hello all, My car is currently at the workshop getting the self leveling system replaced. My mechanic called me today to tell me that the car don’t start any more... He told me that the fuel pumps won’t turn which reminds me of a K-jet problem that has already been described somewhere on this forum by Steve Magnusson or Newman If memory serves... Unfortunately I am unable to find this topics via the search fonction. Anybody remembers this topic? Any link? Many thanks
One easy test for the fuel pumps is to disconnect the connector at the inside of the air valve just below the rubber air duct going to the intake manifold, then turn the key to "ignition" position but do not crank the starter You should hear the pumps running and even hear the fuel going through the pressure and return lines at the side of the air cleaner housing. What this sensor (blue plastic) controls is that it waits for conformation of engine cranking and airflow past the air valve until it energizes the fuel pumps, when you dis-connect the sensor, you are tricking all of the fuses, relays and fuel pump to the "run" position. If you do not hear the pumps running or fuel flowing, begin your electrical testing at the fuses in the main box and the relays below them, then all the way to the pumps under the floor. Gary Or search "fuel pump".
Note: I'm responding assuming that your Mechanic has confirmed that spark is occurring on both banks during starter motor cranking The good news is that there's only a few places where a single failure can cause both fuel pumps to not run. First thing I'd suggest is trying a different Bosch 0332204101 relay in position "T - Relay for fuel pumps" (this single relay controls both fuel pump relays). If still no joy, unplug the safety switch per Gary's suggestion (it's on one of the airflow metering units) and turn the key "on" = you should hear both fuel pumps run: If they do = try starting the engine with the fuel pumps already running If they don't = remove each fuel pump relay and touch a jumper wire from the female 30 terminal in the relay socket to the female 87 terminal in the relay socket: Image Unavailable, Please Login The corresponding fuel pump should run (even with the key "off") when the jumper is in place. If you fail this test, give a shout and we'll go from there...
Thanks a lot! I’ll be at the workshop in an hour. I hope he will have find something or will accept to give your plan a try... Will keep you advised. Thanks again
Well... my mechanic incriminates the pumps (wich, indeed, don’t look nice). Both? Simultaneously? Yes, he answered. Well, if I understand correctly he is a bit overworked and doesn’t want to start working on an electric gremlin before next week... So we’ll go for new pumps and wait and see. At least the shocks are back and on the car. They look nice! Thanks, will keep you advised
Roger, please supply more feedback on the shocks? Were they rebuilt or replaced? Are the new ones self-levelers? Can you advise costs? PM me if you like. Thanks. My 1980 400i apparently had its rear suspension removed at the time it was federalized and it now need new shocks. No intent to hijack the thread so I will start a new one if needed. Mike G.
Those rear springs dont match in static length which Im sure you know. Are you not concerned about different spring rates or are they somehow matched? Theres more than one way to skin a cat but my preference is 4 identical rear springs and shocks, boxer, testarossa, 400, doesn't matter.
And no to both pumps failing at the same time. He'll replace them both then fix the real problem right after that.
Alas, Newman, I don’t know nothing about anything and even less about springs length.... :-( The man told me that the springs have been adjusted and calibrated, that’s all I know. Everything is on the car so I hope he would have noticed something wrong. (The rear shocks are replaced and are no more self leveling, the front ones have been rebuilt and I’ll keep the old parts for a potential rebuild. Don’t know the exact cost yet, somewhere between 2 and 3 K€, I’ll let you know) As for the pumps, Newman, I agree and I can’t see why they would both fail at the same moment but when I tell him about the Kjet stuff he answers that we must start from the pumps. That’s already been discussed in an other thread, as a non even amateur mechanic I don’t have the ability to contradict that guy who has been working on Fcars for more than 20 years... So as pumps are not so expensive (and rusted) let’s go for it and wait and see. Maybe I’ll never know as he might be proud enough to never admit a mistake! I hope to know more next week... Thanks again!
As pointed out above, the simplest and most likely explanation for two independent fuel pumps to stop working at the same time is the single relay that controls them both (there are two others that control one pump apiece) has failed or, even more likely, the contacts have failed. The fuse and relay panels are notorious for having soldered connections that weaken and loosen over time and, because of the poor connection, they overheat and ultimately fail. The one and only time that my 400i ever stranded me in 15 years of driving was when the heat buildup in the relay panel caused that connection to fail. The car was running flawlessly on the trip to where I was going but then wouldn't start later when I came out to continue the trip. Replacing those old fuel pumps may be a good idea since they possibly are original nearly 40 years old but I will bet that they are not the problem.
Old pumps could also draw more amp draw and cause premature failure of the relays and contacts. So if the relays have failed, I would probably replace the pumps also.
So: he only changed the pumps and that’s all.... I had my first drive of the season yesterday! Image Unavailable, Please Login