CIS fuel pump hose reduced size?

rching · 03-10-2012, 09:06 AM

I've been searching the threads here and could not find an answer to my question. I'm replacing my fuel pump and lines on a 73.5 CIS car. It looks like the hose from the tunnel has a connection that increases the hose side to the inlet side of the pump. I haven't pulled the hose off the tunnel, but have a new section of hose that fits the pump. If that is different from the tunnel side, it's going to be too big and hose clamping it down to fit isn't what I had in mind. I'd rather make a line up before I disconnect it. If it's just my imagination then that'll be fine and no problems, but the factory hose isn't one piece and has a connection in-between.
TIA. It's becoming a " while I'm in there" project and now I'm draining the gas tank to check the fuel screen when I just wanted to check the fuel pump. So I'm starting at one end and it's going all the way thru to the other end. So that's why, all of a sudden a little project has my car up on 4 jack stands and I'm spending all this time reading "pelican" posts. All the info is here somewhere, thank goodness,

BoxsterGT · 01:25 PM

I am pretty sure the metal tubes thru the tunnel in a 73 are 10mm OD. Most of the CIS & later fuel injection pumps I have seen have a 12mm inlet, so there must be an expander somewhere in line.

Moving the pump up front is a good step, especially with the crap gas we now must buy with its tendancy to vapor lock. If you live in the south theres more reason to, as the pump is more effective in moving the fuel when its near the tank.

Hope this helps.

Len

rching · 03-12-2012, 11:31 AM

Thanks for the info. 10 mm o.d. looks like 6mm i.d. according to our host. I have some calipers and am going to measure out the line sizes. There is a made up factory hose that starts out small from the tank and has a 3 or 4 inch section that is 12mm just to fit on the fuel pump. I might as well just relocate a new pump by the tank and replace all the fuel lines with new. I have my original pump and a borrowed pump for the original location but I'm not sure if they are working so who wants to plumb to the original location just to find our both pumps have gone south. I would rebuild or test the pumps but they are both off and it seems more of a hassle to find someone who can test them or rebuild them so..... lets update and go new. Anyone know if the fuel pump from our host already has a check valve? Hope so, 1 less thing to take care of, although the forums here will tell me how to do it, just have to look it up. Thanks all.
Dang, am I the only one that has to write a chapter with each post? : {(

rching · 03-12-2012, 11:35 AM

One more thing, braided metric fuel lines. What is the best that can stand up to time and pressure? TIA

BoxsterGT · 10:17 AM

The facts are the braided metal hoses use the same rubber as the plain hoses. No benefit whatsoever except for abrasion resistance & bling. Most of the new hoses on the market have compounds that are better able to withstand the alcohol & other additives we now must use, however time will tell just how long these hoses will last. One benefit w plain rubber is that the age & cracking shows up before an actual failure. With the braided hose its much harder to tell and most important to inspect these hoses regularly. Of course, with race cars, every inch or mm gets inspected before every race, I presume (???).

My German supplier, Cohline, has a specific hose for fuel and a different one for oil. I never could understand why AN hose had only one to be used for either. I offer the best multi-fuel hose available, and can crimp it to whatever Metric fittings you need.

The factory Polyamid tunnel lines have permanent crimps to rubber hose, so now that the hoses are old & failing we all have to buy a complete new hose assy. The Polyamid tube itself appears to last forever, with no known failures of any kind. Its the fittings that rust and the hose that cracks & fails w age.

I can make up new Polyamid Tunnel lines with threaded Male fittings to take any hose combination you can think of. Just give me some lengths & angles and I will give you a quote.

Below are some of the fittings available including the correct Banjo at the fuel pump...............

Hope this helps.

Len

rching · 03-13-2012, 03:44 PM

Hi Len,
My fuel line sizes seem to be, measured on the outside of each line, 8mm for the return and 10mm for the supply. I also have a line that comes from the tunnel at 10mm( supply) and goes into an 8 mm line to the fuel accumulator. Is there an adapter that can splice the two hoses? And it seems that others have measurements of 7 and 9mm. Is that I.D. of my lines or am I suppose to measure my old hoses, or do they have different sizes?

I also have cloth braided at the tank and rubber elsewhere. Do I need to do the same or go all rubber or all cloth braided?
This is all under the car so I don't know if it matters. I do like the T you made up with the braided hose for inside the engine compartment. You said you made that up for the concours guys. What does that cost?

I'm just going to use the hosts Pierburg fuel pump and relocate it in front by the tank, as you suggested, unless you know of a better pump.

If the hose sizes make sense to you, how much is it / foot or meter? plus shipping to southern Calif.?

Thanks,