Fuel Injector question. |
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Fuel Injector question. |
Black914_4 |
Apr 1 2012, 02:09 PM
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#1
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Member Group: Members Posts: 272 Joined: 11-January 12 From: AR Member No.: 13,994 Region Association: South East States |
Stock '74 2.0
How much pressure does the injector need to work properly? I know the fuel reg is set about 29 psi. |
TheCabinetmaker |
Apr 1 2012, 02:23 PM
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#2
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I drive my car everyday Group: Members Posts: 8,300 Joined: 8-May 03 From: Tulsa, Ok. Member No.: 666 |
Hmmm, not sure, but since the specified pressure is 29 lbs, I'm gonna guess thats because thats what they need to operate properly?
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Black914_4 |
Apr 1 2012, 02:35 PM
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#3
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Member Group: Members Posts: 272 Joined: 11-January 12 From: AR Member No.: 13,994 Region Association: South East States |
The regulator lets fuel by and keeps system at least 29 psi.
My question is does anyone know at what pressure the pump kicks on? I never got my fuel pump to run right so I'm just making my own stand alone system. The pump has power whenever the key is on. But to keep the pump from running full time and circulating fuel which would heat the fuel I'm going to install a pressure switch to kick the pump off after pressure is reached. I can get any psi switch I want for about $25. I'm thinking maybe 25psi might be good. I want enough pressure that the motor will get all the fuel it needs but want my pump to have a rest and cool off when not needed like at idle. |
type47 |
Apr 1 2012, 03:25 PM
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#4
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Viermeister Group: Members Posts: 4,254 Joined: 7-August 03 From: Vienna, VA Member No.: 994 Region Association: MidAtlantic Region |
I'm not sure about the idea that the "pump kicks on" at any particular pressure as I thought it ran continuously (other than starting cycle) and the pressure regulator "bled off" pressure by "controlled leaking" gas back to the tank. Injectors open when the ECU sends a voltage signal to the injector and the time-duration of the signal determines the time open and therefore the amount of fuel injected. I would guess that an injector will work at any pressure since it's basically a solenoid (914 D-Jet injector we're talking about, not MFI injector). 'Course you wouldn't get the right charge unless the pressure was set correctly (~29psi). I do have a question about how you think the fuel is heated and creates a problem. I've never seen any thing about temp of fuel and the factory set up having a problem.
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TheCabinetmaker |
Apr 1 2012, 03:30 PM
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#5
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I drive my car everyday Group: Members Posts: 8,300 Joined: 8-May 03 From: Tulsa, Ok. Member No.: 666 |
What Jim said. The pump runs for a half second when the key is turned on. Once the engine runs the ecu triggers constant power to the pump. Pressure has nothing to do with it.
"The pump has power whenever the key is on." Not correct. |
Dave_Darling |
Apr 1 2012, 03:31 PM
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#6
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914 Idiot Group: Members Posts: 14,986 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California |
That's correct, the pump just runs continuously the whole time the engine is turning over.
--DD |
Black914_4 |
Apr 1 2012, 03:56 PM
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#7
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Member Group: Members Posts: 272 Joined: 11-January 12 From: AR Member No.: 13,994 Region Association: South East States |
What Jim said. The pump runs for a half second when the key is turned on. Once the engine runs the ecu triggers constant power to the pump. Pressure has nothing to do with it. "The pump has power whenever the key is on." Not correct. Thats what I needed to know. My factory wire doesn't have power anymore. I ran a new wire from the fuse panel that is hot when the key is on. Being as the pump turns on, then off when you first turn the key on I thought the computer was controlling the pump and turning it on and off "as needed". If it is suppose to run all the time I'll just leave it as it is. I guess I was more worried about wearing the pump out early and the constant fuel flowing all the time but if it's normally that way anyways.... Thanks for the help |
brant |
Apr 1 2012, 04:33 PM
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#8
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914 Wizard Group: Members Posts: 11,625 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains |
Thats why the factory has a return line...
make sure you do also can't you just trace your factory wire back to the point of the problem? |
Tom |
Apr 1 2012, 06:42 PM
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#9
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Advanced Member Group: Members Posts: 2,139 Joined: 21-August 05 From: Port Orchard, WA 98367 Member No.: 4,626 Region Association: None |
The fuel pump shood turn off if the engine dies. That is why the ECU controls the ground to the fuel pump relay. It turns the fuel pump on at three times
1- upon initial key to on, for about 1.5 seconds 2 whenever the starter is engaged - key switch to start. 3- when the engine is exceeding X RPM's The design is for the fuel pump to shut off if the engine stops for some reason. Be careful here as an engine problem due to leaking fuel lines will cause the engine to run poorly or stop. You don't want the fuel pump running if there is a leak. Tom |
Black914_4 |
Apr 1 2012, 06:47 PM
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#10
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Member Group: Members Posts: 272 Joined: 11-January 12 From: AR Member No.: 13,994 Region Association: South East States |
return line works fine.
The factory wires are still there. Just need the car to run right now. I'll try and trace down the problem with the factory wires as soon as I get a chance. You make a good point if anything every happens theres no "auto" shut off unless I am able to turn the key off. |
orange914 |
Apr 1 2012, 08:50 PM
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#11
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http://5starmediaworks.com/index.html Group: Members Posts: 3,371 Joined: 26-March 05 From: Ceres, California Member No.: 3,818 Region Association: Northern California |
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