About to replace fuel pump, have a few questions.

[jlevie]

The lack of a CEL on an E30 when intake leaks are present isn't unusual. The engine management system isn't that sophisticated. Have the smoe test run, even if you have to have the car towed to a shop.

[willfill]

I can't say why it starts easier if you turn on the ignition and wait as there is nothing in the way of how the engine management system works to explain that. But I will say that it sounds to me like there may be intake leaks. Have a smoke test run to find out.

I just called my shop and asked about the smoke test, the guy said it would be about $60, so I'll probably do it at some point. Problem is its uninsured at the moment so I can't drive it down there. He also said that if I don't have a CEL I shouldn't worry about intake leaks. Any opinion on that? To me that seems like one of those things that the computer might not notice. Also idk if this would be connected to that, but since my car is an '87 I can't do the stomp test, so I assume my vehicle diagnostics aren't that great and maybe that's why I don't get a CEL.

[5Toes]

I just bought a TRE unit for my e34 - I was very impressed and the company had great customer service!!!

[jlevie]

That's really weird, because my car was a real pain in the ass to start until I started waiting, and now it starts first try every time. Also my fuel gauge says 55L. Do you think that it's possible that it isn't the fuel pump? The issues I've been having are really hard starts when cold or warm, and intermittent dying while driving (seems to happen more in low RPMs).

I can't say why it starts easier if you turn on the ignition and wait as there is nothing in the way of how the engine management system works to explain that. But I will say that it sounds to me like there may be intake leaks. Have a smoke test run to find out.

[willfill]

You mention tre 255 but then say in tank or external..the tre in tank will eliminate the need for the external and you will want to bypass it (bit of a pain, had to find correct fittings online due to fact fuel line on one side of pump is larger then the other) also you will need to slightly modify the sender for the in tank tre to work.

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Is there a guide of how to do this online?

[willfill]

The fuel pump(s) are controlled by the DME and only run when the DME sees timing data from a rotating engine. So just having the ignition on does nothing as far as the fuel system is concerned.

A 7/87 car should have the 53L tank and the dual pump configuration.

That's really weird, because my car was a real pain in the ass to start until I started waiting, and now it starts first try every time. Also my fuel gauge says 55L. Do you think that it's possible that it isn't the fuel pump? The issues I've been having are really hard starts when cold or warm, and intermittent dying while driving (seems to happen more in low RPMs).

[Poorboyz]

Cool, thanks

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[FLG]

I only ask because my 2001 330ci the pump comes on for 5 seconds once key is in the 2 position, then comes back on when you start cranking the car.

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Yep, not the case with the e30. Newer cars do it, or in my case my e30 does it with megasquirt

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[Poorboyz]

No, it only starts priming when you start cranking.

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I only ask because my 2001 330ci the pump comes on for 5 seconds once key is in the 2 position, then comes back on when you start cranking the car.

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[FLG]

So when we turn the key on the fuel pump doesn't come on to pressurize the fuel system lines until the car is actually on? I thought when key was turned to the 2 position the fuel pump came on for 5 seconds to pressure the lines.

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No, it only starts priming when you start cranking.

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[Poorboyz]

The fuel pump(s) are controlled by the DME and only run when the DME sees timing data from a rotating engine. So just having the ignition on does nothing as far as the fuel system is concerned.

So when we turn the key on the fuel pump doesn't come on to pressurize the fuel system lines until the car is actually on? I thought when key was turned to the 2 position the fuel pump came on for 5 seconds to pressure the lines.

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[FLG]

You mention tre 255 but then say in tank or external..the tre in tank will eliminate the need for the external and you will want to bypass it (bit of a pain, had to find correct fittings online due to fact fuel line on one side of pump is larger then the other) also you will need to slightly modify the sender for the in tank tre to work.

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[jlevie]

The fuel pump(s) are controlled by the DME and only run when the DME sees timing data from a rotating engine. So just having the ignition on does nothing as far as the fuel system is concerned.

A 7/87 car should have the 53L tank and the dual pump configuration.

[willfill]

Do yourself a big favor and have a shop perform a smoke test to find any vacuum leaks.

That's a good idea, I'll ask my local shop how much it would be.

[dnguyen1963]

Do yourself a big favor and have a shop perform a smoke test to find any vacuum leaks.