hacker-pschorr

Rule #1

After doing anything with the fuel system test for leaks.
With a fully charged battery, bypass the fuel pump relay and let is run for a minute or two while you check for leaks.

Doesn't hurt to grab the various connections and give them a wiggle, like the fuel rails to see if those injectors are fully seated and clipped in.

Using a paper towel helps to pick up small leaks you cannot see. Touch every connection with a clean paper towel, make sure it stays dry.

Lopez

I have a question about this subject. I just finished doing an R&R on my fuel injectors and soft hoses. This car is an '82 with L-Jet injectors - the kind that have rubber hoses between the injectors and fuel rails that are held on by barbed connectors with the little hats that go around the end of the fuel lines. My question is: should you use clamps on the fuel rail ends of the injector lines? The factory did not use clamps on either end but I had Witchhunter install new hoses on the injectors for me and they included hose clamps on them. I did not install clamps on the rails I put them back just using the hats and barbed connectors.

So far so good - I did the fuel pump relay bypass to pressurize the system before starting and also watched it for the first 15 minutes the car was running and I don't have any leaks yet. I'm still paranoid about it and have checked for leaks every time I've started the car since and it's still OK. I have to admit I was surprised that with replacing all the fuel lines plus all eight injectors that there wasn't at least one leak to fix (I might have felt better if there was - I mean I can't have done them all right the first time could I?).

Anyway - not that I want to pull them off again but I am wondering if adding clamps to the fuel rails is a good idea or if they can be left alone. I was able to seat all the fuel lines completely when I installed them back on the rails and like I said so far they are not leaking...

JakeS2

Do _NOT_ forget these. We use ATF in power steering system that has flash point (well below normal hydraulic fluids - sub 200'C). If you use old hoses, you end up having small leak in the high pressure line that runs next to your +300'C exhaust manifold, do the math.

Fix is to change the lines (after 10-15 years?) and in addition put Thermotec sleeves on the high-pressure lines.

GT6ixer

I'm in the middle of my top end refresh and read a bit of discussion on this one. Seems like the consensus is that if you use EFI hose and clamps just make sure you don't overtighten the clamps since the barbs are sharp and could pierce the rubber leading to premature failure. The factory hoses were lined with plastic which the barbs "bit" into and are not designed to be used with clamps. Apparently this plastic lined hose is NLA. Additionally Porsche sells a repair kit for these hoses. The kit, IIRC, is for one hose each and contains one hose clamp and two hats. Can't remember what side they want the clamp on, but Roger @ 928sRUs I believe reported back on this kit in a thread once.

Then there is a group who don't use clamps at all and just use the original set up with hats, but not the plastic lined hose. I think Greg Brown is a proponent of this but hopefully he'll chime in on that.

bureau13

I'm confused how you get a sleeve that fits the line to go over the "donut" in the middle...and if you don't (ie you use two sections of the Thermotec) then you're not really gaining the advantage that any leaks drip out the ends, away from harm.

Arnoud

Works fine by using 1 3/8 - 1 1/2 ID thermo sleeve (3 feet long is correct length for the PS high pressure hose).
See more details in this post: https://rennlist.com/forums/928-foru...l#post13423339

dr bob

Can't overstress Hacker's recommendation above in post 16. Use your fingers to feel-and-sniff EVERY connection. A tiny leak, seepage, whatever, won't get your attention especially if the engine is warm. Do your leak-checking with the engine cold so the leaking liquid stays liquid long enough for you to discover the source. That means with all the covers, air cleaner housing etc completely removed.

Remember also that there are pressurized fuel hoses at the back of the car, and that they are exposed to exhaust and road heat and abuse.

Hard connections in the system tend to be ball-flares, connections that are metal-on-metal and depend on good smooth mating faces. There are actual torque specs for each connection, believe it or not, and reasons for those. If a fitting is leaking with the correct torque applied, disassemble the connection and find out why. As tempting as it is to "just snug it up a bit", a leak in a ball-flared connection is caused by something like debris, damage or misalignment of the connection. Tightening more will more often than not cause more damage than it will cure. Disassemble, inspect, solve the problem, reassemble. Make all your connections before you secure regulators and dampers in their brackets, so the connections can align themselves as you tighten. Counterhold the pieces as you tighten.

Clamps on the injection hose has been debated extensively. Consider the hose as a plastic hose with a fabric-reinforced rubber/neoprene protective sleeve. You really don't want to do anything to damage the plastic hose. If you do cause a breach of the plastic liner, and there's a clamp on the end, the fuel will leak and be captive between the layers for a while. Eventually the fuel will soften the outer layer enough for it to burst under pressure. Use the correct hose, and avoid breaking the hose with clamps.

If you really want something that looks like it will hold the hoses over the barb, use plastic cable ties. You won't be able to get enough clamping pressure on the hose to damage the liner over the barbed fittings and connectors. The cable ties will keep the ends of the rubber protective sleeve from flaring with age, a cosmetic issue only. Remember, the rubber is there for abrasion and local heat protection, and to help support the plastic and manage bend radius. The actual "work" is done by the plastic hose; the sleeve is a support network only. Protect the plastic hose.

Mongo

When I did my intake manifold service, I had to go in there twice to repair a defective ISV hose. Upon reassembly, I noticed that one of my injectors was never seated correctly that I replaced. I used a generous amount of WD40 on the new seals to make sure the o-rings slid freely into the rail and the intake, triple checking those clips before firing it back up. Had I been reckless about that injector, I'd probably be browsing this forum in sorrow and regret.

Tony

this..and i took my adjustable regulator and cranked it up..way up.

key is new hoses and proper routing without any possibility of chaffing.

nice thing about gas is you sure can smell it...like bob says, do it on a cool car to elminate the chance of any ignition source.

ROG100

Early 87 hose from the FPR to the console on the top of the bell-housing is 928 110 359 09 - is still available and has been for at least 5 years. My price is $64.56.
On the early 87 the console to fuel cooler hose is NLA but we have the GB hose in stock ---
928 356 081 02#10C for $145

If you have a concern about fuel hoses give me a call as between GB and I we have all the permutations covered.

bureau13

Hmmm...what's interesting is that the high pressure line in the picture in the referenced thread does not have the "donut." Was that eliminated from later model years?

Ad0911

I am not familiar with most parts mentioned in this thread while I am still very much interested in fire prevention. I think there are different "risk parts" like specific hoses on every model. I am right to conclude that the 32V models have their own "risk parts". What are specific "fuel leak risk parts" on a European CIS car like my MY79? I have new high pressure flex fuel lines from back to front and all the way back but what else is there to monitor or replace on an OB? Oh yeah, forgot tho say, I am renewing the flex hydraulic lines from the power stweering as well. Might as well get the sleeves on them. Any chance Pirtek has them? Because I intend to have the flex lines renewed by Pirtek.

Bill51sdr

One of the first Car B Q stories I recall reading about was by a looong time emailer/lister Don Hanson. His A/C system had been filled with propane, said system developed a leak, the propane ignited & the rest is history.

DO NOT USE PROPANE OR ANY OTHER FLAMMABLE SUBSTANCE IN YOUR A/C SYSTEM.

Tom in Austin

As long as we're on the subject, check your A/T fluid lines on pre-GTS cars (someone will know which years exactly) ... some frightful fires have happened when these leak onto the cat converter. IIRC, Porsche eventually made these hard lines in the vicinity of the exhaust so the earlier cars are the ones with the bigger risk.

Mongo

Jesus Tom did you own my car in 2002? Because that is exactly what happened. I drove it one day and saw smoke coming through the auto shifter and center console. I parked it in the garage and walked out the next morning... The floor under the car looked like it needed a Rosie O'Donnel sized maxipad!