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Gregory

USA
62 Posts

Posted - 01/03/2007 :  12:42:03  Show Profile  Reply with Quote
Hi,

Ok here's the deal; I found a feed pump(second version) for my 70' 6.3, at one of my local junkyards the other day, and it works! or it turns rather, when current is applied. How should I go about getting it up to snuff? Just running fuel through it? Should I take it apart and clean it, or could that potentially do more harm than good? I don't know the state of the feed pump on my 6.3 because it isn't exactly in my possesion yet, so I thought it would be good to have a pump at the ready just in case. I also picked up a fuel pump for a 70' 300SEL 3.5, can I use parts from that pump if nessecary? By the way, the feed pump came off of a six cylinder 108. What are your thoughts?

Greg

Chris Johnson

USA
3751 Posts

Posted - 01/03/2007 :  12:58:17  Show Profile  Reply with Quote
Hi Greg,

First, forget the pump form the 3.5. It is a different style, and I strongly encourage you to keep the car is original as possible.

While there are things you can do to your spare pump, I would suggest doing NOTHING to it unless you determine that there is a problem.

These pumps should be tested for flow, and if the flow is correct, then leave it as it is. The "long body" pumps are easier to service than the "short body" pump, but the short body pump is certainly serviceable.

Be aware that the short body pump has a screen filter on the inlet fitting (the long body pump does not). This screen is the smallest filter in the entire system, and is the first to plug with tank sediment. You can tell when this filter is plugging up because the car will drive for a short distance and then sputter out. Wait for a few minutes, start the engine, and the car will go again for a short distance and then sputter out again.

So, check that screen! If it repeatedly clogs up, then you KNOW you have to have the tank cleaned!

With the pump powered up, it should pump AT LEAST a litre (about a quart) in 15 seconds. If not, then either the pump, the tank, the tank screen, the pump inlet screen, or the hose from the tank to the pump has a problem. Pump voltage should be at least 11 volts for the test.

Chris Johnson
"If you aren't constantly IMPRESSED with your car, then it needs fixing."
100.012-12-000790
109.018-12-000019
109.018-12-003834
www.300SE.org
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Gregory

USA
62 Posts

Posted - 01/03/2007 :  13:12:26  Show Profile  Reply with Quote
Dang, that is a pretty fine screen! There is some sediment on it, so would I be safe in unscrewing the intake port and cleaning it?

Greg
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Chris Johnson

USA
3751 Posts

Posted - 01/03/2007 :  13:29:03  Show Profile  Reply with Quote
Yes. In fact, when you reinstall it, get it tight, but don't get is so tight that you can't unscrew it again while "on the road".

I usually keep a 3/8" socket extension bar (to plug the feed hose), a screw driver and a wrench in the car so that I can clean the screen if it clogs while driving the car until such time as I know that it isn't going to be a problem.

Chris Johnson
"If you aren't constantly IMPRESSED with your car, then it needs fixing."
100.012-12-000790
109.018-12-000019
109.018-12-003834
www.300SE.org
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james lawson

USA
1321 Posts

Posted - 01/03/2007 :  16:29:20  Show Profile  Reply with Quote
Also, this pump needs to be primed to pump. It is such an easy job to take out the fuel tank you might want to do it it on principle.

jim
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Chris Johnson

USA
3751 Posts

Posted - 01/03/2007 :  17:06:53  Show Profile  Reply with Quote
This is a common myth (no offense Jim). IF (and that's a big if) everything is okay, these pumps are self-priming.

If the pump won't prime itself, it is indicative of flow problems in the system. This subject comes up on a regular basis on this board, with common complaints relating to vapor lock issues.

IF everything is okay in the fuel system, then, not only will the pump create enough suction head to prime itself, but there will also be NO possibility of vapor lock while the fuel pump is running.

If the engine demonstrates symptoms of vapor lock after a "hot stop" when trying to start the engine, the vapor will be quickly eliminated by letting the fuel pump run for a few seconds before retrying an engine start.

I can see how this thinking comes to be. Virtually every car I have bought over the last several years has had problems with fuel flow through the system. However, I am quite satisfied that the factory engineers did a good job of designing the system so that these sorts of problems did not exist with a clean, unobstructed fuel system. If the system performs as it originally did, you can expect the exact same level of performance.

Chris Johnson
"If you aren't constantly IMPRESSED with your car, then it needs fixing."
100.012-12-000790
109.018-12-000019
109.018-12-003834
www.300SE.org
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james lawson

USA
1321 Posts

Posted - 01/03/2007 :  21:56:25  Show Profile  Reply with Quote
Chris I probably should have said it differently. I don't think it will work if you just put a can of fuel on the ground and try to have it suck it up. I think that there is a reference in the manual that to check the flow there should be a certain amount of fuel in the tank as well. It is an impeller sort and not a vacuum type pump, so even if it is self priming it still is primed.

jim
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Chris Johnson

USA
3751 Posts

Posted - 01/03/2007 :  23:01:17  Show Profile  Reply with Quote
I would agree that putting a can of gas on the ground might be asking a bit much, but if the pump is being feed from the tank on the car, it will suck the fuel into the pump without being primed if nothing is blocked.

Chris Johnson
"If you aren't constantly IMPRESSED with your car, then it needs fixing."
100.012-12-000790
109.018-12-000019
109.018-12-003834
www.300SE.org
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james lawson

USA
1321 Posts

Posted - 01/04/2007 :  00:12:14  Show Profile  Reply with Quote
I thought it important to point this out since it is a spare pump and he might be testing it off the car and so would not assume it needs repair

jim
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Gregory

USA
62 Posts

Posted - 01/04/2007 :  00:53:21  Show Profile  Reply with Quote
The original fuel pump is still on the car. I want to test this spare pump just standing alone. Like I said before, when current is applied, the motor does turn, but past that, I don't know. I am going to remove the intake port and clean the filter; then test its pumping ablitiy. I was just going to fit a fuel hose up to it and let it try to suck up some fuel in a jar or something. What is the proper way to test the unit? And by prime it, do you mean, fill the pump up with fuel first, then turn it on?
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Art Love

Australia
6231 Posts

Posted - 01/04/2007 :  03:05:26  Show Profile  Reply with Quote
Have your can of fuel above the base of the pump like basically it is in the car so it gravity feeds. The pump runs on 12V, be VERY careful of sparks and fuel vapour.
Art
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cth350

USA
1525 Posts

Posted - 01/04/2007 :  10:01:54  Show Profile  Visit cth350's Homepage  Reply with Quote
One means of safely testing the pump is to use kerosene rather than gasoline. It's less flammible and also lubricates better along the way. To some (like my wife), it stinks less.

-CTH
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Gregory

USA
62 Posts

Posted - 01/04/2007 :  14:56:49  Show Profile  Reply with Quote
Ok, here's the update. The pump moves fuel really well, however, it does leak around the negative terminal when the pump is activated and when there is a lot of fuel pressure just from gravity with the pump off. I unscrewed the terminals and discovered that there are o-rings on each connection; I'm guessing that I need to get new ones. Are they available?

Greg
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Art Love

Australia
6231 Posts

Posted - 01/04/2007 :  19:48:06  Show Profile  Reply with Quote
I wrote a response but then noted you had the short pump, not the long, so I have deleted it.
Art

Edited by - Art Love on 01/04/2007 19:53:01
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mdavie02

Australia
334 Posts

Posted - 01/12/2007 :  00:49:37  Show Profile  Reply with Quote
If it's leaking at all, it needs a rebuild.
You can use the pump off the 108's, but get the bracket as well from the wreck so that the pump bolts right on. Yes, it is not original, but if you use the high pressure version from the 3.5, there will be no vapour lock problems. Fuel flow is quite adequate, as discussed extensively in the past. Replacement is then very simple. You can keep the original on a shelf if you wish.


Here is a list I was recently quoted for rebuld of a long pump. I have no experience with the short.

for the pump 0.442.200.007
parts required are
2*brushes $15.00+gst each **
2*springs for brushes $11.95+gst each **
2*orings $39.00+gst each **
1*oring $33.00+gst **
1*valve ( external fitting) 93.00+gst //
There are some other o-rings which we should be able to get, but these are
the main ones

Regards

Michael Davies
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Gregory

USA
62 Posts

Posted - 01/12/2007 :  04:18:16  Show Profile  Reply with Quote
Thanks for the information and pricing. Quick question though...The first time I put 12V across the 3.5's fuel pump, could feel and hear it start to move. The next time I tried it, not thing happend. Does this mean I killed the pump, or is it just gummed up and needs to be cleaned?
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