Monday, June 13, 2011 - 09:20 am, by: Brenton Hill(Brenton_hill)
Hi guys. Not sure if this is a common problem and someone has already put in a post on this, but my 92 UZZ31 v8 will intermittently refuse to start when warm... I have replaced both coil packs (an auto spark mate reckons that would be the problem - wont be asking him anything again, that did nothing!). The previous owner had the starter motor replaced, and the plugs seem ok. The plug on the left hand side coil pack appears to be a bit heat affected, and looks a bit melted but checks out ok electrically. When it's running, it's fine, and will drive perfectly for as long as I want, but as soon as I switch it off it just wont start again until it's cold. Doesn't matter if it's a 5 minute drive or a two hour drive, once it's turned off it just wont start, and sitting for hours waiting for it to cool down is really driving me crazy... Any tips on what might be wrong guys? Any help would be greatly appreciated. Cheers Brenton
Tuesday, June 14, 2011 - 09:28 am, by: Brenton Hill(Brenton_hill)
Thanks Tom. I'll be sure to give that a go. Although I took it out for a short drive to warm it up so as to try the short link in the diag port when it wont start, and after I parked it, switched it off, and tried to restart it, I got absolute bupkiss nothing! No dash lights, no interior lights, no engine cranking, absolutely nothing at all. So I shut the door and went inside for dinner... I'll have a look at it again maybe tonight if possible. Let's hope this isnt another major fault...
Wednesday, June 15, 2011 - 06:05 pm, by: Dave Hart(Davyboy)
I've had that problem for years but sometimes it only takes a few minutes for a restart although on a really hot day it has taken the best part of an hour. Recently had my engine ECU over hauled to see if that fixes things but won't know until summer.
Tuesday, June 21, 2011 - 04:59 pm, by: Brenton Hill(Brenton_hill)
Ok. So I've cleaned the terminals and it started up fine. I ran it for a while so the engine was warm, turned it off, tried to restart it and the usual cranking but no ignition problem. Good. I put a link in between FP and B+, tried to start the car, no ignition, just cranking of the engine. So I guess that means the fuel pump ECU isn't the problem. The overtemp light (the one that looks like a muffler with heat dissipating off it) has come up every time it gets warm, even before I've had the no-start issue. I've searched the forums, and I've got conflicting stories. Some say its a catalytic converter fault, others say its a general engine warning light. Any ideas or tips would be great, because in the very short time we've had the car, it's been more unreliable than reliable (and we all need reliable transport) and I'm now even considering selling it once I've sorted out the problem....
Tuesday, June 21, 2011 - 06:32 pm, by: Tom Richards(Tomr)
measure the voltage at B+ when it will not start. It should be 12v.
there have been cases where the 12v is not present, but i have not seen the reason for it. i had it on my sons car for a while, but then it just stopped happening,
Dan McColl Goo Roo Victoria (The Nazi State) Pretty Red Thing and The Black Beast
Friday, July 08, 2011 - 12:38 pm, by: Brenton Hill(Brenton_hill)
Ok. I've measured the voltage at B+. Got 12v. Still won't start. I've run diagnostics as per the diagnostics thread, the issue's still not resolved. Someone at work has told me to locate the cat converter wires and cut them off, apparently that solves the overheating cat converter light and any faults with that. I'm a bit unsure on doing that though. Anyways, the wife has had enough of me tinkering with it and its unwillingness to always start (it's still intermittent) and as my new job requires me to have my own ute now, we've decided to sell it.
Saturday, July 09, 2011 - 08:59 pm, by: Brenton Hill(Brenton_hill)
Right, so whilst cleaning it for the normal photoshoot for selling it, I decided to have one last crack at rectifying this issue. I cleaned all the white electrical grade grease out of the diagnostic port, and tried the B+ and FP short, no luck. Got the old multimeter out, found NO 12v at B+ as Tom mentioned (the diagnostic port was heavily greased when I last attempted it, I can only conclude this may have affected the readings somehow). Ran a short wire from the battery + terminal to B+, turned the key, car starts! Woo hoo! So to confirm it, I turned the car off, removed the + feed to B+, turned the key, no start. Did this several times to make sure this was the problem (and that I wasnt going insane) and each time it would start when the 12v was shorted straight to the B+ terminal. Now my problem is, why is this happening??? I gather the main ECU is getting no power? And more importantly how do I fix it, as I'm not a major fan of selling defective vehicles...
Sunday, July 10, 2011 - 10:23 am, by: Peter Williams(Skeeta)
Fuel pump ECU, behind trim under rear passenger side window I believe. It's probably cacked itself. It won't hurt to use the short in the diagnostic port until you get another fuel pump ECU to try out, there has been a few for sale on here recently. I have a spare if you can't get hold of one, but I want it back in case mine goes U/S.
Sunday, July 10, 2011 - 10:37 am, by: Tom Richards(Tomr)
it is not the fuel pump ecu.
You lose B+ because REL (from memory)is missing, and the relay to supply B+ does not energise. what causes that , i do not know. Maybe some one with cct diags can track it back? Sorry i only know the problem, and not the cause.
Monday, July 11, 2011 - 09:46 am, by: Brenton Hill(Brenton_hill)
I doubt it's the fuel ECU, as I didn't have to short out B+ to FP once I supplied 12v + to the B+ point in the diagnostic port, which leads me to think the fuel ECU is ok. Thanks Tom, I'll have a search on the internet on how to fix this, I still dont want to sell it knowing it has an intermittent fault...
Monday, July 11, 2011 - 11:07 am, by: Tom Richards(Tomr)
the relay is in the main relay/fuse box behind the battery.
From memory there are 3 "round" relays. the one closest to the engine must energise to supply B+.
When i had this problem on my sons car , i swapped the relays, but that didnt fix the problem. I found that with the ignition on and by "wriggling" the "B+" relay, (round nearest the engine) you would suddenly hear relays clicking in as B+ "appeared. I do not know if it was a bad connection in the relay base as the fault disappeared after my son used this method to get the car started a number of times.
Tuesday, July 12, 2011 - 07:36 am, by: Brenton Hill(Brenton_hill)
Got home and tried the wriggling the round relay trick, I found that tapping it with a screwdriver worked better, I got the engine to start without jumping the 12v to B+ terminal, but the problem seemed to appear again almost straight away. I'm going to look at replacing the relay, I'm hoping this may fix it, although swapping the relays didn't work. I'm hoping its either the relay or a loose connection somewhere in the fuse box...
Thursday, July 21, 2011 - 11:40 am, by: Brenton Hill(Brenton_hill)
Not yet Tom, no luck. I've scuffed the terminals for better contact with the relay. No dice. I then pulled the fuse box apart and checked the wiring underneath. No dice. Looks like I'll be selling it anyways, the missus is definitely over me trying to fix it rather than driving it... Just wish this issue would nick off, I'm not a fan of selling anything that's not in good working order...
Friday, July 22, 2011 - 12:12 pm, by: Tom Richards(Tomr)
hi brenton, when the car will not start do these checks with ignition on. 1) verify no B+. 2) leave ignition on and remove the EFI relay. 3)check for +12v at pin 2 (this comes from the efi 30A fuse.) This becomes B+ when the relay energises. 4)check for +12v (M-REL) at pin 1.(this is the +12v to energise the relay and provide B+) 5) Measure pin 3 to the chassis. Should be 0 ohms. (it is the earth side of the coil)
Monday, July 25, 2011 - 04:18 pm, by: Tom Richards(Tomr)
looking at what we have both found, ie tapping/moving relays in the fuse box it points to a fault in that area.
IMO a likely place is the EFI 30 amp fuse or connectors.(dirty/loose) or at the base where there are 2 wires coming from the output side of the fuse.(bad crimp/joint)
Thursday, August 02, 2012 - 02:49 am, by: Harvey Riddle(Hifimoon)
Thanks guys, I have been plagued with this problem ever since I bought my V8 in March. When I found this thread my car was in the garage refusing to start again. I checked B+, no voltage, pulled the EFI Relay, and as soon as I plugged it back in, B+ had power, and the Engine started. Then B+ lost power, so I took the Relay out a few times until B+ had consistent power. I sprayed ContactCleaner into the socket before refitting it the last time. Despite looking pristine, I can only conclude that one or more Relay Terminals had a bad connection as it does not appear to be failing internal Relay Contacts.