OPS lifespan survey

[ucdavis]

How long have you been getting out of an OPS?

My AC Delco #10243574 = <20,000 mi.

How 'bout your part# & time in service?
Thanks

[David Brady]

UCDavis,
Mine may not be original as I bought the truck with 53K miles, but it is working at 152K yet. I got a good look at it yesterday as I changed to the non EGR intake. It seemed a little cleaner than the rest of the stuff back there. I couldn't tell you what the P/N is.

[david]

175,000 and still going. :eek:

But i carry a spare.

[cruzer]

bought truck w/75,000, replaced for piece of mind
during rebuild @ 135,000mi. It's just as inaccurate as the 1st one.

[tom.mcinerney]

UCD: Can't exactly answer Q; will offer...:
I got lucky and spoke with service/support at Delphi Automotive{i think they mfg most Delco-Remmy stuff}. They said the $20 lift pump intended for mechanical injection pumps comes in same housing with many same parts as the $50 lift pump for electronic injection pump. The second pump was designed later to restrict max fuel pressure to about 8 Lbs as opposed to 14 Lbs for cheaper pump, to improve quality of operation of electronic injection pumps(?).
There seems to sometimes be a lift pump/OPS syndrome. Apparently the pumps occassionally draw more power than the OPS contacts can readily carry. Pannhead wrote the contacts are real puny. Damork installed a relay; the power supply problem was solved for the pump and the OPS. Dr Lee pointed out that most of these solenoid fuel pumps require a fuel filter on their input to activate the new part warranty {speaking of generic pump in aftermarket parts warranty}. I think that like mechanical diaphragm pumps, the key active ingredients with the solenoid lift pumps are the check valves on input and output. It would seem that either they overheat[when sucking air, or when pushing a springy air/fuel column{possibly a result of a lose hose connection at fuel conditioner, or a leaking fuel heater oring}] and degrade the valve seats, or debris particles/fuel additives wear the seats so they no longer seal. Thirty years back i dismantled a couple solenoid pumps manufactured before WWII. They had point contacts in them(not sure just how worked). If the current lift pumps feature electro-mechanical contact points, that's another place where resistance can increase, heat builds up, voltage goes down, more current flow required at low voltage...Or, the points fry closed together, the LP imitates a little immersion heater.
I know, you're thinking 'there's something wrong with this contributor'....
Another thing. There occassionally seems to be involvement of the FSD with the lift pump syndrome(?). Anthony Paganini(another west coaster) was despairing/replacing lift pumps a few months back. He was about to drop his fuel tank. His last post he reported tightening the mounting screws on the PMD/FSD.... My truck ran OK when i got it[considering was no boost], except it evinced "stall after start when warm". I think the cause was low supply voltage from hasty installation of an aftermarket lift pump, twisting wires together with a little tube of electrical tape over the splices to prolong active corrosion cells. When i tugged the wires they parted in a cloud of corrosion dust....
A final point. There are 3 or 4 small gage(as AWG) wire harness grounds from harness to side/rear engine my truck. Each of these are a lead from a ground-splice within the harness[each of the 4 engine-ground-leads connects to several ground circuits within the harness itself]. Two of these are not connected to the same point on the block. One includes heater-blower, fuel heater, etc(Gnd105?). The other includes PCM ground(s) other light loads, and the lift pump(Gnd104?). So, if the ground tab for the PCM/lift pump were loose/corroded each circuit could corrupt the other by trying to seek ground thru the other! On my truck these 104/105 were fastened together beneath the trans dipstick/filler tube when it returned from transmission shop...so the PCM/lift pump could interact with W-wiper/fuel heater/blower fan....