Electric fuel pumps are dangerous .

[Warrens69GMC]

Waiting on a cam for my 383, going on a few months now.
Should be shipping by Dec 15.
This one will have a fp lobe for mechanical fuel pump.

[jjzepplin]

I totaled my 72 Blazer on some ignant MOFO in 2007. The cap DID hit the firewall and popped a couple wires loose. The engine WAS still running. When I hit, my foot slammed the accelerator pedal. My electric Carter fuel pump is still in use today. The body had a 3" lift. The entire tub flung forward and bent all the bolts. I have a roll-over pump switch on the oils pressure. I never rolled though. I was dazed a bit-PISSED AS HE!! ! But the busted exhaust manifold told me to shut it off. I also have a manual switch for the pump. I will probably install an inertia switch now though. I did not have a scratch on me with only a lap belt. The truck was riding on 36" Super Swampers and a 4" spring lift as well as the 3" body. The dana 60 front had no damage at all except a busted spring stud and a bent spring. I rarely drive these trucks on the road anymore as pie holes seem to be multiplying exponentially...

[KQQL IT]

Originally Posted by dmjlambert

Are there different required orientations of the inertia switches depending on manufacturer? i see very little information on the internet about orientation of the switches.

Every one I remember resetting, was vertical.

[crakarjax]

Originally Posted by LS short box

My 98 Wrangler LS swap has almost 15 years on it. On all my LS swap I run -6 SS line. No rubber or plastic fuel lines for me although OEM's use plastic all the time. One complete length of -6 from the FFR to the fuel rail. No splices. Never had a problem but no accidents.
On a typical LS system if the ecm doesn't see a crank signal it will shut down the fuel pump.
Seems to me some folks are using a roll over/rear impact switch from a Fox body Mustang to shut off the fuel pump.
If I did roll it over onto the roof I'm thinking the fuel pick up will uncover and the engine will die in seconds.

How can you run solid line to the fuel rail... The engine moves and vibrates, don't you need something that flexes to avoid the line breaking eventually?

Originally Posted by 72c20customcamper

I have this on both my AMX and my Lark .

https://www.amazon.com/Carter-A68301...02672362&psc=1

How do these work at startup? Since there's no oil pressure at startup there won't be fuel pressure, right?

[Sheepdip]

Originally Posted by crakarjax

How do these work at startup? Since there's no oil pressure at startup there won't be fuel pressure, right?

In a nut shell, the oil pressure switch will have three terminal connection
spades, I, P and S.

I terminal connects to your key switch 12 volt in the on/run position.

P terminal goes out to your fuel pump relay as a trigger wire.

S terminal goes to your starter solenoid that is hot only while cranking the
starter.

While cranking the engine to start, the S terminal now hot activates or
opens/connects to the P terminal to energize the fuel pump.

Once the engine starts and and you release the key, the S terminal is no
longer hot, so S and P terminals close/disconnect.

The oil pressure within the switch will by then or has opened/connected the terminals I and
P to make the connection of 12 volts to the fuel pump.

There is a minimum pressure required to keep it open, usually about 4-6 lbs
or so, if it falls below that required pressure I and P terminals will
close/disconnect the 12 volt feed to the fuel pump relay trigger.

No oil pressure equals no power to the fuel pump.

[jjzepplin]

I guess an added feature is that if your oil pump fails, your engine will not burn up because it won't run.

[crakarjax]

Originally Posted by Sheepdip

In a nut shell, the oil pressure switch will have three terminal connection
spades, I, P and S.

I terminal connects to your key switch 12 volt in the on/run position.

P terminal goes out to your fuel pump relay as a trigger wire.

S terminal goes to your starter solenoid that is hot only while cranking the
starter.

While cranking the engine to start, the S terminal now hot activates or
opens/connects to the P terminal to energize the fuel pump.

Once the engine starts and and you release the key, the S terminal is no
longer hot, so S and P terminals close/disconnect.

The oil pressure within the switch will by then or has opened/connected the terminals I and
P to make the connection of 12 volts to the fuel pump.

There is a minimum pressure required to keep it open, usually about 4-6 lbs
or so, if it falls below that required pressure I and P terminals will
close/disconnect the 12 volt feed to the fuel pump relay trigger.

No oil pressure equals no power to the fuel pump.

Thanks, great explanation! I'd worry that it'd cause extended cranking time in my situation, because I don't have a check valve to restrict backflow and that causes my pump to need to run for a few moments before the rails are up to pressure. I think I'll look into a check valve in combination with this, maybe this one

[pjmoreland]

Originally Posted by crakarjax

Thanks, great explanation! I'd worry that it'd cause extended cranking time in my situation, because I don't have a check valve to restrict backflow and that causes my pump to need to run for a few moments before the rails are up to pressure. I think I'll look into a check valve in combination with this, maybe this one

That's why I added a time-delay relay to my setup. It overrides the oil pressure switch and runs the pump for 5 seconds prior to cranking the engine.

[jimijam00]

So much worry, but there is a simple solution. Stay home, or take the bus when you feel you have to leave the safety of your own home.

[Rubbertiredtramp]

Originally Posted by jimijam00

So much worry, but there is a simple solution. Stay home, or take the bus when you feel you have to leave the safety of your own home.

Life sure is dangerous, might break your neck in the bathtub, or cut your foot off with the lawnmower too.

[MARKDTN]

Originally Posted by crakarjax

How can you run solid line to the fuel rail... The engine moves and vibrates, don't you need something that flexes to avoid the line breaking eventually?....

Yes, there has to be flex somewhere. I have handled fuel a couple different ways. First time I bought a TPI setup from a Corvette. I bought the factory line that connects it too. It has a section of rubber line crimped on in the middle of it for movement. On the C4 Corvettes the high pressure side has the filter there on the rail so I ran the hard line screwed into it and from the pump a short section of FI rubber line to a fitting into the filter. Return side I spliced the lines together with a brass compression fitting. But brass compression fittings really have no place with high pressure fuel. Really should use high pressure steel hydraulic line unions.

For the latest EFI conversions I have done, I bought a Mastercool tool that will make fuel quick connects and GM fuel and transmission type flares. If you are careful, it will also push straight ends into plastic fuel lines. And it does brake line double flares. I actually bought the tool for my '07 Tahoe which rusted a hole in a fuel line and it was going to be a major job to replace. I was able to cut out the bad section which was about 2' from the tank and add a quick connect flare to the remaining line. Then I bought a short plastic line with quick connects and made a replacement for the removed section of fuel line and put it all back. If you have a Mastercool tool, you can make safe hard lines easily. It is one of my favorite tools to use for some odd reason.

[cj847]

MarkDTN,

That tool looks awesome. That is what I need but it is hard to justify the cost for a couple dozen brake and fuel fittings. But, then there is the safety factor.....makes $300 sound cheap.

[MARKDTN]

Originally Posted by cj847

MarkDTN,

That tool looks awesome. That is what I need but it is hard to justify the cost for a couple dozen brake and fuel fittings. But, then there is the safety factor.....makes $300 sound cheap.

It is. I hate doing brake double flares, I never get them right. But with that tool they are right every time. Even if you bought it and sold it off when done I think it would be worth it.

I don't want to derail this thread, but real proper high pressure fuel lines is definitely an area that is overlooked in a lot of EFI conversions. Brass compression fittings are rated for something like 20psi. A typical port injection system is at least 40. At a minimum you should hunt down hydraulic line unions that are rated for several thousand psi. They are more expensive of course than brass. Regular fuel line is also not rated for more than a few psi. Fuel injection rubber line is reinforced to handle higher pressures. Fuel injection clamps have a flat band that completely goes around the hose where a typical worm clamp does not. When using EFI hose you need to have a barb or something to keep the clamp from slipping off. Just blunt cut tube with a clamp or 2 is not sufficient-on the pressure side especially.

Factory applications of EFI fuel lines are pretty much in 2 camps in my experience:
(1) plastic lines, sometimes molded, with quick connects on each end. Sometimes the lines are full length plastic, sometimes they have steel lines that go some or a lot of the length from the tank. Most of these types have no rubber or braided lines. Disadvantage-exposed plastic lines. Advantage-doesn't rust.
(2) mostly steel lines with screw on connections to the fuel rail. This style either has a rubber line built into a section near the engine or has a braided line to take the flex. Harder to work on (connect or disconnect), fittings harder to find. But probably more robust.

There may be other variations, but these are the ones I see most. A good safe EFI installation can use the factory steel lines, you just need to make the connections/transitions correctly. The Mastercool tool goes a long way towards doing that. Then you can also decide about inertia switches or oil pressure switches as the OP suggests.

[cj847]

Sent you a PM to prevent hijacking this thread.

[LNP]

Originally Posted by HO455

I wired in a Revolution Electronics fuel pump controller. The controller sends power to the fuel pump for a couple of seconds to put a shot of fuel in the carb (or the fuel injectors) when the key is turned on. After 2 or 3 seconds it will shut the pump off if no tachometer signal is received. Once the tachometer signal is received the pump starts running again.

In addition I use it to control power to the air bag compressor via a 40 amp relay. With the compressor and fuel pump married together they will run briefly then shut off, if I pause the key in the run position before engaging the starter. I can then start the engine without the compressor drawing current from the battery while cranking

https://www.revolutionelectronics.co...Fuel_Pump.html

I use this same controller. It will make your fuel pump do exactly as it does in todays car/trucks. If in a wreck and the engine died the controller shuts off the pump. You can use it for fuel injection or carb. If you got the key on listening to tunes your fuel pump isnt running.

[Johnl48]

Originally Posted by LNP

I use this same controller. It will make your fuel pump do exactly as it does in todays car/trucks. If in a wreck and the engine died the controller shuts off the pump. You can use it for fuel injection or carb. If you got the key on listening to tunes your fuel pump isnt running.

I believe this is basically what's built into the Holley sniper efi

[LS short box]

In regards to the -6 SS its the braided hose flex type. So plenty of flex at the fuel rail.
Never had a failure.
I've used rubber lined and teflon lined -6 hose depending on the application.