Sarah's 1991 Camaro

TransAmDan

Forum Admin
Staff member
Well not done much on this. For those of you that don't know Sarah got the car about 8 years ago. After 2 years of owning it failed its mot on rust near a seat belt fixing. All welding was soon done, and booked it in for another Mot, it wouldn't start that morning. So pushed it back in the garage, since then it has been rolled out for a new garage to be built, then rolled back in.
A few months ago I tried to start it. Would turn over, so either fuel or spark, fuel was old do popped in a couple of litres of fresh. There is a schrader valve on the fuel rails. No fuel. Checked fuel relay, all looked good.
Yesterday added 5 litres of fresh fuel. Tried to start again, still nothing at the shrader valve. So next is to investigate the fuel pump.
Two options to check the pump, drop the axle then drop the tank. Or cut an access hatch in the trunk. On the TA I went the access hatch route, and will do the same again. The risk of bolts snapping on the tank straps or other bolts is quite high.
 

July92RS

Core Member
You can get to the wiring for the pump where its clipped to the floor to check for voltage or give it a squirt of easy start to see if it fires, confirming no fuel but sounds like the same as mine was when it broke down on the way to hayling show
 

TransAmDan

Forum Admin
Staff member
Didn't have easy start, but it appears carb cleaner is flammable enough and did ignite. So I beleieve spark is there.
 

TransAmDan

Forum Admin
Staff member
IMG_20201010_135938.jpg

Hole cutting started.
IMG_20201010_135952.jpg
Careful not to go too deep as I know fuel lines are beneath.
 

TransAmDan

Forum Admin
Staff member
IMG_20201010_144302.jpg
Access hatch present. Took a while with the dremel, but felt I had more control with depth.

Not checked volts, 3 wires to the pump, appears to be a sealed connector unlike the 4th gen.
Gotta nip out, may carry on later.
 

TransAmDan

Forum Admin
Staff member
You can get to the wiring for the pump where its clipped to the floor to check for voltage or give it a squirt of easy start to see if it fires, confirming no fuel but sounds like the same as mine was when it broke down on the way to hayling show
How did you fix yours? Was it a broken wire, failed relay or pump?
 

TransAmDan

Forum Admin
Staff member
3 wires going to the pump. Wiring drawing says black is ground, grey is positive feed. The purple must be the sender.
Measure between black and grey and barely 2volts.
Remove relay and add a short wire from orange(ignition live) to the grey. Measure at the pump, getting around the same 2V. Measure grey to chassis and I see 12v. So bad ground.
Ohms check from that black wire to chassis is around 80ohms.
I can join this to chassis, and will investigate where that ground comes from. Likely near the ecu.
 

TransAmDan

Forum Admin
Staff member
Earth is hood next to the pump. I can hear the pump running. Tried to start, still. No go. Checked the fuel rails and they have fuel in them, nice pressure too.
Squirting flammable gas in the intake and it tries to fire up.
As earth was bad at the pump this earth comes from somewhere, perhaps Ecu. So perhaps another bad earth. Removed ECU. It was a little corroded at the top end.
Noticed the eprom wasn't clipped in.
IMG_20201011_131958.jpg
That. Is not clicked in.
Checked the back of the board. All joints look good.
IMG_20201011_132007.jpg
Popped it back in the car. Hoping the eprom was the issue. It wasn't still not firing.
Still need to investigate more earth's.

On the LS1 it uses the crank position sensor to know when to quiet injectors and when to fire a spark. With this 3.1 V6 it's a dizzy cap so the firing is done with that. How do the injectors know when to fire? Do they rely on a sensor?
Earth to the block must be good as the starter spins darn hood.
There is a ground from the battery to the chassis and that looks good. So other parts of the wiring loom must be picking it up from chassis. I wonder if there is a map of all the earth points on a 3rd gen.
 

TransAmDan

Forum Admin
Staff member
Security light goes out, so appears to have passed the VATS test.
I could take out one of the plugs to take a look, rig up a jump lead to it and see if it's giving a spark.
 

AmericanThunder

Super Moderator
If fuel is present in the fuel rail, it’s either not getting spark (or at the right time) or the fuel is not being delivered into the cylinders.
Both conditions are easily tested by removing spark plugs and injectors and cranking over. Don’t do both at the same time... we don’t want any fires!
 

TransAmDan

Forum Admin
Staff member
I'll have another play tomorrow. I think it may be the control of injectors, as squirting stuff in the intake it fires up. Also I don't smell fuel coming out the exhaust. I'll do some cranking tomorrow and pull a plug to see if it's wet.
 

July92RS

Core Member
Have you put a jump wire in the diag socket to check code's also, mine has a fuse on the inner wing behind the headlamp, this controls some engine electrics..
 

TransAmDan

Forum Admin
Staff member
Thanks for the link on the crank sensor. Everyone being so helpful. Many thngs to try, I will get it running with all this support. Just need to get some more time on it.
 

TransAmDan

Forum Admin
Staff member
Okay, checked earth point behind the block that goes to the firewall, thi looks good. Earth point under the dash also looks good.
Fuse behind the headlight is either 20 or 30A and looks good.

Checked fuel at the fuel rails. A little squirt came out when pressing the valve.

Cranked the car over and removed a spark plug. Plug looks reasonably heathy, but more importantly, it was dry, no smell of fuel.
1602528155810.png

With the plug removed, joined to the HT lead to the plug and the ground of the plug via a jump lead to ground. Cranked it over again.
Notice how infrequent the spark fired. Should be many times a second. The video may have missed some, but even watching this in person it looked a bit hit and miss.

Looking at the dizzy, its not purely mechanical, has many wires at the bottom.
1602528474659.png


So in summary I have a couple of issues, injectors not delivering fuel and spark isn't right.

Spark may be rotor arm, I'm yet to inspect that. I'll look at more things during this week.
 
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