Mid 80’s chevy suburban 6.2L diesel. The mechanical fuel pump (the lifter pump, NOT the stanadyne db2 injector pump) went bad, leaking lots and probably letting air and who knows what else in the line. I simply re-ran the fuel hoses to an electric pump instead. All works fine, however the mechanical pump is a pain in the rear to remove, yet it is geared to the engine and will turn regardless of whether any fuel is going to it. Is it going to cause problems just leaving it there? In the off chance the mechanical pump needs fuel for lubrication, I rigged a small recirculating tank with old fuel in it, but as the pump is pretty leaky, this empties out over time, and I’d rather not be dripping fuel on the road (even if it is bio). Can I remove this and just let it spin dry? My concern is it might need fuel as lube and without it eventually grind it self into shavings or seize up entirely and either way possibly cause damage to whichever engine shaft it is geared to. Even if it wasn’t a pain to remove, once I removed it, there would be a similar problem of having a big gaping hole where the pump was, probably letting dirt or whatever into whatever engine gearing it was connected to. (What is it connected to anyways??) Going further, could just replace the mechanical pump with a new one to solve that problem, but really that negates the original purpose of fixing the problem cheaply, quickly, and without installing a new part that will probably just fail like the last one. I like the electric pump, they’ve worked well in the past and are damn easy to replace when they don’t. I may want to install a new mechanical pump someday, when I have the time and $$ to make this beast apocalypse-proof, but for now I just want to make sure the bad pump isn’t going to tear up the gearing and make that impossible in the future.
The last time I removed a mechanical fuel pump and opted for an electric one I just installed a fuel pump “block off” plate. They are readily available on the internet (racers use them) or you may find them at your local auto parts store. Make sure to install a gasket to prevent oil leaks.
Thank you, that’s good advice if I do remove the mechanical pump! How much should I be paying for these plates? Might not be worth it if they’re almost the price of a new pump, racers tend to spend a lot…
It also sounds like from what you said that the pump is probably lubricated with oil, so maybe it won’t cause harm just to leave it in place for now? (other than the extra drag on the engine, which shouldn’t be much if it isn’t pumping anything)
That gives me another idea… Can I maybe just run another fluid through the pump? Like something really thick that won’t leak, like gear oil, or better yet something with a stop-leak in it? Anyone know of a good stop-leak that works on pumps? I hear that the coolant ones tend to gum things up, but that the steering and other heavier fluid stop-leaks tend to work well in their respective systems. Any ideas?
Probably in the $10-$20 range. I see that JEGS had one for $7.99 but finding one for a 6.2 may cost a little more.
Make one…Take the pump gasket and fabricate one out of 1/4" aluminum plate…Remove the pump, bolt on the plate…
Thanks! Wow that is pretty cheap, but yeah, what missleman said-- where am I going to find one for the 6.2 diesel?? They don’t race these things!
Guess I’ll have to make one… That’s a lot of work compared to just leaving the dead one in place, though. Anyone know what kind of mechanical pump these are? Centrifugal maybe? How do I find out? Knowing the type would tell me the failure mode…
the mechanical pump used on a chevy gas motor is driven by an offset wheel from the camshaft. the pump has a simple lever that is pushed by the cam lobe. it seems you are assuming the diesel motor uses the same design? why do you think the pump is driven by a gear? you seem to know some thing about the design and assume the pump has a similar block off plate available? 2 or 3 posters here seem to assume it is the same design as well?
I just looked up a 6.2 Diesel fuel pump. According to the picture they drive right off the cam like they have for many years. Take a look. No gears it seems. The block off plate from a big block engine like a 454 should fit your 6.2. I would remove your fuel pump and take it down to the auto parts store just to be sure. I think the 6.2 is actually a Detroit diesel block but the fuel pump gasket design looks like any one of several GM fuel pumps.
Bugnut, why not put on a new mech pump? Seems pretty simple.
Thanks, y’all!
Missleman-- That picture helps a lot. Where did you find it? You’re right, no gears, cam driven. Looks like it is a diaphragm pump maybe? That’s probably good, all lubrication would be on the engine oil side, so it probably wouldn’t mechanically fail with no fuel, nor transfer damage if the linkage broke inside. If it is diaphragm, and that failed, there could be oil in the fuel (no big deal on diesel), or fuel in the oil (not so good, but can’t happen if it’s being run dry not hooked up to a fuel line). So I wonder how they expected to deal with that? Maybe an extra seal inside? Because you wouldn’t want to design it to dump fuel in your oil when it inevitably failed, because Youd never know until damage was already done to the rest of your engine…
And yup, the block is a Detroit Diesel, good reliable commercial-grade motor. Dunno how they mated a gm pump to it though, if that’s the case…
Cavell-- could get a new mechanical pump, but it’s already working fine with a cheap electric pump. New pump is more cost. Moreover, unless I’m missing something, it looks like I gotta take a bunch of other stuff off to get to the bolts, swapping a hose and wiring in an electric took a few minutes. At least with a camshaft design it would mate easily, tho, no aligning gear teeth or anything.
Funny thing, the mechanical pump stopped leaking (even though I’m still recirculating fuel through it in a loop to lube it). I’m thinking maybe my tank lifter pump was feeding too much pressure. Maybe the mechanical pump even has a pressure relief valve built in? Would certainly be a design solution to that above mentioned fuel in the oil problem… Maybe I should just put the mechanical pump back in the line, but this time with a pressure regulator before it? What pressure should the system be at anyways? I used to have a manual for the db2, but can’t find it… Knowing the rated pressure for this mechanical pump, too, would help…