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914World.com _ 914World Garage _ Nother crazy fuel pump question....

Posted by: crash914 Oct 17 2004, 07:10 PM

Thanks all!!

You all rock....

Well I thought I would get my own birthday gift....a running 914...

This is my new 2.7l big 4.. motor is in, I wired up the distributer, oil pressure gage, and all the fuel injectors....

I had relocated the fuel pump to the front trunk and run new steel fuel lines...

Ok, big moment...about 20 minutes ago....noise and smoke....come on....

I got the smoke all right...let that magic smoke right out of the fuel pump relay....

Oh, well, it was a long shot anyway...I did crank it over, does that count??

There is something strange about the fuel pump,

+
(
-

The minus is common with the pump body, I put a ground on the -- and batt on the ++ It was like a direct short????? WTF????.... Ok, the pump body is common with the car body, so I put the batt on the -- and the motor spins????? Only it sounds like it is pumping air into the gas tank....Oh man, this is going to be painful....

So, what is going on???? any thoughts????

--------------------
Herb Berwald

'73 2.0 track car
'79 BMW 320i daily driver
'88 F150 extended cab long bed tow vehicle

2.7 l big 4 in progress......Yea baby!

Posted by: Aaron Cox Oct 17 2004, 07:36 PM

did you revers the input annd out put of the pump?

Posted by: crash914 Oct 18 2004, 05:23 AM

I am sure that the hoses are hooked up correctly...( I will verify.)

S--suction from tank through filter
D-to fuel rail stopped by pressure regulator
R--return to pump, tee'd for leg for tank return.

When I powered it up, it looked like a dead short. took out the fuse right away, So I got a bigger fuse....took out the traces on the circuit board....

So getting smarter, I went directly from the battery. Neg to Neg, pos to pos....The wire got warm and the pump didn't run...

So I got out the meter and verified that the pump body is grounded, Pos to Pos, nothing. Pos to Neg terminal, pump runs. But now I am hearing gurgling sounds in my tank, there is not a lot of fuel in there, so It could be returned fuel, but I am now wondering if I am running the fuel pump backwards??

Does anyone know the running amperage of the fuel pump? Any good pictures showing the + and - terminals? Is it possible to run the pump backwards?

I guess a 30 amp fuse was too large...
Oh well, whats another couple days after a year......

Posted by: URY914 Oct 18 2004, 06:47 AM

What kinda of pump is it. Who makes it?

Paul

Posted by: Mark Henry Oct 18 2004, 07:08 AM

My '74 pump had both a + and a - terminal, you could not just ground the body because of the rubber isolators.

Might be just a piece of crap in it.

Hook the pump up (right way) and give it some light taps with a soft hammer, connect-disconnect-tap-repeat....I've freed up a couple of pumps this way. P-oil might help when you do this.

Posted by: crash914 Oct 18 2004, 11:57 AM

Ok, this is a stock pump in a 73 2.0

I just reviewed the fuel section of the P-car manual....I had plus to plus and minus to minus....????

When I hooked the plus to the minus terminal the pump ran.....Backwards??

When I had it connected correctly, I fried a 30 amp fuse...

I can't see any errors...I do want to pull my hoses and see if I can get any suction...

This should be simple...two wires....what am I doing wrong?

thanks, herb

Posted by: skline Oct 18 2004, 12:25 PM

Well, unless I hear this all wrong, logic tells me if you have the body as grounded, and you touch the positive to the negative terminal, the fuse should blow right away, dead short, if you touch it to the positive side and it is blowing the fuse, there is another problem somewhere. Something is not right.

Posted by: skline Oct 18 2004, 12:27 PM

Also, a 2.7 liter big 4??? Are you running fuel injection on that? If you are running carbs, then you should not be running a stock pump, you only need about 3 to 5 PSI for carbs.

Posted by: crash914 Oct 18 2004, 01:38 PM

You heard right....

2.7l big four...with fuel injection....

I am running IDF throttle bodies and am using megaSquirt for the fuel control..

Does anyone know if you can run the fuel pump backwards?

I might break down and get a new pump with only an inlet and outlet....I only need 2 bar so there are several pumps to chose from....

Posted by: seanery Oct 18 2004, 02:29 PM

I like the idea of the new pump.
Facet makes a higher pressure one.
Pegasus sells them.

Posted by: banderson Oct 18 2004, 02:39 PM

Herb, did you say that you fried the realay bd? I may have a spare if you need one. Its condition is unknown.

-Brett

Posted by: crash914 Oct 18 2004, 02:47 PM

This is the megasquirt relay board....by OEM board is ok...

got another fuel pump??

Thanks, herb

Posted by: SpecialK Oct 18 2004, 07:14 PM

Not trying to insult anyone's intelligence here....but are you sure you don't have the battery (+) terminal connected ground, and vice-versa? Hey, could happen!

Posted by: crash914 Oct 19 2004, 06:33 AM

You could be right about the +and -

It did match the service manual...but see below for the picture of what I did...

when I switched the leads, the pump ran, it sucked in the S port... It blew out the R port and by default, the D port must be the R port.....

Anyway, I will now fill the tank and try it...I have a new relay board comming so we will see what happens......I don't know why nothing matches the book, but well...that is how it goes...

Attached image(s)

Posted by: banderson Oct 19 2004, 06:41 AM

[QUOTE]

Sure do. Yours if you need it.

Posted by: DNHunt Oct 19 2004, 07:11 AM

Herb

Could the problem have been at the MS relay board. As I remember, there was a jumper to solder that determined if you broke the positive track or ground with fuel pump relay, It's been a long while since I put that together but, I seem to remember that was confusing.

If that was backassward it would reverse the polarity.

Good luck

Dave

Posted by: crash914 Oct 19 2004, 07:35 AM

Could be.....but it was the same when I hot wired it off the battery...

As it now stands, it should be ok.....I hope to hear the roar this week...