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fuel pressure linked to alternator?

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Old 06-10-10, 07:18 PM
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Coolant Leak

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fuel pressure linked to alternator?

i recently replaced my fuel pump with an FD fuel pump on my t2 swapped N/A and i've already felt i have put strain on my stock alternator with my electric fan, aftermarket radio but when i put the new fuel pump in it seems like its not getting enough fuel pressure it struggles to start but when its running it runs fine
Old 06-10-10, 08:00 PM
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the alternator should be ok with a electric fan and aftermarket radio. unless of course you have amps and such too.

does it crank slow? sound like its struggling to turn over? when was the battery last checked?
Old 06-10-10, 08:18 PM
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it cranks regular speed but cranks for a period of time and i have to give it some throttle before it will start, also the amp gauge is reading about 9amps while cranking..

the battery is a optima dry cell replaced within last year this is also s5 btw
Old 06-10-10, 08:33 PM
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does your Efan turn on Right away when you hit the Key?
That would Put a Strain on the battery.Trying to Run the EFan ( from the OFF position) would take about 30 amps to get it to go,.Then Starting the car,No wonder it would "grunt" to start the engine.
You should try to Start up the engine without the fan on,then Turn the fan on..This will eliminate the excessive Draw off the battery when you Start up.
See of that makes a Difference.
Old 06-10-10, 08:43 PM
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With a weak 70A S4 alternator, e-fan pulling ~10A & FD fuel pump, I had no trouble. The fan pushed the alternator to the limit, but the fuel pump can't be pulling many more amps than stock. Have you measured voltage output under different conditions? What e-fan are you using? Have you measured fuel pressure?
Old 06-10-10, 08:52 PM
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i have not measured fuel pressure yet, i am running an efan from a fiero and yes it runs at the turn of the key, probably not the best way but at the time was the easiest way to wire it up
Old 06-10-10, 08:56 PM
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if you have to crack the throttle open a tad to get it to start that is a sign of it flooding. wonder if you dont have a clogged/stuck fuel injector.

something cheap you can try is adding some seafoam to your fuel and run premium from mobil or chevron. I keep a few cans stocked at all times. its around $6-8 a can and is called "miracle in a can" by the guys i work with.

if you have a optima then i doubt its an electrical issue. those things have a massive cranking punch.
Old 06-10-10, 08:57 PM
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So the fan runs during cranking? If that's the case, installing a simple relay/temperature switch setup for the fan would no doubt help starting.
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