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1979 BMW 528i fuel problem

I have owned this car for nearly 4 years and it has been a very reliable car this is fun to drive. When I bought the car, the license plate tags were dated 1995, indicating the car hadn’t been driven in at least 11 years. After purchasing the car I soon discovered that the fuel tank had rusted and their was a considerable amount of rust in the tank, causing it to die in a way that it felt like it was running out of gas. I had the tank replaced and that helped. For as long as I can remember (at least 3 years) on a cold start it felt like the car wasn’t responding to the gas pedal. It could be floored and I may only be traveling 15 mph. This would continue for up to 6 or 8 blocks, then would run perfectly fine. To me, it felt like there was some kind of obstruction in the fuel line. I have also thought that there is perhaps moisture in the tank, so I have added heet to the gas on a few occasions. That hasn’t seemed to help much. I told my mechanic about it, whom I trust. He said not to worry about it, that this model is often sluggish. Now, however, this fuel problem is happening sporadically. Cold start or not. Even when the engine is warm. It happens most especially up hill and often I am only able to go 30mph. Down hill it is better. It seems to not do this as often if I have been parked on a downward slope. It is worse if I have parked on an upward slope.

Today, for the first time ever, the car went completely dead when I put it in park. It would not restart. I jumped it and drove home, but it went completely dead again when I put it in park. I would not restart. I monkeyed around with the gear shift (automatic transmission) and got it to start for a nano second, then it went completely dead again.

I think these two problems are unrelated.

Can you help me figure this out? Many thanks.

It’s 31 years old…It’s an antique. How many miles on it? Is it fuel injected? If so, that would be the old Bosch mechanical system with a jeweled movement air-door controlling things…All if this stuff must be kept spotless to work right. The big rubber hoses must be air-tight, no leaks anywhere…

If it’s carbureted, good luck…

It only has 115,000 miles. Can you believe it? My mechanic says it will run forever. I don’t mind spending a little $$ to make it run since I love it so much and bought it cheap. It is fuel injected. What do you make of it completely going dead once its in park? Anything? Weird, right?

Replace the fuel filter and test the fuel pressure.

Remove and clean the battery terminal connections, replace any badly corroded ones.

Replace the “neutral safety switch” that’s buried down in the shift mechanism…If it won’t start in “park” try starting it in “neutral” until you can get the switch replaced…

This car is not ‘sluggish’ when everything’s running right. I almost bought a used one 15 years ago, they were old then! Is your mechanic a good BMW mechanic? You need to have this gone over, including the ignition, fuel injection, compression, valve adjustment, and vacuum hoses. The 528i was outstanding when new, I loved driving my friend’s back in 1979.

my mechanic works only on bmws and has been in business since the early 70s. I think he is great.
I completely agree that it should not be sluggish. (!) He is reluctant to tinker with things until he knows for sure it needs work. I like that about him. I feel like he doesn’t waste my time nor money. I saw him today and made an appointment for him to replace the fuel pressure thingy. I’ll be sure to have him check the things you’ve suggested. Thanks for your help.

Thanks for your help! It started in neutral. I put it in park and it didn’t die. Is it common for a faulty neutral safety switch to work sporadically?

Good, nice to have a thoughtful mechanic instead of a ‘throw parts at it’ one. The 528i was one of the best BMWs of that time, cited as a ‘best used BMW buy’ in Car and Driver several years ago. If that one I had looked at hadn’t been all beat up I might have bought it…oh, well!

Just my opinion but if the gas tank was badly rusted the fuel pump and the filter should have been replaced at that time along with thoroughly cleaning out the fuel lines, IF that was not done at the time of the tank replacement.

The Bosch fuel pumps used on BMWs, SAABs, VWs, etc. are heavy duty pumps that are subject to higher pressures and more abuse than “normal” pumps. This can also cause them to have higher than normal commutator wear (part of the pump motor) and this can affect the pump even on a car that has not seen any rust at all.

The only thing that surprises me is that it ran at all on that pump and the mechanic is incorrect by stating that sluggish running is normal. It’s not.

Now the 528E could very well deserve the “sluggish” lable but the i was a great performer, for a salesmans car, come to think of it 79 may have been a little early for the E engine. Great gas mileage from the E’s but they were a timing belt engine as opposed to the chain in the i’s.

I never truly hated a system on a car until I met up with CIS, well and then there were the inboard brakes on Audi 100LS’s. Can you imagine inboard disc brakes? I ask you, why?all a product of the 70’s. Got fired once for telling a customer the Pinto was just as good as a VW bug,did I deserve it?

“Got fired once for telling a customer the Pinto was just as good as a VW bug,did I deserve it?”


The Audi was not the only car with inboard brakes. The early 70s Subaru FF1s had inboard DRUM brakes that were buried above the subframe and had a wad of springs like many of the old domestic cars. These were a real pain to do a brake job on (thankfully I never saw many of them) as it involved working blind through a hole in the inner fender and with one arm over the subframe.

Flat rate paid something like 7-8 hours just for a front brake job. Ouch.

Right up there with CIS which brings up a question oldschool. There is a site (forget which one) dedicated to CIS and the people who run this site refer to CIS as being the greatest, most trouble-free FI system ever. They say this system seldom ever needs to be touched other than regular fuel filter changes.
I say they’re space aliens. What say you? :slight_smile:

I also have gone to web sites that promote CIS this way, it really makes me feel I missed something in class as I did have quite a few problems with it. That being said I am sure there were quite a few customers that had problems also.The main problem I saw with CIS was its intolerence for dirt,expensive parts, and general complexity when it was not needed, besides things just falling apart. As a VW mechanic I felt right at home with CIS (stuff just falling apart I mean)

Mercedes of all brands stuck with some version of CIS throught most of the 80’s. So I should not have spoke poorly of the bug. OH well, the guy that fired me sold the garage and bought a sandwich shop,then went broke,so much for his business sense.

"“Got fired once for telling a customer the Pinto was just as good as a VW bug,did I deserve it?”


No…The Pinto did EVERYTHING better than a VW Bug…

One other ‘reliable’ car with inboard brakes: Jaguar, at least the E-Type.

I tried to start the car in neutral this morning and it wouldn’t start. It is completely dead. It won’t turn over, but not in the battery ran out of juice kind of way. It is just dead. Analog clock stopped at 6:30, around the time I started it last night. Any ideas?

Do you think the idea with inboard brakes was keeping the weight hung out there on the control arms to a minimum?

I got my Audi job as a very new mechanic, it was a job that thoroughly destroyed my confidence in my ability. I came to find that all the other mechanics refused the job.

That was the reason; keeping sprung weight to a minimum.

There’s a lot of cars out there that are confidence destroyers; or they at least try to be. :frowning: