Vac. Line diagrahm for 1989 GMC C1500 SLE w/350cid?

Tiny
AREA52
  • MEMBER
  • 1989 GMC C1500
  • 90 MILES
I've replaced the throttle body & all it's electronic components. It surges at idle & dies. It stalls upon acceleration most of time. Once you get the rpm up, it acts like its running out of gas & will die if you don't paddle accelerator.
I know the vac. Lines are a problem, just don't know where they run From-To? Some are missing. It sat up for 1yr. Rats may have ate vac lines or they may have just decomposed & fell off. The one line from EGR to EGR solonoid crumbled in my hand as I went to remove it.
Hope ya can help with a vac. Line Diagrahm. I'm a lung cancer survivor & about 45 min to an hour is all I can spend on it a day then muscle spasms sits in where they took out my R. Lung & 2 ribs out. But, it's got me off the couch!
Thanks
Rocky J

Ps. Tried to attach picture, but couldn't get it to attach?
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Thursday, April 12th, 2012 AT 9:26 PM

12 Replies

Tiny
HMAC300
  • EXPERT
Make sure to check for a bad tbi gasket as well and make sure map sensorline is in god condition and not soft.
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+4
Thursday, April 12th, 2012 AT 10:39 PM
Tiny
AREA52
  • MEMBER
So, there's no 2nd vacumn line on the solonoid. It's a vent, right?
I'll have to look up the map sensor to see what it looks like on this critter.
Thanks, I've replaced the entire throttle body with a remanuf. One & all it's attached components, I've got a new EGR valve & PVC valve.
Had this problem 2yr ago, & a new throttle position sensor took care of it. But 6mos later it started the same thing again. I changed it out but nothing changed. So, I eventually just changed the entire TB out. But nothing changed. Limited to one hour a day, it's really starting to P-ss me off. Ha!
Again thanks, the 2nd nipple is just a vent & attaches to nothing. Don't have to worry about it anymore.
Rocky J
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Thursday, April 12th, 2012 AT 10:52 PM
Tiny
AREA52
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Ok, I checked the map sensor. I replaced it when I replaced the TB position sensor the 1st time. But, it's worth rechecking!
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Thursday, April 12th, 2012 AT 11:05 PM
Tiny
HMAC300
  • EXPERT
The vacuum line not the sensor, if the line is old and soft it will suck together so the map can't work right.
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Thursday, April 12th, 2012 AT 11:06 PM
Tiny
AREA52
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Ok,
I'm going to just purchase all new vac. Lines.1/8-1/4 & 3/8" & just replace them all. Their all probably the original lines! It's not like the lines cost the same as Gold! I know the EGR to EGR solonoid line just crumbled. Brittle as H-LL.
If, after that, I'm still having the same problem.I'll update you & see where to go from there.
I really appreciate this. I just don't have the energy to just jump in with both feet & spend an entire day checking every Lil thing like I did before.
Rocky J
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Thursday, April 12th, 2012 AT 11:42 PM
Tiny
HMAC300
  • EXPERT
One other thing if you didn't change teh gasket under the bi they had a bad habit of blowing andcausing a vacuum leak. Then if all esle fails check yoru fuel pressure should be 9-11 psi.
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Thursday, April 12th, 2012 AT 11:44 PM
Tiny
AREA52
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Ok. Again thanks, I'll check it.
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Friday, April 13th, 2012 AT 12:02 AM
Tiny
AREA52
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Update:
I've replaced the Throttle Body before our last talk. Today I replaced the EGR, EGR solonoid, spark control module, pcv valve, all vacumn lines, even the one to the Vac. Canister & it still runs alright for several seconds then Boggs down like its cold or running out of gas. Paddle the throttle a little & it'll catch up & run OK again for several seconds then Boggs down again. It finally tried to idle but it'd start to bogg down & like a governor kicking in, it idle up & run Ok for several seconds again then bogg down again. Like it running out of gas or al older carburetor type engine that's cold & the choke isn't working very well.
Outside of fuel pump & fuel filter problems, I'm at a loss. I've got a code reader coming Tuesday PM & hopefully it'll show me something.
In your last note, you said to check the gaskets under the bi? That's the injectors on top of the throttle body. Right. Or did I misunderstand? It's a new "refurbished" TB, but I've had brand new parts that were defective. Especially starters in the 70's. Am I correct about the bi? I haven't checked those. I thoughtid double check on what you meant.
Any ideas?
I'll let ya know what the code reader tells me Tues. Or Wed. I spent 2.5hrs under the hood today & I'm feeling it. Funny thing is, the EGR was very easy to replace, even though the 2 nuts were a Lil awkward to get to. 20mins & I was done with that part.
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Monday, April 16th, 2012 AT 10:30 PM
Tiny
HMAC300
  • EXPERT
The tbi gasket is UNDER the tbi unit. You should have replaced it when you replaced the tbi unit. Also check your fuel pressure I asked you to do that the last post.
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Monday, April 16th, 2012 AT 10:43 PM
Tiny
AREA52
  • MEMBER
OK.I understand now. It came thru as bi, not tbi. I put a new gasket under the TBI when I replaced it. There were several to choose from in the set. One was approx. 1/4" thick & black. The others were thin like the original. The thin one was the one I used. But I'll check it again after I check the fuel pressure. I just forgot about the fuel pressure. All the chemo messes with a guys memory recall. I'll blame it on it anyway. It stormed for 3 days here before I got back to it today.
Again thanks
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Tuesday, April 17th, 2012 AT 12:27 AM
Tiny
CATHY PAYTON
  • MEMBER
Hey there got same problem. I got 89 gmc replaced throttle sensors put her in shop tried everything think it a vacuum problem?
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Saturday, February 9th, 2013 AT 7:42 AM
Tiny
HMAC300
  • EXPERT
Check for a blown gasket under the tbi unit.
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Saturday, February 9th, 2013 AT 4:08 PM

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