EFI fuel pump ?

[mjr45]

Anybody got a "best" method for priming an EFI fuel pump besides filling up the tank and cranking the motor?

[FastWoman]

If you have the pump off the car, pre-fill it with gasoline. Just pour the gas right into the holes until it won't hold any more. That was enough at least for my new pump, even with air in the new intake line.

Another approach might be to use a mighty-vac in the engine compartment to draw gas from the tank into the pump.

[mjr45]

Thanks. I had thought of wedging the AFM flap open, then connecting a fuel line to the pump outlet and cranking the motor, but that seems like a PIA to do it that way.

Mike

Edited April 7, 2014 by mjr45

[siteunseen]

Can't you pull the bottom hose off the metal fuel filter in the engine bay and put it in a jug? I think that's what I did. It's been a few years!

[mjr45]

Yes, I hadn't thought of that, thanks.

Mike

[Zed Head]

Are you trying to prime the pump because you think that you have to or because it's connected and won't pull any fuel? I've run out of gas before and not had to prime the pump. If you're trying to pull fuel from below the level of the pump though, then sometimes you can just raise the can up a little to get it started, then set it back down to let it pump.

Don't swap Mityvac with vacuum cleaner or shop vac. Fumes through an electric motor might create a flame thrower, if you're lucky, worse if you're not.

[mjr45]

Zed, I took the pump off to change the check valve, O rings and replace some old(read original) fuel lines, so the pump is empty. I'm also blowing out the hard lines up to the bay, all in an attempt to get the air/fuel ratio right and to see if this will correct the stumbling and bucking at RPM under load, I'm also changing all the fuel line clamps on the injectors since I believe there are some small leaks. In a past thread, I thought it was ignition related, but want to make sure all is right with fuel delivery before heading back to ignition. Fuel pressure was good @ idle, not so much under load, don't remember the exact number.

Mike

Edited April 7, 2014 by mjr45

[siteunseen]

Stumbling and bucking were the same words I used to describe my problem. Found out it was the coolant temp sensor needed the potentiometer installed. $5 worth of parts from Radio Shack.

Mine stumbled and bucked until about 4,000 RPM then pulled like a tractor. Now it pulls hard all through the RPMs.

Edited April 7, 2014 by siteunseen

[Zed Head]

I asked because I think that there is a thought out there that pumps need priming. It might even say so in the FSM or Owner's Manual. It may be that the factory pumps do need priming, but the aftermarket pumps seem to fill just fine. I don't know why the factory pump wouldn't also since with a full tank they should fill by gravity.

Anyway, I would bet that if you just re-install everything it will pump right away, with a fairly full fuel tank.

[mjr45]

Site, I've got a new temp sensor and this thing has been running way rich from day one. I believe the potentiometer would only make it richer. I don't believe its running super lean, with all the soft carbon on the plugs.

[FastWoman]

Mjr45, FAIW, an extremely lean condition can result in carbon fouling because of incomplete combustion.

[mjr45]

Sarah, I calibrated my AFM per Atlantic Z, new temp sensor which checks out fine and still have lots of fluffy carbon on the plugs, lots of black carbon on the tailpipe. Wouldn't the carbon fouling from extremely lean condition be somewhat harder? Don't know, just getting info to store in my head. One of the issues I have to deal with, not necessarily related to the thread ? is my altitude of 9000' which I understand affects both vacuum and compression, but shouldn't affect the air/fuel ratio, is that correct?

Mike