Funky Fuel?

Many of you are new to the DeLorean World, having just found a low mileage DeLorean waiting in the garage of an original owner.  Thirty-five year old cars are like a time capsule, you get a lot of positive attention, so much so that you absolutely dread the thought of breaking down on the road.  Today’s Tech Note is focused on fuel system contamination, which is often found in low mileage DeLoreans today …

                Ed Bernstein shared insight to fuel tank contamination in the DeLorean World Tech Notes published in the Summer of 1989, Volume 6 #4:

“On several occasions during the past 36 months, our service personnel have discovered serious fuel system contamination from dirt, rust, moisture, and petroleum tar. Although contaminants may enter the fuel system via the gasoline pump through “dirty” fuel, we find that most damage is the result of owner maintenance neglect or poor quality workmanship by repair people.

The fuel pump is located in the top of the fuel tank beneath the spare tire in the luggage compartment. Access to the pump is gained through a panel in the rear of the spare tire wheel well. Initially, the top of the fuel pump is protected by a “fuel pump cover seal.” Note the condition of the “cover seal.” If it is soft and pliable, you are in good shape. However, if it is hard, distorted, and dried-out, you are probably going to have a fuel pump problem from rust in the near future.  Moisture enters the top of the “fuel pump sealing ring” through spaces around the fuel hoses or edges of the cover seal. These spaces are created by the loss of elastomers in the cover seal from age or heat. Water entering the area remains on the top of the fuel pump, submerging the electric wires, rusting the threaded contact, posts and causing an electro-chemical deteriorating action called electrolysis. If you find the top of the fuel pump submerged in gasoline or evidence of gasoline around the top of the fuel pump, chances are the “fuel pump sealing ring” is beginning to deteriorate from additives, or the fuel itself.


Photo#1, Rigid & cracking fuel pump seal cover

Photo 1 shows a moderate to extreme example of sealing ring deterioration. DO NOT LEAVE YOUR DELOREAN STORED FOR AN EXCESSIVE PERIODS OF TIME WITH GASOLINE IN THE TANK!! The lack of gasoline circulation within the gas tank/system appears to promote a molecular breakdown within the rubber compound that makes up the “fuel, pump sealing ring” thereby creating a “tar-like” substance.  The small tar molecules enter the fuel, system initially by passing through the “fuel, pump filter screen” at the end of the “lower fuel pick-up hose.” They build up in and pass through the fuel pump on their way to, the “fuel accumulator.” We believe that, severe cases of “tar-like” contamination cause failures in fuel pumps and accumulators on a regular basis.

 If we are fortunate, the remaining “tar” molecules and particles are stopped by the “fuel filter” (a cylindrical component strapped to the left rear section of the frame above the air-deflection plate). If we are not lucky, or we do not change our fuel filter every 15,000 to 20,000 miles, excessive tar build-up within the fuel filter may begin to break down and pass into the “fuel distributor”, or into one or more of the six fuel injectors.

Upon examination of a DeLorean, with over 133,000 miles logged, the “fuel pump sealing ring” was observed to still be dense and firm around the area located near the bottom of the pump inside the gas tank. This is a desirable appearance. However, the “fuel pump cover seal” was beginning to become rigid and somewhat dried-out. When further deterioration occurs, i.e. the original size and shape is lost, the time has come to replace this component.


Photo #2, Corroded connectors below cover.

 In sharp contrast, it is common for us to find “fuel pump sealing rings” in low to medium mileage DeLoreans which are deteriorated, ragged and spongy around the portion that extends into the gas tank and is submerged in the gasoline.

 We advise that you or your mechanic examine this area of your DeLorean on a regular semi-annual schedule to verify no contamination exists and that your “fuel pump cover seal” and rubber “fuel pump sealing ring” are doing their job properly.

 We also suggest that if you find moderate deterioration in your “fuel pump sealing ring” that you replace your “lower fuel pick- up hose,” “fuel pick-up screen,” and “fuel filter” in addition to the “fuel pump”!! We believe that new rubber components which are replaced in a piecemeal manner become contaminated from “tar-like” molecules remaining within components which are not replaced and thereby perpetuate the deterioration process.” By Ed Bernstein, (Former Owner of DeLorean One, Inc., Canoga Park, CA)


A complete guide to the R& R of a DeLorean fuel system pump appears on the pages directly following this article in DeLorean World, Summer 1989, Vol.6 #4, pages 33-39.



Avoiding fuel contamination will certainly contribute to years of pleasurable DeLorean ownership.  Should you discover maintenance is needed, you can restore your fuel system components with parts from our current vendors carrying stock/aftermarket equivalent parts. Before you install any new fuel system components or the fuel system below, be sure to perform a proper fuel system cleaning of the Fuel Accumulator, Injectors, Distributor and Fuel Lines.

I would encourage you to also look at the new fuel pump/sender module now being offered by the DMC Factory, #107000. See Photo 3  

Photo#3, New DMC Factory Fuel System

For only a few dollars more, this kit is a truly modern-style replacement for the stock DeLorean in-tank fuel system. The kit replaces all the mild steel and rubber fuel pump components and your fuel sending unit with a single integrated assembly that does both functions.  Ideal for cars that are driven regularly or infrequently, the materials used are resistant to the additives found in modern gasoline, including ethanol. The microprocessor controlled fuel sender delivers more accurate fuel level information and is not affected by fuel tank slosh. Installation is easy with electrical hook-ups using the existing connectors and fully illustrated instructions to guide you along the way. And yes, the individual components are available and replaceable if ever required! 

Photo credits go to Danny Botkin – Service Manger of DeLorean Motor Co. of California 

A clean and healthy fuel system will spare you from most fuel issues on the open road.  Add this inspection to your DeLorean’s periodic maintenance!

Drivin’ the DeLorean Dream…

Gordon Carpenter

DOA Membership Director