3.1 wont run! Been searching for weeks!!

[deathbypsi]

Hello,I am Brian and am new here. I am tryin to find some help for my sons 91 Cutlass Supreme with a 3.1

 

I cant get this thing running to save my life!! The car will fire sometimes and die and other times it just cranks with no fire.It has over 40psi of fuel pressure at all times,fuel pump is new,I have replaced the ICM twice,the crank sencor twice,two ECM's,cleaned all positive and negetive conections,new temp sencor,plug wires and checked as many wires and connections as I can find. I have a $600 code scanner than wont read any codes when its plugged in,keepos saying its not plugged in when it is.

 

Please does anyone have any ideas? I am ready to just scrap the whole car and get him another!

[Crazy K]

http://www.w-body.com/forum/index.php?topic=31177.0

 

please read the above. You never needed a code scanner for this car, all you need is the above to read codes.

 

 

this is what I want to know:

 

does the check engine light do it's "12" flash?

The goal of the is to determine if the computer in the car right now is working.

 

also, it cycles each code 3 times, and will repeat code "12" once completed with all codes, but do report if any other code comes up.

 

 

post an answer to my question and we will go from there.

 

[jdcutty]

i would guess you have a computer problem as ken suggested.

[ns87]

If the computer thing doesn't pan out, check the resistance on each fuel injector. Mine caused so many random drivability problems until I replaced them

[deathbypsi]

I jumped the plug to get the codes the day it died and I get the "12" code then it just flashes so fast you cant even count them! I usually stop counting at 15 flashes,no pauses. So I used a high dollar tester to see if it would just give me the code and thats the one that wont read anything,just says "please plug unit in". I checked ALL fuses and they are all good except for the Aux fan relay which was corroded so bad the termainals were broke off when I pulled it out. The other fan works when I use the jumper wire in the test plug inside the car tho.

 

I have a second ecm in it which is a known good unit.

 

The injectors have not been touched yet however.

[BXX]

The first 3 sentences had me thinking injectors, and I will put money on it.

[deathbypsi]

Whats the best way to test em?

[Crazy K]

I jumped the plug to get the codes the day it died and I get the "12" code then it just flashes so fast you cant even count them!

you are checking with the car in the run position, but without the engine running, correct???

 

 

Whats the best way to test em?

a digital multimeter. Harbor freight has a good enough one for about $5.

[89GP_SE]

unplug the injector and put a voltimeter to it, put it to ohms and check the resistance. Someone will chime in with the right amount of resistance. Do the test on all six.

[deathbypsi]

Thanks guys,I will get on that one next. I assume the upper has to be removed along with the egr tube?

 

Test was done key on egine off.

[Crazy K]

Thanks guys,I will get on that one next. I assume the upper has to be removed along with the egr tube?

yes, and no.

 

remove the 10mm bolt and the 2 13 mm nuts and the egr pipe can be pushed back slightly and stay out of the way.

 

you should also disconnect the throttle body from the upper intake.

 

one at a time, each injector should be OHM checked, basically any less than 12ohms are bad. any below maybe 10ohms would totally disable a car.

 

expect to purchase/replace the following when you go in:

ALL injector O-rings (if you remove the fuel rail or inejctors) ~$8

upper intake gasket ~ $13

pcv valve hose (you'll understand when you see it) ~$5

pvc valve (if bad) ~$5

pvc grommet (if bad) ~$3

throttle body to intake gasket (cut from raw gaket material [i make my own] ~$3) or (pre-cut $9)

 

if you pull injectors, coat all O-rings with silicone (dielectric) grease. by a good tube for ~$8

 

 

[mfewtrail]

You can confirm that you have a fuel delivery issue by buying a can of starter fluid and spraying some into the throttle body. If the car fires immediately with the starting fluid, but will not otherwise crank up, you know you have a fuel delivery issue. The injectors are the most likely culprit. The early Multec injectors have a pretty high failure rate. Even if they don't fail completely, they tend to leak over time(causing hard starting and other driveability issues).

[deathbypsi]

Yes that is exactly what it does.

[deathbypsi]

Ok, I pulled the upper and ohm'ed all the injectors and all 6 were between 12.7 and 12.9 ohms. Is that ok or are you saying all 6 are bad?? I did find that the T.B. gasket was tore bad but I know thats not what was stopping it from starting.

[Crazy K]

hmmm they check to be in spec.

 

Other ideas guys?

[spiderw31]

... I get the "12" code then it just flashes so fast you cant even count them! ... I used a high dollar tester to see if it would just give me the code and thats the one that wont read anything,just says "please plug unit in".

 

...I have a second ecm in it which is a known good unit.

 

I dunno, but this doesn't sound like a healthy ecm to me. Try switching it out with your know good unit and see if that helps.

[BXX]

Yup, sounds like a bad ecm...

 

orrrrrrrrrrrrrrrrrrrrrrrrrrr..

 

A blown fuse

[GOT2B GM]

ok, without reading this whole thread, my old CS vert 3.1 had a similar problem.

 

The coolant temp sensor went bad, telling the ECM that coolant temp was -40.

 

Therefore the ECM dumped fuel like crazy trying to warm the engine up, effectively flooding itself out.

 

Wouldn't start unless you held the gas to the floor while cranking, and wouldn't run under 4000 rpm. Smoked black like crazy too.

 

Super rich.

 

Replaced the CTS, and the o2 sensor, ran perfect.

[deathbypsi]

The origanal ecm did the same thing as the new one in it which is a known good ecm. None of the fuses are bad.

 

I am going to get new plugs and wires for it to see what that does once I get the intake back on.