L84 fuel pump drive cable

[Michael G.]

The cable from the distributor to fuel unit on one of my 63s is acting weird. It wobbles when the car is sitting at idle. Am I looking at an imminent cable failure?

[William C.]

Re: L84 fuel pump drive cable

Probably so, neither of mine act that way, the cable should not actually contact the inside of the casing.

[John D.]

Re: L84 fuel pump drive cable

Customer called recently complaining his repro drive cable only lasted 300 miles. When I asked him what kind of grease he was using on the cable his answer was NONE. So I told him to use any brand of disc brake wheel bearing grease when he got a new cable.
Michael I really never knew just how difficult it is to install a drive cable housing assembly in a 63 (without scratching anything) until I put the one in my own car.
In the old days when I drove a 63 FI car daily I didn't use a housing. No way could the cable fly out as the FI unit had a wobble pump. I just used the longest cable available.
Beware of the last cable that GM sold over the counter. The one wrapped in plastic is very stiff and prone to break quickly. Best cables are the ones that are most flexible.
Remember the cable is turning over 1/2 engine RPM so everything must be dead nuts or look for early cable failure. JD
P.S. Issues with the high pressure pump can result in early drive cable failure. Along with the pump of course.

[Jerry G.]

Re: L84 fuel pump drive cable

The cable system is by design encased in the housing. it is there to support the cable and reduce harmonics. Drag in the high pressure pumper OR as i have discovered, an accumulation of junk on the screen inlet to the spill valve will cause cables to be under stress and break. Check your screen, i have a 10 micron filter ahead of my unit and still get crap on the screen. I use a VERY light lubricant so as to prevent drag inside the housing. Jerry

[Michael G.]

Re: L84 fuel pump drive cable

This car never had such casing motion before, it happened on the first start after three months of sitting. This unit was run on both cars last Fall and it ran well on each one. After putting it back on the blue car this Spring, it ran fine initially, but after two or three minutes seemed to bog down on acceleration. Then it ran fine again. I'm going to drain the old gas and put in new, as well as remove the cable to check. I have a spare cable somewhere.

I can look at the screen while its apart. I'm also going to put the repop coil back on, as this start was with an original 091, rather than the repop that had been on the car. Thanks, guys.

[Michael G.]

Re: L84 fuel pump drive cable

Here's a pic of my cable. It doesn't look so good. It looks like it might have been too long (or its unwinding). Are there different cable lengths?

IMG_0030.jpg

[Jerry G.]

Re: L84 fuel pump drive cable

There are different length cables and housings. JD sells nice cables. That, however is not your problem here, too much torque to turn pump. look at HP pump or inlet screen to spill valve. Don't try and use this cable.

[Gerald C.]

Re: L84 fuel pump drive cable

Michael,

My drive cables were breaking even when I was just running the car during the winter. Several people on this forum helped me tremendously (John and Gary Summerville). In the end, the problem was a poor quality cable purchased from a Corvette supplier. I bought a couple from John DeGregory and my unit rebuilder (Ken Hansen) had one sent to be from Ron Jones. I installed John's and didn't have any problems. In fact his is about 20mm thicker than the repro. I cleaned out my casing and loaded it with green wheel bearing grease.

Good luck.

Jerry

[John D.]

Re: L84 fuel pump drive cable

Glad you had or have success Jerry.
Here's a new technical detail I learned from Don Baker about distributor drive cable issues.
In 2013 Michael Garver complained his cable wobbled.
Don Baker said he has seen a few original distributor cross shafts that do not have the square in the shaft in the center. The square in the cross shaft is off center. Hence the cable is going crazy wobbling around. This is a new for me folks. But something to keep your eye on just in case you run up against this problem.
One might think you would have this problem with some of the repro distributor cross shafts but to find this issue with an original is not typical. Go figure. John D.

[Michael G.]

Re: L84 fuel pump drive cable

Thanks, guys, but this thread is four years old...I solved this by changing to one of John's cables...been fine ever since