Electrical Issue?

[Duffman]

Leon, no haven't tried that, but did replace the E12-80 module. Coil runs warm, as expected, but does not run unbelievably hot.

[LeonV]

Regarding ignition advance, have you taken a timing light and checked at different rpm to make sure your advance is working?

Otherwise, tape the fuel pressure gauge to the windshield and take it out for a drive. This is how I diagnosed my fuel delivery problem. At idle, I'd get 3-3.5psi but under load pressure dropped to zero or near zero. Before that, I was not sure if it was a fuel or spark problem either, but that sure helped pinpoint it.

If fuel pressure checks out, I would hook up a timing light and put that inside the car while you drive so you can visually check if you lose spark.

[Duffman]

Leon, will follow up on your suggestions tomorrow, with some assistance from a sharper mind than mine when it comes to ignition advance issues!

[Duffman]

Ok, looks like distributor is fine. Back to fuel delivery as the most likely culprit! Had the tank taken out and boiled a few months back, could have an air leak in one of my pipes in/out of my tank (?). I realize that I need to check the mechanical fuel pump, the fuel lines between the tank and pump, and the tank itself. Any thoughts on the best way to review each? Not sure if you can determine a leaky fuel pump easily. Figured to do a visual check of fuel lines back to tank. May have to remove the in/out line from the tank, requiring some welding/unwelding to remove. Any other thoughts/

[Duffman]

Forgot to say that the fuel pressure gauge was bouncing around when car started (between 3 to 4 psi) before settling somewhere between 2.5 to 3.5 psi. Thinking air is getting in line somewhere causing the number to change. Also, picking up slight whistling sound when I just start car, goes from low to high, then seems to disappear or not as noticeable. Will try to pinpoint where that sound comes from.

Edited September 20, 2011 by duffman

[beermanpete]

The pulsing pressure sounds normal. The pump delivers the fuel in pulses so until the float bowls fill it seems reasonable to have some pulsation in the pressure.

To check the various components and sections of fuel line start by looking for fuel stains and/or very clean spots around the fuel line at each end of the car.

The fuel pump should hold pressure for a little while after shutting off the engine. Not hours necessarily, but long enough that the gauge should not drop like rock when shutting off the engine. Fast pressure drop can be from leaky float valves, a bad check valve in the pump, or a bad pump diaphragm (in this case the fuel could leak into the crankcase, look for high/increasing oil level and gas smell in the oil.)

Check the volume of fuel delivery per the factory manual isntructions with the engine running and everything connected normally. If the volume is low, or you see air in the fuel comming out (looks foamy or bubbly when going into the test bottle) you probably have an air leak.

To test for cracks in the steel lines by-pass them with rubber hose. Connect one end to the inlet on the fuel pump and the other end in a fuel can. If it is good start connecting the various segments of line back into the system and perform the flow rate test each time. If it is good all the way back to the last section that connects to the tank then the tank has problem. You could do this in the other direction and start at the tank. Either way you will find the section of line that is the culprit.

This method will not include the filter screens built into the carbs. Check those by visual inspection.

We used this method to locate an air leak in the pick-up tube inside the fuel tank of our car. It works fine but take a lot of time.

[Duffman]

Thanks, Pete, good stuff!

[beermanpete]

The fuel pump should hold pressure for a little while after shutting off the engine. Not hours necessarily, but long enough that the gauge should not drop like rock when shutting off the engine. Fast pressure drop can be from leaky float valves, a bad check valve in the pump, or a bad pump diaphragm (in this case the fuel could leak into the crankcase, look for high/increasing oil level and gas smell in the oil.)

I just realized the return line will bleed off the pressure. To check for pressure leak-down you will need to close the return line. Use a C-clamp, Vise-Grip pliers, or similar tool to squeeze the return line (gently). This should seal it and allow you to perform the pressure leak-down test.

[Duffman]

Good point, Pete. Am afraid that it will be the same problem you have, due to my having the tank boiled recently and the pick-up tube being a good possibility. Am hoping for something easier to find, however!

Have noticed a wide variety of fuel pressure readings; from 1.5 to 3.5 psi, at different times of running the engine. Would think that the psi should register a consistent number once it is up to pressure. Mechanical fuel pump visually looks pretty good; top diaphragm is intact, no leaks anywhere. Was a rebuild from about 4,000 miles ago, not much use. Still thinking the pickup tube in the tank. How did you fix yours, Pete?

Edited September 21, 2011 by duffman

[beermanpete]

We installed a new pick-up tube where the fuel gauge sending unit goes. We machined an aluminum disk to replace the sender. In the center of this we installed a -6 (3/8") AN bulkhead fitting. The tank side has a 3/8" aluminum tube attached that is bent to reach the bottom of the tank near the inner baffle wall. The outside has a hose barb adapter for connection to the 3/8" rubber tubing. The original steel line is still in the tank; we simply sealed the outer end.

We use our car at the race track and don't care about the fuel gauge. If you need/want to retain the fuel gauge you will have to replace the original steel line. Any shop that can repair leaks in the tank should be able to cut out the old line and weld in a new one. It might be possible to install a bulkhead fitting directly in the tank near the sender opening and retain the fuel gauge. We decided we did not want to cut or weld on the tank ourselves, hence the path we chose.

[Duffman]

Interesting, thanks Pete.

[Duffman]

UPDATE: Well, problem solved! After having the distributor checked out and cleaned up, I realized the distributor was not the problem. But I did improve my electrical lines, added a ground, etc, which had to make it work better! Realizing it was back to a fuel issue, I ran my mechanical fuel pump off a can of gas thru a clear hose and saw good fuel pressure and no "flutter" on hard revving. Then, I ran the same setup from the hard line from the gas tank and saw the same thing. Thinking it had to be the gas tank, I then ran the clear hose from the gas tank to the hard fuel line. Again, ran great, no air bubbles, no problems! So, I deducted that it had to be the hose (or connections) from the gas tank to the hard fuel lines. The hose was a fuel injection rated hose, fairly new, and visually looked fine. The only thing I could see was that the hose was splitting when squeezing the ends. So, I picked up a fuel rated hose and replaced it and my fuel pressure runs up to 4 psi, I get no "flutter" under hard acceleration and she runs like a top! Sometimes, dogged determination wins out over limited intelligence!!

Appreciate everyone's thoughts and opinions!

Edited September 24, 2011 by duffman