Should my A1000 run constantly with key on??...

[JP_Stang]

Hey guys,

I buttoned up my fuel system today. I still need to purchase a belt tomorrow so I couldn't turn it over. My question is, when I turned the key to the on position I heard the fuel pump kick on but only for a second or two, then it shut off. I didn't build any fuel pressure or anything. Should it shut off like this or should it continue to run in the on position? Is there anything I need to do before I try to start the car once I get my belt on?

Thanks for the help in advance guys!

 

[98 Saleen Cobra]

Mine has it to where when the key is on it primes like a reg. pump

 

[pacific4v]

It should only run with the key on, engine off for a few seconds. It should build pressure tho so u might have any issue with that.

 

[JP_Stang]

So you think that it should have built pressure that quickly? Even using -10 feed lines and -8 return lines? I figured it would take more than the pump being on for 1-2 seconds to build pressure.

 

[encasedmetal]

the fuel pump won't build pressure, nor is it it's job to.. welcome to the world of big pump and big lines. once you start the car, the pressure should be there.

 

[JP_Stang]

Ok, good! Thanks for clearing that up for me Encased!

 

[1996MysticSnake]

The reason it probably only came on for a second or two is because you are using the factory fuel pump trigger for the switched 12 volt. That is not enough time for A1000 to build fuel pressure especially with a -10 feed.

You should run the switched 12v to an independent switch for the fuel pump that runs off something like the defroster switch, conv top switch, etc. This way you can build some fuel pressure before trying to crank the car. I just went through this and without building fuel pressure before starting the car i had an extremely hard start condition, i would literally have to crank it 7-10 times for 5-10 seconds each before the car would start because the fuel was draining back through the pump. I had to get a check valve to prevent drain back when trying to start the car and now 2 cranks and it starts right up everytime. The check valve should go right at the pump on the outlet side.

Heres an example of a check valve
Aeromotive One Way Check Valves 15106 - 15107


You need fuel pressure for the car to start especially with aftermarket rails and lines since they hold so much more fuel. Even if your fuel pump has a built in check valve i would get one of the external ones to help hold pressure while cranking and after shutdown.

The factory setup does build fuel pressure with that 2 sec interval that the pump primes but that is because the lines and so small it doesnt need much time.

Another thing to consider is that you want to make sure the car holds some fuel pressure in the rails to cool everything down after it has been running for a while. If all the fuel drains back quickly you will actually cause vapor lock where the fuel goes from a liquid to a gas state due to the engine heating it. This is going to cause hard start conditions especially if the car is only shut down for a short period of time plus over the long term its no good for the injectors.

 

[encasedmetal]

The reason it probably only came on for a second or two is because you are using the factory fuel pump trigger for the switched 12 volt. That is not enough time for A1000 to build fuel pressure especially with a -10 feed.

You should run the switched 12v to an independent switch for the fuel pump that runs off something like the defroster switch, conv top switch, etc. This way you can build some fuel pressure before trying to crank the car. I just went through this and without building fuel pressure before starting the car i had an extremely hard start condition, i would literally have to crank it 7-10 times for 5-10 seconds each before the car would start because the fuel was draining back through the pump. I had to get a check valve to prevent drain back when trying to start the car and now 2 cranks and it starts right up everytime. The check valve should go right at the pump on the outlet side.

Heres an example of a check valve
Aeromotive One Way Check Valves 15106 - 15107


You need fuel pressure for the car to start especially with aftermarket rails and lines since they hold so much more fuel. Even if your fuel pump has a built in check valve i would get one of the external ones to help hold pressure while cranking and after shutdown.

The factory setup does build fuel pressure with that 2 sec interval that the pump primes but that is because the lines and so small it doesnt need much time.

Another thing to consider is that you want to make sure the car holds some fuel pressure in the rails to cool everything down after it has been running for a while. If all the fuel drains back quickly you will actually cause vapor lock where the fuel goes from a liquid to a gas state due to the engine heating it. This is going to cause hard start conditions especially if the car is only shut down for a short period of time plus over the long term its no good for the injectors.

the big pumps will not build pressure before starting cause they're not running constantly like you said. But I will say that your hard to start, and hot start condition have nothing to do with the pump or pressure. It's a tuning issue that deals with fuel injector pulsewidth. If you have a hot start condition- you need to datalog where that condition occurs and decrease your crank fuel pulsewidth. I have a Weldon 1100 A- which is much larger than an aeromotive A1000, and I have zero problems cranking it. It also has a built in checkvalve and won't build pressure until the car is started.

 

[1996MysticSnake]

I agree with you on the start issue but if you use a constant switched 12v as the trigger for the pump relays vs the factory trigger the pump can run continuously with the key switched on and build pressure, you just need a switch on the constant 12 before it goes to the relay so you can control it if necessary.

You still will run into an issue with fuel draining back too quickly when the car is shut off and that will result in vapor lock depending on the pump. It is very bad for fuel to flow back through these pumps and significantly shortens the life.

Check valves on these pumps are typically on the inlet side of the pump not the outlet . You need one on the outlet side to prevent any flow back into the pump and to keep some pressure in the rail during initial startup.

 

[JP_Stang]

Thanks for the advice guys! I will look into that check valve deal. I am not sure if the A1000's have internal check valves or not so this maybe something I need to do.

 

[encasedmetal]

I agree with you on the start issue but if you use a constant switched 12v as the trigger for the pump relays vs the factory trigger the pump can run continuously with the key switched on and build pressure, you just need a switch on the constant 12 before it goes to the relay so you can control it if necessary.

You still will run into an issue with fuel draining back too quickly when the car is shut off and that will result in vapor lock depending on the pump. It is very bad for fuel to flow back through these pumps and significantly shortens the life.

Check valves on these pumps are typically on the inlet side of the pump not the outlet . You need one on the outlet side to prevent any flow back into the pump and to keep some pressure in the rail during initial startup.

that's what the return line is for. vapor lock is not from fuel going back through the pump after you shut off. vapor lock is from hot fuel being returned to the tank via the return line and heating up the rest of fuel. after enough of this cycle you start to get vapor lock. however this is not true with all big external pumps as a proper setup with venting will not have this occur. IF you're talking about the A1000 specifically- then sure, they have had problems, but a generic statement of "run your pump constantly" is not the answer. I guarantee that running your pump full time will both wear out your pump and regulator quicker than any vapor lock.

 

[JP_Stang]

I don't plan to switch it to a constant 12. I like it being connected to the stock pump wire.

Encased, would you get this check valve if you were me?

 

[1996MysticSnake]

Yes that is one way you get vapor lock. If the fuel flows back when you shut the car off and the rails have a minimal amount of fuel in them while the motor is still blazing hot the rails will heat up the fuel to the point where it will turn from a liquid to a gas aka vapor lock.

Also I'm not saying run the pump constantly and all will be fine. What I'm saying is instead of using the factory fuel pump trigger that only gets power on key on for maybe 2-3 secs use another switched 12 in the car to power the relays so you can control how long the pump primes for.

The A1000 is not a continuous duty pump and if it is going to be used on the street you need a step down box and a fuel cooler no question. The reason those pumps die is because guys run them contionuously without the above.

 

[98 Saleen Cobra]

I've had zero issues and my pump runs continuous. I run the pum in southern weather and again no issues. I've driving 4hrs with it etc etc..

 

[JP_Stang]

I havent even heard of anyone using a step down box or fuel cooler on our cars.... I am not saying I shouldn't, I have just never heard of it nor has anyone ever mentioned it to me.

98, do you run these parts? Do you run a check valve with yours?

 

[98 Saleen Cobra]

Nope no check valve. I run a A1000 with post and pre filters, -8 feed -6 return and A1000 regulator, FORE Rails, 80lb injectors..

 

[1996MysticSnake]

Then you are one lucky person. Google is your friend...there are TONS of guys who run the A1000 on the street and the pump either has died or constantly overheats search and take a look.

You have to understand I'm not saying your setup wont work but if you want stock like reliability from the fuel system when running these big pumps its the small things that add up and also increase the life of the pump significantly.

Regardless if you have heard/not heard of guys running this stuff on our cars its a fuel system. Big fuel pumps Aeromotive, Barry Grant, Weldon etc heat up the fuel way more than stock. Hot fuel causes vapor lock and robs hp plus depending on how bad it gets can cause driveability problems. After spending probably 2k on the fuel system another 300 is cheap insurance. Look at it this way if your pump dies, you have your car towed 100 bucks, then you replace the pump 300-500 bucks, now your back in the same place with none of the things you need to keep this from happening again.

This is why you will see all the posts from the guys that have killed that pump....if they would have done it right the first time this would be a non issue. I've built multiple 700+ hp cars, Grand Nationals, Corvettes, Mustangs etc, you ask anyone that deals with these crazy aftermarket fuel systems they will tell you for street driven you need a fuel cooler and/or a pump controller. When you think about it why do you want to be flowing enough fuel at idle to support 800+hp..it just doesnt make sense.

To answer your question about the check valves it depends on the size fitting on the outlet of your pump..aeromotive makes -6 and -10 check valves, if you need a -8 i would recommend Speedflow

 

[98 Saleen Cobra]

LOL Ok well then I guess I'm lucky.. And I guess my shop has no idea what they are doing with fuel systems either.. Call Drew at AED and tell him that lol.

I have zero driveability issues, not had vapor lock etc. I've street raced my car in heat with zero issues as well lol. There are plenty of people running big pumps with zero issues btw..

There are two ways of doing it, you run it your way and other run it a different way.. If my pump dies than I'll look into it.. The pump has 10k+ miles on it with zero issues in all sorts of weather just so you know.

 

[KlugSS]

Op, like everyone else said its complete normal and should start right up.

I have a magnafuel 4303 that runs 100% all the times and it sits right above an exhaust pipe and i have never had issues. Only time i have ever seen a car vapor lock is because the fuel system isn't designed properly.

 

[JP_Stang]

Ok, cool. 1996MysticSnake, I believe everything your saying and I am not disregarding your information. I run a -10 feed so I could do the check valve. This car is by far a daily driver, but at the same time I do like reliability. I think I am going to try to run the fuel system the way it is for now though. I appreciate the information and definitely keep it in mind if I do run into issues down the road.

Thanks for all the reply's guys! I feel better about the fuel pressure now. Now, I need to get a belt on order ASAP so I can fire this girl up and make an appointment with my tuner!