[purplerider]

imported post

I've got an 84 Interstate with fuel pump issues. There's voltage to the pump, but apparently not enough. According to my voltmeter, I have voltage, but almost no amperage. I thought it might be a groundproblem, so I jumpered ground directly to the battery, still nothing. Continuity says the ground is fine. I replaced the fuel pump relay, that works. And the fuel pump works because I jumpered that to find out if it did. Now, according to my wiring diagram, the current should draw from the coil pack, it runs on all cylinders. But I'm not totally clear if the power comes from that, the voltage regulator, or the engine control module.



I'm stumped, not sure what to look at now- HELP!

 

[gaswing]

imported post

What amps reading are you getting?

 

[purplerider]

imported post

Almost none. The voltage reading I'm getting is about a 1/2 volt lower than the battery.

 

[purplerider]

imported post

Almost none. The voltage reading I'm getting is about a 1/2 volt lower than the battery.

 

[redwing52]

imported post

The 1200 uses a spring operated diapragm type pump. If the spring is pushing againt the diapragm and the pressure is high enough you would get just what you say. It might be normal and you are barking up the wrong tree. What's the big picture? What does it do or not do?




Second thought. If I remember right it has a safety built in it somewhere. The pump will only run for a few seconds after you turn the key. If the motor is not running by then it shuts off. Very vague recollection. I think it's so the pump would quit if there was fire rather than keep pumping and feeding the fire.

 

[glhonda]

imported post

The current to operate the pump comes from an ignition source on the black wire. The CDI controls the fuel pump relay.

Jumper from the black wire to the white wire at the relay and see if the pump runs.

 

[purplerider]

imported post

Ok, two possibles. Question. Or should I say a couple.

Provided it is the cd box, and I jumper past it, is that a perminent fix? Might I have future problems with the cd? The old fuel pump gave out, I replaced it with a Napa marine fuel pump. Now, when that pump builds pressure, and stops, is that normal?

 

[smokepole]

imported post

redwing52 wrote

The pump will only run for a few seconds after you turn the key. If the motor is not running by then it shuts off. Very vague recollection. I think it's so the pump would quit if there was fire rather than keep pumping and feeding the fire.

Pump will run for a few seconds?
AND WHEN IT DOESN'T I should look where?
Mine doesn't , never has. Probably why I have to use either in the spring. Does run after it starts (or sputters a bunch)
20 years I've been fighting the spring start. If I wasn't so lazy, was thinking a momentary contact switch to prime the thing

Excuse the hi jack.
But as long as your warmed up to pump electricity, seemed like a good place

 

[purplerider]

imported post

Well guess what, when the pump doesn't start up to begin with, then I'd guess its electical.

No smokepole, I don't excuse you. Clearly you aren't willing to work on your own.

 

[Feetup]

imported post

There are two wires to the pump, one black/blue, one green.

Green is ground.

Black/blue will be dead when you first turn the key on, but will energize when you hit the starter button, and remain that way till you turn the key off. I don't believe there is any safety built into this system on the 84.

Many people have gone looking for electrical faults since they find that the black/blue wire is dead even with the key on. Try pressing the starter button and check again.
The power for the relay is drawn through the fuse block, but the signal to energize the relay comes from the ignition module.

The pump will only operate when the float valves in the carbs open. otherwise it will maintain a slight positive pressure (via the spring in the pump pushing the internal diaphragm.) against the float valves. The solenoid in the pump merely resets this spring, and sucks another load of fuel from the tank for the spring to push into the float bowls.