Fuel Line Insulation

[Pathfinder]

Sending unit was cleaned, replaced the float which was rotted out and replaced the sock. The gas is clean. I believe the timings good but will double check and advise him of the oil cooler. What should the timing be set at? The weird thing is this has been happening every few weeks since i took delivery in May. It seems to goes away and we think we're good, and then it returns. But this time it seems to be sticking around.... Pics to follow! - Thank you!

[Pathfinder]

Just thought to add: I don't get any warning lights on the dash, but also the fuel gauge doesn't work. Not sure if those are more clues....

[classicchevyowner7]

For a powerglide, it's 13 degrees BTDC. For turbo air with a synchromesh 4 degrees BTDC. Super turbo air synchromesh is 13 degrees BTDC. This is at idle of course

[bbodie52]

Just thought to add: I don't get any warning lights on the dash, but also the fuel gauge doesn't work. Not sure if those are more clues...

It is a somewhat common problem in 1965-1969 Corvairs (Corsa, Monza or 500) for the instrument panel to develop problems with the electric gauges (fuel, head temperature, tachometer, clock, and display lights) due to a loose or faulty ground. Securing the ground connections and ensuring a good ground for each gauge will often clear instrument panel display problems. As shown in the illustration, there is a single instrument panel ground point for the Monza instrument cluster. If the attaching screw is loose or corroded, the ground strap can be poorly connected to the chassis ground provided by the dashboard frame. Check the connection, and you can also use a multimeter to check for electrical continuity between the metal components in the instrument cluster and chassis ground. (The instrument panel on Late Model Corvairs is non-conductive molded plastic, so it relies on the metal strap to provide the ground for the lights and instruments).

The speedometer and Corsa vacuum/boost pressure gauge are the only gauges in the instrument cluster that do not run on electricity. The speedometer uses a mechanical cable to spin the speedometer mechanism to provide a speed reading, and the Corsa vacuum gauge uses plastic tubing to connect the mechanical gauge to the engine vacuum balance tube or turbocharger manifold port.

If not a grounding problem, the single wiring harness multi-connector on the left could also be loose or unplugged.



=========================================================================

Although not associated directly with the instrument panel, your ignition coil relies on a steady source of voltage from the ignition key switch for power when the key is in the ON position. It is conceivable that a corroded or loose connection in the wiring harness at some point between the ignition switch and the coil could be causing an intermittent, possibly vibration-related power connection problem for the ignition coil.

Although locating such an intermittent connection would be a little time-consuming, if such a possibility seems reasonable, a temporary jumper wire between the battery positive terminal and the coil plus (+) terminal would provide continuous voltage. If such a temporary ignition key power bypass were to be tried, and the problem went away, you would have confirmed a power lead breakdown somewhere in the harness and connectors between the ignition key switch and the coil.

1965-1969 Corvair Interior Compartment Wiring Diagram

1965-1969 Corvair Interior Compartment Instrument Cluster Wiring Diagram

1965-1969 Corvair Engine Compartment Wiring Diagram

You can follow the path of the coil wiring between the coil and the ignition switch by starting at the coil positive terminal (on the bottom wiring diagram, near the top center). This wire is labeled 20 B/Y. Trace it downward, past a two-pin connector, and through a resistor wire labeled 20 W/R/B and into a 12 pin multi-connector. The other half of this multi-connector is to the left, and the wire continues from the third pin up from the bottom-right. The wire is now labeled 20 B/P and exits the diagram as the last wire on the bottom left.

The 20 B/P wire continues on the next diagram up, and leads to another multi-connector on the upper-left part of the diagram, in the instrument panel/dashboard (2nd pin from the bottom-left). The connection next appears on the top wiring diagram.

On the top diagram, you will see another 12-pin multi-connector on the top-right. The coil circuit appears on the second pin up on the bottom-right (now labeled 18 B/P). Trace it until it meets a wiring junction point. One of the other wires tied to this junction point is labeled 14 B/P, and it is connected directly to a connector on the IGNITION SWITCH.

As you can see, the ignition coil receives its power via a wire that travels through two 12-pin multi-connectors and the connector that plugs onto the back of the ignition switch. Over a period of 45 years or so, the metal connection pins in each connector can become loose or corroded — particularly the one in the engine compartment, since it is subjected to vibration, heat, and moisture. This could cause added circuit resistance or an intermittent power connection to the ignition coil that might be aggravated by engine vibration as you accelerate through the gears. Such an intermittent ignition system power connection could cause a misfire in the ignition system.

If this appears to be a possibility, you can unplug each connector — starting with the connector in the engine compartment. Examine the pins inside each half lf the plastic connector and look for damage or signs of corrosion. Sometimes simply unplugging the two connector halves and reconnecting them will establish a better connection and clear the problem.

[Pathfinder]

Problem Solved! Disconecting the fuel pump return line did the trick. Of course this was after replacing lots of parts, ok, she doesn't quit after 10 minutes (or less) anymore... I'm happy.

[terribleted]

Problem Solved! Disconecting the fuel pump return line did the trick. Of course this was after replacing lots of parts, ok, she doesn't quit after 10 minutes (or less) anymore... I'm happy.

Fuel pump return line???? Never seen anything like that. Where does it go what does it hook too? Fuel pump has 1 intake pipe and 2 outputs only. There is no "return Line"

[bbodie52]

The fuel vapor return line is one of those unique features of the last few model years, along with the SMOG pump plumbing and other unique engineering features GM invented to satisfy the SMOG police, California Air Resources Board, etc. The car in question is a 1969 model year.

Fuel Vapor Return Line

Fuel Vapor Return Line.jpg (14.72 KiB) Viewed 958 times

[terribleted]

Can not tell from this thread that the car is a 69 unless I missed it somewhere it is not stated. Been working on these for 30 years and have never seen a return line on anything except a turbo. If fact I have only ever worked on one car here in the east that had any smog stuff on it and most was deactivated (removed the rest). Seems like if the smog system is in place the return line might be needed and should not just be disconnected and plugged? If the rest of the smog gear is gone then plugging should be fine.

[Pathfinder]

Here's my engine bay/fuel pump. Note the brass T at the top and where we capped off the pump, etc. My understanding it's 69's only - our Club mechanic was a little surprised as well, though he may mind me saying that:

[terribleted]

The rest of the smog stuff...pump etc. appear to be removed. Blocked return should cause no issues. Wonder if you still have smog exhaust manifolds on it? If it was mine and they were on there and smog was not I would change them out for less restrictive non- smog exhaust manifolds.

Seem the pump was sending a lot of your fuel in a circle back to the tank:)

[Pathfinder]

Yeah, that was totally it. Have to say I'm proud of my mechanic for thinking of this... it seemed to be way off the charts, though after the fact I found it mentioned on a few other posts. Went through 2 coils & new wires, a new fuel pump, new gas tank float and sock, and then finally this occurred to him, right before I almost shelled out big for an electronic pump. This only cost me a case of Bud Lite, and it got me 15 miles to our Annual Long Island Corvair Club show where I took home a trophy for best LM Open (had to throw that in sorry). I think it was mostly the CA cars equipped w/ the smog stuff - this car was originally from CT. Maybe they were rigging all the cars for the future or ran out of the older style pumps, being the final run and all...

[terribleted]

Gratz on the award!!

[azdave]

I see the vapor return line often here in AZ on 68-69 models but what is weird is that everyone in the Corvair world has always told me that the vapor return line was added specifically to prevent vapor lock on the SMOG engines because they ran hotter than a non-SMOG Corvair engine. This fix report makes it sound like the vapor return line CAUSED your vapor lock. Oops!

In the thread below there is some debate about its real function/usefulness.
http://corvaircenter.com/phorum/read.php?1,327174

SMOG engines were seen as early as 66 on Corvairs built to sell in California but the vapor return line seems to have appeared on maybe late 67 SMOG engines and certainly on all SMOG 68-69 engines per what I have read here and on CC.

Photo below is of a 69 model with only 15 miles reported on the odometer at the time of the photo.

[mikes1964]

I was having the vapor lock issue on my 64. I put Taylor thermal protective sleeving on fuel the lines running from the fuel pump to the carbs and that seems to have solved the problem. However just a word of caution the sleeve (7/16 max diameter) will not fit over the fuel line running from the tank to the fuel pump.