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Topic Review (Newest First)
05-18-2007 06:21 PM
Rambo_The_Dog Thanks everyone I finally got it figured out and running.

The reader at first showed no codes - but I forgot the battery had run down and I had removed the cables and cleaned the terminal ends before charging - this resetting the computer - doh.

It still wouldn't start and so I started with the spark plugs. I pulled #1 and #8 both were fouled and wet with gas. I think I has read somewhere that these low compression engines have a tough time with fouled plugs.

I looked the plugs up online and neat...the truck had the completely wrong sparkplug - one made for a smaller truck .035 gap. The ones that fit the truck where a different #, shorter and had a .045 gap.

That being said, once those were replaced - the truck started right up and ran like a top...drove it around the block flogging it the whole way and thought I had the problem solved.

Got home, shut her off - wouldn't start again.

So I got the reader out and it was reporting the CTS - once that was replaced (and the sparkplugs) now it starts and runs like it always should have...I should have looked at this back in Nov. 06 when I bought it - probably would have saved me 100.00 bucks in fuel alone!

Again thanks everyone for their suggestions. Now who wants to buy this thing?
05-08-2007 01:23 PM
RadPreacher
Pobably the TPS

I had a 87 K-10 350 TBI that had idleing problems.

Have you ever changed the O2 sensors? If they are bad, the TPS will get a false reading.

The sensors are cheap, but with the age of your van....they won't come out with ease
05-08-2007 12:31 PM
oldbogie Ya know it might be a simple thing. The fact that it runs only with your foot on the throttle suggests that when it comes off the fast idle motor, the throttle opening is insufficient to feed idle air. Given that there is no fuel connection to the throttle it certainly isn't a carburetor's choke and accelerator pump that keeps it going.

This is not to say that there isn't a problem with the temp sensor or the throttle position sensor. But I'd get the manual and make sure the throttle adjustments and the fast idle motor are working and adjusted properly.

Bogie
05-08-2007 12:13 PM
Rambo_The_Dog
Quote:
Originally Posted by Rambo_The_Dog
I was going to get a code reader but this '89 C30 Step Van doesn't have an ODB1 port (that I can find) so the suggestions on manually testing the components really helps.

I've unfortunatley run the battery down and probably won't get to test anything today as its charging right now.

Thanks Everyone - this gives me some ammo to start with...
OK - I found the port and got a scanner - I needed one anyway (the best excuse to buy tools) and nothing is being reported

TPS checked out, as did the CTS using an ohm meter...

I pulled #1 plug and it was fouled and smelled of gas, #8 was fouled and wet with gas...so I'm heading down to get some new plugs as the old ones look really bad at the electrode anyway....

Any other cheap ideas? My only other option is to have this thing towed to a shop and I'd rather not go that route for a rig I'm trying to sell!
04-28-2007 08:51 PM
chieftain you don't need to buy a code reader. try to find the connector like the one pictured, with the key in the off position, run a paperclip from a to b and turn the key on. The service engine soon light will start flashing. Should flash code 12 first- one flash followed by two flashes. Should do that twice than flash the code that originally is the problem, the one I had last I think was a code 15 for the ect. Than it will flash code 12 again when it's done.
The aldl connector should be on the drivers side under the dash.
04-28-2007 12:12 PM
Rambo_The_Dog
Quote:
Originally Posted by crash70rs
Start with the coolant temp sensor.

If you have an ohm meter (or a multi meter set to ohms) Check the coolant temp sensor described by GMC Boogie.. I don't recall the values but I think somewhere around 10k at 70 or so degrees? Info should be available online.
If there a infinite ohms or zero ohms then its bad.. This would cause a flooding problem.

You can use the same method for the tps, hook up the ohm meter and the resistance should change as you move the throttle. You will have to look at a schematic to figure out which two to measure.

Something that recently happened to me that caused that symptom was a clogged fuel return line.. making the pressure sky rocket. I suggest checking fuel pressure as well.

That'll give you a few things to check at not cost..

Good luck! lets know how it goes!
I was going to get a code reader but this '89 C30 Step Van doesn't have an ODB1 port (that I can find) so the suggestions on manually testing the components really helps.

I've unfortunatley run the battery down and probably won't get to test anything today as its charging right now.

Thanks Everyone - this gives me some ammo to start with...
04-27-2007 10:21 AM
crash70rs Start with the coolant temp sensor.

If you have an ohm meter (or a multi meter set to ohms) Check the coolant temp sensor described by GMC Boogie.. I don't recall the values but I think somewhere around 10k at 70 or so degrees? Info should be available online.
If there a infinite ohms or zero ohms then its bad.. This would cause a flooding problem.

You can use the same method for the tps, hook up the ohm meter and the resistance should change as you move the throttle. You will have to look at a schematic to figure out which two to measure.

Something that recently happened to me that caused that symptom was a clogged fuel return line.. making the pressure sky rocket. I suggest checking fuel pressure as well.

That'll give you a few things to check at not cost..

Good luck! lets know how it goes!
04-27-2007 09:07 AM
GMC boogie Possibly could be the TPS. The CTS has been the culprit most times for me.

Best thing to do would be check the trouble codes before you start throwing parts at it.

Good luck! Let us know what you find
04-27-2007 08:53 AM
SSon18s
Quote:
Originally Posted by GMC boogie
The most common cause would be a faulty Coolant Temp Sensor or connecter. It threads into the intake manifold, left side of the thermostat housing facing the front of the engine.
I disagree with the coolant sensor. My 1990 Camaro with tbi also had this same problem. Try changing out the Throttle Position Sensor (TPS) it is located on the drivers side of the throttle body. That did the trick for me.
04-27-2007 08:25 AM
GMC boogie The most common cause would be a faulty Coolant Temp Sensor or connecter. It threads into the intake manifold, left side of the thermostat housing facing the front of the engine.
04-27-2007 07:40 AM
Rambo_The_Dog
89 GM TBI 350 - Quit Running...Where to Start?

I just wanted to throw out some symptoms and get some ideas on what to look at before spending a bunch of money.

Bought C30 Step Van Nov 06 - has had history of starting ok but after 15-30 seconds the fast idle would "kick-off" and I'd have to feather the gas until warm.

I lived with it but now that its for sale and I had a potential buyer with me the other day it decided to quit on me 2 miles from my house and had to have it towed back - needless to say I lost the sale

Symptom is cranking over - would start only if foot on gas -(which shouldn't ever be needed with this type of system) and would idle once it cleaned out (was flooded at this point) but as soon as I dropped the truck in gear and try to give it gas it falls on its face and dies

Anyway, while I was waiting for the tow truck - I pulled the air cleaner and cranked the motor over - a lot of fuel was being poured down the throttle body by the 2 injectors.

With the air cleaner off I could get it running as described in above but same thing when dropping into gear it would die but I still noted fuel was still being pushed down the TB - so fuel alone is obviously not my issue...the amount and regulation must be!

Just for fun I pulled the nearest injector wiring-plug so that only 1 injector was active - then the truck started right up and idled as it should, without applying the pedal - but it would still fall on its face when putting into gear and trying to give it gas.

So - this thing is old enough the new readers don't work on them and I need to start troubleshooting. Any ideas?

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