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JHG762002

318i fuel pump for efi

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Does anyone know how difficult it would be to retrofit the intank high pressure pump from the 90-91 318i to the fuel sender of the older prepump style sender? I have the older style and replacement hi-pressure pumps are pretty reasonably priced. From the picture of the two pumps below it looks possible.

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Take the old one out, put the new one in, hook it up, done.

They never changed the mounting tabs on the E30, so it should fit without any trouble.

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Take the old one out, put the new one in, hook it up, done.

They never changed the mounting tabs on the E30, so it should fit without any trouble.

That would be ideal, however I only have the low pressure version of the 318i pump. I am thinking of installing a new hi pressure replacement in place of the low pressure pump.

Here is a link to one at

http://sd.autohausaz.com/autohausaz/detailw.jsp?sid=rpo141rb53xfyxnrymcour45&partner=autohausaz&product=P74006

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I think you could make it work if you really wanted. You would have to replace a bit of the fuel line with high-pressure, and bypass the high-pressure pump and one of the regulators. The pump you showed is pretty generic and fits many different applications, so I would think you could pull it off. Let us know if you try it.

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What injection are you using? If MS, then the 318is pump will supply enough pressure.

As for the line, if you have a later car(72>), do as they did on the tii. Use the metal line for the pressure side and the plastic for the return. Replace all rubber lines on the pressure line with new high pressure fi fuel line. Same with the return. Install clamps on all connections. I like the crimp style. The worm screw style will work just as well.

Thats it. For the sender, get the proper plug to fit the e30 sending unit and splice the 02 harness in or get the proper connectors from BMW to shap into the plug for that clean install.

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The AutohausAZ link is for a replacement pump only and you will have a fun time trying to fit it in with the tubes that are bent for the LP pump.

It is also possible to find a good used 325IS pump or one from a 325IX about the same year or earlier than the 90-91. It doesnt have the return nozzle on it however. That's what I run and have 2 spares. If you get one from a Cash for Clunker car, it should be ok. Otherwise make sure it is not dead. My return goes to the return on a Tii pickup. I have also used an inline pump like the Tii arrangement except it is a 3 bar pump.

These are 3 bar system pumps. You can easily test a pump for flow capability at pressure by attaching a hose to a can from the return on the regulator. If it flows good, it holds the required pressure at flow conditons. A pump always has to flow more than what the engine needs at the regulator pressure, or the engine will run out of fuel.

Whenever fluid is being pushed thru a tube, it is under pressure. I also do not recommend using the in cab plastic pipe. Get a leak and the car gets filled with gasoline the KABOOM. The plastic line was always under suction with the carb and mechanicla pump. Std for fuel injection is to have both lines outside the car. It's you risk, go for it if you like.

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Thanks for all of the replies. Yes this is for Megasquirt using 318i hardware. Here's what I ended up doing, this is yet untested. Hopefully I will have the car running in a couple weeks. I shopped rockauto for compatible fuel pumps and found one on closeout for around $20. I figured I'd give it a shot. I basically used the original sender as a guide for length and installed the new HP pump. I lucked out in that the new pump had the same diameter as the old LP pump. This allowed me to modify the bracket that holds the pump in place. I had to solder in a new wire harness for the pump, which, thankfully, was included with the pump. Obviously the sending unit is too short, I am planning wiring the low fuel warning light into the dash top light, it's a '76. As to the return line, I ran a new steel line under the car next to the original line. Like many others here I didn't like the idea of using the old plastic line.

Here are some pics

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