Fuel Pump Noise Cured!

[DMCVegas@xxxx]

[ moderator's note: It's been said many times already but DISCONNECT the battery before working in the fuel tank areas. ]


A while ago the topic of the fuel pump getting noisy when hot was 
brought up again. The problem was identified as a colapsing pickup 
hose that connects from between the prefilter screen in the baffle to 
the pump itself. The hose is made of soft rubber which becomes softer 
still when hot. Many fellow DMLer's posted responses with various 
solutions on how to help quiet the noise, but nothing to prevent the 
hose from fully colapsing. In one of the postings David Teitelbaum 
mentioned the insertion of a spring into the hose. Through a few 
private e-mails with David, he explained to me what parts he used, 
and how. After installing the hose, I finally got the chance to test 
it, and it does work!

On an 89° day, with less than ¼ tank of gas, the pump ran silent, and 
the car did not hesitate once! My car was also run up and down some 
steep hills. Steep enough that the needle on my gas gague bottomed 
out at 0. I need put put this (along with some other items) into a 
write up(s) for the technical library. I'll see about it this 
weekend, but just incase I don't get to it, here's the quick run-
thru. I'll put the full details in later.

The spring is a screen door type available from Home Depot. Size is: 
9/16"x16-1/2"x .054.

1. Drain the fuel tank (run a siphon hose under the trunk, out from 
the right wheel well for best results).
2. Disconnect the pickup hose from the fuel pump.
3. Remove the pickup hose and the entire baffle.
Note: On my car the filter screen on the pickup hose has a barb 
attached to it. But the barb is attached to the screen assembly with 
some sort of resin. Durring the removal of the baffle, the resin 
crumbled. Needless to say I now have debries at the bottom of my gas 
tank. Take caution.
4. Clean the baffle and the pickup hose (or use new hose).
5. Using some heavy wire cutters, cut the spring a little shorter 
then the hose stretched out. Measure the hose from between both 90° 
elbows on the ends.
6. Place the spring into the freezer, and soak the hose in some hot 
water for about 2 minutes.
7. Take some dishwashing liquid and pour it into the hose. Rotate to 
coat.
8. This will take a little time, and a lot of patience. Slide the 
spring into the pickup hose. As you progress you'll need to pour a 
little more soap into the hose, and also reheat the hose again in 
some hot water. Try not to get any soap on your hands to keep a good 
grip. Plus don't get burned. Once the spring is about ¾-½" from the 
end, pull it through with some needle nose pliers. 
9. Pull the spring to strech it out, then cut off what you don't 
want, and tuck the rest in. Do this on both sides, and bend the sharp 
end of the spring into the center of the hose.
10. Flush the hose with cold water for about 20 minutes.
11. Reassemble the baffle
Note: If you have a difficult time getting the hose to silde back in 
thru the rubber gromet, use a little soap again. Just wash with cold 
water again for 20 minutes.
12. Dry the hose (and baffle if applicable).
Note: The fuel tank is not something that you want to always open up. 
Especially if you need to access the baffle (if you've come this far, 
you now know why). So you will want to replace the prefilter screen. 
Since the old one had that crumbling resin all over, I decided to 
just use a generic replacement from Car Quest. A different shape, but 
still fit in the bafle. Bondo makes a product called Marine Epoxy. It 
comes in a putty form, and is resistant to gasoline. Use this to 
affix/seal the barb to the filter. Attach the filer when the hose is 
dry.
13. Reinstall the baffle and seal the gas tank (it is possible to 
insert the baffle when fully assembled. I'll post how to do that 
later...).
14. Filler' up and you're ready to go!

I'll post the more intricate details for some of the instrucitons 
above in the Technical Library write up. Many thanks to David 
Teitelbaum who had the idea of the spring. I am very happy with the 
results. My fuel pump no longer buzzes, my car doesn't hesitate when 
low on gas, and accelleration has improved slightly.

This summer I'll put the spring and the heavy duty radiator to the 
test. I'll be driving the DeLorean to down into Death Valley and then 
back up the grade to Rhyolite. I figure if the D can survive the 2nd 
hottest place on earth, then I've got no worries!

-Robert
vin 6585