I'm selling this car if I can't get it running right.

[Jim Ayres]

I'm selling this car if I can't get it running right

--------------------------------------------------------------------------------

I have an '87 GN with 72k miles, original paint, as nice a car as you will find inside and out. The car was purchased with a bad engine and a 1k built engine was purchased to take it's place (GN1 alum. heads, 206/206 hyd. roller, roller rockers, girdled crank, ported plenum, etc.). When engine was installed it was scary fast (481 rwhp on dyno) and ran great. Then the car sat up for some few months when my son got a Ford Lightning to play with, and was jump started a few times. Then the car runs like it's in limp mode or something, no power, knock retard gauge went off when under load and applying gas.
I bought the car from my son knowing this. When he drove it over to my house it backfired one time only, it had never done that before.
I get the car to the house and then it doesn't want to start. I've replaced the crank sensor, the cam sensor, the electronic spark control sensor, and ohm'd out 2 coil packs as good and had 2 ignition modules checked as good at O'Reilly's. I even put in a new ignition switch. The plug wires are new and good with new plugs. The car has Scanmaster 2.1 and Direct Scan, also Translator + 6.? and a 3.5" MAF.
The car will start sometimes cold and 5 min. later not start at all and it wants to backfire sometimes attempting to start.
I'm just about fed up with this car and if someone can help me it would be greatly appreciated !!! I have even tried a different ecm and another chip, all to no avail. It's a beautiful car and drives like a dream when it is running.
I think I may sell the car even if or when I get it running properly again.

Please Help Me!!

 

[ChrisChow]

Check engine grounds. Especially the main from pass head to battery. If that's loose at all there will be problems.

Check the cam sensor is in the correct location and did not rotate out of position. Carefully remove the cam sensor cover and inpsect that the tab (the metal dish inside) is not broken off.

Assuming all the electrical systems are OK try the following hardware checks:

A compression test and check to see if any pushorods are bent.

Hope that helps.

 

[JDSfastGN]

Agreed witht he above, sounds like a ground wire came loose, either on the back of the drivers head, or the bundle of grounds on the passengerside head or intake(some relocate). If not it is also sounding like a bad MAF sensor or just a simple intercooler hose that popped off (usually it won't cause a no start but just check them all closely anyways.

 

[idaho gn]

what chip is in the car ? what injectors? double check you translator and maf ......maybe the maf is bad or the translator switches arent right

 

[larry33kc]

try checking the computer to see if it is bad, I had a truck do the same thing drove me nut's changed everything twice then I swapped out the computer and it ran like a top then HTH

 

[rob86gn]

Want to make sure you know the chip has to match the injectors- If you replace the injectors with higher flow inj make sure you get a chip to match. I learned that the hard way and my car sounded like yours.

 

[GNVYUS 1]

Cam sensor or Fuel Pump.

My cam sensor died about 4 months after the rebuild and its possible your pump died on you.

Do you have a fuel pressure gauge off the rail to check?

 

[Jim Ayres]

Both chips I've tried are burned for the car as is with 57 lb. injectors, etc. and the Translator+ is set according to chip specs. I have 45 lb. fuel pressure at the rail with the key on. I have tried a different ecm with the same results. The grounds were redone and rechecked as good.
I'm pulling my hair out (what I have left) over this ordeal. I guess some of the wiring could be bad; it shouldn't take long for me to check all that, maybe till Christmas.
Please keep the ideas coming, I really appreciate your suggestions guys. I guess I just have to keep a positive mental attitude regardless.
Thanks,
Jim

 

[DavzGN]

Does it do it with the directscan cable disconnected? If the cable is pushed into the ECM too far it can also cause problems.

HTH
David

 

[DCVING]

Possible Ground Issue

I have read that aluminum is not the best ground so if you are having a problem you might want to relocate the grounds from the heads and put them to the block or frame. Just my opinion. Good luck

 

[VadersV6]

Aluminum is an excellent ground as long as the mating surfaces arent oxidized. Its also MORE conductive than iron. 60% as conductive as copper.

 

[turbot2496]

Black smoke? Plugs wet? Does it hold the fuel pressure when you shut the motor off? ..... Injector stuck open????

 

[turbot2496]

Also check Maf as JD suggested. Maybe jump starting fried the translator??

 

[87gnfan]

my car was doing similar,changed computer and a new throttle position sensor and starts and idles fine now

 

[Jim Ayres]

Car has same symptoms with or without direct scan connected, grounds have already been relocated, holds fuel pressure for quite a while with key off, I've tried 2 good known Maf's, and am presently checking the harmonic balancer for maybe a slightly bent or out of shape blade that passes through the crank sensor.

Thanks guys,, keep them coming!
Jim

 

[GS70350]

So when the car will not start, IE when its warm, does it have fuel and spark when you turn it over? I know it has fuel at the rail but if you can figure out if the injectors arent pulsing or the ignition isnt firing then you have narrowed it down a bit.

Mine is doing the same thing. It always fires up when its cold

 

[GS70350]

So when the car will not start, IE when its warm, does it have fuel and spark when you turn it over? I know it has fuel at the rail but if you can figure out if the injectors arent pulsing or the ignition isnt firing then you have narrowed it down a bit.

Mine is doing the same thing. It always fires up when its cold first try and runs and drives fine. I park it and when i go to start it again, it will hit once then it wont try to fire again. I can turn it over as much as i want and it wont start. Exhaust smells like fuel, then after a few more tries of turning the fuel pump on and off and the same with the key, it will eventually start. Last night it wouldnt start at all but this morning it did and now i cant get it to not start so i cant troubleshoot.

Anyway i think mine is ignition related and im going to check it out next time it refuses to start for me. Ive been through this junk before and its not fun. Check GNTTYPE.ORG for diagrams and a No-Start troubleshooting guide.

 

[Pronto]

http://www.vortexbuicks-etc.com/ Good place to start.

 

[Jim Ayres]

It's now starting right away will run about a second and die. It has done this repeatedly this morning. Last night I changed out the harmonic balancer ( I found the one on the car had a slightly tweaked blade ). Will try again to do more troubleshooting later, maybe I have a little air in the fuel line from draining old fuel and replacing. I did run the pump untill I got gas out of the fuel rail at the end of this process, but maybe I just have to start it a few more times to get the air worked out?

Thanks guys, I'll let you know what I find!
Jim

 

[Pronto]

Don't forget that they are finicky about the starting voltage so make sure you didn't run your battery too low.