suburban not running well
- Thread starter BIGdaddy
- Start date
Theres a valve on the throttle body that allows the engine to idle. Normally when you arent pressing the pedal the throttle plate is closed. This, through the use of a motor, controls the amount of air that bypasses the throttle plate.(assuming you have FI.) If you have throttle body injection, Im not sure if you would have this control. I had an 85 F250 with a 302 that had throttle body injection.
For the life of me I dont remember what its called...Idle air control or something like that.
For the life of me I dont remember what its called...Idle air control or something like that.
warrpath4x4
Adventurer
An 89 is TBI unless they have changed it to a carb. This is such a general question to try to answer, could be the TPS (throttle position sensor), an o2 sensor, fuel filter. You can take it to autozone or shucks and they will usually check the computer codes for you for free.
Most likely cause is the throttle body base gasket has sucked in and you have a huge vacuum leak, get a gasket, undo the 3 throttle body bolts and check the gasket, if it isn't buggered replace it regardless, it is a very common problem. I was a GM mechanic for 5 years.
Good luck,
Mark.
Good luck,
Mark.
BIGdaddy
Expedition Leader
nope its TBI...o2 sensors are fine, fuel filter is brand spankin' and its even installed in the right direction!
I'll have to see if it'll make it to autozone.
Grim Reaper
Expedition Leader
Did you ask it what is wrong?
You can get the codes out of it with a paperclip.
My bet is the EGR is stuck open or you have a broken vacuum line. The base plate gasket being bad is common but it will usualy idle just idle rough. A broken vacuum line to the MAP it will not be happy to do much of anything. The MAP is the little black box behind to the passenger side of the throttle body (might be over the passenger side valve cover but on my 88 with 454 thats where it is) and has a 3/8s (I think thats the size) vacuum line running to the base of the throttle body. That line gets baked by the intake manifold and cracks. Had that happen on mine.
If it still has the hard plastic vacuum lines I would start replacing them. They are very brittle and break easily.
You can get the codes out of it with a paperclip.
My bet is the EGR is stuck open or you have a broken vacuum line. The base plate gasket being bad is common but it will usualy idle just idle rough. A broken vacuum line to the MAP it will not be happy to do much of anything. The MAP is the little black box behind to the passenger side of the throttle body (might be over the passenger side valve cover but on my 88 with 454 thats where it is) and has a 3/8s (I think thats the size) vacuum line running to the base of the throttle body. That line gets baked by the intake manifold and cracks. Had that happen on mine.
If it still has the hard plastic vacuum lines I would start replacing them. They are very brittle and break easily.
Colorado Ron
Explorer
Id pull the throttle body off, have a look at the base gasket(usually leaks there) and give it a good cleaning. Id also replace the fuel filter and give it a whirl. Could be other things though too. Spark plug wire arcing on the manifold?
BIGdaddy
Expedition Leader
ok well, we were able to drive it home, so now i can dig in a bit. When i went to start it just now, it turned over like 20 times before it caught. when it did it ran for about 20 seconds then quit. I turned over the air cleaner so that the air filter was getting a bit more flow, and it fired back up on the first or second turn of the starter.
It ran fine all the way home, and when i asked my wife to start it again, it again didn't start till the 9th or 10th turn of the starter and idled kinda rough
when it did.
again, also, once it smoothed out, it ran fine just sitting there.
wierd.
I'll do some checks.
I personally side with the spark plug wires idea. Are all the boots connected tightly? are the wires melted?
I have a 5.7 tbi in my 93 blazer. I had the same problem twice. Once the spark plug boot came loose and another time one of my spark plug wires were melted by the manifold at it was arching.
same problems you are describing.
Maybe your looking at a fuel pump?
just my 2 cents...
I have a 5.7 tbi in my 93 blazer. I had the same problem twice. Once the spark plug boot came loose and another time one of my spark plug wires were melted by the manifold at it was arching.
same problems you are describing.
Maybe your looking at a fuel pump?
just my 2 cents...
+1111111111
I had a broken EGR do the same thing. Had to hold it about half throttle to keep it running.
pete.wilson
Adventurer
Hey
When it doesn't start; remove the aircleaner and see if your getting gas into the carb from the jets, if not you have a bad fuell pump which is most likely in the tank. If your getting gas but no spark, look at the coil unless yours is an HEI. Intermittent fuel pumps can act just like that. Good luck.
Pete Wilson
When it doesn't start; remove the aircleaner and see if your getting gas into the carb from the jets, if not you have a bad fuell pump which is most likely in the tank. If your getting gas but no spark, look at the coil unless yours is an HEI. Intermittent fuel pumps can act just like that. Good luck.
Pete Wilson
Grim Reaper
Expedition Leader
I have seen a few pump failures and they were run or don't run never "run bad at low RPM"
The MAP will give those symptoms because as you floor it the manifold vacuum drops. Thats what the MAP reads so running better at Higher RPM when manifold vacuum and fuel consumption catch up with the mis reading sensor.
The VERY first thing the factory manual tells to look for is vacuum leaks and bad ignition components. Every problem I have had with my Burb has always proved too be one of the two and repairable for $50 or less.
pete.wilson
Adventurer
Hey
His problem is a lot like a problem I had with my 87 full size Blazer; sometimes it wouldn't start (no fuel or very little) and other times it ran good with no problems, I had it to where it would not start, then started run ok for awhile then intermittent. I had it replaced at a dealer and two weeks later the new one died. Replaced under warranty, was good after that. Obviously there is always more than one option as to what can be wrong, this was my experience with a fuel pump in a similar vehicle.
Pete Wilson
His problem is a lot like a problem I had with my 87 full size Blazer; sometimes it wouldn't start (no fuel or very little) and other times it ran good with no problems, I had it to where it would not start, then started run ok for awhile then intermittent. I had it replaced at a dealer and two weeks later the new one died. Replaced under warranty, was good after that. Obviously there is always more than one option as to what can be wrong, this was my experience with a fuel pump in a similar vehicle.
Pete Wilson