BJ40 1976 Fuel feed pump problem (1 Viewer)

[Erwin]

After 6 years of resto I finally got the license plates on the car. And on the first test run the engine started to stall after a few kilometers. What a drag...
The engine has been fired up regularly during those years, and I have driven it some meters just to keep it alive. No problems with the engine.
It is pretty sure it is the feed pump because if I use the priming pump when it starts to run uneven it is good again at once.
Both the valves 22515 are new as the old ones had a tendency to get stuck. System is bled for air.
Any suggestion?

 

[roalco]

Hi Erwin, it sounds like you are slowly sucking air from the tank side of the pump. If you can pump while the engine is running, you have air in the system. My experience is that unscrewing the pump when the engine is running will shoot the pump plunger out fully, and it will be impossible to depress until you relieve the pressure by stopping the engine and opening the filter bleed screw. Start at the pump inlet banjo fitting, remove both copper sealing washers and anneal them to soften, then reinstall them and tighten up the banjo bolt. These seals work harden and often cause small air leaks. If no joy, start heading back up the line to the tank, tightening everything. The B series engines are delightfully simple, and almost anything can be fixed, just be careful and methodical! Good luck!

 

[Erwin]

@roalco
You have a good point there about the priming point. I will certainly check that out.

 

[Erwin]

@roalco
Seems like that did the trick. Annealed the washers and tightened all clamps. Seems ok now, will test drive tomorrow.

 

[roscoFJ73]

If you have a problem with it again, just replace it with a Bosch unit used on Mercs. Cheep fix

 

[Erwin]

Hm, still not good. BUT, after some browsing of this forum it struck me, the return line! I haven't paid much attention to that and the hose was old and stiff. Only the return line I thought... But on these cars they are on the suction side of the pump, and any leakage here means air is sucked directly in. So I changed it, and all looks good, so far.
That is also the beauty with these cars. They are so simple that you actually can understand how they work. Not like moderns that are a bunch of interconnected black boxes.