Getting Old Hoses Off Barbed Fuel Injectors

[Captain Obvious]

So I was this many years old when I learned this.

I did the other five injectors today, and not only was there no damage at all to the barbs, but there was no swearing required! Well... I may have said "Dammn that was easy!!", but that was it!

I made a shallow cut to expose the polyester reinforcement lattice. Doesn't have to be neat:

Then I stuck the hot soldering iron all up in there and melted through the polyester weave and the rest of the tubing. After maybe fifteen seconds of wreching around in there, I was able to pull the tube off:

After all these years and all that swearing!! Thanks again Zed Head for bringing it up!! 

[Zed Head]

Have you thought about the internals?  I built a flow tester (wide open only) using a spare fuel rail and wiring the injectors in series.  Fill a bunch of Coke bottles and compare.  I've posted pictures occasionally.  The ones that came on my car were way unbalanced but I think that they were aftermarket.

I don't know what you're working on but the thought came to mind.  Since they're out.

[Captain Obvious]

Yeah, the plan is to build some sort of test and cleaning rig. I don't know how fancy it's gonna be, but I do plan to put something together.

I remember your Coke bottle pic. So when you did yours, you wired all the injectors in series and connected them to what? Car battery? How long did you leave them powered to fill those bottles that far?

[Zed Head]

Yes, a car battery.  Along with a pump.  Probably took 1 - 2 minutes minutes to fill the bottles halfway.  190 c / minute is the rate I think, or close to it.  1/2 bottle is about 240 cc.

It seemed like a long time with all of that vaporized fuel shooting in to the bottle.  My first try was in an open garage but then I moved it outside in to the open air.  Actually, to be honest, it still feels risky, especially when I tested some injectors with better vaporization than the Nissan injectors, which shoot a straight stream.  Be careful, of course.  Stay upwind.  Use long control wires and a spark free switch.

[Captain Obvious]

Thanks again. So you mentioned 190 cc/min as the target flow rate. Do you have a document source to back that up? I've looked in the past for some hard evidence about what the target rate is and I've got lots of speculation, but nothing totally conclusive.

I checked the flow of the injectors installed on my car some time ago and they were all pretty much the same. At that time I didn't care about the absolute, just the relative with respect to each other. And they were all about the same, so I was happy.

[Zed Head]

The AltlanticZ site says 188.  I'm pretty sure that the Bosch 028-150-105 (up to -114 or -115) injectors are what the Nissan injectors are copied from (the hose lengths are different in the Bosch series) and there are numerous sites that say 190.  Here are a few links.  They seem to all be at 3 bar, even though the early Bosch injectors used 2.5.  Apparently many of them just copied from other sources.  Except the last link which clearly says they did the measurements.  They got 222 for the Bosch analog.

http://www.atlanticz.ca/zclub/techtips/injectors/index.html

http://users.erols.com/srweiss/tableifc.htm

https://www.motormanfuelinjection.com/Fuel_Injector_Flow_Rates.html

https://injector-rehab.com/knowledge-base/flow-rates/

[chaseincats]

I always understood it as by the time the hoses are dry-rotted, it's probably time for new/reman injectors

[Zed Head]

I don't think that material quality was very good back in the early days of fuel injection.  Nissan had a team of engineers create a document about changing hoses.  So, it was probably a thing back then.

Much of the garage lore we all picked up is only based on who the oldest, most authoritative guy (best BS'er) in the garage was at the time.  Just saying...I learned a lot of not-quite-right stuff.