C3 "S" Rubber Hose Replacement - Fuel Pump

[Paul L.]

(I posted this on CF but there may be more ideas here.)

The rubber "S" hose (frame to fuel pump) on my 1974 is leaking at the pump end. I did this job on a 1979 (without A/C) once and it was fairly simple. Just remember to clamp things off when working of course.

I have the stock-style replacement "S" hose and also a good length of 3/8" ID fuel injection hose if need be for backup. Keep in mind the best I can do at home is jack up the car, put jack stands in place, and remove the LF wheel. I do not have a lift. That is my working room. I use a battery-operated lamp so no electrical spark can occur.

The pump end of the hose is no problem. But I can barely see the frame rail area from above where the rubber hose attaches to the steel line. This is because of the A/C compressor and associated apparatus. Is there a trick to getting that rubber line in place? Or do I have to loosen and put aside the compressor (without removing the pressure lines)? I would very much appreciate advice.

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[Alan S.]

Re: C3 "S" Rubber Hose Replacement - Fuel Pump

Hi Paul,
I can't help with a/c suggestions, but from my non a/c view I'd first determine the position of the spring clamp, (I'm assuming it's still a 'spring', and not a 'tower' or 'worm'), so that the pliers you use has the easiest access to the clamp from above or below. Turn the clamp on the hose first if needed.
Then I'd move the clamp on to the steel line; get the new line WITH another clamp already slid onto it in position, pull the old line off and slide the new line on. This should stop the flow/leak enough so you can grab the clamp and side it into the proper position on the hose. You can then open the old clamp to get it off the steel line.
Good Luck!
Regards,
Alan

[Terry M.]

Re: C3 "S" Rubber Hose Replacement - Fuel Pump

I would be inclined to stop the flow of fuel by clamping (gently and no more than absolutely necessary) the hose at the fuel tank to frame line at the back of the car. No muss no fuss.

[Paul L.]

Re: C3 "S" Rubber Hose Replacement - Fuel Pump

Thanks Alan and Terry,

I appreciate your comments! I'll screw up my courage and give that job a try in coming days. But I can't see doing it without moving the A/C compressor out of the way. So be it. Sometimes I question my own judgement in buying a convertible with C60. It really does not make sense with a convertible and being in Canada.

*Edit* - As I said I have the factory style "S" hose but I don't trust that rubber and modern fuels. I did a mock-up using 3/8" ID fuel injection hose and it works without restrictive crimps. That will be my choice. People may say that it just a matter of pressure differences but have a look at the SAE fuel resistance ratings as well (30R7 vs 30R9). Old rubber has been superseded.

[Rich C.]

Re: C3 "S" Rubber Hose Replacement - Fuel Pump

I've changed it from below, using just jack stands. My car has A/C and a 454. Piece of cake. Clamping the rear hose would have been a lot less messy though!

[Jim T.]

Re: C3 "S" Rubber Hose Replacement - Fuel Pump

I did about the same as Rich. I jacked up the right front of my 68 with a floor jack and used a jack stand for safety since I was going to be under my car. I had to change out the fuel pump and disconnected both fuel lines, one rubber from the tank and the steel line going to fuel filter above, from under the car. Both ends of the rubber supply fuel line are accessable from under the car.

[Paul L.]

Re: C3 "S" Rubber Hose Replacement - Fuel Pump

I did the deed today. It was not a easy task but basically I came at the upper end of the "S" hose through the wheel well. I did not touch the A/C. The old hose was clamped shut 3/4 down as was the new at the bottom end. The job would have been cleaner if I had clamped at the tank end as suggested but I did not. I pre-positioned the new hose beside the old at the frame rail end and yanked the hose off. Before I got the new on I had lost perhaps 6 ounces of fuel into a pan below. Quick and dirty I know but it worked. Hopefully the new hose is good for a few years. I don't enjoy these jobs although they are essential when driving a 30+ year old car.

Sometimes I muse about a clean, low-mileage C5....

[Paul L.]

Re: C3 "S" Rubber Hose Replacement - Fuel Pump

Sometimes you win, sometimes you lose. And sometimes you just mis-diagnose problems. It does not hurt to have new hoses on the pump but the leak ultimately turns out to be the vent holes at the top. So a bad diaphragm. Minor leak but it keeps coming back when the car is sitting. Engine running those fumes blow away with heat and air flow and strangely the car runs pretty well. But it is a fire hazard so the car is parked, inlet hose to pump clamped, and I have a new pump on order. Should arrive Tuesday.

Now how I am going to get that pump off with a car on jack stands is my next adventure. Not much room in there!

[Jim T.]

Re: C3 "S" Rubber Hose Replacement - Fuel Pump

Paul I do not know what your experience is when it comes to changing a fuel pump on your 74.
If you don't have previous experience and do not know about the short bolt at the front of your block, removing this bolt and replacing it with a longer bolt before you remove the pump may save you from speaking words you may not use often.
The longer bolt will reach into the block and hold the fuel pump rod. The longer bolt only needs hand tightening to press against the fuel pump rod.
If this is not done the fuel pump rod will slide down and will be against the plate that bolts to the block. It can be difficult to move the rod up to install the replacement pump.
There was a picture of a block showing where this bolt is located in the archives. The bolt does hold anything and is only screwed into the front of the block.
There is also a procedure in the archives for rotating the engine which will move the cam lobe to its lowest level to have the fuel pump rod up into the block for easier fuel pump installation.

[Paul L.]

Re: C3 "S" Rubber Hose Replacement - Fuel Pump

Jim,
I would say my experience is NIL. I have not done a fuel pump for...many years. The last was in a 1963 Impala with a 283. That will date me!

I have read the thread in the archives that discusses that front bolt.

https://www.forums.ncrs.org/showthre...+pump&uid=9533

It seems some blocks had the hole, some had the hole with a 3/8 x 3/4" bolt, and some did not have the hole machined. Mine has the hole with no bolt; With a small mirror and flashlight I can see the shaft of the pushrod. Strangely that hole never seemed to leak oil? This is mentioned in the thread. If I get this job done I will install a short 3/8" bolt with thread sealer to close up that hole.

I believe the procedure is to get #1 on the compression stroke for best results.

Just a pic from someone else showing that hole location.

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