Great Forum. I have a 1991 740 wagon with Regina coil/fuel pump. Recently it stopped running 5 minutes after a cold start. You can keep it running in neutral with a lot of peddle fluttering, but the engine blubbers like it is running out of gas. Put it in gear and it stalls.

We put a new fuel pump assembly in (part # 3507495) and are getting 45psi.
It runs like a top for 5 minutes, then stalls again. Any suggestions?

Dennis5353

 

are there any errors on the OBD (onboard diagnostic) blinky-box ? you don't need any tools to read these, the ECU (fuel injection) is on pin 2, the ICU (ignition) is on pin 6, and the button and LED are built in, you push the button and count the slow blinks.
Engine and OBD Diagnostic Codes


I wonder if its running too RICH rather than running out of gas? maybe the ECT (engine coolant temp sensor) is misreading. maybe the cold start injector is stuck open. you'd probably smell gas fumes at the exhaust when its struggling if this was the case

 

Try unplugging your mass air sensor and see if it stays running that is a cheap way of testing it for anomalies without buying a non returnable item!

 

Thank you both very much. I will try those things on Monday. I forgot to mention I replaced the battery 3 months ago. The car ran fine after that, although there were problems with the return fuel line leaking at the time. I have read the car must re-learn after a battery change. Could the change of battery be related to my current problem?

Thanks again: great forum

Dennis5353

 

Codes are all good: 1-1-1.

dennis5353

 

My mechanic gave up. He pulled codes with nothing found. He tested cold start injector, ect, oxy sensor, mass air. He said he can't figure it out: it always runs fine for 5-10 minutes, then sometimes it seems to run rich, sometimes lean.


I'm still trying to figure what is wrong. Any ideas?


Dennis

 

i have zero experience with regina systems.

maybe the ECU itself is conking out when its electronics warm up? bad capacitors on the circuit board or something.

 

Just a quick update. The intake air temperature sensor was loose and not directly in the air flow, so ecu always thought it was cold, so always running rich.
The Reginas do not have a MAF, but this air temperature sensor instead. Also replaced the preheat hose (50mm x1350 flex) from the exhaust manifold to the air box. Without that hose, the intake air does not get warm.


Also, the manifold connection (rubber elbow into hard plastic line) to the MAP sensor was badly cracked, allowing a bad reading to the MAP. Replaced that elbow.


Line from the intake manifold to the flame trap (3/16") was missing and nipple on manifold was plugged (intentionally). Replaced the flame trap and the 3/16" line.


Removed throttle body and air intake hoses. The crud in there was really something. Ice and gunk covered the invert of all surfaces. Caused by rich running or bad flame trap, I don't know, but I cleaned them up and paid special attention to the small openings.


Finally, I replaced the cap and rotor as the old ones showed evidence of arcing.


Thanks to all who helped: great forum!
Dennis