What have you done to your square lately??

[Ricko1966]

Drove over to my uncle in laws to trouble shoot with a mechanically inclined partner. Please GMSB keep in mind I don't know as much as I want to about this truck and it's TBI system as I want to, and my uncle in law doesn't either.

When I got there we tested the battery in DC and it tested good at 12.6 volts. We turn the truck on and the battery voltage jumped up to 14.9, as in, the alternator is doing it's job. So then the test drive.

He rode with me and experienced the rough ride and stuttering. He mentioned thinking it could be fuel related. We talked about the fuel pump, the missed fuel pressure test( I could not seem to ever thread the TBI specific port fixture to the flex line a while ago and abandoned the test). So he suggested maybe the tank wasn't venting properly so he suggested trying to drive it with the gas cap off. It maybe ran rougher after that, so we put the cap back on and headed back to his house, only after the truck cut out on us when I put it in reverse to turn around. We made it back to his house and he brought out a vacuum test. We tried hooking it up in the ports on the canister, with no pressure change, leading me to believe the canister system may be deleted on this truck or just dead old.

Then we started looking for ports to test pressure in and around the throttle body. I explained to him what all the electronic sensors were. He started unplugging and plugging back in on: PCV(pressure shot out immediately and engine revved, once re-plugged the engine settled and smoothed out), The EGR(nothing happened???), the MAP sensor(again, pressure shot out, engine revved, plugged back and engine settled, and smoothed out). After this the engine was idling much smoother than before we started tinkering with the ports on the TBI. He wished me luck and we talked about changing spark plug wires potentially and replacing the EGR(which I have never done) in the next few days.

I put the truck in reverse to leave and it had plenty of power. Put in drive to head home and the truck had all the power it normally should. It is currently driving like nothing is wrong. So strange. All I can think is it had something clogged in the EGR(or one of the other ports maybe) and when we messed with them something got knocked out or unclogged. SMH.

EGR has zero effect and is completely disabled at Idle and acceleration. It is only active at steady cruise. Which is why I think it so pointless and self defeating to delete it you lose the good stuff ( better mpg and cooler combustion chambers) and it never did do anything at all to WOT or Idle.

 

[JamesSam]

EGR has zero effect and is completely disabled at Idle and acceleration. It is only active at steady cruise. Which is why I think it so pointless and self defeating to delete it you lose the good stuff ( better mpg and cooler combustion chambers) and it never did do anything at all to WOT or Idle.

I do not want to delete the EGR. I may replace it is all I am saying. The evap canister is what I believe may have been deleted.

 

[bucket]

EGR has zero effect and is completely disabled at Idle and acceleration. It is only active at steady cruise. Which is why I think it so pointless and self defeating to delete it you lose the good stuff ( better mpg and cooler combustion chambers) and it never did do anything at all to WOT or Idle.

The EGR has zero effect at idle and acceleration... IF it isn't carboned up and occasionally sticking open at idle. I've had that happen a few times.

If it's acting up, sometimes you can lightly and repeatedly tap the EGR with a small hammer while the engine is idling rough and it will unstick the EGR and the idle will smooth out.

 

[JamesSam]

The EGR has zero effect at idle and acceleration... IF it isn't carboned up and occasionally sticking open at idle. I've had that happen a few times.

If it's acting up, sometimes you can lightly and repeatedly tap the EGR with a small hammer while the engine is idling rough and it will unstick the EGR and the idle will smooth out.

Possibly may have happened while we were messing with stuff. I did tap it a few times just pointing it out.

 

[Ricko1966]

I do not want to delete the EGR. I may replace it is all I am saying. The evap canister is what I believe may have been deleted.

Your test was completely inaccurate unplugging,plugging in etc EGR does absolutely nothing at idle. If you think EGR is the problem if it sticks it will cause a rough idle. If its Idling fine now pull and plug the EGR vacuum source,if your problem never returns you found a problem with the EGR if the problem returns,move on to something else. I'm not certain you can read any vacuum at a vapor cannister logic says you can't. You should be able to check vacuum to it one line for purge valve it would have vaccum and the pcv hose which evacuate s the cannister.

 

[JamesSam]

Your test was completely inaccurate unplugging,plugging in etc EGR does absolutely nothing at idle. If you think EGR is the problem if it sticks it will cause a rough idle. If its Idling fine now pull and plug the EGR vacuum source,if your problem never returns you found a problem with the EGR if the problem returns,move on to something else. I'm not certain you can read any vacuum at a vapor cannister logic says you can't. You should be able to check vacuum to it one line for purge valve it would have vaccum and the pcv hose which evacuate s the cannister.

Ok

 

[JamesSam]

Your test was completely inaccurate unplugging,plugging in etc EGR does absolutely nothing at idle. If you think EGR is the problem if it sticks it will cause a rough idle. If its Idling fine now pull and plug the EGR vacuum source,if your problem never returns you found a problem with the EGR if the problem returns,move on to something else. I'm not certain you can read any vacuum at a vapor cannister logic says you can't. You should be able to check vacuum to it one line for purge valve it would have vaccum and the pcv hose which evacuate s the cannister.

I did mention that the engine did nothing when the EGR was unplugged. I assumed it would since the PCV and MAP sensor made the engine fire up and digress when unplugged and plugged back in.

 

[Terlingueno]

I had a small header exhaust leak so spent a couple hours replacing the gaskets with Fel-Pro's and since two of the header bolts were found to be missing, replaced all header bolts with new ARP units...

No Mo exhaust leaky noises

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[JamesSam]

Your test was completely inaccurate unplugging,plugging in etc EGR does absolutely nothing at idle. If you think EGR is the problem if it sticks it will cause a rough idle. If its Idling fine now pull and plug the EGR vacuum source,if your problem never returns you found a problem with the EGR if the problem returns,move on to something else. I'm not certain you can read any vacuum at a vapor cannister logic says you can't. You should be able to check vacuum to it one line for purge valve it would have vaccum and the pcv hose which evacuate s the cannister.

@Ricko1966 I appreciate your feedback but please realize I do not know exactly what I am doing here. I am learning as I go and have the service manuals as well. We did not have a specific goal today, we just wanted to see what we could find out.

 

[78C10BigTen]

I've got a question for the forum...

My 1978 square is a basket case due to the original body being so rusted that I can't salvage it. But I'm trying to salvage the chassis with a frame swap.

So the question is, there is what looks like a heater hose nipple coming out of the radiator, and another one on the top/front of the intake manifold. Every small block I've ever worked on before had the heater hoses come from the water pump and then into the manifold. So there is no nipple on the water pump at all? Am I seeing this the right way? Does the heater hose go from the radiator to the heater core? And the other hose from the heater core to the intake?

A picture or illustration would help.

Heres a current and better pic for ya.

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[WFarm]

Today I finished up blasting and painting my spare tire carrier and wheel, had the spare re-mounted and buttoned everything up. Not real happy with the wheel finish and may end up re-doing that one day.

The spare tire is the one that came with the Blazer. It’s an old Uniroyal bias ply tire. I don’t know how old it is but seeing as it’s just for display I’m fine with it.

I had been wanting a different style spare tire carrier and one finally showed up on eBay but the seller was asking too much. So given that and the fact my Blazer was built for the side mounted carrier (mounting points and bolts all still there) I went ahead and installed this one after blasting and painting it. I pulled up the carpet to remove the mounting bolts, put the carpet back down and ran a 1/2-13 bolt in from the bottom side so I could see where I needed to put holes in the carpet. Used a torch to heat up a 1/2” socket and burned holes for the two bolts.

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[Travlr]

Heres a current and better pic for ya.

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Thanks. That pic shows what I was asking about.

 

[mxer147]

Drilled screw holes for head liner trim and then installed…..a few less parts hanging out in the house.

 

[Ricko1966]

Inlet should have a restrictor? What size?

Sorry almost forgot. I did measure it it's a loose 5/16ths didn't get a pic didn't have my phone on me.
Edit Loose 5/16ths means to me that when it was new it was 5/16ths but 50 years of wear has eroded it.

 

[bucket]

Sorry almost forgot. I did measure it it's a loose 5/16ths didn't get a pic didn't have my phone on me.
Edit Loose 5/16ths means to me that when it was new it was 5/16ths but 50 years of wear has eroded it.

I have noticed many of those "restricted" nipples over the years, but never put 2 and 2 together. I always just assumed that the nipple was a thick casting for some manufacturing reason.

My ignorant self has replaced them several times with more open fittings and never noticed a difference in heater performance. Maybe it doesn't matter so much, or maybe I'm just ignorant... it could be either, lol.