thanks for being patient, i am highly interested in doing efi like everyones on my own slant and other cars.

A quick update - my cold start problem has been resolved. Pretty stupid in hindsight, but the fuel pump relay was wired to a "run" circuit, not a "start" circuit. Turn the reds on and the fuel pumps whir away and do their thing, turn the key to start and the pumps stop - problem was you could not hear them stop because of the starter noise. Change the relay trigger and the car will start without the test-mode process described in an earlier post.

So why only this problem when the car was cold? I'm guessing because I don't have fuel pressure check valve, which maintains line pressure when the engine is off. Slowly overtime the pressure drops in the fuel line, so when I'm cranking there is no fuel in the system to inject. When the car has been run for a while pressure exists and has not diminished or drained back, so when I go to restart the injectors have fuel despite the pumps not working. Certainly enough fuel for the car to fire, at which time the pumps come back on and everything works as it should. That's my theory anyway!

I've ordered a check valve, so hopefully everything will be resolved within the next couple of weeks.

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Why not add a "start" relay, to the fuel pump circuit?

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

I'm not sure if I understand what you are suggesting here? Add another relay?

I ended up moving the fuel pump relay trigger from my fuse-box to the ECU. Basically if the ECU has power, my fuel pumps have power. Seems to work fine so far.

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The only problem with that is in case of accident it will continue to pump fuel even though the engine is not running. If there's a broken fuel line and/or a fire that would potentially be a very serious situation. With the oil pressure switch controlling power and a seperate relay to provide power until the engine lights off and builds oil pressure that situation is prevented.

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David Kight
'62 Valiant Signet, White
'98 Dodge Dakota
'06 Jeep Liberty

Growing older is unavoidable but growing up is strictly optional.

I see the logic in that. I wonder if I can use my factory oil-pressure switch to trigger the relay? Problem there is I need to build fuel pressure before I start the motor - i.e. ignition on, let the fuel pumps pump for 5-10seconds, start. That wouldn't work if I wire up the fuel relay to the oil pressure switch...

Anyway, it's 2.45am and I need so shut-eye. I'll have a think about this in the morning when I'm fresh. In the meantime please feel free to suggest how you would wire this thing.

cheers,
Eyman

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Yes, you can, as long as you've got an oil pressure sender that's equipped to run an oil pressure warning light, and not just to run a gauge. There is a combo sender available if you're running a gauge and a light. Beyond that, all you need is a normally-closed relay with its terminal #85 tapped into the oil pressure warning light wire. Terminal #86 gets key-switched +12v. Terminal #30 via a fuse to key-switched +12v. Terminal #87a to the fuel pump relay's terminal #86. Then you run a wire from the small (solenoid) terminal on your starter motor to terminal #86 of the fuel pump relay. The result of this setup: When the oil light is illuminated (no oil pressure), the relay will be open, and the fuel pump relay will not activate. When the starter motor is operating, power will be shunted to the fuel pump relay to run the fuel pump during cranking regardless of oil pressure. If the engine stalls or oil pressure is lost, the fuel pump relay will be deactivated and the fuel pump will stop.
Wow, that long...? Why? I would think a quick 1-second fuel pump burst would be more than adequate to build pressure, in which case the starter solenoid fuel pump actuation described above would be adequte. But if for whatever reason you really need 5-10 seconds' worth of priming, there are a couple ways you can do this. You could install a manual primer button on the dashboard consisting of a momentary-contact pushbutton switch fed by +12v and feeding terminal #86 of the fuel pump relay. As long as you hold the primer button, the fuel pump runs. That'd be the simplest way to do it. If you want to automate the process, you could install a timer relay with 5- or 10-second release delay and hook it into the dome light switch on the driver's door such that when the door is opened, it'd trigger the timer relay, which would run the fuel pump for your 5 or 10 seconds. By the time you'd got your seatbelt on and the key in the ignition, the system would be all primed and ready to start.

But I'm still curious why such a long priming period should be needed...

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

My truck had a problem with fuel pressure after sitting awhile. It didn't have a circuit to prime the pressure, so after sitting the pressure would eventually be lost and it took some cranking to bring it back up......

Anyway, it did have a test connector for testing the fuel pump without running the engine. The test connector was an additional ground path for the fuel pump relay. (if you don't have the test connector, run a wire for this additional ground to the 'cheap timer')

Anyway, the 'cheap timer' is to get a large capacitor and hook it up the extra ground wire. When you first turn on the system there's no charge on the capacitor. While the capacitor is getting charged it acts like a normal ground until it gets charged up. Once charged, the fuel pump relay shuts off.

I got the capacitor for about a buck at an industrial liquidator and it's capacity is around 30,000 mfd........ You may need to experiment on size to get the fuel pump run time you want.

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

This elegant solution makes me smile.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks for the suggestions, there certainly is a lot of knowledge around.

I now think I've got it right, as per the ECU manufacturer's wiring diagram. Apologies in advance if my terminology is not correct.

The ECU switches the fuel pumps on and off. The fuel pump relay has two inputs from the ECU. Trigger (terminal 86) and gnd (terminal 85). I changed my +ve trigger source from a post on the fuse box to the "ignition on" wire from the ecu, as per the MicroTech wiring diagram. Terminal 85 is an earth trigger from the ECU. Basically when the engine shows zero rpm, 85 open circuits and the relay shuts off thereby cutting power to the pumps. So whenever the engine stops firing (like in a crash-type situation, or if the engine stalls) the fuel pumps shut off.

What the ECU also does is if you leave the ignition on for 15seconds or longer without starting the motor, it shuts the pumps off. I have been using this feature to prime my fuel system.

Why do I need to prime my fuel system for so long? I believe I do have a fuel delivery problem. My lift pump is suspect, and I think that it takes a while to fill my surge tank. I believe I get drain-back once the car is parked, and after a long park (say 4-5 hours) she fails to start, which brings us back to the start procedure which prefaced all this discussion. I got both fuel pumps from a wrecking yard out of 20 year old GM cars. It turns out I don't need to prime the system for quite so long, but 3-5 seconds is definately required when the motor is left overnight. If she has been driven and parked (like going to the shops and returning), no priming is required - I can lean in the window and turn the key and she will start first click. I'm hoping that a one-way valve placed on the fuel line will prevent drain back through the pumps and hold pressure in the fuel rail overnight, enough to start the car without priming.

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Does anyone have a part number for a fuel line check valve? If you have a through system that inputs at one end of the rail, and then goes to the pressure regulator, will a check valve bfore the rail do its job of maintaing pressure in the rail. What keeps the fuel from simply flowing on through the regulator, and pressure being lost?
Sam

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The check valve's job is to prevent fuel draining back via the supply side of the system, down through the lines and backwards through the fuel pump into the tank. The fuel pressure regulator is the return-side check valve! If it's open and letting fuel flow when the engine's not running, it's bad and needs replacement.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks. I will install a check valve in my fuel system. I guess that would cure the slow start after it has set a few days. Is there a part number out there anyone can recommend?
Sam

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Here is a nice Aeromotive one: Summit Racing

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Here is the check valve I bought today for $35, along with the two -6 barb fittings for $6/each.


I finally got the idle control valve fitted to a suitable mounting plate. Now to find some where to fit it. I'm leaning towards the accelerator cable bracket at this point.




I've got a little free hoist time booked at my friend's workshop tomorrow night, so hopefully I can get everything fitted up.

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