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JFairman JFairman is offline
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Join Date: Jul 2006
Location: S. Florida
Posts: 7,289
I measured the amperage draw by removing the blade fuses one at a time and touching the leads of the digital amp meter to the spade terminals in the blade fuse holder while the motor was off and the pumps were on.
It doesn't matter if the motor is running or not because the fuel pumps move and deliver alot more fuel than the fuel injection can use and the rest is returned to the fuel tank. With CIS the tiny fuel pressure regulator in the side of the fuel head does that. All return line type fuel pressure regulators big or small work that way.

I listened to your video and it sounds like your fuel pump is dry or the rollers are worn and and chattering as they spin and buzz in the fuel pump race they spin around in. It's not accurate to try and diagnose it by recorded sound like that because whatever you used to record it will have an effect on the sound quality. I'd have to hear it in person with my own ears when it's stone cold and again when it's been running for an hour or so to make a judgment.

I did notice there was no voltage arcing or sparking at all as you touched the wire to the pump terminals. Mine spark alot when you do that because of the current draw. It's as if there is no fuel in your pump and no load on the pump your testing. And the way it slows down kind of slowly and lazily when you removed the wire also makes it sound dry inside. Mine stop real fast when you remove power from them.
It's just too hard to say without hearing and doing that myself in person. I'm not going to say you need new fuel pumps because they are expensive and yours may be ok.
They don't last forever but the origonal Bosch fuel pumps made in Germany from 20+ years ago are the best quality and usually are good for around 100,000+ miles. The newer current day Czech Republic made bosch pumps are pretty good I think but I really doubt they are as well made as the old German made ones.

Have you removed and cleaned the round fine screen fuel filter in the bottom of the fuel tank and after that changed your fuel filter in the engine compartment with the correct Mahle fuel filter recently?
Have you hooked up a CIS fuel pressure gauge to check system and control pressure and are you sure the fuel supply and return lines are not clogged or pinched anywhere?

Also check to see that you're getting the full 12 volts to the pumps when the motor is off and around 13 volts to them while the motor is running with the headlights on at idle speed, and about 13.5 volts while the headlights are off.
Old 04-01-2012, 07:29 PM
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