MFI injector cleaning

[rowingone]

Who do you recommend for MFI injector cleaner and testing? Is this something I can do myself? 1972 911T

[LuftWaffle]

I ended up buying one of these. Cleaning fluid is a combination of kerosene and ATF. Did a good job on an old set I had. I'm sure it's possible to build something similar for less.

https://mercedessource.com/store/bosch-mechanical-fuel-injector-mfi-tester-and-cleaning-kit

[rowingone]

Good suggestion . . I have watched his videos. I just emailed Pacific Fuel injection to see what they would charge for clean and test.

[LuftWaffle]

I'm just up the road from you in Cheyenne. I'd be glad to clean and check them if that would be helpful.

John

[rowingone]

Well that's nice of you John! I appreciate the offer and I will let you know soon.

[reclino]

Search eBay for Diesel injector pop tester. Direct copy of the Bosch tester for about $100, or you can make your own from a bottle jack.

[r lane]

Originally Posted by rowingone

Who do you recommend for MFI injector cleaner and testing? Is this something I can do myself? 1972 911T

This is the whole taco. Don't know how you can effectively clean these guys. The upstream piece is the filter, fine mesh on the top side and a microscopic hole on it's bottom. Then the spring controlled valve. Don't know what sonic type cleaning could effect if deposits have collected in the screen pod.. Bob

[stownsen914]

I believe the pump rebuilders like Pacific and Mark Jung offer an injector testing service.

[rowingone]

Everyone that maybe used to clean and test the mechanical injectors doesn't do it anymore. You can clean them by backflushing the injector to clean that little screen but if the spring is not up to the task . . it won't matter if its clean or not. Just not happy to pay $125 a piece but that might be the best solution.

[rowingone]

Injector Masters in Oregon says they will clean and test crack pressures and flow volume for $25 each . . he says he has good results with the MFI injectors.

[E Sully]

Originally Posted by reclino

Search eBay for Diesel injector pop tester. Direct copy of the Bosch tester for about $100, or you can make your own from a bottle jack.

In the past I ran the fuel pump with the injectors in containers to check flow patterns.

I think I will get one like this for $90 shipped and put a 100 psi gauge on for my CIS injectors. Then I can better check for opening pressure, leaks and spray patterns.
The 73.5 injectors are unique and very expensive, about $250 each. I've acquired 22 used ones and this should help me sort them out.



I've played with some of them to back flush the internal screens

[gled49]

I converted my Diesel nozzle tester to MFI. Gus at Pacific FI gave me the name of a gauge company. Liquid gauge is locked at MFI injector opening pressure. Tool can be locked to flush and opened to check pressure.

[E Sully]

CIS needs a lot less pressure, I'll just change it to a 100psi gauge.

[RDM]

Originally Posted by LuftWaffle

I ended up buying one of these. Cleaning fluid is a combination of kerosene and ATF. Did a good job on an old set I had. I'm sure it's possible to build something similar for less.

https://mercedessource.com/store/bosch-mechanical-fuel-injector-mfi-tester-and-cleaning-kit

My experience is that the innards of this pressure pump turn to crud, migrate through the line and foul the injectors. I backflushed afterward and got serious gunk back out, but there was no way to check afterward.

I believe Jonny042 had a similar experience.

Are these pop injector testers any different?

[E Sully]

If you watch the video for the one in post 2, it seems they had to update their pump due to contamination issues. He addresses that in the video here,
https://youtu.be/wOuJna_wRv4?si=OQRfTQdlwComKFAo

I ordered from a different company, all reviews were positive. Mine arrived an hour ago, and unfortunately UPS was not exactly gentle. They managed to snap the threads off the gauge.
Going to be hard to do anything, claim filed with UPS and sender notified.
Besides not having a gauge, it seems very solid. The one mentioned in the video shows how they started adding a filter. The one I have has an integrated filter for the fluid.

[rowingone]

I had an idea to use a pressurized injector cleaner with solution like this from Amazon. If I hook this up with the appropriate pressure at the MFI pump fuel inlet why wouldn't this be an effective way of cleaning both the pump and the injectors? It won't backflush but seemingly would require little labor. They also make some injector cleaner that will support combustion, designed to run through a running engine. Thoughts?



https://www.amazon.com/dp/B09KNNSDFH/ref=vp_d_vp_d_fuw_pd_pd?_encoding=UTF8&pf_rd_p=f20fcda8-2440-4bfe-9c09-83295cb4a15a&pf_rd_r=NN02FN1MWQCSFVSV2P47&pd_rd_wg=jlwOC&pd_rd_i=B09KNNSDFH&pd_rd_w=iqw2E&content-id=amzn1.sym.f20fcda8-2440-4bfe-9c09-83295cb4a15a&pd_rd_r=4d91eca6-fbda-4805-a040-4d64954fa3f9&psc=1

[stownsen914]

The trick would be to get enough pressure to crack an MFI injector. That system mentions 140 psi, I think that's not enough.

[manbridge 74]

The only thing that back-flushing won’t clean is rust particles, which are more common than you might think.

Also, DM me and I will check/clean them for free with a Bosch tester as I’m right down the road…

[manbridge 74]

I use slightly diluted Naval jelly type products to dissolve rust at filter side, does a good job,

[rowingone]

What I was trying to avoid was removing all the injectors from the car. After soaking in penetrating oil over two days they still seem too tight to remove easily. The needed pressure to open the injectors would be provided by the MFI pump if I add the cleaner at the MFI pump fuel inlet. Thanks Jeff for the generous offer . . I will let you know should I decide to remove the injectors.