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THIRD time's a charm...
'77 630CSi (e12 chassis, help?)

I've had this car for a few months, but rarely driven. Ever since I've owned it, it hasn't wanted to rev above about 3k. Seems like it runs out of breath.
Luckily I can go 70 in 4th at about 3k. PO mentioned the need for a fuel pump, but there were larger issues, so I didn't mess with/LOOK at it till now.

Like the title says, no change whatsoever from my trip to and from Vintage (1000 miles), except now she'll crank and crank, but no run. I got underneath the car, and found that the fuel pump and filter bracket was on backwards, with ONE bolt, and three zipties. With a loaded suspension, it appears that one of the rubber fuel lines was rubbing on the pass. side halfshaft...

Another "oh, by the way" we found that the AFM door was sticking a little bit in it's track, but putting in a non-binding AFM did NOT fix the "breathless" act.

A few questions:

1) I found this "expansion tank" welded to the fuel filter and pump bracket. Am I okay just leaving it out of the loop? If so, I guess I'll cut that tank off the bracket one of these days...


2) I have a one pump (external) system, is the fuel gravity fed? When I pulled the pump off the feed line, I expected a little bit of fuel, but my expectations were overwhelmed with a flood and an ALARMINGLY large and spreading puddle of fuel very quickly. After a few seconds of panic and trying to blink and spit fuel out of my face, I plugged the line with my thumb, pulled the new pump over with my foot and unwrapped it with my free hand, then popped that baby on the line. Whew!

3) We tried the AFM trick, and hear the pump running, but we still have no run. I guess next I need to check spark? Points? I'm really leaning towards new points and cap and that may solve our start problem, and the unwanted 3k revlimiter, what do you think?

I'm not sure about the fuel pump issues - there is an in-tank pump as well as the one you're having so much fun with under the car.

Regarding the "soft" 3k rpm rev limit, I've encountered this several times, and embarrassingly, the most common culprit seems to be that I've usually reattached the intake boot from the AFM to the throttle body in such a way that the hose clamp is preventing the throttle from opening fully. You might check that for the first and hopefully easiest fix.

Basically, the throttle lever contacts the screw on the clamp preventing the throttle from opening fully. Beyond that, again, I'm stumped. To borrow a phrase from GripGreg, my shade tree is still rather small.

Keep us posted!

The pump isn't gravity fed, but it can syphon nicely. On the accumulator you can bypass it if you want, BMW played with a couple of different things like that for a while before dropping all of them. Points and condenser are cheap, if not long lasting. Points especially. Throw a new set in if you're having problems, at worst it won't hurt anything except you'll have to retime it.

You can check for fuel pressure/fuel regulator issues by partially clamping the fuel return line. Do that, take it for a drive, and see if it changes anything. If it does, you probably have a bad regulator.

grumpsjr wrote:Regarding the "soft" 3k rpm rev limit, I've encountered this several times, and embarrassingly, the most common culprit seems to be that I've usually reattached the intake boot from the AFM to the throttle body in such a way that the hose clamp is preventing the throttle from opening fully. You might check that for the first and hopefully easiest fix.

Basically, the throttle lever contacts the screw on the clamp preventing the throttle from opening fully.

That happened to me when I first had my e12 and I was taking my girlfriend for a first ride. She sure thought it was a lame car

Still having trouble, guys.

Replaced fuel pump (external) cap, rotor, filters, installed Pertronix and new coil.

I had fuel with key in start position, I have grounded a plug wire and plug on separate occasions while trying to start, there is spark.

The door for the AFM was opening while trying to start, but after I tightened everything back together in the Combo Relay area, AFM is inop.

I can hear the Combo Relay clicking pretty hard when trying to start.
What is the relay ON TOP of the little panel there with the red white and blue capped Emissions crap?

I'm leaning towards something electrical, as the car ran the 1000 miles to and from Vintage then decided one day not to run.

I had been messing with the AFM before it stopped running. I traded an 001 AFM (stock for 630 that has a binding door) to an 004 AFM from a 530 (should work, right?) Now the car does not run with even the old binding AFM in it.

Any help would be awesome, I just want to drive her.

Sorry to hear that you are having trouble still.

Start with the basics....

Do you know if you have fuel pressure? I imagine that you could disconnect the return line in the engine compartment, coming out of the pressure relief valve...put it in a suitable container...turn on the ignition and see if you get some flow. If you do, then you know that the system is pressurized enough to flow past the valve. I am assuming that this is a test that would work, but going on the little that I know. More may chime in on this one.

Do you have spark? Pull and spark plug wire...put a spare plug in it....rest it on the engine and crank the ignition....do you see a healthy spark at the plug? A nice blue spark.

Do you know when the car last ran properly? If you do, do you know what has been touched since then?

Blaise

Blaise wrote:Sorry to hear that you are having trouble still.

Start with the basics....

Do you know if you have fuel pressure? I imagine that you could disconnect the return line in the engine compartment, coming out of the pressure relief valve...put it in a suitable container...turn on the ignition and see if you get some flow. If you do, then you know that the system is pressurized enough to flow past the valve. I am assuming that this is a test that would work, but going on the little that I know. More may chime in on this one.

Do you have spark? Pull and spark plug wire...put a spare plug in it....rest it on the engine and crank the ignition....do you see a healthy spark at the plug? A nice blue spark.

Do you know when the car last ran properly? If you do, do you know what has been touched since then?

Blaise

We pulled the feed line from the "T" before the rail and I cranked. Fuel poured into a juice bottle. We didn't measure it or anything, but it looked pretty good.

I have spark. That is exactly how I tested. new plug, blue healthy spark.

I'm really starting to lean towards a combo relay, or something in the area, but I don't have a ETM for '77 630... grrrrr

I guess I should check timing, too, as it wasn't running the GREATEST before it quit.

ldsbeaker wrote:We pulled the feed line from the "T" before the rail and I cranked. Fuel poured into a juice bottle. We didn't measure it or anything, but it looked pretty good.

I have spark. That is exactly how I tested. new plug, blue healthy spark.

I'm really starting to lean towards a combo relay, or something in the area, but I don't have a ETM for '77 630... grrrrr

I guess I should check timing, too, as it wasn't running the GREATEST before it quit.

While you are probably right about having fuel, checking past the valve would tell you if it is up to standard pressure.

Sounds like you have good spark. Did you test all the leads? You might as well be sure at this point and check.

Why do you suspect the combo relay? I imagine that it did the same thing in the 630 as in the E12. My understanding is that this relay fires the fuel pump (yours seems fine) and provides power to the ECU (engine harness). Check out the article in FAQ and you should be able to verify that it works.

Here is the diagram for a 1977 630csi:

These are high resolution photos....just click on it....go to the photo and click on the magnifying glass icon above the photo. You should be able to view any detail you need.

<table><tr><td><a href="https://picasaweb.google.com/lh/photo/6 ... site"><img src="https://lh3.googleusercontent.com/-GSPq ... _00135.jpg" height="288" width="215"></a></td></tr><tr><td>From <a href="https://picasaweb.google.com/1030509870 ... te">Wiring diagrams BMW</a></td></tr></table>

Here it is for a 1977 530i:

<table><tr><td><a href="https://picasaweb.google.com/lh/photo/T ... site"><img src="https://lh6.googleusercontent.com/-y-Tw ... _00134.jpg" height="288" width="215"></a></td></tr><tr><td>From <a href="https://picasaweb.google.com/1030509870 ... te">Wiring diagrams BMW</a></td></tr></table>

You may consider looking for a vacuum leak. Any intake plug that has fallen off or cracked could cause one.

Thank you soooo much for the diagrams and replies!

(By the way, your build is quite impressive, I'm jealous!)

Just to add to the amateur maybe's,...

Guru Lenny D. always starts with grounds. Every last one anywhere, all clean, polished, like new or,...after thirty years, clipped, re-soldered on a new end. New braided straps, no exceptions.

Just for fun, a long time ago I had an ignition control unit ( spendy aluminum box bolted to the inner fender ) go bad. Turned out the healthy looking spark just looked that way. The bad unit wasn't doing its booster job so the engine killed, ran goofy, caused head scratching.

I might +1 on the grounds theory. That car sat outside in the mud in PA for quite a few years before finding its way back into good hands.

MikeB7 wrote:I might +1 on the grounds theory. That car sat outside in the mud in PA for quite a few years before finding its way back into good hands.

Thanks for checking in, Mike!
It's amazing, the more I dig into this car, the more I see that it WAS loved intensely at one time. Bilstiens, H1/H4 headlights, my friend said it has the brightest tail lights he's ever seen. Little stuff that makes a huge difference.

The paint is pretty dead, but once I get this electrical gremlin nicked, it's going to run awesome. Then I can REALLY justify some intense cleaning and love. (... and maybe show my ugly mug over at BForums again...) I put in an E21 sport wheel, and it sets off the interior so well.

Yes, it was once somebody's baby. Definitely worth saving, and I'm glad you are.
(Ok, maybe a little disappointed that it isn't me, but I had my chances!)