LUVTruck.com

I have air coming out the vent on top of the pump. I think it should suck air in. The truck backfires when shifting between gears. Don't know if the pump is bad or the switching valves.

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76 LUV

Vent on top of the pump is a relief valve. It only opens if the pump pressure exeeds specs. It is either defective itself or--there is a restriction in the output supply hose somewhere. Possible bad diverter valve assy.

I'm thinking about pulling the belt and letting it go at that.

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76 LUV

Diverter valve is bad.

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Certified pilots, looking down on people since 1903.

'76 still requires bi-annual smog so you'll likely have to fix it at some point.

BTW, on our '76, the diverter valve went bad a few times and caused the same symptoms. Eventually my dad did the same thing and just pulled off the belt. Soon after that he pulled all the smog equipment. Then, eventually he had to put it all back on.

Maybe someday they'll move the smog cutoff up to '85...maybe...

Has anyone bought a diverter valve lately.

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76 LUV

I probably have a used one in my shed. Wouldn't know if it's any good or not, but might be worth a try if a new one is pricey or unavailable.

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OK, I'm over it. Where's the beer?

Thanks Rondog. I've checked all the parts stores and no luck. I checked my parts book and it shows 3 valves on this system with the smog/air pump. The Air By-Pass, Mixture Control and Air Switching. Does anyone have a short explanation on how the 3 valves and pump work together (Emissions 101).

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76 LUV

Have you checked rockauto.com?

Nothing from Rock Auto. Can these valves be re-built.

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76 LUV

I have one... if I'm correct. I'll shoot you a pic of it. It's the one that mounts to the right front corner of the head.

Screw it. I've been trying to make this smaller for 30 mins. I'm just glad I got it to post.

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OK, I'm over it. Where's the beer?

They say bigger is always better. That looks like the one under the smog pump.

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76 LUV

I forgot about that one. Yea that's probably what it is.

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OK, I'm over it. Where's the beer?

Ben, We have a Senator in CA working on that. Bill SB 1224, only got voted down by 1 vote, but plans in the future are going to try and get it through. It will make years 1976 to 1980 Smog exempt.

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1980 Luv 4x4 with a 5 speed tranny.



"When all else fails, follow the directions".

I pulled the hose off the pump that goes to the check valve and the pump stopped venting. It was blowing a good amount of air out of the hose. I could feel a vacuum on the check valve. As soon as I put the hose back on the check valve the pump started venting. Could this mean the check valve is bad, not allowing the full amount of air from the pump to pass through the check valve.

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76 LUV

Yes, it could mean the check valve is just stuck. Take a pencil or something and push in on the check valve. It should allow air to go in one way but not allow exhaust to come back out and damage the pump. Give it a try.