BMW 528e

1985 BMW 528e Engine Hesitating When accelerating Always

engine hesitates a little then accelerates normally then hesitates again and continues to do this under normal acceleration so it feels like the car is surging. under full acceleration it is not as apperent, you can still feel a slight stumble that still pulsates/surges. Car has 94,000 miles, had it since new. Automatic and all svc is current. could it be carboned up vales ? or fuel/air mixture control or both ?

Thanks,

John

THis is most likely a sign of tarnish or sludges have accumulated in the fuel deliver system. A good going over the fuel system with a quality fuel cleaner should help. Also take the time to clean the Map and Mas sensors with some carbarator cleaner. And finally, when was the last time you did a tune up on the engine? Let me know and we can proceed from there.

tune up was about 20,000 miles ago but a few years. sounds like a tune up, adj valves, mas & map scrub along with throtlebody scrub too.

I would start on the Map/Mas and see what effect it has. No sense doing extra work unless you enjoy that. Let me know..

1985 BMW 528e Engine   

Hi, I recently changed the alternator in my 1985 bmw 528e. When I put all the wires back on and the air cleaner back on, I went to start my car and it wouldn't turn over. I'm getting spark but no turn over. I checked all the fuses and relays, and all are checking out to be fine with a test light. Please help.

Hello, Do you have an Owner's Manual?

I'm going to look to see if disconnecting the battery will cause a security system issue upon reconnect....

Roger

Yes I do, I also have a Haynes Repair Manual for my car. Right now I have the battery disconnected hoping that it will reset the computer and I'll try starting it again when I reconnect the battery.

I didn't see anything in replacing the alternator that would effect security system function.

I did notice when reconnecting the battery the steps are connect negative first followed by the positive.

Did that happen?

Roger

No I took the positive connector off the battery only, should I have disconnected the ground too?

Yes, I believe so. Further to blled all memory down I hold the foot brake down for one full minute while the battery is disconnected before I reconnect the battery.

This extra hoop I jump through is a habit I found useful particularly on Fords and I do it as a personal commitment.

Roger

How long should I leave the battery disconnected for?

Ten minutes is all I feel is necessary.

Roger

Ok I'll go reconnect the negative wire on the battery now

I'm not really expecting a miracle here. My thought is to follow the written instructions and see what happens. Here's hoping...

Roger

I just reconnected the battery and still no start... it has to be something with the fuel don't you think? Do you think it could possibly be the fuel pump relay? I already replaced the fuel pump fuse so I know its not that. I mean how could changing an alternator cause this problem?

I'm perplexed that changing an alternator would induce this problem.

There is a Bulletin about fuel pump relays that talks about not mixing brand names. But you didn't replace a relay.... and when I read the bulletin it was concerning the 325E.

I'll look at the info again. Do you have spark?

Roger

Yes there is spark going to the engine

Then there must be a fuel supply problem. Have you located the fuel pump relay socket? With the key on how many terminals have power?

I would expect that two should. Can you jumper the terminals and make the fuel pump run?

Roger

We used a test light on the back of the fuel pump relay where the wires from the battery come in and 4 on 4 of the wires the light lit up and the 5th wire a brown one didn't light up. If the relay was bad would the wires coming out of the connector have power?

Do you have a wiring schematic? If you'll advise your email address I can send one to you.

What I have shows four wires to the fuel pump relay and a fuse #1 (15 amp) involved.

Roger

My e-mail is [redacted]

The diagram is on the way.

Bedtime here,

Roger

Hey, we just sprayed gas down into the enging and the car ran so it is definetly fuel/electrical related... any info?

Have you used the wiring diagram to test for power and ground on the fuel pump relay socket?

Using the diagram you can also see which wires to jumper to make the pump run.

Roger

The fuel pump has power we went under the car and put a test light on it and it lite up... as far as a ground we connected the test light to the one wire on the fuel pump and to the hot and it lite up

Can you test fuel pressure? What is it?

Is this engine fuel injected or carb?

If fuel injected test the injector connectors for power when the key is ON. Check for pulse of voltage when the engine cranks.

Rog

It's fuel injected, where are the connectors for the fuel injectors?

Each injector has it's own connector attached. One wire is power and the other is ground path to the computer.

R

1985 BMW 528e Fuel System   

"Hi, I recently changed the alternator in my 1985 bmw 528e. When I put all the wires back on and the air cleaner back on, I went to start my car and it wouldn't turn over. I'm getting spark but no turn over. I checked all the fuses and relays, and all are checking out to be fine with a test light. I also sprayed gas down into the eniging and it started, so it has to be fuel. Please help."

Always check fuses when you have electrical failure especially after electrical parts replacement.

You may have fuel pump failure that just happended to show up now, but I'd check fuses/links/connections first.

Was the battery disconnected during replacement?

we just check the fuel pump and it has power going to it... all fuses are good. Any other ideas?

If the pump has power going to (positive and ground) and is not operating the pump is defective.

But how can changing an alternator cause a fuel pump to not work? Also there is no noise coming from the fuel pump when the key is turned and try starting the car.

Is there is power to the pump and it don't do anything, that would indicate it is defective. How are you testing for power?

You need to first concentrate on fuses, links, etc, especially if the battery cable wasn't disconneted in which case wiring can easily short.

Im using a test light... I put the test light on the ground wire on the fuel pump and the hot wire and the light lite up... but when i turn the key the fuel pump makes no noise... where is the fuel pump relay located?? I thought that it was right next to the fuse box, but the picture of the relay on bavauto.com looks nothing like the relay that is next to the fuse box

Does the test light go off when the key is turned off, this would confirm you have the right wires.

Yes

1982 BMW 528e Fuel System Won't Start When starting No pattern

About half of the time...this happens. When we try to start the car, it turns over, but it won't start...it sort of seems like it isn't getting the fuel. We have to hold the accelerator down to the floor to get it to catch, but sometimes that doesn't even work, and it'll start to sort of sputter. A lot of the time it'll take 5-6 tries to get the car running. Once it's going, the engines seems great. We thought maybe the fuel filter or pump need to be replaced? Thanks for your help.

If you spray carb cleaner into the carb/throttle body does it start sooner? Be careful with the carb cleaner, it's extremely flammable.