Bob, I have had two mechanical pumps on my C fail shortly after being rebuilt. When I took them off they were filled with motor oil due to the diaphragm disintegrating from the ethanol. There is no divider between the diaphragm and the mechanical linkage into the engine. So when the diaphragm opens up the electric pump could pump fuel into the engine. My thought was if I had had an aux. electric fuel pump it would have continued to provide gas to the carb for a short period but it would have also pumped a lot of gasoline into the engine oil. I am not an engineer but my mechanic told me it could do a lot of damage and perhaps explode in the engine. I am also concerned that even using a elec. pump as primer to start the engine if it were pumping through the mech. pump; Suppose the diaphragm had disintegrated during storage what would the gasoline do to the engine in the oil before starting or after it would not start. And was left stored that way until it could be fixed.....!!?? A proper way to do it may be to do a buy pass with a switch and check or one way valves (isolating the Mech. pump) to use the electric as a back-up and put it on a emergency off switch using a separate oil pressure switch. Everyone seems to agree this is a good idea. J D Jung Retromobilia.net ----- Original Message ----- From: "Bob Jasinski" <rpjasin@xxxxxxxxxxx> To: "Chrysler300" <Chrysler300@xxxxxxxxxxxxxxx> Sent: Friday, October 14, 2011 2:25:05 PM Subject: RE: [Chrysler300] Re: AUXILLARY FUEL PUMP That's why you use a push button switch, don't leave it turned on, and only use it for priming. Sorry to disagree, but I've had an electric pump on my G for 30 years and have never had a problem. If you have a failed diaphragm in the mechanical pump, the engine won't run. Of course, you could always eliminate the mechanical pump entirely if you wanted to, but I don't want to. Bob J From: Chrysler300@xxxxxxxxxxxxxxx [mailto: Chrysler300@xxxxxxxxxxxxxxx ] On Behalf Of retromobilia@xxxxxxxxxxx Sent: Friday, October 14, 2011 1:33 PM To: Ryan Hill Cc: Chrysler300 Subject: Re: [Chrysler300] Re: AUXILLARY FUEL PUMP I would never run an electric pump before the mechanical pump because ... On numerous occasions when the mech. pump diaphram failed due to mod. fuel it allowed a direct passage to the engine oil sump. I cannot imagine what would happen if the mechanical pump failed and the electric continued to pump and the car did not stop for several miles ........? J D Jung Retromobilia.net ----- Original Message ----- From: "Ryan Hill" < ryan_hillc300@xxxxxxxxxxx <mailto:ryan_hillc300%40hotmail.com> > To: paulholm@xxxxxxxxxxxxx <mailto:paulholm%40ameritech.net> , chrysler300@xxxxxxxxxxxxxxx <mailto:chrysler300%40yahoogroups.com> Sent: Friday, October 14, 2011 11:24:40 AM Subject: RE: [Chrysler300] Re: AUXILLARY FUEL PUMP Many of us have run electric pumps alone that way without incident but it's dangerous if you're running a mechanical pump as well, especially with modern fuels that seem to deteriorate the mechanical pumps faster than in the good old days. Also, if you're running an electric pump full time as your only pump on a carburated car, I would think you should have a low oil pressure kill switch or inertia switch installed in the event of an accident where the key is not turned off. Nothing like having a fuel line rupture and a pump continuing to run and spray raw fuel all over. Ryan Hill To: chrysler300@xxxxxxxxxxxxxxx <mailto:chrysler300%40yahoogroups.com> From: paulholm@xxxxxxxxxxxxx <mailto:paulholm%40ameritech.net> Date: Fri, 14 Oct 2011 13:54:07 -0400 Subject: Re: [Chrysler300] Re: AUXILLARY FUEL PUMP On 10/14/2011 1:27 PM, Ryan Hill wrote: > > One important thing to remember when running an auxiliary electric pump like this. If the electric pump is left running and your mechanical pump fails, you could potentially fill your engine with fuel. (If the diaphragm fails, it will leak internally) The damage can be catastrophic! Also, in the past, some have mentioned the convenience of having a second pumping source to limp home on in the event their mechanical pump fails......this should only be done after bypassing the mechanical pump for the same reason. > Make sure the pump is being shut off, I would set it up with a push button rather than a switch so it's only on when I push it to prime the carb. > Ryan Hill way back when, we used to just wire the pump to the 'hot when key on' source that way if the key was off and out the pump was Not running -- Paul Holmgren Mine: 2 57 300-C's in Indy Hers: 05 PT GT R/T HO Stage 1 Hoosier Corps L#6 [Non-text portions of this message have been removed] ------------------------------------ To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx <mailto:Chrysler300%40yahoogroups.com> To unsubscribe from this group, send an email to bob@xxxxxxxxxxxxx <mailto:bob%40simplexco.com> or go to http://autos.groups.yahoo.com/group/Chrysler300/join and select the "Leave Group" button For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm For archives go to http://www.forwardlook.net/300-archive/search.htm#querylangYahoo ! 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