|
This is all true; however the 300 needs good fuel flow at WOT, and restricting the suction side of the stock pump (any pump!) is for sure , engineering wise, not a good idea . Pumps can handle output side restrictions, but input suction causes lots of problems-- if suction effort rises, ----not the least of which is the flow drops a LOT, and gas vaporizes, aka vapor lock. There is much misunderstanding about vapor lock, I think…..gas in the line after pump is under 4-5 psi pressure , it cannot vapor lock, and if it did (boil to a vapor at relatively low temp) any bubbles get instantly pushed right through and out via carb needle until liquid flows. Yet we see attempts at protecting that line ‘from vapor lock” ? (chevy guys wrap them with aluminum foil ). Maybe for cooling for racing….maybe. Vapor lock, true vapor lock, must happen in hot suction line right at fuel pump..It cannot suck gas vapor in…or only erratically . I get into this, as like many others doing old cars, we know the tank can puke junk into the fuel line after storage—mostly rust flakes; this gets into mechanical inlet valve of pump and prevents seating, which stops the flow after typically 10 miles, (too far to walk back) , or weakens the flow rate . The filter is usually after the pump, under pressure flow, which is OK if big enough and gas clean . It is there to protect carburetor passages. . . Think about that. Why not before? There is a very good reason. I used to routinely put one (large clear body so I can see) before pump to grab tank junk, it works until WOT; then engine starves and lean mixture, = ? badly burned valves if continued very long. And only at high RPM, so you do not really know. The ,er , low cost solenoid ‘clicker” pumps (aka cheap junk) came to us from Lucas designs and 1000 cc 4 cylinder cars. It both cannot keep up flow itself (IMHO) and restricts main pump , view from 2015. So what to do? I trust Carter, they do know a bit about all this, they make a nice all metal rotary vane pump for about 100$, it can keep up. Might even grind up rust, mini insinkerator. (only kidding) Then run power wire (14 ga) through GM /Buick type oil switch with SPDT switch on it (3 terminals) and a spring return toggle switch in parallel with oil switch . It runs pump with ign on, oil pressure on (until/unless oil pressure is not there) --- if you are holding toggle it runs without oil pressure -- spring toggle fixes that prestart issue, cannot be left on, it is in parallel across oil switch, manual prime . Note this is opposite of normal oil switch..this one closes one contact with pressure..so if engine stops, pump stops . Important, right? (accident) . Other pin can be a new nicely integrated big red warning light for low pressure. One good use for idiot lights . Common switch terminal to +12 ignition hot though 15 A fuse . On Studebaker, I do not use toggle anymore , I crank till hemi oil pressure closes it, pump starts, full carbs in a second . That IS nice for me and hemi . That way, there is no mechanical pump, mount Carter at tank , use 3/8 or 7/16 inlet suction fuel line( yes a bigger line into tank..you want it right?) . In that line I put a BIG race filter made by Moroso (for one) about 5” long and an inch in diameter with a stainless mesh cylinder inside the full length. You can take apart to clean. No flow restrictions like paper filters . About 80$ and worth every cent, as opposed to 2AM at side of road.. (Summit). The other way is use a Carter mechanical high output pump and this filter in inlet back at tank , ideally bigger suction line back into tank. Using two pumps in series has a very bad failure mode, a cracked diaphragm on mechanical pump (how they DO fail) = whole tank of gas pumped onto front of your car as you cruise along. In minutes. Not just into engine. No warning till PUFF. Pump is often vented to air on purpose or just not sealed(varies) ; into engine is not good either . Using it “just for prime” risks restricting inlet flow, poor performance. Ok for silver Toyota style drivers? I am not sure if anyone makes a 3-4 lb in tank pump; that may be best of all, if car is used regularly (zero inlet restriction) (FI pumps are 40psi) , but Moroso / Carter outside at tank and large suction line lets you fix in minutes any junk problems, plus it holds a lot of junk without a problem . And carry spare carter. Carter has never failed. I have Hot Heads equipped 56 354 in a Studebaker coupe, 50 starlight, Turbo 400, where all this was evolved /learned. Still fighting 2 piece drive shaft vibration in that. For another day… Hope it helps, my .02, John PS maybe ram cars do starve for fuel….now. So burned valves are blamed on the gas? That said, ethanol gas is awful, requires different A/F ratio, less air /or more gas flow through jets for same HP, can never run right in gasoline AFB. It is set up one way or the other. Ethanol into stock 300 AFB gasoline setup= lean mixture. For sure, wrong A/F ratio. Add fuel pump restrictions to that… PPS; above is why Edelbrock AFB always gets 10 mpg, I think. Ethanol mix calibration. From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of 'mgoodknight@xxxxxxxx' mgoodknight@xxxxxxxx [Chrysler300] There's no risk of damage to the engine operated pump or to the electric diaphragm pump when using both pumps in the same line. The electric/solenoid pump does not need a bypass system to control or limit the pressure. It's the spring working against the diaphragm that provides the correct low pressure. The solenoid simply reloads the spring as the fuel is released from the pressurized chamber. When there is no longer any flow from the pump the oscillation of the solenoid-diaphragm-spring ceases. At least that's the way that most of our accessory pumps work. --------------Marshall Goodknight
I believe the way the electrical pump works on our ’55 C-300 is that it will pump through the mechanical fuel pump when the key is turned on and continue to do so until the bowls are full and the float valve shuts off the input. I can hear the pitch of the pump change when this happens and it make take 15-30 seconds. I know then that the engine is good to go. Give the accelerator pedal a couple of pumps to put some witch’s brew into the manifolds, pull the chokes out by 3/8†on a cold engine and it starts IMMEDIATELY. I don’t know why the manual chokes are on the car but assume it was hard starting while the car was earning its keep in the Colorado Springs area for 30 years. I think my fuel pump is a positive displacement pump, operated by an oscillating solenoid. It must have a bypass built into it to limit its outlet pressure. And, yes, I put my car at risk of a blown mechanical pump diaphragm that would allow gasoline to flow into the block. I did have the electric pump wired to only operate when I pressed an additional push button but the car acted a little starved so I changed it to full time. Now I see the poor operation may have been due to the ignition wire problem previously discussed. Rich B. From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On Behalf Of John Lazenby french_fryguy@xxxxxxxxx [Chrysler300] Good thought Ryan but several of my cars don't have electric pumps and they are still failing. John Lazenby On Monday, March 2, 2015 2:16 PM, "Ryan Hill ryan_hillc300@xxxxxxxxxxx [Chrysler300]" <Chrysler300-noreply@xxxxxxxxxxxxxxx> wrote: John, with all due respect. You were just stating you're replacing your mechanical pumps annually on all but one of your cars. Are you certain it is only due to ethanol? Is it possible the failures are linked to pushing fuel through your mechanical pump while the engine is not cranking or running? To: ryan_hillc300@xxxxxxxxxxx; pffkllc@xxxxxxx; jsnowosacki@xxxxxxxxx; fabe7445@xxxxxxxxxxxxx I've experienced zero problems with electric pumps. John Lazenby On Monday, March 2, 2015 12:56 PM, "Ryan Hill ryan_hillc300@xxxxxxxxxxx [Chrysler300]" <Chrysler300-noreply@xxxxxxxxxxxxxxx> wrote: Just a curious thought. Are any of you guys experiencing pump failures using electric auxiliary pumps to prime your systems? I know they're low volume pumps that are generally being used but wondered whether pushing fuel through a mechanical pump could do any damage to the valve/diaphram? To: french_fryguy@xxxxxxxxx; jsnowosacki@xxxxxxxxx; fabe7445@xxxxxxxxxxxxx Query, does Ethanol erode neoprene as well as lesser materials? I think the newer materials being used to rebuild fuel pumps may be more resistant. Comments will be appreciated. Pete Fitch In a message dated 3/2/2015 3:32:09 P.M. Eastern Standard Time, Chrysler300-noreply@xxxxxxxxxxxxxxx writes:
__._,_.___ Posted by: "John Grady" <jkg@xxxxxxxxxxxxxxxxx> To send a message to this group, send an email to: Chrysler300@xxxxxxxxxxxxxxx To unsubscribe from this group, send an email to bob@xxxxxxxxxxxxx or go to https://groups.yahoo.com/neo/groups/all/manage/edit 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#querylang __,_._,___ |
Back to the Home of the Forward Look Network
Archive Sitemap