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I disagree. At least take some small stuff to cope with something minor. I will admit in the many years I have driven my Delorean, it is very rare I had to use anything on my car. My car is very well taken care of. I DID have occasion to do repairs when with groups of other Deloreans, some not as well taken care of as mine. Often it is problems of an electrical nature. One essential thing to take is a fire extinguisher.
What are you disagreeing with, exactly? Everyone? Me? Something specific? You'd think after giving help for decades, you'd learn to address specifics.Quote:
Originally Posted by David T
Yes, but that's not part of my toolkit; it's behind the seat.Quote:
One essential thing to take is a fire extinguisher.
Probably true, but don’t know if I would want to tackle that job on the side of the road or parking lot. On that note, has anyone installed a inline fuel pump? Seems like a much easier way to go. I don’t know why I didn’t think of it when I changed mine. (Of course, my tank was full of junk anyways)Quote:
Originally Posted by ssdelorean
The Delorean has a high pressure fuel system. To use an in-line pump it would take a long line under a lot of vacuum to get the fuel out of the tank. Typically when you do that you have a low pressure transfer pump in the tank to keep the suction line as short as possible to avoid boiling the fuel and getting vapor lock. That pump pumps the fuel to the in-line pump that raises the pressure of the fuel for the fuel injection system. Not the way they did it. You want to keep the suction line as short as possible to avoid vapor lock. Using the one pump saves the cost of the second pump and all of the additional wiring and relays and power consumption. Most modern cars now use just the one pump inside the fuel tank. Keeps it cooler and keeps the noise level down and also keeps the suction line as short as possible.
Most modern GDI have two pumps. One in the tank and one at the engine. They are also returnless and PWM drive the in-tank pump based to maintain line pressure. The latter could be made work on K-jet if you were technically inclined.
I firmly believe that lot of fuel pump issues, fuel odor, etc., could be alleviated by getting the radiator pipes away from the fuel tank.
I don't think that Lotus/DMC really thought the whole plan of "lets put the fuel tank and two pipes containing 200F+ liquid in a sealed metal box" through.
When I was running the original type pump, I put a temp sensor if the feed line at the tank and the return line at the tank. My pump would buzz when the feed line hit 130 deg. F. The return line ran about 2 deg. F. above the feed line so that makes me think the heating of the tank is due to the returned fuel (heated by the engine). I also had the Hervey fan deflector. I was only able to stop the buzz by running the return line wrapped around my AC accumulator.Quote:
Originally Posted by FABombjoy
With the new style pumps it seems the buzz is not a problem anymore however I still have the return line cooler still functioning.
There was one incident where a group of Deloreans was waiting for a ferry in the heat and one-by-one they all started buzzing. The less fuel the quicker the buzzing. It is obvious the temperature of the fuel affects the fuel pump. Running the cooling system pipes right next to the fuel tank was not the best thing to do, it winds up heating the fuel. Using the A/C to cool the fuel is a good idea but realize you are giving up some of it's capacity to cool the cabin. Hotter fuel vaporizes at a lower pressure and that is exactly what the pump is doing on the suction side, lowering the pressure, vaporizing the fuel and causing cavitation in the pump which you hear as the buzzing. Prolonged cavitation affects the fuel pump's life causing it to fail early.On modern cars the fuel pump is actually immersed in the tank so the suction line is as short as possible. Immersing the fuel pump also cools the pump. The OEM set-up has the pump isolated from the fuel and the suction pipe collapses when it gets hot under the vacuum. The newer design (common on modern cars) has the fuel pump immersed in the fuel. A redesign of the fuel system would include a way to get the cooling system pipes away from the fuel tank (or at least insulate the tank) and use a fuel pump assembly that immerses the fuel pump in the fuel tank. The "dam" helps a little by redirecting some of the heat from the radiator but it is likely not significant. Keeping the tank full would help too, more mass will take longer to heat up. If you are still running on the OEM fuel pump set-up consider putting a spring inside the suction hose to prevent it from collapsing.
Running at idle speed causing the buzzing just confirms most of heating is due to the return line. At idle you get the most returned fuel.
I get the fuel tank buzz on extremely hot days. It mainly happens with low fuel in the tank. It also doesn't matter if I am idling or running 75mph on the highway. The two main factors for me are HOT days and low fuel in tank.Quote:
Originally Posted by Bitsyncmaster
Only a couple times has it happened with 3/4 of fuel in the tank.
I am still running the original style pump. The newer original stye pumps buzz more than the older original style pumps. My guess would be cheaper internals (since most "new" stuff these days is not made to last.
Useless Fun Fact: My car has the prototype fan deflector shield installed from Dave Bauerle. Of whom Hervery made his version.
Did you track fuel heat against coolant temps? I would think that would be more indicative of source. I have a hard time believing all of that heat is from the return line when the tank is enclosed in a metal coffin along with the main coolant pipes. I suspect that your return fuel heat exchanger helps to keep things below the boiling or cavitation point.Quote:
Originally Posted by Bitsyncmaster
At idle the coolant system runs hotter too since it bang-bangs against the higher temp on/off points of the otterstat, rather than the thermostat temp. And very little airflow over the tank and closing plate. Idling cars getting noisy makes sense.
Those pumps can still cavitate but its quieter. I'm working to solve this now on an FG0089 as summer long highway cruises cause problems with weird noises at the fuel pressure regulator. Initial plan is to PWM the pump speed down as it's flow level is pretty overrated for any PRV.Quote:
Originally Posted by Bitsyncmaster