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Post by ellpee on Jun 3, 2018 16:29:24 GMT -6
Fired up the Magnum this morning for its weekly short run around the neighborhood. Started well as usual, ran nicely for a few minutes, but then started stalling if I let it drop back to idle. Started up again each time, no problem, but had to keep feeding it gas to finish my run. Gave a quickcheck for loose vacuum hoses, etc., all seems okay. Any thoughts on where I should start to isolate the problem? It's obviously getting fuel and spark, so I assume something carb-related. Have been running it about once a week (on the road) for just a few minutes just to keep evrything lubricated, but in between it's been parked in the driveway in the hot AZ sun. Just put a gallon of fresh gas in it a couple days ago, same gas I run in my truck without problems.  NEXT MORNING: UN FREAKIN' BELIEVABLE! Fired it up this morning and watched "under the hood" for clues, and the replacement fuel pump that solved my no-start issues last fall is doing exactly what the old (OEM) one was -- allowing gas to be sucked up the vacuum line straight into the intake manifold!!!!!!!! (Fortunately I was smart enough to replace that vacuum line with transparent tubing, so it was at least easy to spot.) The scooter has only been run for 5-10 minutes a week, maybe 4-5 street miles in total. Everything was fine from November until yesterday, and now the fuel pump has apparently failed AGAIN! So it looks to me like I need to replace the piece-of-crap pump again, but this time with a generic after-market one that will last longer and keep my Magnum happy. I'll of course be googling like crazy, but any tips on vendors and items, positive or negative, are always welcome. Also any advice on switching to an electric pump, and on specs that might be important -- PSI, GPM, whatever. I'm already seeing that many scooters apparently use electric pumps, so am guessing that won't be a problem other than a little re-wiring, but want to get one that's right for the Magnum engine and carb. Don't want to starve or overflow the carb. |
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Post by cyborg on Jun 5, 2018 7:59:43 GMT -6
I'd go electric myself,,,don't know the fuel situation but I suspect alcohol in the fuel,,,it's hell on rubber,,,I think an electric pump and a mechanical pressure regulator will do the trick
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Post by ellpee on Jun 6, 2018 8:27:55 GMT -6
Well, our gas has 10% ethanol at least part of the year. Maybe that's causing the pump diaphragms to fail ....
Pressure regulator? New subject for me. Would an an E-pump have one built in, or is it an add-on? And in the latter case, what pressure do I want? Will educate myself online. Theoretically I imagine the needle valve should shut off the flow at the appropriate point and prevent overflowing from too much pressure, but I can see way too much might override that.
Later, after some googling: I see many electric fuel pumps, most not very expensive, and all with fairly low pressure ratings in the 2-6 psi range. Unfortunately the ones that have failed me don't say anything about pressure, so may just have to roll the dice unless somebody knows the answer for the Magnum.
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Post by cyborg on Jun 7, 2018 7:51:28 GMT -6
I'd stick with 2-3 pounds ,,,it'll have good delivery without over riding the bowl valve,,,
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Post by ellpee on Jun 8, 2018 7:50:07 GMT -6
E-pump on order, inexpensive and supposedly lifetime guarantee. Will have to wire it in and find a way to mount it, doesn't match existing holes, but that's okay if the darn thing will just WORK! It's 3-6 PSI and 19-20 GPM, hoping that works out.
Hey, just for curiosity, does the location of the electric fuel pump -- above or below the fuel tank and the carb -- matter? The OEM vacuum operated pump was mounted way low on the frame, but I might find it easier to mount at some other higher attaching point if it doesn't create any problems. That being said, I can imagine having it higher than the fuel tank might lead to it sucking air after a period of non-use.
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Post by cyborg on Jun 9, 2018 23:28:46 GMT -6
Below the tank would be where I’d place it
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Post by ellpee on Jun 10, 2018 9:55:36 GMT -6
Okay, falls under better safe than sorry sounds like. Where's everybody else these days? Seems like it's just us two.
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Post by cyborg on Jun 12, 2018 7:22:37 GMT -6
Not sure I stop by pretty much every day,,,
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Post by ellpee on Jun 13, 2018 9:48:39 GMT -6
I'd go electric myself,,,don't know the fuel situation but I suspect alcohol in the fuel,,,it's hell on rubber,,,I think an electric pump and a mechanical pressure regulator will do the trick I'm guessing that with an E-pump, polarity will be important -- reverse the wires and it would run backward. Can anyone confirm? If not, I'll just test it with a bucket of water before installing it. |
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Post by cyborg on Jun 14, 2018 6:48:58 GMT -6
Should only have 2 wires black and a red or green and red red being hot feed ,,doubt if it'll run backwards but testing isn't such a bad idea,,,just make sure you tap a switched hot,,that's only on while ignish is on
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Post by ellpee on Jun 14, 2018 9:06:34 GMT -6
Should only have 2 wires black and a red or green and red red being hot feed ,,doubt if it'll run backwards but testing isn't such a bad idea,,,just make sure you tap a switched hot,,that's only on while ignish is on Bench-tested it, polarity does matter, runs when correctly connected, does not run at all if connections are reversed. Will install it this weekend and see what happens. Puts out a pretty good stream of gas (or water, in the case of my test), so hoping PSI will be okay, if not may need that regulator thingie. As to tapping, have used the connection to the enricher, which is live as soon as the key is on, otherwise dead. Can't imagine the load for those two things will be excessive. |
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Post by cyborg on Jun 15, 2018 8:00:05 GMT -6
Good ,,,can't wait to hear the results
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Post by 2stroked on Jun 15, 2018 15:33:52 GMT -6
ellpee the electric pump upgrade is a brilliant idea. Hopefully you won't need to regulate it. If you do there's other ways beside the separate pressure regulator in line with the pump. There's also the method of pulsing the pump in time with the spark. Thus later method is implemented by Honda in the 86 Helix, and it doesn't have a pressure regulator at all. Unfortunately those damn pumps are not cheap, but I would expect it to be simple to have your current choice of pump work the same way. Either way, looking forward to hearing how it goes. Good luck!
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Post by ellpee on Jun 16, 2018 13:59:11 GMT -6
ellpee the electric pump upgrade is a brilliant idea. Hopefully you won't need to regulate it. If you do there's other ways beside the separate pressure regulator in line with the pump. There's also the method of pulsing the pump in time with the spark. Thus later method is implemented by Honda in the 86 Helix, and it doesn't have a pressure regulator at all. Unfortunately those damn pumps are not cheap, but I would expect it to be simple to have your current choice of pump work the same way. Either way, looking forward to hearing how it goes. Good luck! Hoping for the best. Hoee/Tube issues, 1/4" versus smaller, but progressing. Have electrical all set up as far as I know, so any problems beyond that have to be fuel flow, including too much or too little fuel pressure. Will see how all that works out, and report here about it. |
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Post by cyborg on Jun 21, 2018 7:29:39 GMT -6
Hey good morning,,,any status update on the fuel pump?
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