A simple guide to your Porsche MFI pump
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- Опубліковано 19 гру 2018
- Hopefully some of the questions asked about these can be answered in this video! I have tried to give an insight into how adjustable these are and the basic operation of them. The other main component not mentioned here is the space cam and stylus but more on them later! Hope you enjoyed and maybe even learnt a bit watching this.
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Thank you for the great video. At 2:52, you explain the load adjustment screws. I know the previous owner had the pump adjusted, but it seems to be adjusted incorrectly - too lean at low and mid RPM range, and too rich at the top. I've been through the linkages and I've checked fuel pressure, all is well (and so is the cold starting system). It seems like a lot of people do not recommend adjusting the individual load screws.. but why? As long as you keep track of your adjustments, I cannot see why it would not be recommended? Is it hard to remove the back plate?
Thanks for your comments. It certainly sounds like the low speed of the governor is incorrectly adjusted. Have you checked the engine compression? These engines really need to be in a healthy state for the MFI to operate correctly. The reason most people say to not adjust the individual load screws is it is easy to get lost in them and the time involved to adjust is also a factor, due to having to drain the pump, then removing the end cover is not easy. I have seen before where the leaf spring detents have been bent and no longer stop the screws moving. In short, I would not advise removing the end cover or adjust any of the internal adjustments!
@@SpyderautomobilesAu Thank you for the response. The oil question was actually my next question - I Imagine the area is bathed in engine oil? My MFI unit is not actually on a Porsche, but it's quite similar (both being Bosch) as mine is on a Mercedes 280 SE (1970). It really does seem like an incorrect adjustment to the governor was made and I really thought that it was possible to remove just the "thumb screw" (or external slotted screw) and perform the adjustment without having to remove the entire back plate.
@@JackpodyDK no the thumb screw is the idle mixture adjustment. The governor is situated behind that and the cover, the governor screws are around the outside of the idle mixture screw. Yes, the pump is feed from the engine oil galleries and drains back to the sump. Check to make sure your thermostat is working correctly on the pump for the temperature enrichment and the pump timing is correct. There are a few differences between the Mercedes and Porsche pumps but, they are basically the same, in operation and setting them.
@@SpyderautomobilesAu Ah, I actually thought the governor area did not have an oil supply (like the rest of the pump), but as anything mechanical, it needs lubrication so that makes perfectly good sense. Wouldn't it be possible to just remove the two screws holding on the thumb screw / idle screw plate which seems easier than removing the entire back plate? It seems like there's a service hatch just for the load screws, but that may just be me. I'd like to thank you again for the responses, I really don't want to open the pump before I know exactly what I'm doing.
@@JackpodyDK you are in a way correct it doesn't have a pressure feed just a splash feed as the internals sits in a reservoir of oil. The governor screws need to be adjusted evenly in pairs and each pair controls a different rev range that is why it is difficult to adjust it evenly with either cover removed. The access is far better with the larger cover off!
Hi! Is it safe to remove right side cover to check proper movements and also front one to see if the main rack adjustment screw is still in place? Because i feel like it's all the way in and cant make the mixture leaner. Thanks!!
Removing the side covers is perfectly safe except the gaskets can distort easily and therefore not seal correctly. Which screw are you talking about in the front cover? Unless you have some prior knowledge and experience I would not reccomemd removing it. You could well find yourself in more trouble than you are now!!!
@@SpyderautomobilesAu first, thanks for the answer! I mean the part load screw, is there a safe way if it's still working properly? Cause it reached a limit turning clockwise.
@@pszemia I would expect you have another issue if you have reached that point! My suggestion would be see someone who specialises in these! it is so easy to get lost in the settings! Have you checked all the linkage settings and pump timing? There are 19.5 turns from one extreme to another on the main rack screw and on each turn there is 6 clicks of which each will make a noticable difference, under normal circumstances! So I would think you could well have an internal pump problem or something else happening affecting it!
@@MikeJacobson thanks a lot for the help, maybe i turn in more than it should be, i think that remove the right side windo just to check without touching anything won't do any harm, excepto something came out when i took the cover. the pump is indeed working just a slight difference in CO2
@@pszemia Nothing should come out in theory when the cover is removed! Which cover was it? the lower rear or the higher one under the altitude compensator?
Hi! Do you know what minimum pressure fuel pump i would need for an 8cylinder version of this? (PES 8KL)
thanks!
The delivery pressure to the mfi pump typically is 15 psi and the pressure out of the mfi pump is 120 to 150 psi that pressure has to open the injector and it also atomises the as it is delivered into the inlet port
@@SpyderautomobilesAu thanks so much!