I've got a stalling issue on my wife's 1993 Volvo 240 Classic wagon with the super rare manual transmission (not that it matters in this case), and I could use some assistance from the group. After swapping all the typical items like the white fuel pump relay, fuses, AMM, computers, pressure regulator, cleaning grounds, etc, I was able to isolate the problem to the fuel delivery system as I'm able to keep the car running on starting fluid being blown in via a vacuum hose to the manifold.

Having recently blown a main pump on my 740, I replaced the main pump and filter on this car, but without improvement. If anything, it got worse. The car could run for 5 to 7 seconds previously, and now it only runs for 2 to 3 seconds. I repeated the replacement again just in case the first two were bad, but still no success (so she's on her 3rd good/used pump now). I also re-installed the original pump on my 740 and it's running fine with it. Moving on to the in-tank pump, I found the factory original AC branded one to be intermittent and replaced it with a bench-tested good identical replacement but the stalling issue remains.

I'm grabbing at straws here. I can validate the pulse data signal coming from the flywheel position sensor with my oscilloscope, and likewise have checked the fuel injector pulse width modulation to see that it has good strong square waves while it's running and stalling out (thus not caused by the computer leaning out or shutting down the engine). Ignition problems are ruled out because I can keep the car going with starting fluid.

What am I missing here? During all the pump changes I believed I may have kinked a fuel hose from the filter outlet that runs forward to the fuel rail. -could it have kinked enough to cause this behavior? (while previously suffering from a clogged filter that's now out of the picture) I doubt it, but it's a possibility... What else could fail or get clogged to allow a brief startup but quickly followed by a stall out?

Any thoughts, suggestions, or advice would be greatly appreciated. Another friend's 240 recently was suffering from random stalling issues, that would resolve themselves in about 5 minutes, and a mechanic (not me) finally discovered some candy bar wrappers and pine needles floating around in his fuel tank that would randomly clog the in-tank pump takeup foot/screen. I have checked inside my tank and this is not the case...

I may end up building a temporary & separate fuel supply system with a pump and new filter running from a 5 gallon gas tank, just to verify the integrity of the rest of the system and narrow down my list of culprits.

Thanks in advance for any advice, and also a huge thanks to Art for maintaining his website and doing the research for us to benefit from on this topic. http://cleanflametrap.com/transferPump.htm

God bless and have a great day,
Fitz Fitzgerald.

'93 245 B230F with M47
'90 745 B234F
'88 780 B280F
(and formerly a matched pair of his & hers blue and silver '87 245 wagons that were driven till they rusted out at 385,000 miles and 435,000 miles)