new fuel injection hose problems

c911s · 08-23-2009, 10:38 AM

Just wanted to pass on recent experience with new fuel lines on engines.
Installed new fuel injection hoses on recent clean up of engine when it was out of car. Have not put many miles on it since re-install, probably less than 500 mi. On thursday while in the city I noticed a strong fuel smell, stopped in the lane I was in to check engine and was shocked to see fuel flowing over rear of engine. Moved pretty quick to shut it off. Hose at rear of CIS had come off and pump was pumping fuel over the rear of the engine. Very fortunate it did not catch fire. After about 45 minutes of trying to get the line attached was successful and able to drive home. There is not much room behind the CIS to work and the line and clamp had to be put on by feel as it was not visible. there is also a couple of wires plugged in near the fuel line further reducing access.
Anyway, having had another fuel leak on recently installed new injection lines on a 1800ES, I have come to the following conclusion.
The new rubber on the hoses is hard when the clamps are first applied. I tightened them all as tight as possible at initial install. Over time the compression of the clamps displaces rubber under the clamps resulting in loosening. I checked all the other clamps on the lines and found that some took 1.5 turns to retighten. ie they will leak if not retightened.

T77911S · 08-25-2009, 05:41 AM

if you are using regular hose and clamps with CIS, that is a no no. buy the small hard lines and use the barbed banjo fittings that are designed for CIS and the high pressures. the banjo ends are not hard to put on. i replaced one years ago, i think i sprayed maybe WD40 on it and it slid right on. i waited until the next day and gave it a good tug to make sure it was staying on and its been fien for years now.

BoxsterGT · 11:02 AM

T77911S is absolutely right!

Do not replace the CIS plastic lines w rubber.

If you have already fitted rubber hose, take it off & buy the correct Polyamid tube.

Its available from our host.

The barbs on the CIS banjo fittings are designed for the Poly tube, not rubber hose.

Or find a set of used CIS metal lines from a fellow Pelican.

The hose is not the problem as it will take the pressure; its the design of the barbed fittings that are for hard plastic, not soft rubber.

If need be, I may have some of this Poly tube leftover from a job I will send you.

Just my .02 cents.

Len at autosportengineering.com

c911s · 08-25-2009, 07:06 PM

I have only replaced rubber lines and have used fuel injection hose clamps. Fitting that blew off was rubber onto a bulbed metal fitting.

BoxsterGT · 08-26-2009, 03:32 AM

You should be fine then.
I have seen one catch fire so I was concerned.
Len

T77911S · 08-26-2009, 04:01 AM

i would still go back to original.

can you show pics? not sure what metal fitting you are using. if it is the original fitting, i would not use it with anything but the hose it was designed for. CIS has around 70-80 PSI, i think the electronic FI is much lower, 45 psi? or so. anyway, why not just go back to original?

c911s · 08-26-2009, 07:36 PM

photo enclosed of the problem fitting - it's not easy to photo being behind the CIS....
but a lot more difficult to fasten when off

boyt911sc · boyt911sc's Garage

Quote:

Originally Posted by c911s

photo enclosed of the problem fitting - it's not easy to photo being behind the CIS....
but a lot more difficult to fasten when off

Carl,

The connection to your CSV is like a ticking bomb. While many have used clamps, this is one CIS fuel connection I'm reluctant to use micro clamp. You were quite lucky to avoid an engine fire. Why take unnecessary risk? And it does not cost much to get the correct fuel lines.

The fuel pressure at the CSV is much higher than the system pressure of the FD. Plus the fact that it is almost impossible to visually inpect the condition of the connection with the engine installed unless you have a probescope.

Tony

T77911S · 08-27-2009, 04:11 AM

original!

if not for safety, the original stuff looks better.

c911s · 08-27-2009, 09:54 AM

please indicate what was the original line/connector. I just replaced what was already there. The spare engine I have has the same rubber fuel line in that location.

c911s · 08-27-2009, 11:12 AM

Manual seems to show rubber fitting and clamps for this line - fuel distributor to start valve item 19 in parts diagram hose and clamp items 34 and 36. item 6 in fuel flow schematic.

Jesset100 · Jesset100's Garage

Plastic fuel line

Metal fuel line

c911s · 08-27-2009, 04:40 PM

I believe the lines were changed on later cars - mine is a 73.5

T77911S · 08-28-2009, 06:21 AM

yours does look different. what does the other end look like?

if that is stock, i think i would try to upgrade to the newer style for safety reasons.

cmetzner · 09-29-2009, 08:22 AM

Quote:

Originally Posted by T77911S

if you are using regular hose and clamps with CIS, that is a no no. buy the small hard lines and use the barbed banjo fittings that are designed for CIS and the high pressures. the banjo ends are not hard to put on. i replaced one years ago, i think i sprayed maybe WD40 on it and it slid right on. i waited until the next day and gave it a good tug to make sure it was staying on and its been fien for years now.

I ordered the correct 3mm polymid lines from D&S Sales for the line from the WUR on my 1981sc to the FD. I am currently using rubber line because there is no way that I can push the line on that fitting. DS says to heat the line in very hot water but it still does not push on. Are you sure that you used WD40. I tried that and still a no go.

I ordered a fitting from DS and have used that one as a test fitting for the line. I'm glad I did. I have even used a pliers to try to push the line on and it still doesn't fit.

Does anyone have a method for installing this line?

Gogar · 09-29-2009, 09:46 AM

I have a 73.5 motor, and the line to the CSV looks like that.

IMO, I'd put a Norma Schellen "fuel injection" clamp on there, though, instead of the hardware-store clamp.

dailyATX82sc · 09-29-2009, 11:15 AM

Quote:

Originally Posted by cmetzner

I ordered the correct 3mm polymid lines from D&S Sales for the line from the WUR on my 1981sc to the FD. I am currently using rubber line because there is no way that I can push the line on that fitting. DS says to heat the line in very hot water but it still does not push on. Are you sure that you used WD40. I tried that and still a no go.

I ordered a fitting from DS and have used that one as a test fitting for the line. I'm glad I did. I have even used a pliers to try to push the line on and it still doesn't fit.

Does anyone have a method for installing this line?

i have some 3.5 mm hose for this and it is WAY to big....is 3mm correct. On mine it comes off the fuel head via a metal line then for about a foot its rubber to the barb fitting on the WUR.... is that correct...our host shows a plastic line that attaches to the WUR different...

CMDR Perry · CMDR Perry's Garage

CM here is how I do it.

1. Clean the fittings with alcohol. Cut the tubing to length with a very sharp blade so you do not squish it down. I.E. a nice square cut. Wrap the fitting large end with a rag and place in vise securely so barb is pointing out horizontally.

2. Get a Pyrex measuring cup and boil 1 cup of tap water in the microwave. Insert tubing end for about 20 seconds to warm it (wear gloves). Remove tubing from hot water and holding it (tubing) very close to the end push onto barb about 1/2 way with firm steady pressure.

3. Boil more water in the microwave and pour it over the fitting and tubing to reheat everything. Again wearing gloves push the softened end of the tubing onto the barb the rest of the way.

4. You are done!