F.I. engine quits running 5 seconds after key returns to ON position

[John D.]

Re: F.I. engine quits running 5 seconds after key returns to ON position

Richard, Very confusing post until Jim Lockwood cleared it up by stating you have a 7380 FI unit. I was mislead as your post says 63-64.
To repeat what Jim said using my language. A 64-65 7017380 FI unit is unique in the fact that it will start and run a few seconds using engine fuel pump pressure feeding the Skinner valve (starting solenoid).
In fact you could take the drive cable out and put it in your pocket and the car will still start up. The FI unit can be literally trashed and the car will still start but only run briefly.
Many good suggestions above.
Remove the drive cable housing completely. Just put the bare drive cable in the high pressure pump and the distributor. That way you can see it turning.
Make sure the end of the cable is not rounded off. Next get a helper. Remove a nozzle line and put a little can under it. Pull the coil wire. Crank the engine to see if you have a healthy stream of gas coming out the nozzle line. If so then your FI unit may be OK and you have electrical issues.
How is your ignition coil? Original of repro. If you suspect coil problems go to NAPA for a UC12 black coil. Or GM 12337166 U505. Replaces the 202 coil.

Jim Lockwood etal. When installing the tiny brass anti-siphon valves in the fuel meters (not for a novice) do not put them in dry. Use Permatex Threadlocker Red aka as PX #27100 or just Permatex 271. Now this stuff is permanent. The valve will never fly out then. Jerry Bramlett taught me this. But put the 271 on carefully with a toothpick. Don't get it in the hole-just on the edge.

Could the needle and seat be stuck under the float. Was any teflon tape used anywhere in the fuel system? If so a hunk could have gotten under the FI needle and seat making it stick and therefore not enough gas flow.
Hi-pressure pump issues although I doubt this. The drive gear on the pump shaft has a short pin holding the gear on. Could this be a problem. I only ever saw this happen once though. The pin was too short holding the gear on and the shaft turned but the gear did not. Therefore no pump pressure.
Is the engine fuel pump OK
One time this same thing happened to a member of the Pittsburgh chapter. Just remembered this as it happened 20-25 years ago.
The culprit was the POC gas cap. The 65 would start and run about 5 seconds. I had just rebuild the unit. Was very frustrated when I went to his house and couldn't fix the problem. So I decided to look in the gas tank and the cap about blew off when I took it off. I left the cap off and started the car and it ran like a clock. We put a rag where the cap goes and went out for a long ride in his coupe.
Another time the same thing happened and it was the ballast resistor.
One more: One time the igntion points were closed big time. Opened them up a tad and the car started and ran.
Another time it was a faulty repro coil.
Remove the distributor shield and put it on the shelf. They are totally junk you know. Should be outlawed so they should. The distributor shield could have cut a wire or shorted out the plug wires.

[Richard S.]

Re: F.I. engine quits running 5 seconds after key returns to ON position

thanks for tips john. will try to answer in order. yes its 380 unit.cable is good not rounded ran with out shield to test.fuel bowl full of gas, gas cap off. mechanical pump good and filter clear. no shielding(non radio car). checked all voltages when engine died and still had correct voltage at coil, balast etc.

[Michael H.]

Re: F.I. engine quits running 5 seconds after key returns to ON position

Richard,

Could be a broken axle/link assy. Not at all uncommon and the results would be just as you described.

[Jim L.]

Re: F.I. engine quits running 5 seconds after key returns to ON position

Richard,

Could be a broken axle/link assy. Not at all uncommon and the results would be just as you described.

The axle and link in Richard's FI unit is a brand new reproduction, like the one in this photo:




The typical failure for axle and link assemblies is worn pivot holes in the counter weight arms. The wear is caused by movement of the flat crimped pivot pin acting sort of like a spade drill bit. Here is a picture of an extreme example:


The high quality reproduction addresses this wear two ways:
1. The counterweight is steel, unlike originals which are pot metal
2. The pivot pin is retained by tiny "C" clips which can not cause the typical wear seen on original axle/link assemblies.

Obviously it's not impossible for the axle and link to have failed. But it's pretty unlikely.
Jim

[Michael H.]

Re: F.I. engine quits running 5 seconds after key returns to ON position

The axle and link in Richard's FI unit is a brand new reproduction, like the one in this photo:




The typical failure for axle and link assemblies is worn pivot holes in the counter weight arms. The wear is caused by movement of the flat crimped pivot pin acting sort of like a spade drill bit. Here is a picture of an extreme example:


The high quality reproduction addresses this wear two ways:
1. The counterweight is steel, unlike originals which are pot metal
2. The pivot pin is retained by tiny "C" clips which can not cause the typical wear seen on original axle/link assemblies.

Obviously it's not impossible for the axle and link to have failed. But it's pretty unlikely.
Jim

That's a nice looking reproduction. Who makes it?

I wonder how they balanced it with a steel counter weight instead of pot metal?

I've seen quite a few originals that are broken at the axle/pivot. I still have 4 or 5 in my tool box from decades ago.

[Jim L.]

Re: F.I. engine quits running 5 seconds after key returns to ON position

That's a nice looking reproduction. Who makes it?

I bought the axle and link used in Richard's unit from John DeGregory.

There are other reproductions. Made more like the original GM assemblies, the pivot pin is secured with epoxy. The trouble with these is two fold:

1. Being soft pot metal, they will wear just like the old GM pieces.
2. The epoxy constrains the pivot pin and makes the movement of the assembly very stiff. An FI unit with such an axle and link will be unresponsive and balky. Air/fuel ratio will vary wildly. In one extreme case that crossed my bench, the axle and link would not move at all (and predictably enough, the "restored" FI unit didn't even work):

I wonder how they balanced it with a steel counter weight instead of pot metal?

The repro I use is measurably heavier overall than an original. However, it is perfectly balanced, unlike the GM originals it replaces.

That deserves explanation: Late GM originals, like the NOS pieces that often show up on EBay, have a pivot arm that is not correctly balanced. This is due in large part to an uncompensated change by RP from a .155 roller tip to a heavier .187 roller tip. This has a slight effect on idle mixture but is essentially unimportant at hiway speeds. The point is the repro is a higher quality piece than an original.

I've seen quite a few originals that are broken at the axle/pivot. I still have 4 or 5 in my tool box from decades ago.

The design of the axle and link assembly seems to have been a work in progress for the entire time FI was in production. I can think of at least 5 different design variations. There were changes to counterweight pivots, pivot pin diameters, counterweight materials, pivot arm design, roller tip diameter, link design, etc etc.

What I'll call the 2nd design counterweight is, in my opinion, the worst of the bunch. Besides being made of cast pot metal which can wear rapidly, the arms of the counterweight are thin and prone to breakage. Compare the 2nd design counter weight (left) to the 3rd design (right).



With the exception of being slightly heavier and ever so slightly slower to respond to changes in venturi vacuum, the reproduction axle and links that John sells fix all the problems any previous design had.

Jim

[Michael H.]

Re: F.I. engine quits running 5 seconds after key returns to ON position

I bought the axle and link used in Richard's unit from John DeGregory.

There are other reproductions. Made more like the original GM assemblies, the pivot pin is secured with epoxy. The trouble with these is two fold:

1. Being soft pot metal, they will wear just like the old GM pieces.
2. The epoxy constrains the pivot pin and makes the movement of the assembly very stiff. An FI unit with such an axle and link will be unresponsive and balky. Air/fuel ratio will vary wildly. In one extreme case that crossed my bench, the axle and link would not move at all (and predictably enough, the "restored" FI unit didn't even work):





The repro I use is measurably heavier overall than an original. However, it is perfectly balanced, unlike the GM originals it replaces.

That deserves explanation: Late GM originals, like the NOS pieces that often show up on EBay, have a pivot arm that is not correctly balanced. This is due in large part to an uncompensated change by RP from a .155 roller tip to a heavier .187 roller tip. This has a slight effect on idle mixture but is essentially unimportant at hiway speeds. The point is the repro is a higher quality piece than an original.



The design of the axle and link assembly seems to have been a work in progress for the entire time FI was in production. I can think of at least 5 different design variations. There were changes to counterweight pivots, pivot pin diameters, counterweight materials, pivot arm design, roller tip diameter, link design, etc etc.

What I'll call the 2nd design counterweight is, in my opinion, the worst of the bunch. Besides being made of cast pot metal which can wear rapidly, the arms of the counterweight are thin and prone to breakage. Compare the 2nd design counter weight (left) to the 3rd design (right).



With the exception of being slightly heavier and ever so slightly slower to respond to changes in venturi vacuum, the reproduction axle and links that John sells fix all the problems any previous design had.

Jim

The broken one looks familiar. I think I have one like that too.

There must be a better way to secure the axle. A washer between the crimped ends of the axle and the weight would eliminate the problem.

Decades ago, a friends father, a semi retired machinist, made an axle/link assy and ratio lever out of titanium for me. It was never balanced or assembled but it would sure be a great piece once completed and it would last forever. I still have it.

[Jim L.]

Re: F.I. engine quits running 5 seconds after key returns to ON position

Decades ago, a friends father, a semi retired machinist, made an axle/link assy and ratio lever out of titanium for me. It was never balanced or assembled but it would sure be a great piece once completed and it would last forever. I still have it.

Can you make and post a picture? I'd love to see that one-off piece.

[Michael H.]

Re: F.I. engine quits running 5 seconds after key returns to ON position

Jim,

Sorry for the long delay. Half of my parts are here in FL and half are still in Illinois. I've looked through many boxes of FI parts for the titanium axle link and it's not here. Must still be in IL. Next planned trip to the frozen north is June or July. I plan to bring the rest of my parts back then and will dig out/photograph the axle link.