While in the process of replacing all of the coolant hoses and pipes, I noticed a bit of frame rust around the fuel tank, which I covered in a previous post. This necessitated the removal of the fuel tank for the first time, and I thought it was a great excuse to both clean the tank and replace the fuel pump with a modern solution. The fuel pump that I had in the car was only about 13 years old, but it would whine on really hot days, which I found both annoying and unsettling.
I bought a modern fuel pump kit from DeLorean Industries and was very impressed with the kit. It came with a fuel pump with an integrated sender unit, which meant that I could get rid of the existing fuel sender (tells the gauge how much fuel is in the tank), braided stainless steel feed and return lines with stainless steel fittings (other versions of this use rubber lines with hose clamps), and very nice electronic connections.
The unit uses a Delphi FG 0089 pump and sender unit. It definitely is an expensive kit at over $500 USD, but this should last the lifetime of the car.
First, I had already removed the fuel tank closing plate to access the coolant lines and hoses around the tank. Here's what the 13 year old pump and fuel send looked like before I messed with anything:
After leaving everything alone for a few days, the tank ended up dropping part way out of the car by itself, which was convenient. Here are a few reference photos I snapped after the back end of the tank dropped down:
I pulled out the fuel pump and disconnected the electrical connections and pulled the tank the rest of the way out of the car. I then peeked inside to see how the fuel looked and what else remained in the tank. Here is the Special T baffle in the tank of gas, as well as how much fuel was still in the tank:
The tank and the gas looked extremely clean, which made me happy since I hadn't touched the tank in the 10 years that I've owned the car. I then pumped out as much gas as I could with a battery operated liquid transfer pump that I got at Harbor Freight. It made quick work of the rest of the fuel and I pumped it into a gas can and subsequently put that gas in one of my other vehicles to use since the fuel was still in great shape.
Here's what the tank looked like after pumping out the gas, before starting to clean it up:
I then removed everything inside the tank and proceeded to wipe down the inside of the tank as best as I could with acetone and a rag. There really wasn't much as far as particles and grime. Here is the inside of the tank all cleaned up:
The outside of the tank was another story. After I cleaned the inside of the tank, I taped off the tank openings and went to town on the outside of the tank.
After the outside was all cleaned up, I started going through the process of getting the new parts put in the car. The kit came with new feed and return lines, so I cut the old ones off and then had to remove the barb fittings that screw onto the hard lines that run to the motor. These were a pain to break free, but I eventually got them both to come off. Here's how they looked after coming out of the car:
The new feed and return lines are beefy and with them replacing those barb fittings, they shouldn't ever have to be replaced, nor should they have any problems with leaks.
I then installed the pump in the tank, which I found was pretty easy to do with the tank out of the car. The instructions were a bit unclear as far as how far down the pump sits in the hole, but just know that the rubber gasket that goes around the pump doesn't fit all the way down into the hole of the fuel tank, but that you just get it as snug as you can, then the clamp on the outside holds everything into place. It's very important that the clamp holds both the top of the fuel tank opening and the top of the fuel pump at the same time so that it keeps those two together. Otherwise, the pump isn't in all the way and will likely leak fuel when driving or filling up. Here's how it looks once installed:
I then put new foam padding on the tank and on the frame, all of which I got from DeLoreanGo. It doesn't need to be perfect as it just keeps the tank from rubbing on metal and nobody will ever see it but you. I then put the tank back in the car. It was a snug fit with all new foam that hadn't been compressed for 40 years, but I got it in.
The most time-consuming and frustrating part of the entire installation was dealing with the electrical connections that came with the kit. It was really easy to know which colors of wires went where, but the connectors came with the pins uninstalled and installing those the right way took the better part of an evening. I was most concerned about having solid, reliable connections, but luckily everything appears to be working with the wiring. Here's everything hooked up, including the feed and return lines on the pump:
I discovered remnants of old padding under the spare tire that looked like old thin pieces of beef jerky. You can kind of see the remnants of what was left in this photo:
When it came time to put back on the fuel tank inspection cover, I found that the fuel tank sat too high in the body to allow the cover to line up with the screw holes, so I had to remove the fuel tank closing plate and push down the fuel tank until I had enough space to put on the inspection cover. I literally had to climb into the trunk and use the weight of my body to push down in order to move the tank. That was the difficulty it took since I had installed new foam padding around the tank to keep it firmly in place.
Once I verified that everything was working and the car ran well, I decided to fill the tank up completely with fuel. During that first fill attempt, I noticed it was taking much more gas than I anticipated, then found a river of fuel running out from under the car. I didn't bring any tools with me to get into the fuel pump area to see what the issue was, so I had no choice but to drive the car home to inspect it there.
What I found was disturbing. The black fuel tank sender cap was just sitting on top of the tank, not installed, but just sitting there. I could look into the tank and see the full tank of gas. I put it back on and tightened it down, then called it a day. The next morning, the cap was just sitting there on top of the tank again. It had come off by itself overnight. I discovered that the o-ring gasket that came with the cap appeared to be too big and it was preventing the cap from being installed all the way, possibly causing the threads to be crossed.
When I would tighten it down, I had one of two things happen: 1) I would tighten it until it felt secure, but if I kept going to make it even more snug, it would suddenly become loose and I'd have to start over, like something was getting in the way of the threads, or 2) I would tighten it until it felt secure, then I would leave it alone and it would eventually pop off, or I could bump it and it would pop off.
Here's a video of what scenario two looked like:
I closely inspected the cap and found that the o-ring did appear to be the problem. It just didn't fit right on the cap as it seemed too large:
If I removed the o-ring, the cap would thread on correctly and wouldn't pop off, no matter how much I fiddled with it. This confirmed that the problem was the o-ring gasket. I decided it was worth a try to remove the gasket, tighten the cap down, and then see if it was enough to seal the tank. So after putting on the cap without the o-ring, I returned to the gas station and topped it off, but alas, the cap leaked without the gasket:
I don't know if the fuel sender that was in the car had any leaking issues, but I knew I couldn't keep the new cap in the car in its current state. The vendor didn't offer any solution to the problem, so I decided to order a different fuel tank sender cap from a different vendor and put in the original fuel sender back into the tank until the new cap arrives. Here's the style of the fuel sender gasket, which is a rubber ring that appears much less susceptible to leaks:
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