Help! Done some welding now my car won't start!

[Charged V6]

Hi all, I have been doing some jobs to get my new car up to spec for my first trackday, needed to weld in some brackets for my bucket seats. I have been welding on and off all day.

My battery was disconnected and I had a good earth close to where I was welding. This isn't the first time I have welded the car but the last time I unplugged the ECU just to be safe, but forgot today.

Gone to start it after all my hard work and now it won't start, it turns over but just won't fire!

I'm cacking myself that I have fried the ECU. No fuses blown under the bonnet or in engine compartment but there are a LOT of wires and relays about.

I have no idea what to look for as the car is fully custom.
Woodsport converted V6 supercharged.

Any help appreciated.

[cdwood2010]

Did you disconnect the battery? Anything removed during the work you did? Where on the car were you welding?

C.

[Grenade]

I have welded with the ECU's plugged in on Quads, snowmobiles, motorcycles and cars. Never had a problem. I was told that I shouldn't do it, but never unplugged them. So I'm not sure that the welding hurt you, it might be something else.

[Phaeton]

Start with the basics, do you hear the pump prime when you switch on the ignition, get a can of easistart & have somebody spray into throttle body as you turn it over does it try to fire?

[snowtigger]

Check your fuses first

[sketchy]

check the basics, fuel and spark....

if you pulled the battery, risk is very small. unless you used the ECU as your earth point....

[Charged V6]

As I said I have checked fuses, batt was disconnected. Amperage kills fuses though not volts I believe.

I am just going back down today to check fuel and spark. But it started just fine yesterday.

I was welding the seat frames. So mid chassis.

So is welding not dangerous to ECU electronics?

I did have a couple of small fires from the under seal, maybe I frazzled a fuel pipe or wire?

[Charged V6]

Just been back out to check again.

Usually when I turn on the ignition, my charge cooler kicks in and you can hear it pumping water round the system before start up. None of that.

No spark, checked cylinder 4 and 6 as random checks.

No fuel pump priming. It is deadly silent on first ignition click although I deffo have power, battery is trying its darnedest to start he thing :(

Wipers work too.

How many fuse boxes are there on these? Bearing in mind it's a v6 conversion. Found one in engine bay with about 8 fuses and one under bonnet that is OEM with about 7 fuses.

Is there one inside the car?
I still think I have cooked the ECU!

[Paul Woods]

I can't offer any real help because it could be literally anything but if you get stuck bring it to me on a trailer and i will diagnose and fix it for free, treat that as a last resort though.

[thomp1983]

Sounds like a dead fuse or earth somewhere, it's unlikely your charge cooler is wired to your ecu so id say that's probably ok