Fuel Pump Change- What do I need?

[content22207]

The return line can not dump more fuel than the pickup line draws. It will not keep your baffle full. A completely closed baffle should help with very little hills but will not work on long hill climbs.

Our baffles are not "completely closed" -- look closely and you will see small hose drilled around the base. These holes allow fuel to slowly enter the baffle as tank level drops below its edge, yet still hold it in place during movements that would otherwise expose the pickup.

The tank itself is triangular shaped. There is less volume in the back (the apex) than there is in the front (the base). As fuel moves towards the rear, it has not choice but to also rise in height. Of course there is a level at which this effect still can not keep the pickup covered, but anyone who drives their fuel tank that low is courting problems anyway (what about the so called "hot fuel" problem everyone is so worried about -- less fuel in the tank means more heat absorption). When Louie and I drove to New Orleans, we passed through a section of Alabama that did not have a gas station for at least 50 or 75 miles -- what would have happened if we tried to drive that on less than 1/4 tank? As AAA says, purposefully driving the tank low is a bad idea.

Bill Robertson
#5939

[Bitsyncmaster]

I agree and when my tank gets to 1/4 full I start looking for a gas station. I have run it lower around town and even once had the low fuel light come on.

The point of having the pickup in the rear of the tank is going up hill requires more gas (power). Going down hill of course would be bad but you would not suddenly stop and be able to coast safely to the side of the road.

[content22207]

Speaking for myself, I have never experienced any of the problems simplified baffles and pickups are supposed to suffer (baffle rust or disintegration, fuel starvation, etc). Perhaps a poll for all forum users to respond in one place would be in order.

Bill Robertson
#5939

[sean]

Our what would have happened if we tried to drive that on less than 1/4 tank? As AAA says, purposefully driving the tank low is a bad idea.

I agree and when my tank gets to 1/4 full I start looking for a gas station. I have run it lower around town and even once had the low fuel light come on.

I think this is the key, keep gas in the car and any baffle will do. Get low and attack some hills, expect some problems.

[content22207]

Jim Edwards (Flyinglow) is missing his tank stud. If he ever rematerializes, and if he goes through with his planned carb conversion, he won't need any sort of baffle whatsoever.

I only include baffles for other carb converters because I still need to eat.

Bill Robertson
#5939

[TTait]

Won't happen. My baffle after 7.5 years in the tank

Sorry Bill, I was misinformed. I know you have had good results, but I had seen a can once that had started to rot along the seam where the bottom met the sides, and then it has spread into the steel. Obviously that car had water in the tank for some time.

Hervey's setup does not suck to the bottom as well as yours, but I think the baffle may have a larger volume to help compensate?

Did you get your pickup tube and screen from Hervey, or source your own somewhere?

[Canon20DFan]

The Delorean fuel estimation system is just that - an estimation. I never trust my fuel guage enough to go below 1/4 tank.

Because you may run into a fuel delivery issue if you allow your tank to get below 1/4. I opted for Hervey's setup in my first car, and I would occasionally run into this problem. It may be more pronounced if you live in an area with a lot of hills. Granted, YMMV, but having the baffle toward the rear of the tank helps keep the pickup submerged during acceleration when the fuel level is low.

The newer (improved) pickup hose is thicker and more resilient than OEM, which should help prevent it from collapsing on hot days. This is a common complaint of the original setup, which is why the "alternative" configuration was conceived.

I would caution you to keep your stock baffle in a box somewhere in case you ever want to go back to stock; the originals are really hard to come by.

[David T]

All of the internal parts should be pulled, cleaned, and examined. To clean them use Acetone. You should be using Nitrile gloves, a respirator, eye protection, and a fan. Work in a well ventilated area, preferably outdoors. The baffle parts should be salvageable. Replace the pick-up hose and return hose, both boots, and if necessary the fuel pump and the short wiring harness. Be very careful with the hard metal fuel lines so as not to kink them. If the outer fuel hoses are in good shape, just the outer covering is coming off, you can recover them with a couple of wraps of electrical tape. The original fuel sender is not reliable so it should be replaced. Be careful not to over tighten the stud in the fuel tank but if you do break it loose some have had success in reinstalling it. Heat it up and quickly stick it back into the bottom of the tank. It will melt itself back into place. You must be very careful when reinstalling the pump to keep the pickup hose from kinking. Many have added an internal spring to keep the hose from kinking or collapsing under vacuum. That fuel pump can suck HARD! Hard enough to collapse a soft pickup hose! Especially on a hot day with the radiator and A/C heating up the fuel tank. Be sure to wipe out all of the junk in the tank. After using up a tank of gas, replace the fuel filter. Do not remove the fuel tank for better access, it doesn't help unless you are fixing rust or paint.
David Teitelbaum

[content22207]

Hervey's setup does not suck to the bottom as well as yours, but I think the baffle may have a larger volume to help compensate?

A tuna baffle is almost exactly the same size as a Hervey baffle:

Baffle2.jpg Baffle3.jpg Baffle4.jpg

Of course it doesn't matter how big a baffle is if it can't hold fuel. A bottomless 55 gallon drum is just as useless as a bottomless thimble.

For comparison purposes, those pictures were taken in 2003 (pictures in Post #11 are the same baffle, taken this morning).

Eeek:

Baffle1.jpg

Bill Robertson
#5939