un sticking fuel injectors

[Dave WM]

This is off the intake manifold on my spare engine. I am toying with the idea of trying to get it running on the existing parts to base line it before any decisions are made as to rebuilding the engine.

So 1st order of business is to get the fuel injectors working. So far I am up to 3 working. here is a video of my setup to unstick some frozen injectors. The 3 remaining hard cases are now off the rail so I can get some PB blaster down the inlets hoses. The one under suction did NOT come unstuck. I will run them for several hours and see if anymore come unstuck. If not I will try the suction approach again, but will use my 2 stage vacuum pump rather than the little hand held job. I was hoping the reverse flow would work better since I presume there is spring loaded plunger that would be pulled up by the vacuum, assuming its stuck down (closed). I did try rapping them with the back of a large screw driver, in an attempt to shock break them.

I also have the bolt buster induction heater, that seems like a last ditch method as I have no idea of how it would effect them. I could try holding the large body in the center of a ring and give it a few seconds just to see what happens.

 

Edited February 6, 2019 by Dave WM

[Zed Head]

Suction would act on on a very small area, the pintle seat.  Probably not much force generated, atmospheric pressure on that small area.  I've tapped some open, with a heavy screwdriver.  You could probably just tap them upside down on a board or soft surface also.  The spring holds the pintle down, the solenoid pulls it up. 

You might even just blast them with a full unresisted 12 volts, a tap at a time, maximum magnetic field.  I know that people worry about having resistors in place but that's for current, which causes heat.  A short full current blast won't overheat them.  They still see 12 volts before they're grounded, they just don't see maximum current when the resistors are in place.

Pretty sure you know all of that, it's just a reminder.

[TomoHawk]

This sounds like a good Arduino project.  The thing would pulse the injectors using 12V and a MOSFET.  You could add a momentary  pushbutton to start a single cycle, or a toggle switch to start continuous pulsing.

Otherwise, I'd probably put some leaner through the injectors with light pressure or gravity-feed.  if you set up a glass reservoir and recycle the cleaner, you could see when they are un-stuck or spraying well, then have your work pay-for itself by cleaning injectors for others.  ?   FYI-  I've been told by a few "technicians" that you can't clean injectors- you must replace them.  ?

Edited February 6, 2019 by TomoHawk

[Dave WM]

I will give the shock treatment another try. Good point about the area of the pintle restricting just how effective pulling a vacuum is.

[240260280]

Use carb cleaner. It works nicely.

[Dave WM]

3 hours ago, 240260280 said:

Use carb cleaner. It works nicely.

This works to unstick, I just assumed it would not work other than as a cleaner?

Follow up on the all night soak in PB blaster (injector body soaking in cup, and have PB blaster in the inlet fuel line. After all night none of them freed up, I bumped the current up to about  .8 amps.

The bodies were a little bit warm to the touch after the all night, so I will keep a close eye on the temps at the higher current. It would be nice to know exactly what is the failure, gummed up old fuel or rust. My guess is fuel but that is just a guess.

 

 

[Captain Obvious]

Back when I had my Z32, I dissected a couple failed 300ZX injectors (different style), but I've never done any autopsy work on a 280Z injector. I'd be happy to do so if you (or someone else) wants to send me a surplus injector or two.

I would have to dig out my Z32 injector box to be sure, but I don't think they used stainless steel. I think it's carbon steel, and therefore susceptible to rusting. I assume they believe that situation won't occur as long as the internals of the injectors are constantly bathed in dry fuel not containing any water. Just like the gas tank.

But if the car sits for a long time with the system open, water can accumulate where the fuel is/was. Just like the gas tank.

The point is... If they didn't make the internals out of a magnetic stainless, then there may be some rust inside inhibiting movement.

[Dave WM]

there was a ebay ad for remanufactured 280z injectors. The ebayer insisted that they do it right, even had pictures of a disassembled one. It was hard to tell exactly what was there but it did look like the correct injector. had the long pin, some kind of circlip etc... internals.

I was always under the assumption that they can NOT be disassemble with out destruction. they seem to be crimped together. I never followed up on the ad since I decided to just get mine cleaned at a local marine shop.

[Dave WM]

here it is

 

[240260280]

I took toys apart

[Dave WM]

looks like if you could get a cylinder shaped pushing tool over the needle (to avoid damage) but inside the body you may be able to tap the plunger. I am sure trying to push it on the needle itself with enough force to break the jam would no doubt damage it. I am wondering about that ebay ad now as it seem there is no way to disassemble with out destruction. It all seems to be crimped together, not intended to be serviced. I also doubt a tool thin enough to do what I am describing would be strong enough to exert the force needed as well. Oh well I will keep soaking an running the 1/2 wave current thru them just to see what happens.

Edited February 6, 2019 by Dave WM

[Dave WM]

is that a threaded hole in this pic? I removed the filter and can see what looks like a hole, maybe that one, and if threaded, perhaps a screw can be inserted to use as a tool to pull back on the plunger.