andi4eyes Posted May 9, 2022 Share Posted May 9, 2022 HelloShortly after getting my 1600 VX, my electric fuel pump wouldn't come on one day when I was about to start the car. After power cycling using the master switch the pump came on without a problem. That was about a year and a half ago and I didn't have any further problems.Fast forward to about two weeks ago. With revs quite low driving down a 20mph road the engine cut off. I was out getting petrol, driving for about 10 minutes when the Facet pump had stopped running. I checked all the fuses which were fine. After a few minutes I did turn the master switch back to ON an to my surprise the pump started working again.After reading stories about failed Facet pumps I decided to install a new pump so I got myself a new Facet 40105 (3-4.5 psi) which seems to be the right model for those small displacement engines running two DCOE 40s. I installed the new pump in the same place as the old one, this time with the supplied fuel filter. The old setup didn't have the filter installed.A short 5 minutes test drive on Saturday was successful so I wanted to do a longer one yesterday. After only about 200 meters the car backfired (I assume because the mixture went too lean to ignite in the cylinders) and the engine stopped. The new fuel pump had stopped working again. I suspected that my wiring had failed so I pushed the car back to the garage. Only there I decided to check if the pump was back running after cycling the power and of course it was...The wiring in my car doesn't seem to be standard, maybe because it's an ex Graduates Classic race car. There seems to be no fuel pump relay: I removed all three 4-pin relays (+ the indicator relay) but the pump was still running. The pump seems to be wired directly to ignition switch position 2 but I didn't trace the wiring as of yet.What is your experience with a setup like that? You can see my installation in the picture below. The pump I grounded on the aluminium panel same as before. I only installed soft mounts with an additional wire from one side of the rubber to the aluminium panel (as per Facet soft mount kit).Under what conditions do these pumps shut off? As far as my research go they shouldn't stop pumping when they see a certain pressure. As they are supposed to run whenever they see 12V I would assume the pump would come back right on after a quick drop of voltage or loss of ground.In both circumstances, old pump and new pump, the fuel level in the petrol tank is very high. Could that point in a certain direction?Thank you for your input Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 9, 2022 Member Share Posted May 9, 2022 "The pump seems to be wired directly to ignition switch position 2 but I didn't trace the wiring as of yet."Please let me know if you'd like a copy of the factory wiring diagram.Jonathan Link to comment Share on other sites More sharing options...
OldAndrewE Posted May 9, 2022 Share Posted May 9, 2022 Not sure if this is relevant to your problem but the instructions for these pumps say install it at approx 45 degrees with the inlet pointing down. Yours looks as if it is horizontal. I have no idea what difference this makes and perhaps others can comment Link to comment Share on other sites More sharing options...
andi4eyes Posted May 9, 2022 Author Share Posted May 9, 2022 Thank you very much, Jonathan, I'll send you my email address via PM. I have seen a few diagrams already, maybe you have one for a 1999 live axle.Andrew: Yes you are right. Facet actually recommends mounting the pump in a 45 degree angle (flow going up) but horizontal seems to be acceptable as well. The pump was fitted like that before and I can't imagine this setup being prone to failure when the car was raced for many seasons exactly like that.I wonder is the pump would just stop working if there wasn't enough fuel supply due to less than perfect mounting or if it would only loose prime (you would be able to hear that, the noise gets quite a lot louder). My understanding is the later. Thinking about it now and looking at the wiring diagram provided by Facet I wonder if the pump is wired through the oil pressure switch. A faulty switch and/or low oil pressure at/near idle could cause the circuit to break. I have to drive to the garage and check that.I don't know how those switches work: I assume the circuit would be closed when the engine isn't running or otherwise the fuel pump would get power at all, correct? If the switch is triggered, would it be consistent with the behaviour I experience? No pump activity while battery power is still on but back to normal operation once battery power is cut and re-established? Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 9, 2022 Member Share Posted May 9, 2022 Can you post an image or URL of that Facet wiring diagram?Jonathan Link to comment Share on other sites More sharing options...
andi4eyes Posted May 9, 2022 Author Share Posted May 9, 2022 Yes of course (see link to PDF below):PDF: https://www.facet-purolator.com/wp-content/uploads/2019/12/42664REVC_1-cube-E.pdf Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 9, 2022 Member Share Posted May 9, 2022 Thanks.If an oil pressure switch is being used then it's interrupting the feed to the pump rather than acting as a control input to the pump or a controller.Jonathan Link to comment Share on other sites More sharing options...
flaps7 Posted May 9, 2022 Share Posted May 9, 2022 A shot in the dark but.....I had the random fuel starvation that was caused by vacuum in the fuel tank. Car stops, you fiddle with something (giving time for vacuum to fill) and car works again. So next time it happens you fiddle with the same thing and the car works again. I discovered the vacuum by removing fuel filler cap after car stopping and hearing the inrush of air. Just a thought.Rick Link to comment Share on other sites More sharing options...
andi4eyes Posted May 10, 2022 Author Share Posted May 10, 2022 Thanks Rick. That is a good point. The very high fuel level in the tank currently could explain why the pump stops quite soon after starting the car because there isn't much air in there to begin with. I will ask Facet if the stopping of the pump would be consistent with a vacuum. I imagine it would as the pump would have to work harder and harder and eventually shut down.I have to admit I don't know how the venting of the fuel tank is supposed to work. I have an aluminium fuel tank for carburetted engines and the following filler cap: Venting must be integrated into the cap as I can't see where else it would be. Could someone please enlighten me? Link to comment Share on other sites More sharing options...
Amos91 Posted May 10, 2022 Share Posted May 10, 2022 On my Sigma for reference, the vent is attached to the filler and goes down the RHS of the fuel tank. There is a one way valve to only let air into the tank and no fuel / vapour out. Link to comment Share on other sites More sharing options...
andi4eyes Posted May 10, 2022 Author Share Posted May 10, 2022 Thank you Olly. The filler necks for the newer cars seem to be quite different.Can anybody tell me how venting is done on older carburetted cars (VX, Crossflow)?I will drive over to the garage to have a look at my fuel cap later tonight. Link to comment Share on other sites More sharing options...
OldAndrewE Posted May 10, 2022 Share Posted May 10, 2022 "Can anybody tell me how venting is done on older carburetted cars (VX, Crossflow)?"Via the filler cap on mine Link to comment Share on other sites More sharing options...
Area Representative Golf Juliet Tango Posted May 10, 2022 Area Representative Share Posted May 10, 2022 Can anybody tell me how venting is done on older carburetted cars (VX, Crossflow)?As #12, on my Crossflow through the cap. I drilled a small hole under the lock flap which works well on the road. (yes, obviously I did this with the cap on the bench not on the car) Link to comment Share on other sites More sharing options...
andi4eyes Posted May 10, 2022 Author Share Posted May 10, 2022 Thanks, I will inspect my filler cap tonight.I remember having a hard time removing the cap last time I filled up. I don't remember hearing a hissing sound when I finally got it out but maybe I didn't pay attention or there was too much background noise. Link to comment Share on other sites More sharing options...
andi4eyes Posted May 10, 2022 Author Share Posted May 10, 2022 According to Facet (who replied quite quickly to my question) there aren't any shut off conditions for the pumps. They didn't immediately understand the vacuum problem so I take this with a pinch of salt. If true however, the potential fuel cap vent issue becomes unlikely as the pump clearly wasn't running when the engine cut out and this goes back being a potential electrical issue. Link to comment Share on other sites More sharing options...
andi4eyes Posted May 17, 2022 Author Share Posted May 17, 2022 I'd like to give an update or the (likely) solution to this problem:The master switch seems to be the culprit. The "key" fits ever so slightly sloppy in the socket. By chance I realized that a slight touch or wiggle of just a fraction of a degree cuts power to one of the small terminals. All the other terminals stay powered.My brand new RRS branded replacement master switch I had in my garage for over a year was basically broken out of the box so I couldn't really test with a new switch.I hope one of those "Made in Germany" ones are better quality than the RRS one but I understand that these parts are consumables. I will keep an eye on the condition of the new one. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 17, 2022 Member Share Posted May 17, 2022 Well done. Thanks for adding the answer.Jonathan Link to comment Share on other sites More sharing options...
ECR Posted May 17, 2022 Share Posted May 17, 2022 A useful fix for a doubtful master switch is to superglue a small washer to the end of the key. This pushes the internal contact faces more firmly together. The contacts don't "wipe" together when the key is operated and so can oxidise. Putting more pressure on the contacts usually works Link to comment Share on other sites More sharing options...
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