Will not start hot

Tiny
KAM
  • MEMBER
  • CHEVROLET TRUCK
My 89 chevy 4x4 truck with 180k, TBI 350 will start good cold and run for about 10 minutes until hot then idles up and produces slight black smoke and then dies and will not start back up. I've rebuilt the throttle body and installed a completely new distributor.
Any help?
Do you
have the same problem?
Yes
No
Sunday, July 22nd, 2007 AT 8:53 PM

12 Replies

Tiny
RASMATAZ
  • MEMBER
Lets do a fuel pressure check and see what's happening in that system. Also when it dies out, look for sparky-no sparky could mean bad ICM/CPS/Coil.

Could also be the fuel pump relay when heated out, it shorts out and fuel pump looses its power from it or the pump itself.

Good Luck
Was this
answer
helpful?
Yes
No
-1
Sunday, July 22nd, 2007 AT 9:04 PM
Tiny
KAM
  • MEMBER
Fuel pressure is runing 11 psi. Started up and ran for about 15 minutes until hot. Then shut down again. Fuel pressure never changed. Checked spark after dying and had spark at No 1 cylinder.
Seems the fuel is flooding the engine out. Alot of fuel is spraying in when I try to recrank after dying. Also just before it dies, it seems to idle up slightly and then bogs down and smokes out of exhaust like it's running rich.
Was this
answer
helpful?
Yes
No
Saturday, July 28th, 2007 AT 12:59 PM
Tiny
KIN CHAN
  • MEMBER
Hey ras.I think u are forgetting our old friend the CTS---> ur favourite. My uneducated guess will be chking the O2 sensor if it is switching. Just fixed an impala SS with no code but bad O2 sensor. Put a new 1 in there still the same. Turns out the plug was so bad in 1 bank that carbon even bridge the gap on the plugs.
Was this
answer
helpful?
Yes
No
Saturday, July 28th, 2007 AT 2:12 PM
Tiny
KAM
  • MEMBER
History on this old truck. A lot of the sensors have been disconnected since I've owned the truck. O2 sensor is not connected nor any smog stuf. Also I only use this 4x4 truck for hunting and it sits for a while sometimes. I had to replace the battery two times befor any of this happened. New batteries were dead and not rechargeable.

Today I pulled all of the plugs just to do a compression check. The plugs were covered in carbon very badly. Cleaned them, regapped them and put back in. Ran engine again and it's not dying now, but idleing up higher than normal. Fuel psi is still 11 psi. Seems to try an stall sometimes, but catches up and idles up and continues to run now. Still not driving it on road. Worried about dying still.
The vacuum hose to the diaphragm type EGR valve has been disconnected for a while too. It would rough idle when idleing slow. Disconnecting the vacuum hose to it solved the problem about 1 year ago.
I know, I've got a mess.
Was this
answer
helpful?
Yes
No
Saturday, July 28th, 2007 AT 8:44 PM
Tiny
KIN CHAN
  • MEMBER
O2 sensor start taking over fuel ctrl once the ECM see the engine temp is warmed up.U yanked it out. EGR sys lean out n cool off engine combustion temp & u yanked that out. If thats the case.U should yank out the whole ecm sys. Cuz partial is gonna do worse than a basic carburetor sys.U r making thing worse. No wonder ur truck is running rich.
Was this
answer
helpful?
Yes
No
Sunday, July 29th, 2007 AT 4:25 AM
Tiny
KAM
  • MEMBER
First of all, I didn't yank out anything. I've owned the truck for about 10 years and the O2 sensor is in place, but not connected. Never has been since I owned the truck. It's run fine for the last 10 years until lately after I let it sit up for a while.
Didn't yank out the EGR system either. The EGR valve on the valve cover is operating properly. The EGR diaphragm on the manifold is not functioning properly. If the vac line to this device is hooked up, the truck tries to run very rough idle when moving slowly. Planning to replace it. Not yank it.
Oh well, you can't seem to understand what I'm trying to discuss but your response to my last update. Thanks, but no thanks for your help. Would prefer someone with much more experience, knowledge and understanding to help rather than tell me how messed up it is. Your smart remarks don't help me improve the situation, at all.
Not great on advice are ya?
Have a good day!
Was this
answer
helpful?
Yes
No
Sunday, July 29th, 2007 AT 11:27 AM
Tiny
KIN CHAN
  • MEMBER
My apology to my smart remarks n understanding of automotive electronic ctrl on OBD1 89' chevy truck. I was n am doing diagnose problems base on how a manufacture build any particular yr, make n model. So far with my liimited experiences not knowin how to circumvent a system that is design n engineering what a complete system should operate. However with all the availablle info from library, professional class training, internet. All the way to manufacture pay website didn't include the information u want. This is gotta be my problems. More sincere apology
Was this
answer
helpful?
Yes
No
+1
Sunday, July 29th, 2007 AT 2:34 PM
Tiny
KAM
  • MEMBER
No apology needed, but thanks and I accept. Maybe I can start over here. I'm definitely not a qualified technician. That's why I'm using this forum.
I also noticed I used the wrong terminology. I was referring to the PVC valve on the valve cover and EGR valve on intake manifold.

Anyway, I replaced the EGR valve along with the EGR sensor. Truck is still starting up and running now and not dying, but it still idles high. Start up cold and it idles high as normal until warm and then idles down to normal. Then if I put it in gear or drive it, it starts to rough idle and then idles up high like the throttle is trying to stick. Throttle is not sticking though. Remember I'm trying to make an 89 engine with 180,000 miles on it run better for now. I'm planning on changing the engine when I can afford it, but feel this problem is not due to the worn out engine. Unfortunately since someone before me has unhooked numerous devices the OBD tool doesn't work or tell me anything. Makes it tough to troubleshoot. Just looking for ideas like I received from the first response I got.
Thanks for your time and comments. I'll eventually figure it out. This is my project for weekends.
Was this
answer
helpful?
Yes
No
+1
Sunday, July 29th, 2007 AT 5:24 PM
Tiny
RASMATAZ
  • MEMBER
Try doing a compression/cylinder balance test and vacuum check. Could be a vacuum leak when the engine is warm-up and showing up. Who knows
Was this
answer
helpful?
Yes
No
Sunday, July 29th, 2007 AT 6:22 PM
Tiny
KIN CHAN
  • MEMBER
Ras.I conceded.U r the man. Mr. CTS!
Was this
answer
helpful?
Yes
No
Sunday, July 29th, 2007 AT 6:34 PM
Tiny
GTX440SIX
  • MEMBER
Check the MAP Sensor vacuum at the rear of the throttle body, if no vacuum remove the throttle body and clean the restricted port
Was this
answer
helpful?
Yes
No
Friday, August 10th, 2007 AT 5:41 PM
Tiny
KAM
  • MEMBER
Thanks for all of the suggestions. I just rebuilt the throttle body and the ports are all clear.
The truck starts and runs now, but still has a high idle once it's warm and driven. I'm looking into testing the IAC, (Idle air control). Maybe this is my problem. It idles high when first started and then idles down to normal after a few minutes. The start driving and it idles back up high and stays there.
Was this
answer
helpful?
Yes
No
Sunday, August 12th, 2007 AT 1:09 PM

Please login or register to post a reply.

Recommended Guides