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85 GT won’t run

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Roadfury View Drop Down
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Post Options Post Options   Quote Roadfury Quote  Post ReplyReply Direct Link To This Post Topic: 85 GT won’t run
    Posted: 02 April 2008 at 7:59am
So I did an engine swap on my car, same V6 engine, and it'll start up but won't stay running. It runs when you spray gas into the intake but once you stop spraying it quickly dies off. I'm getting good spark, fuel pumps running, ive  got good fuel pressure, i cleaned the injectors with meneral spirits, both fuses are good, checked and cleaned all grounds. I'm not sure what elese to do to make it start and my car has to be out of the schools shop ASAP, Help! 
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Dr.Fiero View Drop Down
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Post Options Post Options   Quote Dr.Fiero Quote  Post ReplyReply Direct Link To This Post Posted: 02 April 2008 at 4:00pm
Got a spare ignition module, or can you borrow one?

Yes, I know you have spark...  trust me....

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Matt View Drop Down
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Post Options Post Options   Quote Matt Quote  Post ReplyReply Direct Link To This Post Posted: 02 April 2008 at 4:23pm
Stale gas in the tank? Or yeah firing problem. When you turn the car over and then pull the plugs what do they look like? Dry? Wet? Burnt?

Do you have to prime the fuel pumps on those engines? What I mean is, I've heard of NOS being so old that the "baffles?" inside the pump stopped working or gets brittle due to old age. Where did you check for fuel pressure?




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Blair View Drop Down
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Post Options Post Options   Quote Blair Quote  Post ReplyReply Direct Link To This Post Posted: 03 April 2008 at 6:21am

When I had that problem the power sup. to the injectors had come unplugged at the harness plug by the battery.

It's a long shot put it's worth a try.

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Post Options Post Options   Quote Roadfury Quote  Post ReplyReply Direct Link To This Post Posted: 03 April 2008 at 7:39am

Originally posted by Dr.Fiero Dr.Fiero wrote:

Got a spare ignition module, or can you borrow one?

Yes, I know you have spark...  trust me....

Yah thats what me and another guy in my class had figured reading the hayes manual but the shop teacher said no no deffinatly not the problem I'll try that and report back.

Originally posted by Matt Matt wrote:

Stale gas in the tank? Or yeah firing problem. When you turn the car over and then pull the plugs what do they look like? Dry? Wet? Burnt?

Do you have to prime the fuel pumps on those engines? What I mean is, I've heard of NOS being so old that the "baffles?" inside the pump stopped working or gets brittle due to old age. Where did you check for fuel pressure?


There was about an eighth of a tank left that had been sitting for a long time but my shop teacher topped it up with 93 oct. before i could drain it, and im not one to toss free good gas.

We basiclly just loosened the connection on the fuel rail, cranked it over and started cleaning up the gas that sprayed everywhere. (Very half a**ed way of doing it but my teacher isn't that good and i've only recently found out that you can actually hook up a gauge)

Originally posted by Blair Blair wrote:

When I had that problem the power sup. to the injectors had come unplugged at the harness plug by the battery.

It's a long shot put it's worth a try.

The 6 or 7 point plug yah we've connected and reconnected that.

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Post Options Post Options   Quote Matt Quote  Post ReplyReply Direct Link To This Post Posted: 03 April 2008 at 9:50am

**I'm not that familiar with the 2.8L because I've not worked on one for a long time.**

It's not getting gas to the plugs, because it fires and runs when it does. So just slowly move from the tank to the engine checking every place you can for fuel movement. Check for old or plugged fuel filters, pinched fuel lines, etc. If your tank is rusty and you ran the car near empty, there could be a good deal of debris in everything.

I had an old Monte Carlo that I had to change the fuel filter twice a week to keep it running.


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Post Options Post Options   Quote Roadfury Quote  Post ReplyReply Direct Link To This Post Posted: 03 April 2008 at 2:47pm
so i replaced the ignition module, no luck, the injecters all for sure work, and it gets loads of fuel to the rail, im stumpped and angry!
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Post Options Post Options   Quote Matt Quote  Post ReplyReply Direct Link To This Post Posted: 03 April 2008 at 3:26pm
It's either spark, fuel or air.

Have you

1. Checked cap and rotor, wires?
2. Oxygen Sensor?
3. vacuum lines?

We'll beat this dammit! You just hang in there!


Edited by Matt
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Post Options Post Options   Quote Roadfury Quote  Post ReplyReply Direct Link To This Post Posted: 03 April 2008 at 6:31pm

1. All brand new (bought the tune up kit from the fiero store)

2.Nope, would that prevent the car from continuing to run?

3. I had to make up pretty much all new ones.

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Dr.Fiero View Drop Down
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Post Options Post Options   Quote Dr.Fiero Quote  Post ReplyReply Direct Link To This Post Posted: 03 April 2008 at 6:47pm
No, the O2 sensor is ignore by the ECM for the first 60 seconds after startup.

You have spark, you have timing, you have compression (since it runs on ether!).

I've seen a bad distributor ground kill cars.  They get corrosion between the base plate where your module goes, to the shaft/housing.  Quicky try - run a ground wire off the battery to one of your distributor cap screws.  Takes 30 seconds and eliminates that off the list.

You're down to fuel (since you replaced the ignition module). 
Check for +12V at the pink/wht & the pink wires on the connector going to your injectors (that 2 row semi fat one near the t-stat housing).

If you have power there (with the key on!), then...  and this one is semi risky...  run a wire off the green and blue wires on that same connector.  Every time you ground those, ALL your injectors will fire.  You have a choice - you can pull the intake (again...  I'm sure!) and then lift out the injector rail leaving it hooked up, then with the key on, TAP it to ground for a SPLIT SECOND and see if they all squirt, OR leave it all hooked up in place, and have someone crank the car while you again tap it QUICKLY to ground.  If the car starts and then dies, just keep quickly tapping it to ground in spurts to see if it will keep going.  DON'T hold it on ground for more than a tiny shot at a time or you'll flood the hell out of the engine, maybe hydro lock it, or burn out your injectors!  You've been warned....   ;)

Anyhow, if that checks out, ring out all the wires going from your distributor back to the ECM, then do the same with the injector harness.

You COULD have a foobarred ECM.  I've replaced only about 3 over the years, covering probably 100 cars.  But it does happen.

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Post Options Post Options   Quote Dr.Fiero Quote  Post ReplyReply Direct Link To This Post Posted: 03 April 2008 at 6:52pm
If you don't already have it, here's a drawing that might help you see what you're doing with the above info:




Edited by Dr.Fiero
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Roadfury View Drop Down
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Post Options Post Options   Quote Roadfury Quote  Post ReplyReply Direct Link To This Post Posted: 03 April 2008 at 7:36pm
Just brainstorming...... I've got a battery charger hooked up to my battery while im trying to start. Would that have any affect? Would my alternator being dead have anything to do with it... like i said just brainstorming
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Post Options Post Options   Quote Dr.Fiero Quote  Post ReplyReply Direct Link To This Post Posted: 03 April 2008 at 7:52pm
Nope - wouldn't have any effect.

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Post Options Post Options   Quote marcelvdgn Quote  Post ReplyReply Direct Link To This Post Posted: 04 April 2008 at 10:56pm

you mentioned that you were getting spark,.

where did you check that????? did you check at the coil or at one of the spark plugs????

i ask because ive had a rotor short out on me. which means i had spark at the coil and goin into the dist cap but nothing coming out to the spark plug........ obviously the engine would not do anything.

i keep an extra rotor and cap in the trunk at al times!!!

just another thought......Marcel

Marcel 86SE V6 Auto
85SE V6 Auto
85 2m4
soon to be sleeper 3.8sc 5 speed
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Post Options Post Options   Quote Roadfury Quote  Post ReplyReply Direct Link To This Post Posted: 05 April 2008 at 8:56pm
Originally posted by marcelvdgn marcelvdgn wrote:

you mentioned that you were getting spark,.

where did you check that????? did you check at the coil or at one of the spark plugs????

i ask because ive had a rotor short out on me. which means i had spark at the coil and goin into the dist cap but nothing coming out to the spark plug........ obviously the engine would not do anything.

i keep an extra rotor and cap in the trunk at al times!!!

just another thought......Marcel

I KNOW im getting good spark and its on the right order because when i continue to spray gas in the intake it continues to run..... PS the rotor, cap, plugs, and wires are new

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Post Options Post Options   Quote marcelvdgn Quote  Post ReplyReply Direct Link To This Post Posted: 05 April 2008 at 10:47pm

i have had a new rotor short out on me after ten minutes of use

obviously a defect that doesnt happen too often

M

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Post Options Post Options   Quote Matt Quote  Post ReplyReply Direct Link To This Post Posted: 06 April 2008 at 12:49am
I had too much humidity get up under my distributor cap. Had good spark, seemed to be firing properly. But the car would only run for a short while, if at all before backfiring and eventually flooding.

A trip to Canadian Tire + $25 (I believe) fixed it perfectly.

I've been told, if the car misfires once, the cap and rotor may be fouled. Though that doesn't seem like your problem.

It does seem like you may have injector problems though. Or at least something fuel related as we've ruled out spark and air. I'd try Dr. Fiero's suggestions towards checking injectors and/or swapping ECM's.
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Post Options Post Options   Quote Roadfury Quote  Post ReplyReply Direct Link To This Post Posted: 07 April 2008 at 8:33pm

Dr. Fiero.....

I've found the reminantes of two hacked up security systems....

Could the immobilizers allow the car to start on the cold start injector and not the others?????

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Post Options Post Options   Quote Dr.Fiero Quote  Post ReplyReply Direct Link To This Post Posted: 07 April 2008 at 8:36pm
Yes!  There's a good place to start.

Rather odd way to immobilize (most people take out the ignition system), but...

This all falls back under the posting of "ring out all the wires back to the ECM".  :)

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Post Options Post Options   Quote Roadfury Quote  Post ReplyReply Direct Link To This Post Posted: 10 April 2008 at 8:21pm

so weve ripped out the old alarm systems, biig pile btw....

checked the power to the ECM its good, signal from the distributer is getting to the ECM, spark is getting to all 6 plugs. I do have a 87 Gt ECM sitting here but thats all i know about it.... is it compatable the numbers all read,

the service number is 1227170

the number under that is 860022 M622503058

the barcode number under the little cover is 533014106006204

i heard something about an oil pressure sending unit sometimes causeing problems...

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