j.kenzie@sbcglobal.net

Thanks, Roger and Greg.
I really think the hose is the most important component here. I actually believe that I could run without clamps or hats since the fuel rails constrain the hoses, and the hoses fit so well. I really don't want to cut the hoses off just to install hats. The proper EFI clamps that I have installed will gently restrain the ends of the hose in a manner similar to the hats, I think. Time will tell, and if I smell gas, I will order hats and re-install the hoses with hats.
Dave

GregBBRD

I would tend to agree.....but since I do things for people that expect the hood to close and only be opened when the oil level sender tells them that they need oil, I need something there, just so I can sleep at night.

Those "hats" are pretty clever pieces, if you study them....there's obvious engineering time and testing there.

That being said, that hose onto those barbs is impossible for me to remove, without cutting the N020 281 1 hose lengthwise. The injectors are captive and the fuel rail is captive (unless the hardware for the fuel rail falls off)....so it's not like the dimension from the injector barb to the fuel rail barb can ever "grow" and allow the hose to "blow" off.

j.kenzie@sbcglobal.net

The hose that he mentions above is 7.0mm.
Dave

j.kenzie@sbcglobal.net

Hi guys,
Here's a two week update. Hoses look great, and absolutely dry and vapor free. The fit of the hoses look perfect.
Thanks for the guidance,
Dave

granprixweiss928

Hi Everyone

Wanted to update this thread with my experience on this topic.

A year ago, I did an intake refresh on my 81 928. I replaced the feed and return lines on the side with Gregs top-end hoses, and the little ones at the injectors with a kit from Roger. I didnt intend to use the injector hose kit with clamps very long....until I sourced the proper hose.

I found the hose thereafter at my local air-cooled VW show, the N0202811 part number as mentioned earlier in this thread, and pictured.

Recently, when starting from a dead cold, I had a very strong raw fuel smell. I found later on the problem- 3 injectors were leaking and the fuel spray was visible on the tops of the cam carriers




after running the car for about a minute, it would no longer leak. weird.

new hose



anyway, time to replace those hoses. removed from car:


Look how loose the hoses were once I loosened the clamps. with some wiggling I could just pull them off



damage inside


new hose 50mm length vs what came off. the hoses that came off were labeled 3/8 and swelled/soft


All back together




put this all back on the car, and no leaks. Car starts up WAY better now.

The Forgotten On

I had an issue where the previous owner only replaced some of the lines on both fuel rails. Some weeped, some didn't, and some were original to the car.

I replaced them with the correct hose and all was well again and fixed a minor fuel odor issue. It was enough to smell like fuel but not enough to get any metal wet, only 3mm of the hose.

BTW granprixweiss928, your 81 sounds so smooth and quiet, all that work must have really paid off as it sounds like it is running very well.

j.kenzie@sbcglobal.net

It really does pay to use the correct hose.
Dave

hacker-pschorr

Same here on my supercharged 81, and that was with 120+psi of fuel pressure before I changed fuel injection systems.

ROG100

Unfortunately even using the correct hose is going to cause major issues due to the crap they put in our gas these days. Look at the way it effected the Gates "Barricade" hose that Mark took of his injectors - swollen!!! The Barricade is made to be compatible with the current fuel. The Cohline hose is the same hose that has been used for years on our cars in different diameters and we have all seen the effects of age, heat, oil & gas vapors on them.
What I find strange is that all my cars have the EFI hose and clamps and I have never had a single issue with any of them over a number of years. I inspect them every year and ensure the clamps are tight.
I no longer sell the hose and clamp kits but sell the "correct" Cohline hose with the sealing washers. Time will tell on how they stand up to the gas.

Looking at Mark's video tells me that those clamps were not tightened at all so no wonder the hose was loose on the spigot. Dave had similar issues. There is no way you could do that with my hoses on my cars. The clamps need to be tight - just common sense. The only thing going for the Cohline hose is the exact metric ID so a better push fit onto the spigot. I hope the gas does not swell the Cohline hose because they will come loose a lot easier without clamps.

Now I just need to convince Gates to make the Barricade hose in the right metric size.

hacker-pschorr

That brings up a good point. If memory serves, the fuel hose I used was sourced by Tim Murphy and is NHRA certified for methanol, which is far worse on components than even the worst chemicals in pump gas.

granprixweiss928

I will add , that as you can see in one of the pics, I did not have the clamps tightened fully. I was afraid that they would clamp too much and cut the hose at the barbs.

in the video, the clamps are all ready loosened. I was intending to show that the hose itself on the barb was not a tight fit. they came off very easy.

ROG100

Information for all users of this "correct" hose N 020 281 1.

Either purchased directly from Porsche, Contitech, Cohline or others this is standard EFI hose with a 7mm I/D. This hose, like any standard EFI hose, should not be used with barbed fittings. However this is probably the best substitute because the size makes a better fit on the barbed connections.

Personally I would recommend using two EFI hose clamps as well as the hats for double redundancy - what worries me is the hose swelling and leaking - at least the clamps would stop this happening.

Only hoses with a polyamide veneer on the ID wall are suitable for use with barbed fittings.

As of yet I have not found the correct hose - closest seems to be 7.3mm. But I am still searching.

j.kenzie@sbcglobal.net

Thanks Roger. What hose was used originally?
Dave

ROG100

At the moment I do not know exactly - however I will know soon. I ordered the repair kit from Porsche 928 110 903 00 - hose and hats to see for myself.
What had me check was that Porsche only uses the N 020 281 1 as a breather hose on 911, 914 & 924 cars. Does not appear to be used as EFI hose. It is definitely an EFI hose suitable for 70+ psi fuel so exceeds the 50 psi on this application.
It is old rubber technology and not compatible with the crap in our gas. It also does not have the polyimide veneer for use with barbed fittings.
So far the best choice because of the tighter ID of 7mm.
The OD of the barb on the injector is 8.83mm and the OD at the smallest section is 7.82mm so the 7mm ID hose is really being stretched and the barbs will certainly cut into the inner surface of the hose.
So far this is all theory and in practice we all know either choices will work - it would be nice to find the right hose for the job.

ROG100

Wanted to report back on my findings with respect to the "correct" fuel hose for the injectors as per the thread title.
I purchased the injector hose kit from Porsche 928 110 903 00 list price $25.68 for one injector kit.
Kit comes with two hoses, two caps and two EFI clamps as per the picture.
Fuel hose was the 7mm EFI hose N 020 281 1. So enough for two injectors in reality.

Seems like Porsche wants us to use the EFI clamps when using standard EFI hose to a barbed fitting - interesting. Double redundancy always a good thing.

I learned a lot from this exercise.