Stalling out when decelerating. HELP!

[gordon415]

Can't figure out what is wrong with my 02. I'm hoping someone here may have had a similar problem and know what's wrong, or can otherwise give advice. I've taken it to 3 mechanics - two reputable professional BMW mechanics in my area, and one general German car mechanic. None of them can identify the problem.

 

This is what happens: Occasionally, when decelerating to come to a stop or slow down at low speeds, the engine completely dies. Dash lights all light up. If I'm going downhill I can put it in gear and the engine will start up again. It will take anywhere from 5-15 minutes to restart the engine after this happens. It's a great way to make friends in traffic.

 

Here's a specific example from today: I was in second gear climbing a steep 22% grade towards a ridge (Marin St. to Grizzly Peak Blvd in Berkeley, for those familiar). All good getting up there and making it to the level ridgeline road. Went a few miles and slowed to come to a stop that was at a slight down grade and it stalled out about 20 ft before the stop sign. Took just about 15 minutes before it would start up again. Crank away, nothing. 

Second time on my way home, I was coming downhill to another slowdown to make a sharp left turn. Did it again. Fortunately it was my street and just popped it into 2nd and it ran beautifully to my house like nothing happened.

Just to be clear, this doesn't always happen going downhill, but it did today after picking it up from the mechanic who replaced the loose positive battery terminal (which they thought could be the culprit for the stalling, but weren't positive).

 

There may be a correlation with high rpms and the stalling. The first time this happened, about a year ago, it stalled out upon quickly decelerating after I was at very high rpm in 2nd gear going around someone who blew a stop sign and the stopped in front of me. Today it was after climbing a steep grade. 

 

Things that have been done or checked, but stalling still happens:

- Pressure tested - had a vacuum leak that was fixed

- Has spark

- Timing adjusted

- No problem with fuel

   - It stalled out when I was pulling into a gas station once. There was no vacuum suction when I took the gas cap off just after.

- Carb tuned and checked out - all good

- Coil - good

- Positive battery terminal replaced

- Voltage regulator replaced (not sure this would have anything to do with it anyway)

- I have a bluetooth 123Ignition (love that thing) and it was connected and working fine when the engine wouldn't start today.

 

My 2002 is mostly stock except for IE exhaust, bluetooth 123Ignition, and W&N extra cool radiator. 

Built 11/70, so considered a '71 but is still in the old style. 

 

Help!

 

(P.S. I have searched through the forums using the search function and have found some helpful posts, but haven't found anything that addresses my problems. Found a few things about the carb and fuel, but I've checked those and have had professionals check them too and all is good with them.)

 

Edited May 13, 2017 by gordon415
adding info.

[John76]

What carb are you running? This almost sounds like a bad float problem.

Did your mechanics check this??

['76mintgrün'02]

If you have a Weber replacement carb, the floats can be either brass, or plastic.  The settings are different for each, 40mm/35mm, I believe (please double check that though).  The brass ones can take on fuel, which you will hear/feel, if you remove them and shake em.  The plastic ones will actually absorb fuel and I believe you weigh them, to see if that has happened.

 

Is there any smoke out the tailpipe when it stalls?  Have you been losing any brake fluid?  The reason I ask is because I have read threads about the brake master cylinder failing and allowing brake fluid to leak into the brake booster.  When it gets full enough, that fluid will slosh into the booster's vacuum line and get sucked into the number four intake runner.  This will cause a poof of white smoke out the tailpipe.  I don't recall whether that can cause it to stall though.  I suppose it should start right up afterwards, even if it did.  It is the one thing that comes to mind, having to do with coming to a stop.

 

Have you inspected the fuel lines coming off of the tank in the trunk, under the plywood panel? Old cloth covered lines can let air get sucked in.  Installing a piece of hose that is too long could allow a kink to form, or a hose could be pinched, where it comes out from under the floor board, if something heavy was sitting back there.

 

All this seems a little far fetched, but I will go ahead and post, since I've typed it already. 

 

This is a good one.

[gordon415]

I have the original Solex carb. It was inspected by two mechanics who know more than me and said it was fine. BUT, I'm not sure to what extent they checked the float. The mahal choke mecganidn is stdrt tomkobfsdv 

Spiver I took the top of the carb off once and saw the float but didnt know better to recognize any problems. My only experience with carbs prior to this is from a moped, which is very different. 

 

Do you recommend replacing the whole float? Anything else? I'm kinda desperate e point and wiil try anything.

 

In terms of smoke, I haven't seen any.  The fuel lines were all replaced within the last 5 years. 

 

my brakes were inspected today and all is normal. 

 

 

 

[Simeon]

Might be mistaken but sure @NickVyse has had a problem (or suspects one) with his 123 cutting out. It sounds like an unusual one and the 123 is probably the most unusual part of it. 

 

What curve are are you running?

[NickVyse]

16 minutes ago, Simeon said:

Might be mistaken but sure @NickVyse has had a problem (or suspects one) with his 123 cutting out. It sounds like an unusual one and the 123 is probably the most unusual part of it. 

 

What curve are are you running?

 

my problem with the 123 was voltage spikes coming from the regulator that had the overload protection cutting the thing out for a split second. 

[dang]

Have you been able to test systems WHILE it doesn't start or has it always been after it starts again at a different time?

['76mintgrün'02]

8 hours ago, gordon415 said:

Do you recommend replacing the whole float? Anything else? I'm kinda desperate e point and wiil try anything.

 

I recommend inspecting the float, but only replacing it if you find a problem.  It seems like a 'sinking' float would not be so intermittent

... so I may be sending you in the wrong direction there.

8 hours ago, gordon415 said:

The mahal choke mecganidn is stdrt tomkobfsdv 

Spiver

?

 

[Stevenc22]

What kind of choke? Choke might be set too tight.

[gordon415]

Manual choke. It's linkage is worn, but works fine and the mechanic tested it to make sure all is as it should be. The problem happens on cold and warm days, whether I used the choke or not. It has never stalled out while the choke was engaged. 

I think that's what I was trying to type that turned into gibberish in my last response. (Trying to type on my phone, tending to a screaming baby, and doing too many other things at once). 

 

I have not not been able to have it tested just after it stalls out. And one place I took it to tried to replicate the problem but it didn't stall out when they test drove it. It'll go through waves where it will be fine for several days and many miles. Rarely will it stall out more than once in a single trip. After it got a tune up in mid March, it ran beautifully up until the first week of May when it stalled out again. 

 

Ignition curve - I set it back to the original curve that was preprogrammed with the distributor. 

 

I had voltage spikes, too, which I discovered when I upgraded to h4 headlights and my low beams burned out twice. replaced the voltage regulator yesterday but stalled out even with the new one in place. Would the voltage spikes cause permanent damage to the ignition? Although I opened the app yesterday while the car would not start and it was connected. 

[HBChris]

What coil and ballast resistor do you have?

[Healey3000]

Is your fuel pump electric or mechanical?  Not being able to start the car for five to fifteen minutes after stalling sounds like a flooded engine (or vapor lock in the fuel line).  Either fuel, oil or coolant is getting into the cylinders during high suction periods, such as decelerating from high RPM.  I'd probably discount the possibility of it being coolant or oil but you never know.  Have you looked at the spark plugs in the stalled state?

Edited May 13, 2017 by Healey3000

[gordon415]

Bosch blue coil. See pic. I am not sure what else is going on there. 

 

Mechanical fuel pump. I have no idea when it was changed last and I've thought of replacing it. Maybe I should. 

I did not get any suction when taking the gas cap off after it stalls.  I thought it could be a flooded engine too. 

The spark plugs get spark even after it has stalled. I haven't removed them to see the color but they're working. 

[HBChris]

You shouldn't use a ballast resistor with a blue coil, it reduces your spark, but that isn't the problem unless coil is old and it overheats.

[jgerock]

What bulbs are in the H4 headlights?  Does the car stall when the lights are on? No matter what the responses are, I highly recommend adding relays to the high and low beam circuits.  Susquehanna Motorsports sells a wiring harness kit that works well and you don't have to modify the stock harness.