Just wondering if anyone else here has had issues with voltage drop on their fuel pumps under full load. I've begun to notice this on my CRX via slight hesitations and fuel pressure fluctuations. I've also been able to get a voltage reading at the pump during normal to full boost driving and the lowest it's gotten so far is 10 volts. I have a Walbro 255lph with stock injectors and will be upgrading to 1000cc this week using E85. Last thing I want is a fuel pump with inadequate power supply on my rebuilt engine. After some research on preventing voltage drops at the fuel pump, I found a few links including this that a lot of DSM guys use on the 1st gen to keep voltage stable. http://www.plymouthlaser.com/rewire.htm and http://www.vfaq.com/mods/pump-relay.html it seems to be a good idea. Checking to see if anyone else has done this. I'm gonna install one this week and see how well it works. I'm gonna try this one from Summit Racing http://store.summitracing.com/...-1025 since it's already got the harness on it for a cleaner install.


Modified by mrchris1979 at 10:41 AM 1/4/2008

 

Adding a relay and running a larger power wire is HIGHLY recommended. I do this on ANY car over ~300HP. Most all high power cars on this site run the same type of setup.

 

Yea but instead of connecting it too the battey, connect it to the altenator instead so it keeps 12v at all times....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18c1turboedEK &raquo;</TD></TR><TR><TD CLASS="quote">Yea but instead of connecting it too the battey, connect it to the altenator instead so it keeps 12v at all times....</TD></TR></TABLE>


voltage output at the alt and the battery is the same. if its not, you have other problems to worry about other than your fuel pump wiring..............that, and if your only getting 12v's from your alt, you REALLY have problems lol


Modified by Turbo-charged at 2:40 PM 1/4/2008

 

I recently moved my battery to the trunk to make room for a tony1 catch can. I ran a 10 gauge wire to the walbro and it definantly woke it up. You can tell the high pitch wine they make got stronger.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sp00led &raquo;</TD></TR><TR><TD CLASS="quote">I recently moved my battery to the trunk to make room for a tony1 catch can. I ran a 10 gauge wire to the walbro and it definantly woke it up. You can tell the high pitch wine they make got stronger.</TD></TR></TABLE>

Make sure you have a fuse on that power wire for the pump as well

 

Sounds good. Seems like this should definitely solve low voltage issues. Thanks.

 

also another thing to consider is this a Low pressure pump ? don't these things have a lot less volume at high loads when compared to a high pressure pump?

 

I rewired my Intank to the plug and my Inline with independent Relays triggered by the OEM power wire to the Intank, 10 Gague Power from the relay, grounded to chassis and a 8 Gague from rear mounted Optima to the Relays, also running 1000cc and E85. As stated above it definately woke up the pumps, they definately wine alot louder than before.

You dont have to buy the Summitt Kit, just go to your auto parts store and get a 40 amp relay and some 10 and 12 gague and some connectors and wire it up.

 

for now til i get off of my lazy ***, i have the stock fuel pump wire feeding my relay for my weldon. 12ga works fine. it will have a dedicated switch and circuit in a few days if i get motivated. and it is off of the battery. and what joe said.

 

 

The stock pump wire provides PLENTY of current to power a relay. No additional switch is really needed.

85 to stock pump wire
86 to ground
30 to 12 volt constant source (a fused, larger size power wire (8awg is fine) run directly to the battery or like source)
87 to fuel pump (larger size power wire, 8awg is fine)
87a NOT USED

 

even 10 or 12 gauge wiring would be sufficient and has enough current carrying capacity... you dont need to go to 8 gauge.

 

I would stick with 10 gauge if it's a long run but yes 8 could be considered overkill for most pumps. I have tons of 8 lying around so thats what I use.