Alternator or Fuel Pump? - Automotive Wiring and Electrical


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Alternator or Fuel Pump?

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worn_chaos789
Novice

Feb 23, 2014, 9:16 AM

Post #1 of 3 (1397 views)

Alternator or Fuel Pump?	Sign In

2001
Chevrolet
Cavalier
2.2
95,000 miles

Can a bad fuel pump cause the alternator to act strange? I figured since the fuel pump pumps fuel to the engine, if it weren't pumping like it should, then would that cause the engine to idle lower or sputter, causing the belt to turn slower, causing the alternator to perform poorly, resulting in dim dash lights, radio cutting out, and blower fan slowing down?

Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Feb 23, 2014, 9:54 AM

Post #2 of 3 (1374 views)

Re: Alternator or Fuel Pump?	Sign In

An alternator doesn't really care what turns it but needs a minimum RPM on it to work within range. Anything that lowers that would cause lower output on a normal one.

So, if idle is lower substantially it would effect it. The problem is why the idle can't stay at norms not the alternator if it behaves with RPMs held higher,

T

Discretesignals
Ultimate Carjunky / Moderator
Discretesignals profile image

Feb 23, 2014, 10:29 AM

Post #3 of 3 (1370 views)

Re: Alternator or Fuel Pump?	Sign In

Most fuel pump issues will cause no starts, rough running engine, or lack of power on acceleration. Normally a fuel pump itself doesn't cause alternator performance issues. If you believe you have a charging system problem, measure the voltage at the battery terminals with the engine running. The charging system voltage should be around 13.8-14 volts. Also measure the AC voltage, with all electrical loads turned on at the alternator output lug, to be sure you don't have excessive AC ripple.

Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

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