I’ve known Dick for over 40 years. He’s a car guy’s car guy. His classic ‘57 Bel Air coupe got lots of thumbs up on the Hot Rod Power Tour. And I’m pretty sure not one of his family’s fleet of a dozen cars has ever seen the inside of a shop for mechanical work. Dick fixed them all.
He has owned an Opel GT since 1996. Well, he owned two actually. He took two partial GTs and cobbled them together into one very cool car.
Body parts from one were welded on to the other – in his driveway. He completely rebuilt the engine and painted the car – in his single car garage. He designed, wired, and installed power windows and locks for it. It’s fair to say Dick knows this car inside, out, and sideways.
For several years, he drove the Opel regularly. But after a couple of moves, the Opel sat for a long time. After a few years, that led to some fuel problems that were hard to solve. When Dick would fire it up, it was hard to start and idled poorly.
Following Occam’s razor, which says the simplest solution is usually the right one, Dick started with the most likely culprits.
“When the idling problems started, I noticed that the air filter had started to deteriorate,” Dick told me. “It was an open element foam filter and I could see the foam had started to break down and getting debris in the carburetor.”
Dick replaced the air and fuel filters, and then examined the carburetor. Dick’s Opel has a single Weber downdraft, a nice performance upgrade from the stock Solex carb. There weren’t any obvious problems or debris in the carb throttle body or float chamber, but Dick cleaned them out and reassembled it.
And it worked. For a little while anyway. Initially the Opel started right up and idled smoothly, but the previous problems came back and Dick took his diagnosis to the next level by delving deeper into the carburetor.
Pulling and disassembling the carb further than he’d done previously showed some possible causes of the fuel system problems. “There was a little bit of crud from them sitting too long,” Dick said. Once again he set about the task of cleaning the surfaces of the carb, the jets, and venturis.
The thorough cleaning and adjustment seemed to help, but again, it was temporary. Soon the GT was once again not running correctly.
Occam’s razor wasn’t cutting it. Dick had to look at the more complicated – and difficult – possible cause: the fuel tank.
Removing the gas tank on many hot rods is a pretty easy task. It is not easy on an Opel GT.
As Dick painfully recalled, “You have to climb behind the front seats and remove several panels from below the rear window. Then you have to take out the spare tire and the shelf it rests on. Then there are four screws along the seam of the gas tank that hold it in the car. Once you get them out – which isn’t easy – you have to pull the tank towards yourself and wiggle it out of the car.”
Fortunately, Dick had the help of his son David for that last part. David is younger and more flexible than Dick is and he was able to finagle the gas tank out of the passenger side door.
Removing the sending unit (below), showed it had excessive rust, and had to be replaced. And by looking through the hole where the sending unit was, Dick could see that there was rust or sediment in the tank. He suspected that he’d found the likely root cause of his fuel problems.
Fresh Opel GT gas tanks are not a common part at swap meets, so Dick opted to try the Gas Tank Renu process. In the Renu process the tank is media blasted back to bare metal inside and out, any holes are repaired, and the tank is coated inside and outside with different proprietary Renu coatings.
Dick managed to get the tank back in the car himself, and set out to freshen up the rest of the fuel system. He had installed new steel fuel lines during the car’s build, and they looked to be in good shape. He blew them out with compressed air just to make sure.
Next he replaced all of the small rubber hose connections between the gas tank, fuel pump, fuel lines, engine compartment, and carburetor. For added insurance, he put a second fuel filter in series with the first to make sure the gas was completely clean when it reached the carburetor.
David had given Dick a book on Weber carbs and Dick found that the carb had some additional jets buried down inside that are not obvious – and are not easy to get out. Using a 3 mm tap, Dick carefully extracted these jets and cleaned them out.
“We got everything back together,” Dick reported, “and turned the key and it started immediately and ran perfectly… from fast idle thru the warm up cycle. It stepped down through the choke fast idle cams, and settled into a nice 800 RPM idle at full temp.”
William of Occam was wrong this time, the simplest solution was not the right one. But using that approach gave Dick a great blueprint for diagnosing and solving his fuel system problems. Starting with the simplest (which are usually the least expensive) possible solutions is a great way to approach – and solve – almost any hot rodding problem.
For more information on the Gas Tank Renu process,
check out their web site at www.gastankrenu.com
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