I didn't spill any fuel doing this:
And if you pull the electrical plug for the tank pump/sender, you could connect an external battery to test it with reversed polarity. The tank pump is centrifugal, so it won't "suck", just be a little weaker if the polarity is reversed due to the angle in the pump's volute.
Not sure how much volume a stalled main roller cell pump will let by depending on its age. One 3 years old might be pretty tight yet.
On the CI cars, I?d block the return to test the main pump? if the pump briefly stalled or immediately wrapped the gauge to the ~150psi internal relief (whatever that is in metric units?) I?d pronounce it ?serviceable?, especially if it sounded smooth/ current draw looked good on the scope with the brushes turning each winding on & off?
Idk what the hell im doing?
If it cavitated, sounded gurgly or was at all slow to build pressure, I?d pronounce it ?marginal at best? as main pumps go?
?78-?85 supposedly has a 3psi lift pump, ?86+ has a 6psi tank pump.
On the 240Ts, I?d cut the tube on the sender and use the tall 700T style tall lift pump I confess?
Never heard the main pump run so quiet in years on those cars after that?
That said, I have mixed feelings about the modification and stirring or frothing the fuel around more on the later 240 tank setup with the 7/9?turbo in tank pump ?upgrade??
I don?t run the tank below the ?red,? (Never drier than 12.8-13.1 gallons and make a habit of filling the tank completely & keep ~25-100 gallons of gas around or used to @ $1 off/gallon35 gallon max allowable fill ups) don?t park in the sun on hot days over hot pavement to top off with/don?t run around on a nearly dry tank for prolonged periods with a little bit of hot gas/sediment on the bottom the tank?
The pump seems least stressed on the 2.5bar fpr LH efi 240s?I kinda think they had that aspect (pump & filter longevity / service life with plenty of neglect?) right for passing evap emissions and everything else in the 1960s chassis with evap compliant tank band-aided into what started out as a ?67 140 (I think they had D-jet in mind as an option the way the 140 FI tank is designed and those cars came with alternators basically from inception in the USA market, however?) running lower pressure with a bit stronger lift pump ?86-?88?
I half suspect they went to one parts bin that shared more with the 700s as well as being CA emissions compliant with EGR & same LH2.4 parts bin as the 7/9s on the ?89+ 240s??
Kinda redneck/shade tree in my case & not particularly scientific?
Maybe I?m way off base in my limited understanding of how this thing is supposed to work?
The last of the 240 senders have better sealed terminals & more fuel rot resistant vibration damping accordion hose from the tank pump if not remember well?
Clamp on return line on ?86+ fuel level senders?
Push-on PITA PET with the bubble flare on the return to be careful with on the -?85 senders should you choose to keep the original -?85 type sender if possible?
Nothing lasts forever, obviously, but if the pickup sock isn?t all gross/clogged or dissolved/shredded & the owner doesn?t run the tank low for prolonged periods or park over hot pavement & changes the filter on time, pump longevity seems quite good?
Hot weather cars running around below half a tank of fuel with clogged or gross sock & filters parked in the sun I changed considerably more pumps and filters on if I remember well (such a one has any memory left / try to be careful around all those gas fumes?)?
?I?m reasonably certain with the OE quality parts, the pumps can last 20-30 years & 200kmi +, particularly on the 2.5 Bar FPR EFI 240s?YMMV?
Idk that the dealer or formerly reputable brands are reliable sources of OEM or better quality hoses & pumps, anymore? Even if properly installed & verified good?