willo51590

I have an 87 Trans am with a 5.7L that wont start. It stopped while out driving recently and so I had it trucked home. I noticed the fuel pump didn’t pressurize when I turned the key so I checked the manual and it suggested putting power to G on the ALDL and that did fire the pump in to action. Still wouldn’t start tho. Got spark engine cranks OK so checked fuses etc and noticed a mish mash of past owner mods underneath in the form of old sound systems and an alarm. Both were inoperative. System security light comes on with ignition and turns off after a few seconds. I decided to bight the bullet and dismantle all the additional wiring and put it back to how it should be but it still wont start. Add to this dilemma that I live in Australia so car has undergone right hand conversion and there are no auto electricians familiar with this vehicle and none that are interested. I went down the VATS route for a while and in fact found and eliminated the resistors that were present because they didn’t appear to be hooked up correctly according to my research but the fact the security light goes out and it still cranks suggests maybe its something else. If it were the VATS would it have just cut out as I drove along? Any help would be greatly appreciated.

lonestar7

iTrader: (1)

Welcome to the 3rdGen message boards. If you haven't already, use the search function here to check previous discussions on the topic of "won't start", "fuel pump", etc. If you get spark when cranking, then the only other things that could be involved are the air or fuel supply. That being said, a lot of things could cause those problems. I would check the fuel pump relay first. If that's ok, I would start looking at the ignition switch and its wiring.

vetteoz

iTrader: (13)

VATS is only in effect when cranking the engine over

If it won't start with pump running then you 1st need to check if you have pressure at the engine
( hose in the tank could be leaking so you have no pressure to the engine)
If you have 43 psi at the engine then you have to consider that the injectors are not being fired by the computer
which is another problem
Do the tests I outlined and report back

You also need to pull the engine codes to see if anything showing
See
https://www.thirdgen.org/forums/tech...s-dumbies.html
A elec problem may cause the injectors not to be fired

If he has spark then Ign / wiring to the coil is fine

willo51590

I haven’t checked the pressure with a gauge yet but I removed the Schraeder valve cap on the fuel rail as part of the preliminaries and there was no fuel. But after I powered up G on the ALDL I got power at the fuel relay and there was fuel in the rail.

Unfortunately the battery went dead before I was able to get the codes from the computer.

I don’t have power at the B1 C16 or A1 on the ECM as I should have which still leans me to thinks it’s wiring.

Is passkey different to vats? Again I suppose it still only applies when it cranks.

I will check the fuel pressure with a gauge and report back.



thanx

vetteoz

iTrader: (13)

Same

Should have mentioned that up front
B1 and C16 are battery feeds to the ECM , you have probably blown the fuse that feeds them
( see diagram below)
You won't have power out on A1 ( pump relay control ) because there is no power into the ECM
If the fuse is blown then you first need to work out why it has blown because if you just replace the fuse
it may well blow again
You need to meter between the fuse and C16 /B1 on the ECM connector to see if you have continuity or a short

willo51590

I have no continuity between the fuse (in the fuse box) and C16 or B1. There is between C16 and B1 so I assume ECM internals must be good. The fuse tests OK and I also removed it to probe both sides of the slot. Is there another fuse I should know about? That diagram is great thanks.

vetteoz

iTrader: (13)

The one in the fuse box you are checking goes to A5

Not sure about 87 but probably the wrong fuse
As noted in diagram above ,'88+ have a inline fuse on the permanent feed from the battery , not in the fuse panel
Feeds the fuel pump through pump relay and the OP switch that runs the pump as well so your problem ( a short ? ) could also be on those parts of the circuit

See
https://www.thirdgen.org/forums/elec...e-problem.html
https://www.thirdgen.org/forums/elec...line-fuse.html
https://www.thirdgen.org/forums/elec...t-battery.html

Will be ,as shown in diagram they come from a common feed

dads old blue 9

you need to ck the fuel pressure there is a common problem that most people dont discover till they spend alot of time and money that they didn't have to .. they turn the key to on hear the pump and think its ok. well the pump may be fine but there is a rubber fuel line in the tank about 2 inches long conecting the pump to the hard line. what happens after 20 yrs is the rubber line splits , sending the pressure back to the tank it will send some fuel up the rail , but just enough to mislead you into thinking that you have fuel. this has happened to me and lots of other people I know ,so DO A PRESSURE CHECK!!!!!!!!!

vetteoz

iTrader: (13)

As I noted above.
But first he has to work out why he has no power to the ECM

TreeFiddy

Hey there Willo - where you located? Not in Sydney by chance?

willo51590

Hi treefiddy. Adelaide but tell me you're an auto elec and I'll treat you a holiday.

Good news tho - don't break out the beers yet - but I found a fuse tucked in behind the battery that's blown and blows again when i replace it. (lucky fuse)

I have continuity to B1 C16 and one end of the relay at E.

I'll have to study your diagram a bit closer vetteoz but at least I've found something that's broke.

vetteoz

iTrader: (13)

Problem is the feed from the fuse splits to several items and metering each end wire won't identify
which wire has the short on it
( unless you open up the splice to meter each wire individually )
I would start by disconnecting everything shown to remove them from the equation, ,
if you still have a short between the fuse holder terminal and ground you know the short is in the wiring
If you read the link I posted for you above some have had a faulty OP switch with a direct short to ground
that is blowing the fuse

TreeFiddy

Not an electrian or mechanic, just an enthusiatic amateur with a pretty good track record

Vette has got you well covered there. I'd love the opportunity to check out someone else's car - theres a few Aussies here on tgo, just none in Sydney.

vetteoz

iTrader: (13)

What happened to the local F-Body club (their www.fbodyaustralia.org site is gone now)
They used to have a pretty active scene out west a couple of years ago , lots of cruise nights , etc

TreeFiddy

Never heard of them, or come across them online. Couldn't say last time I even saw another thirdgen in traffic, been several years at least. They all appear to live in the other states heh

willo51590

Yahoo. vetteoz your a champion if you're ever in Adelaide look me up I owe you a beer or 2.

Disconnected oil pressure switch..... ignition on ......all ok fuse holding .... Hooked up OP again to confirm..... still didn't blow...... strange I thought...........start motor.

I'll get a new switch must be an intermittent fault there.



Thanks to all those who assisted/replied.

vetteoz

iTrader: (13)

FWIW ,
you don't actually "need" the OP switch.As shown in the diagram it is a backup should your fuel pump relay fail.
Not having it connected will have no effects on your engine operation
Check your PM's