Here’s a thought. Maybe they could just add a knock out to the metal stamping die. Kinda like the knock outs on an electrical box. No need for cover or hardware unless you actually need to knock it out for service…just relatively minor tooling expense and no increase in unit cost…
Those knockouts are perforated. That is a series of holes that could allow fumes to enter the interior of the vehicle. Filling these slots with some potting compound would work, but there’s that added expense again.
You still have to re-do the die to get the knock out in there.
Some boxes are almost completely punched through with a tab left. Others are not all the way through and must be punched out like breaker boxes or perhaps like the newer soup cans you peel open. They’re weakened but not separated…
Bing, it could be added but I prefer to believe it should have been there in the first place as part of the original design. Not much add on cost when it’s being made initially.
…or, you can have the misfortune to own a Volvo from the '70s.
After the factory warranty expired, I wound-up replacing my '74 Volvo’s Bosch electric fuel pump every 11-12 months.
The good news was that I became very skilled with this repair.
The bad news is that this POS vehicle couldn’t seem to run for more than 1 year on a fuel pump before it failed.
1 Like
I would have looked for a way to hack a different brand of fuel pump into a car like that. Even if it required modifying the car.
Did that Volvo have an external fuel pump, which seemed to be common for european vehicles of the era?
Do you happen to remember if it was a Bosch?
And did that Volvo use K-Jetronic?
Yes, one of the few good things about that car was that the fuel pump was located above the tire in the left rear wheel well. I got very proficient at changing the damn thing. AFAIK, Bosch was the only brand available at the time.
The FI system was the mechanical Constant Injection system, IIRC. It was a major PIA.
I will admit to making my own access panel to replace the fuel pump in my Avalanche so I didn’t have to drop the tank. Cut through the floor guided by pictures off the internet and made a nice patch panel with foam sealing tape held in place by self-tapping screws.
BTW, the fuel pump itself did not fail, the pump assembly had lines outside the tank that rusted until they leaked.
Those old CIS injection fuel pumps took a real beating. Whereas a lot of FI systems run 30–40 PSI of pressure the CIS pumps ran double that.
The knock-out panel suggested by Twin Turbo is a great idea BUT somewhere a bean counter would be saying hold on a minute; that’s adding another 20 cents to the manufacturing process… 
The real “ouchie” came when it was time to replace the fuel distributor for those vehicles running CIS
They didn’t drop left and right, but when they did, it was EXPENSIVE
And from what I seem to remember, they always used considerably more fuel, versus comparable cars running EFI
I suppose it was superior to carburetors and TBI, but I wouldn’t necessarily say it was superior to EFI. Obviously, I’m comparing it to the EFI which was avaiable at the time, let’s say late 70s through early 90s
I also seem to remember BMW either didn’t use CIS, or if they did, they dumped it earlier than Benz did. I heard one of the british manufacturers . . . Rolls Royce, perhaps . . . used it several years after Benz gave up on it. But that wouldn’t be surprising, as the british vehicles were always quirky in one way or the other
GM sold 10 million cars worldwide in 2016. Let’s say half were really cars. Even if the cost to put a trap door in for the fuel pump cost 20 cents each, the total cost is $1 million. It could be more like a buck each. Losing $5 million in profit just to put that trap door in would be a tough sell in any boardroom. I’d like to have them in all my cars, but I understand why they don’t. Not just everyone’s favorite whipping post, GM, but all the manufacturers that don’t do it.
I doubt adding the cost of $1 would seriously hurt the car market, but then they could raise the price by $1.10, advertise how they build in options to save their customers hundreds if repairs were needed, $500,000 profit, good PR, Think it could be a sell in the board room.
I doubt that 1 out of a hundred people looking at a new car would even care if there was an access place for the fuel pump.
1 Like
Do you think the average customer is going to care if the vehicle has a fuel pump access plate or not?
They’re interested in the looks, power, fuel economy, trunk space, payments, etc.
I suspect far less than 5% of the customers would be interested in such a thing, when they go shopping for their next new car
Okay, so the fuel pump repair will be cheaper, if the car ever needs one. But then the customer will just talk smack, when the brake job is expensive, or it costs a lot of money for the next set of tires. You can’t win
Even if the fuel pump hatch was a feature added in on the production line at no cost whatsoever to the consumer it would never be mentioned during a sales pitch. Never.
That’s because the connotation could be the car may have a problem and no sales department will ever even come close to insinuating that while trying to sell a car.
BMW actually did use CIS in the late 70s/early 80s although I don’t remember the time frame. I know this because I’ve worked on a few BMWs that were fitted with it. They were equally cursed just like other Euro cars.
And yes that fuel distributor is extremely pricy on top of being a bit touchy.
I remember the VW factory rep coming around one month and getting POed at the negative attitude towards CIS.
According to him, CIS is a “forget it’s there” item as it NEVER acts up. Never. Ever.
1 Like
Remember that accursed “co tower” . . . the one with the ball that prevented messing with the adjustments, and the screws which could only be tightened, not loosened
As far as I recall, once installed, to do ANYTHING pretty much required carefully breaking that co tower off and installing a new one, and NOT installing that ball until it was absolutely certain everything was in excellent shape and all adjustments were correct. Of course, you could always “forget” to install the ball, which is something I did, from time to time.
If my memory isn’t totally shot, I think some Benzes with CIS had 2 . . . ! . . . . external fuel pumps. “Fortunately” on those models, the pumps were easy to replace, but pricey. And the fuel sending units were relatively easy to replace. In any case, easier than on your typical pickup truck
Back in the 80s at the SAAB dealer all, and I mean ALL, new CIS SAABs had a slightly rough idle right off the transport truck.
The CO on every one of them was around .75% which was the limit. I used to (in violation of Federal law) “adjust” every one of them to about 1.25% on the CO. They would idle smoothly then.
The biggest problem was that no potential customer would ever consider buying a new car that shuddered at idle so it was a “have to” procedure.
I figured that if something ever came down on me I would just play dumb and say it was at .75 when I did the PDI.
I’m not famliar with the CO ball. That must be a Benz quirk. The SAABs, VWs, and BMWs originally used a rubber plug with a wire loop handle for removal. This was eventually replaced by a tamper-proof aluminum plug which had to be drilled and carefully removed to access the CO adjustment.
No matter the option, there’s much better alternatives than CIS. Even the old Bosch AFC is better and SAAB replaced that with CIS. From the pan into the fire… 
Gotta kinda agree with OK. If a salesman mentioned a trap door to replace the fuel pump, you’d immediately think, why would I have to replace a fuel pump? Is this a problem area? Yadda yadda. Kinda like what they were afraid of back in the 50’s with adding safety features for fear the public would think cars unsafe.
1 Like
I’d probably make some comment about having to replace the fuel pump often if they made it so easy just to get the price down, but I’d be pleased that the trap door was there.