MFI injector cleaning

[manbridge 74]

Use the double wrench method. It’s where you have one on injector, one on line and squeeze them together with one hand. The torque on these is not supposed to be super tight.

[E Sully]

I got a replacement gauge for the tester, and all is well. The seller refunded me the cost of the gauge. One thing to know if you want to change gauges, they seem to use BSPP European threads. They are a straight non-tapered thread that uses copper sealing washers. The US NPT on American gauges will not fit without an adapter. BSPT is the version that is tapered, but none of the 3 will work together without adapters. It is also highly recommended to flush them out to clear any debris, oil, and grease before using.

[E Sully]

The question of how to back-flush these injectors is a challenge. I had an old injector that had lost the valve tip, so I cut it open. This was the worst of my collection, it's been sitting out for years. I figure that is why it has a bit of internal rust. The others have been kept in a sealed bag with WD40. Internally it is a little larger dimension from the MFI injector picture earlier in the thread.
The one part that I was happy to find was the retainer for the back of the valve pin. If I pull the pin out and slide this under the tip, I'll be able to back flush them without too much trouble. I can then slide fuel line over the tip and connect it to the pump since it won't need full pressure. I will also try and make another holder from the injector cap, far right in the picture, to make a tip holder that will allow fluid to pass by.
I don't know if the MFI injectors could be done in a similar way.



To address the internal rust issue, I was thinking of using Metal Rescue. With the injector open, I am going to soak them in this, and then flush them forward and backward. I used this product in my 1972 motorcycle's gas tank.
It won't harm any other materials and it worked great. It eliminated all the rust and left a nice surface.