View Full Version : fuel pump

10-31-02, 09:51 PM
does anybody know about the fuel pump aspirating air from the fuel lines? i replaced a section of the line and two small holes on the side of the pump have been releasing a large amount of fuel, even after idling the car for quite some time...

Tom Bryant
11-01-02, 12:14 AM
Sounds like a bad fuel pump diaphram to me. You should never get any fuel coming out of the pump anywhere, except the line outlet of course.


11-01-02, 12:32 AM
I agree with Tom. The hole in the pump acts as a weep hole, just incase there is a diaphram falilure. Instead of the fuel dumping into the crankcase, it's directed out in the open.

11-01-02, 04:35 AM
alright, sounds fair enough, but how do i replace it....there's not a lot of literature on the fuel pump itself...

11-01-02, 08:05 AM
I replaced the fuel pump on my '69 BB last year, and I found two tricky parts to replacing the pump. First. you have to be very careful at removing the fuel lines so you don't knock the edges off the fittings. I had some cheap line wrenches that I tossed out in favor of a set of good 6" Crescent (adjustable) wrench. The other problem I had was getting the new push rod to stay in position so I could get the lever on the pump under it. If you have the oil pan off you can probably hold it in place from underneath the car. I ended up putting some wheel bearing grease on the upper end of the push rod. The grease held the rod in place long enough to slip the fuel pump lever in under it. Of course, you'll need to hold the pump against the block to counter the spring force on the lever while putting in the pump bolts. You should probably use new pump bolts and don't get caried away and overtighten them. While I was at it, I also replaced the lines and filter between the fuel pump and the carb. It was very tough to get at the lower end of the hard line that goes from the pump to the flter. Be sure to check it carefully for leaks ... you don't want your Vette to go up in smoke! Good luck.

Tom Bryant
11-01-02, 12:06 PM
Before I forget again I'd like to welcome both of you to the Corvette Action Center. I know that you will enjoy your time spent here.

Bill brings up a few excellent points here for someone that hasn't replaced a fuel pump before. The grease on the pushrod trick is something I have used for 40 years. Always works too.
There is a steel plate on the block that the pump bolts through.If you remove this the rod will fall clear out. It's a good time to replace this gasket anyway. Wipe the rod off and check the ends for wear. If they show cupping or indents from the pump arm just replace it. They don't cost much.

Here's another little trick that I use. After I grease the rod and insert it in the block and replace the steel plate I take a half paper towel and roll it up. Then I insert it into the opening. This will make sure that you can get ahold of the rod and push it back up again if it slides down while you are getting the pump ready to slip in. When the pump is ready just stick your finger in there and push up on the rod to make sure it is all the way up, pull out the paper towel and slip in the pump arm. Make sure you hold it straight and feel for the arm to contact the rod. There should be spring pressure you are working against when you tighten the bolts as Bill said. If you don't feel this and the pump don't seem straight the arm is off of the rod.

As Bill said this is the time to replace the fuel filter and the hard or flexible lines if necessary. If that flexible line from the tank line to the pump is old I would replace it now. The inner lining gets soft and can suck shut under hard acceration and shut off the fuel. (Voice of experience) One other thing. The fuel pump is lower than the gas tank. Use some vice grips or c-clamp and clamp off the flexible line before you loosen the connection to the pump. You don't want the fuel tank to empty itself on your garage floor. Replaceing the flexible line is going to be messy as you will have to hold your finger over the tank line to keep the fuel in while removing and reinstalling the new one.

As for wrenches, buy a quality set of line wrenches. You will use these many times over the years and be glad you have them. They look like a 6 side box end with the end left open. A good one will prevent the corners of your fittings from getting rounded off. I have Craftsman, Mac and Snap On in my box. I must like the Mac best as that seems to be the ones that end up in my hand.

If you have double fittings on the pump be sure to hold the pump fitting with a open end wrench while loosening/tightening the line fitting with the line wrench.

Good luck on your pump change and if you need any help just holler.


PS. If you need a correct numbers matching pump Paragon Reproductions can probably fix you up. If not AC, NAPA or others can supply service replacements,

11-01-02, 12:13 PM
Tom, I wish I'd had you around when I was trying to figure out how to keep that darned rod in place. I'll take your advice and replace the soft lines between the fuel pump and the tank. Mine are probably original. My Dad bought this Vette new in '69, but I wasn't around during most of the time from when he bought it until he passed away. I'm slowly figuring out what he replaced (both correctly and not correctly) and what he didn't touch.

By the way: Where should I post questions about radio removal and transmission swapping?

Tom Bryant
11-01-02, 12:33 PM
Glad to be of help. I think it is awesome that you have the Corvette that your dad bought new. Then to be a 427 1969 is even better.

Post your trans and radio questions on the C3 Tech Forum. I think you will get the best response from those that have been there.