I have a question I’m hopeful the group will be able to solve.

The Volvo has been running good, but when we get over 25 mph, the exhaust starts to shake.

Yesterday and today when my daughter was driving, it choked out and died (I can restart it if it sits for 15 or 20 minutes).

Thinking it was exhaust related, I took it to an auto mechanic I know to see what they thought about replacing the exhaust system.

They checked it out and told me it was the EGR valve and pipe, but they we’re not going to take it off because they don’t know where they could get parts.

Everything I have researched says Volvo didn’t put EGR valves on Volvo prior to 1991 (but it does have an egr light on the cluster).
If there is one, could someone post a picture of it. I can’t find anything related in what I read. I have found two very small round valves with vacuum tubes coming out of them, but I’m not sure.

At least They didn’t charge me for their analysis.

I’m frustrated and trying to decide what to do.

I need to figure out something in a week, because that is when I go back into the office and will leave my daughter without a vehicle if I can’t get the Volvo going reliably.

Thanks for the consideration and letting me vent.

 

Voluparts.com is a good source for parts.

 

Where to start - Yes if you have a B21f engine you have EGR. I'll attach the parts page for it. If you have a B21e you have/had a belt driven air pump. Could have been air pump for 49 states and EGR for California - I seem to remember air pumps in the south eastern US but - that was a long time ago. However - I would not expect egr to cause your problem. EGR recycles a small amount of exhaust gasses into the intake under certain vacuum conditions, and never at idle. The EGR pipes commonly clog and don't pass anything, the valves are easily tested with a vacuum source - and the movement of the valve is usually visible. If a EGR valve is stuck open the car runs, it will just have a terrible idle or stall at idle - Don't touch your EGR (unless the valve is stuck open) Fixing an EGR on a 45year old car - everything you touch is going to break. I'm sure your shop is reluctant to work on a 45 year old car - I certainly would not - unless you were a really strange collector and wanted to spend $$$$ to fix really old cars. (Sorry, that's just reality)

I would check basics first - Ignition, condition of spark plugs, cap/rotor/wires etc. Then - you need to find someone who knows about CIS fuel injection systems. It's simple - but has not been used since the early 1980's. Your problem sounds like the fuel pressure is dropping off. The CIS fuel system requires at least 65 PSI fuel pressure for the injectors to fire. When the fuel pump/pumps get old -that pressure does not happen, usually first occurring after the pump/fuel get hot after driving for x period of time. Sometimes keeping the gas tank full will keep the fuel cold and the pressure up for longer. I don't think a 1976 had a feeder pump in the gas tank when manufactured, that should have been added later and was on all later model CIS cars.

You will need a fuel pressure gauge capable of connecting to the fuel distributor to be able to measure line, control and rest pressures. You might be able to T inline at the fuel pump or filter to measure line pressure - that's the most important value for your "stops running after 20 minutes and will restart after it cools back down" problem. A gauge looks something like this.


The valve on the gauge is used to check control and rest pressures. -

2 fuel pumps - main pump under the car, under drivers seat, and feeder pump in the gas tank. Usually the feeder pump goes bad and damages the main pump. Other possibilities - the feeder pump connecting hose inside the gas tank breaks and you lose fuel pressure, worse when below 1/2 tank. Or it's just a worn out 45 year old main fuel pump. Also make sure the fuel system relay does not have any cracked solder connections in it - commonly cracks occur and when the relay gets hot the cracked connection creates resistance and limits or ceases the flow of current to the pump/s. Then everything is ok after the relay cools back down.

Here's what egr looks like

 

This is awesome information. Thanks!
The old gas tank just had a side mount fuel pump.
I have replaced the tank, sending unit and fuel pump.

I have a mechanic friend looking at the Volvo, so I will definitely send this information to him.

I have thought about selling the car because of all the work I have put into it and still has issues popping up, but my grandfather bought in 1976 new, and it barely has 100,000 miles on it.

 

It takes a special main pump for a CIS car - one that can generate 80 or so psi. Later Electric fuel injection systems only need about 45 psi. And yes the 76 had a fuel pump mounted close to the tank vs under the driver. Note #27 in the diagram - that's the feeder pump that attaches to the fuel sending unit - that may not have originally come with the car. - but was found to be needed to keep fuel pressure up.