardless since I need a new project. (On a side note, car hasn't been registered since 2008 and I imagined a rotten fuel tank filled with sappy varnish and a bad pump.)

To resolve this issue, I decided to go with the obvious route first:
Replaced the starter (old one was very rusty and worn looking, a Delco Remy re-man) and car started up immediately. Turned it off, turned it back on. Same positive results. Repeated this 10 times. I thought my problem was solved.

Went to get oil and a filter (driving a different car). When I got back home (I was gone for 25 mins), attempted to start it up so the oil would be nice and hot for easy draining...no start. The starter sound never engages, only the fuel pump whirring and the lights on the dash turn on. After several attempts, it started.

Yesterday, I decided to replaced the fuel filter, which I knew was way past due. Upon removing it, I banged the old filter on the cement and a large amount of dirty fuel came out of the inlet end. The fuel was not yellow or brown, but looked like someone had poured pepper inside a glass of water, you get the idea. Installed new fuel filter and air filter, and attemped to start her up, she started up immediately. Repeated turning her on and off with success.

I went for a test drive and floored it in each gear - no bogging or hesitation. Idle was good at stop signs/stop lights as well. No surging either. Went back home and parked her while I cleaned up my tools and took a break. About 1.5 hours later, attempted to start it up, back to the same issue.

What are the next steps to troubleshoot this issue? Maybe bad fuel pump or bad ignition or VATS?

ex-x-fire

Make sure the big ground wire is clean & tight. Make sure the starter mounting surface is clean of rust.
Get a volt meter & measure the voltage(12v) at the big & small starter wires, the big should be hot all the time while the small one is hot only when cranking.

ASE doc

The 91 is a VATS car. Check the key for the resistor pellet just below the key head. Try cleaning this with a soft cloth. Look into the key cylinder with a flashlight and insert the key, watching for the contacts in the cylinder to mate with the pellet. If the car doesn't start, try wiggling the key to loosen a sticky contact spring. There are a few articles on diagnosing the VATS system. I'll give you a brief rundown. Look at the steering column under the dash for two small wires together , one ppl/wht and one wht/blk. These go to a small connector where they meet two small black wires. Disconnect this connector and test for resistance(continuity) between the black wires with the key in. The resistance will vary according to the key code. There were 13 different codes, each code denotes a different resistance. The highest is 7500 ohms, the lowest is 402 ohms. You should get a reading somewhere in this range. If not, there is a problem with the key contacts in the cylinder and you can try to carefully clean them, or replace the cylinder.

If the cylinder tests okay, find the starter enable relay under the drivers side kick panel. Test for power on the two yellow wires with the key in the start position. If no power, check the ignition switch electrical portion for power at the yellow wire with the key in start. If not okay, check for power on both red wires and back to the fuse links. If power is okay on the yellow wires at the relay, check for power on the tan/wht wire with the key in start. If no power, listen for the relay to click if the relay clicks and no power at the tan/wht wire, replace the relay. If no click, check for ground at the blk/yel wire of the relay with the key in start. If no ground at the blk/yel wire with the key in start, and you have verified that the key and cylinder are okay, you have either a poor wiring connection at the VATS module, or a defective VATS module.

If you get power at the tan/wht wire, check the clutch safety switch for contact with the clutch depressed, and the wiring to the starter.

Wiggles

Thanks for all the replies - found out what the problem was:

On the clutch safety switch harness, it appeared that someone had stripped the wire insulation on both the purple and yellow wire, twisted the exposed copper wires together, then used electric tape to bind them, which seemed to be a bypass. I thought the switch itself was bad so I replaced it, and it still didn't work. I then unplugged the harness from the clutch safety switch, and using a 14 gauge wire with a spade connector on each end, bypassed the switch. Car starts up every time now.

eseibel67

You better rig up that clutch safety switch or else someday, you will forget and start that thing into a brick wall.

Wiggles

Ha, thanks for concern; I always leave my manual transmission cars in neutral with the parking brake on.

All I need is a new harness for the safety and it's set.