Deterioration at Temp

[wit61]

I have broken a basic rule and replaced several items over the last few months and now I have an issue that I'm sure was not there before. Prior to changes, the car ran a little sluggish, but no real concerns. Anyway, before I start undoing things. I thought I'd try the collective wisdom of this forum.

Here's what I replaced/repaired :

Cap and Rotor (not points which looked ok)
Plugs and plug wires
Fuel filter
Plugged a quarter-sized hole in the lid of the airbox (made by the PO)

Here's what happens now :

The car starts and idles fine (a little smoother even)
Gradually as things get up to temp, a miss develops at higher rpm and gets progressively worse (ie: becomes evident at lower and lower rpms and becomes more pronounced) until the car loses power and stalls. Letting the car sit for a while clears things up and the cycle repeats.

Here's what I'm thinking :

I'm not sure that I can point to anything I did that would produce these symptoms, but the basic diagnostic process says I introduced the change. Where would you start? Any/all ideas welcome......

1964 230SL Auto
1970 Porsche 911E
1972 BMW 2002tii


If you go flying back into the past and you see someone flying forward into the future, it is probably best to avoid eye contact...

[glennard]

Crud in the tank?  Make up fuel into "Shroud of Fuelin" plugged.?

[ja17]

Hello wit61,

Glennard may be on the right track.  Try adding some more fuel to the tank to raise the level above the "flower pot"



Joe Alexander
Blacklick, Ohio

[Cees Klumper]

Maybe the new fuel filter is just that bit more restrictive that the lack of proper fuel flow caused by the fuel tank being contaminated now shows up where it did not before. There's a similar situation being discussed now at another thread where a problem arose even though the owner did not do anything that would seem to have caused the problem. I had such a situation last year also, when I swapped out my fuel injection pump; the car immediately started running poorly so I swapped the old pump back in - then it turned out the poor running condition was a bad spark plug, rather than anything to do with the injection pump.

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

[wit61]

OK,

I pulled the fuel filter and it was filthy so I thought AHA ! I dropped the tank and cleaned it out (some varnish) and cleared the intake hole in the flowerpot. I put everything back together and took the car for a ride. It took a much longer time, but the same thing happened. AAARRGGHH !!

I do have the smaller older fuel pump and have heard of vapor lock problems with them. Could that produce these symptoms? Fuel distributor? I'm still stuck on why it seems to be temperature related, and why sitting for a few minutes with the engine off makes it go away.

I do have a Crane 700 unit which I have been hesitant to install since I don't want to introduce yet another factor, but I'm thinking of turning to the ignition side of things if fuel is ok. Thoughts ?

1964 230SL Auto
1970 Porsche 911E
1972 BMW 2002tii


If you go flying back into the past and you see someone flying forward into the future, it is probably best to avoid eye contact...

www.classicvelocity.com

[bpossel]

Hi Wit61,

Based on your original post, you stated that the car ran ok before you changed out the rotor, cap, plugs, wires, fuel filter and plugged a small hole.  

Obviously the add'l work on the fuel system sounds like it was needed. Since the fuel filter was dirty, did you replace it again?

I would suggest to keep it simple and stick to the items that you recently replaced.  As odd as it sounds, I would re-install the old plugs, wires, rotor and cap.  Then do a test drive. If it runs ok, then start to replace one item at a time and do a test drive to narrow down the exact issue.

It's only labor and time.  Dont introduce anything new at this point, ie the Crane.

Good Luck!
Bob

bpossel  (Memphis, TN.)
'71 280SL  /  '97 E320

[ja17]

Hello wit61,

Check to see if your electric fuel pump has the screen built in the intake fitting of the pump, it may be clogged.  Some of the earliest versions did not have a screen however. These screens are very small and clog easily. The fact that it took a much longer time to occure, leads me to believe you are on the right track.

Joe Alexander
Blacklick, Ohio