Guest bastaad525 Posted February 11, 2004 Share Posted February 11, 2004 I got a baaaaaad feeling about this. Been noticing over the last couple days... my new MSD pump been making some funny sounds. well when the car is sitting at idle, usually the pump sounds like... just a nice steady hum, but sometimes, just sitting there, like when I'm letting the car idle down after parking before shutting her off, I will hear the pump kinda... I dont know how to explain it, surge maybe? Like the tone of the hum will change, very abrubtly. Best way I can describe it is like this... there is just the one nice mellow hum, and all the sudden it sounds like someone flips a switch that causes the pump to change tones, like it's suddenly working much louder. Then it will suddenly 'switch back off' and go back to the 'regular' tone. Sometimes it only does this once or twice, sometimes it keeps switchign back and forth, but never stays 'switched on' with the louder tone for more than a second or two. As far as I can tell it doesn't affect the way the car is running, though a couple of times it did seem the idle got a bit rougher for a brief second. Tell me this is normal I really dont want to think I got a bad pump. OH for what it's worth, the pump is wired thru a relay, and also, I've kept a close eye on the amp meter while it was doing this and saw no fluctuation there, so I dont THINK that it's any kind of power surging, but I could be wrong. Quote Link to comment Share on other sites More sharing options...
QWKDTSN Posted February 11, 2004 Share Posted February 11, 2004 My pump rises and falls in pitch from a low hum to a grumble... I am not using a relay and have had no problems... It is a Holley Blue pump feeding my 350. Granted, this is a far cry from your high-PSI EFI setup, but what you describe doesn't sound too major to me.... Anyone else have an opinion? Quote Link to comment Share on other sites More sharing options...
Tim240z Posted February 11, 2004 Share Posted February 11, 2004 yeah it's normal! Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted February 11, 2004 Share Posted February 11, 2004 I've never used one, my Bosch sounds the same as the factory unit. Shane tried the MSD pumps and had bad luck - they burned out on him, two of them. I'm thinking it was just where he mounted the pump, not completely below the sump pickup. The stock location on a Z should be ok, at least a 280; I don't know where you mounted yours on your 240. Quote Link to comment Share on other sites More sharing options...
Xander Posted February 11, 2004 Share Posted February 11, 2004 I am using the msd pump on my megasquirted 260Z. I used to have it in the back near the tank. It had the same effect as you described. I think it has to do with cavitation (sp?). The pump is not pulling enough fuel from the tank or even is pulling as little air with the fuel. This can cause the humming. I now hav a low pressure pump in the back that feeds a little surgetank under the hood. I have the pump mounted below the fuel level. It is very quiet now. no surging at all. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted February 11, 2004 Share Posted February 11, 2004 I am using the msd pump on my megasquirted 260Z. I used to have it in the back near the tank. It had the same effect as you described. I think it has to do with cavitation (sp?). The pump is not pulling enough fuel from the tank or even is pulling as little air with the fuel. This can cause the humming. I now hav a low pressure pump in the back that feeds a little surgetank under the hood. I have the pump mounted below the fuel level. It is very quiet now. no surging at all. was thinking something like that as well, my first idea was that it sounded like it was sucking in occasional air... the first time I heard it was the other day, I ran the fuel tank a bit lower than I usually do before refilling (I usually aim for refills at about 1/4) and I thought maybe with the fuel being too low and sloshing around in there, the pump mighta pulled some air in. But it was still doing it after I filled up. I figured it to be normal BUT, I will say, it did NOT do this noticeably the first week... just started a few days ago, so that's why it worries me. Ah well... got no other choice than to keep running it and it if dies it dies I got AAA... heheh and anyways I'm sure PAW will replace it for me. Quote Link to comment Share on other sites More sharing options...
Xander Posted February 11, 2004 Share Posted February 11, 2004 Do you use the stock fuel pickup from the tank? I had a lot of problems there aswell. I ended up welding some 3/8 npt thread on the tank. This helped a lot. there is a picture of the tank in my album. There is also a filter between the tank and the pump. This got gloged up fast since there was rust inside my tank. I removed the rust and coated the inside with a epoxy resin. No more filter problems for me. With these mods the fuel pump has a lot easier life and there for no noise. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted February 11, 2004 Share Posted February 11, 2004 Not using the stock pickup, using the drain at the very bottom center of the tank as the new fuel feed. Never had any surging problems running it like this. The tank was cleaned and recoated not more than two years ago so buildup in there shouldn't be a problem. When I used to run carbs and a see-thru filter those things stayed looking new forever, up until I switched to turbo and efi some half-year ago, so I assume it's still clean in there. Quote Link to comment Share on other sites More sharing options...
ZR8ED Posted February 12, 2004 Share Posted February 12, 2004 Don't let that volt guage fool ya. I ahve the same pump in my 280. Works awsome, but when i hooked it up using the stock wiring harness (my 280's original wire harness) and placed the fuel pump in the stock bracket (fits nicely) it would surge, alternate between higher normal pitch and a lower pitch...oddly enough, it did it when I had my turn signal activated and I was idleing.. when driving, it sounded fine... My alt was new and running perfect, and my guage didn't show anything out of the ordinary voltage wise... I guess the pump was drawing too much voltage and was struggling for power with the "same?" part of the fuse as my turn signals... Heavy guage wire from the battery is the best solution... Quote Link to comment Share on other sites More sharing options...
Tim240z Posted February 12, 2004 Share Posted February 12, 2004 Scott, I wired it for him. It uses a relay with the oem +ve used to activate the relay and a 8 gauge wire directly from the battery (actually from the main terminal of the starter). I'm using the same pump on my LT1 and it also sings at varying octaves. Tim Quote Link to comment Share on other sites More sharing options...
COZY Z COLE Posted February 12, 2004 Share Posted February 12, 2004 For what it's worth, I listen to my sidepipes singing, my blower joining in on cue , and the fuel pump as back-up to this music humming from a low to high pitch or even at times silence. This has been going on for a year now!!!! On the other hand the radio.......... forget it!!!! .......LARRY Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted February 12, 2004 Share Posted February 12, 2004 Don't let that volt guage fool ya. I ahve the same pump in my 280. Works awsome' date=' but when i hooked it up using the stock wiring harness (my 280's original wire harness) and placed the fuel pump in the stock bracket (fits nicely) it would surge, alternate between higher normal pitch and a lower pitch...oddly enough, it did it when I had my turn signal activated and I was idleing.. when driving, it sounded fine... My alt was new and running perfect, and my guage didn't show anything out of the ordinary voltage wise... I guess the pump was drawing too much voltage and was struggling for power with the "same?" part of the fuse as my turn signals... Heavy guage wire from the battery is the best solution...[/quote'] That's exactly how it's wired, using a relay. That's why I'm baffled, it SHOULD be getting great, constant voltage. The pump DOES surge when my turn signals are on, also when I hit the brakes and brake lights come on, also when I turn the headlights on... yeah... definately seems like there's not enough power to go around. However, this surging I'm talking about is specifically when I'm just sitting still, idling, lights off, parking brake on, nothing else going on (that I know of) to drain power away from the pump. Quote Link to comment Share on other sites More sharing options...
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