Fuel injector hoses - PeachParts Mercedes-Benz Forum

pxland · #1 03-30-2006, 01:59 AM

I hate to rely on you guys solely for all of the information I gain in my life but....

Do I need to worry about relieving the fuel pressure from the injector rail when I remove and replace the injection hoses on my 108?

Is there anything I should know about this job?

I figure, without knowing what size hose I need in advance I'll just remove and label them and then buy and cut to fit their replacements. Does this sound reasonable?

bill4247 · #2 03-30-2006, 02:27 AM

I used 7.9mm fuel injection hose from napa. Worked fine. Don't use the regular 8mm fuel line hose. I don't remember losing much fuel when I opened the line. I did it in the morning. If the nipple on the injector has ridges you don't need a clamp to hold it on just push it on. It should hold. If the nipple is smooth use a clamp. Always use a clamp where the line attaches to the rail.

Tomguy · #3 03-30-2006, 10:22 AM

Remove your gas tank cap first. Any positive pressure in the system will take the easiest way out, usually your return line!

Otherwise, don't turn the key after removing the lines and it'll go well. Make sure the engine is cold, it's well-ventilated, and you should lose the pressure by giving the cold start injector a 2-3 second pulse (from a 12v source)

pxland · #4 03-30-2006, 10:24 PM

Whilst I'm in there should I pull the injectors, clean 'em, and replace the seals? The car runs pretty well, or it did before I found the leaky lines, but I'm sure that 20 years worth of gummed up gas has affected their spray pattern.

deafen · #5 03-31-2006, 10:08 AM

You'll probably need to replace the lower seals, especially if they're still the original ones. Make sure you have them before you start the job.

The upper "seals" aren't really seals at all, but rather rubber cushioning rings that sit between the hold-down doohickey and the injector. Mine were still in good shape.

pxland · #6 04-08-2006, 09:07 AM

It wasn't the fuel injector hoses that were leaking (although I am keeping my eye on 'em). It was the return line from the back of the fuel rail. $1.20 later I have solved a couple of problems becasue it also seems to have lost it's hot start issue now.

I looked through numerous threads and I am going to actually look at the car next time I'm out there but....Other than the return line (at the fuel rail), the hoses from the tank to the pump, and the return to the tank, is there anymore of that braided hose that I need to switch out?

I searched for a past thread, in which someone (CTaylor?) advocated that changing this return hose could fix a hot start issue, so that I could add my findings but to no avail.

Anyway we are back on the road and looking forward to throwing the new spring kit underneath in the next few weeks.

Thanks again guys

cth350 · #7 04-08-2006, 11:08 AM

just replace every hose you find. It's all 5/16" FI hose, except for a small piece of 3/8" hose between the tank and the pump.

Replacing that 3/8" one will get you pretty wet with gas. Be sure to wash up afterwards. Modern gas is not at all good for your skin. Having a fuel line blocking clamp helps, but you're still going to get wet.

-CTH