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I installed a Racetronix fuel pump kit in my buddies LT1 Camaro that basically adds a fuel pump relay right at the pump. It uses heavier gage wire that runs right to the back of the alternator. This bypasses all the factory wiring eliminating any voltage drop at the pump. I am thinking about making my own harness up to do the same thing in my Blazer. What do you guys think? Overkill?
Only needed if there is an aftermarket pump installed that draws more current than the factory pump, otherwise, you're just adding complexity and more parts that could fail to the car.
Even with an aftermarket pump if the engine does not need MORE FUEL, it's a waste of time. It will still work, but voltage will drop at high demands, but still supply enough fuel, unless motor needs MORE FUEL!
Watching fuel pump voltage at high RPM WOT is a determining factor if this upgrade or pump is needed. Some masks/ALDL data already have this. If not a voltage gauge wired into fuel pump feed can be used...
Before even getting into this watching fuel pressure at WOT is a determining factor. Do you need MORE FUEL?
IDK about pump voltage at WOT.... but pressure at WOT is always an excellent indicator.Quote:
Originally Posted by EagleMark
Yup, they kind of go together... so you add bigger pump and it runs out of poop because not enough voltage/amp draw in stock wiring. I've seen the voltage drop when aftermarket pump is installed and demands are high, then pressure drops too. Other then that voltage and pressure is fine.
We were doing one here that had fuel pump voltage of 13.8 IIRC and would drop to 12.2 at high RPM. So if voltage drops, so does supply, which can effect pressure depending on regulater...
Back to OP, you don't need 2 relays and all the complexity. Look at what you installed and wire it for one relay where origanal is. I never understood that kit except simplicity of install to make a system more complex? More importantly is the fuel pump ground wire back to block and not to frame or body.
Quote:
Originally Posted by EagleMark
I do not need anymore fuel just trying to keep the voltage consistant at the pump
From Racetronix web site
High performance fuel pumps need a good power source in order to perform to their full potential. On average a Walbro high-performance fuel pump requires twice as much power as a factory fuel pump. Factory wiring is just enough for a factory pumps power requirements because manufacturers need to save cost and weight. Racetronix field tests have shown that running a high-performance fuel pump off of the factory wiring can cut pump performance by 30% or more. Problems with failing factory relays, connectors/terminals and fuse contacts are also common when excessive load is placed on them.
The factory circuit which supplies the pump is much longer and more complex than many people realize. The circuit looks something like this. Pump connector > in-tank bulkhead connector > external tank connector > relay > fuse box > steering column ignition switch > fusible link > starter solenoid > battery > alternator. Some of these circuits which the fuel pump sources its power from are shared which can compound the voltage drop problems.
The Racetronix harness bypasses the entire factory circuit path to provide maximum voltage at all times to your pump. The Racetronix harness uses heavy 10 gauge copper wire to reduce voltage-drop to very low levels so as not to impact pump performance. Our power feed comes off the back of the alternator where voltage is highest. The voltage at the alternator's output is typically 0.5-1.5 volts higher than at the battery voltage depending on the charge current. It then runs through a weatherproof fuse holder and then to the back of the car. The Racetronix harness has connectors which plug inline with the factory harness at the back of the tank. No cutting or splicing is required. High-quality weatherproof fuse holders and relays are used for maximum reliability. The Racetronix harness has a redundant ground upgrade as it is necessary to improve the harness on the negative side of the pump's supply as well. The only function the factory harness serves is to trigger the relay in the Racetronix harness (0.1 amps) and to supply the level sender signal to your dashboard fuel gauge.
If your Wide Band says you need more fuel at WOT, then you need more fuel. If pressure drops then you need more pump. When you add more pump you need to supply it with power. The kit your referencing is a simple add on kit so no modifications are made to vehicle, just add on, if you took half of the kit and replaced the stock fuel pump circuit it would do the same thing.
I wouldn't argue any point made by what they said, except they should have left some hype out and stuck with facts... like
"The factory circuit which supplies the pump is much longer and more complex than many people realize. The circuit looks something like this. Pump connector > in-tank bulkhead connector > external tank connector > relay > fuse box > steering column ignition switch > fusible link > starter solenoid > battery > alternator. Some of these circuits which the fuel pump sources its power from are shared which can compound the voltage drop problems."
They lost my interest at steering column and ignition switch. That is really a stretch of imagination.... Good charging systems have been around since EFI, if it's working properly there is no voltage drop especially at off idle RPM. Wiring to an over sized motor in fuel pump, is weak link. But it's power never comes from an ignition switch... still don't like power from altenator? Positive battery terminal as output of alternator so I don't understand that, I do understand not taking power from an overtaxed fuse block... but LT1 has a main post from batterey at underhood fuse block... run power to relay from there to avoid a possible, just possible voltage drop?
But I'm not a big racing parts supply company making millions or racing for money and sponsors either. So I run a big wire from battery positive with fuse not fuse block or terminal at fuse block, to big relay to big fuel pump and big wire back to engine block, not an add on to body which won't work if it's an old car without grounding straps, back to block is fool proof. Anyway it's only like $50. and it works, so it's not like it's a rip off or snake oil. Why add a circuit to supply bigger fuel pump when you can fix the circuit?
All I read there is marketing hype, which too many people are sucked in by.
It seems that article just casually mentions the negative side of the circuit . If you must run bigger wire , run it from pump ground to engine block ; never enough ground wires. Stay suspicious when reading sales literature ; it's about overselling. You'd think one less wire would be a good thing after wiring up an EFI system . Be safe...Bob.
Ok, thanks guys. Thats why I asked. Like you said I may just mod the stock wiring going back to the pump and beef up the ground wire. Or I may just leave it alone:wtg:
That kit is for incapable or un-knowledgeable of fixing what's there...