Intermittent E30 Engine Problem

[98_s14 0]

Hi there,

I'm having some engine trouble with my E30 320i engine. I've had an intermittent (well 90% of the time) engine fault since having a roll cage installed (it may be completely unrelated), the engine will start, idle ok and drive a short distance before spluttering a bit or just losing all power and dieing.

Since then, the engines been completely rebuilt, I've had the alternator tested, it has a new battery, air filter, fuel filter, spark plugs and I've adjusted the air flow meter to make sure its on fresh carbon. The engine started fine the first two or three times after putting it back in the car, and would idle, rev a bit etc but wasn't driven. Then last night it started fine, idled ok, would respond poorly to throttle, I drove it up the driveway and it died and wouldn't start (but had enough voltage to crank the engine).

So, what can I check? The fuel pump? Fuel pump relay? The coil? Is there an easy process I can go through to check these things with limited equipment? I don't think the engine is flooded because it starts fine. I don't know whether parts like the dizzy rotor or cap can cause an intermittent fault?

Thanks a lot in advance, I won't be racing at Hampton Downs this weekend if I can't get to the bottom of it

Edited November 25, 2009 by 98_s14

[e30ftw 410]

Have you done anything with the fuel system yet ? Changed out fuel filter?

Could be a bad fuel pump supplying low fuel pressure, bad FPR, bad injectors, or even just crap in the fuel tank?

[98_s14 0]

Have you done anything with the fuel system yet ? Changed out fuel filter?

Could be a bad fuel pump supplying low fuel pressure, bad FPR, bad injectors, or even just crap in the fuel tank?

Thanks for replying,

Yeah it has a brand spanking fuel filter, injectors have been cleaned and flowed, I don't know about the FPR, whats the best way to test the fuel pump?

[e30ftw 410]

Wait for someone more knowledgeable to chime in.. But have you checked the fuel pressure at all?

[*Glenn* 854]

Could be many things causing this. How did you adjust the AFM without a gas analyser ??? I would check fuel pressure with a guage first and if no pressure check power feed to the fuel pump on crank, then fuel pump relay in that order first. If you have limited tools or knowledge to do these things safely ...get a proffessional to check it. It may be something quite simple.

BTW: alter your profile so we know were your from

Edited November 25, 2009 by *Glenn*

[98_s14 0]

Could be many things causing this. How did you adjust the AFM without a gas analyser ??? I would check fuel pressure with a guage first and if no pressure check power feed to the fuel pump on crank, then fuel pump relay in that order first. If you have limited tools to do these things safely ...get a proffessional to check it. It may be something quite simple.

Yes I suspect it is something quite simple. I didn't change the spring tension on the AFM, just the little arm that sits on the carbon track (to make sure it has a good contact).

I don't have a fuel pressure gauge, I can borrow and ammeter to check the voltage at the fuel pump. I'm guessing I could swap the fuel pump relay with another relay to check it perhaps?

Edit: Location added, thanks for that

Edited November 25, 2009 by 98_s14

[*Glenn* 854]

Who did all the other install work for you ? Maybe get them to check it for you. Where abouts in Auck are you from ?/

[98_s14 0]

Who did all the other install work for you ? Maybe get them to check it for you. Where abouts in Auck are you from ?/

We put all of the bits and pieces back onto the rebuilt engine, but the problem was happening before the engine was rebuilt. It happened after a roll cage was welded in which makes me wonder if something electrical got damaged (the battery and ECU were disconnected at the time).

The car is in West Auckland.

Edit: So your initial thought would be fuel and not spark?

I have a spare used fuel pump, I could swap that in and try it.

Edited November 25, 2009 by 98_s14

[*Glenn* 854]

We put all of the bits and pieces back onto the rebuilt engine, but the problem was happening before the engine was rebuilt. It happened after a roll cage was welded in which makes me wonder if something electrical got damaged (the battery and ECU were disconnected at the time).

The car is in West Auckland.

Your probably right. Check that none of the fuel lines have been crushed. Failing that I'd advise getting a professional to look at it for you. We could here next week, but were in Botany South

[98_s14 0]

Your probably right. Check that none of the fuel lines have been crushed. Failing that I'd advise getting a professional to look at it for you. We could here next week, but were in Botany South

Ok thanks for that Glenn, I'm hoping to get it sorted so I can race this weekend. Even the fuel lines are new. Is there a similar relay I can swap for the fuel pump one? Are they expensive?

[*Glenn* 854]

There should be 3 relays on the L/H front strut mount. The centre one is fuel pump. Bridge pin 30 & pin 87. If the car runs properly, the relays knackered. I'm not using your chassis #. This could be wrong.

Edit: You sure you havent mixed up the supply & return fuel lines ???

Edited November 25, 2009 by *Glenn*

[98_s14 0]

There should be 3 relays on the L/H front strut mount. The centre one is fuel pump. Bridge pin 30 & pin 87. If the car runs properly, the relays knackered. I'm not using your chassis #. This could be wrong.

Edit: You sure you havent mixed up the supply & return fuel lines ???

I don't think I've got them mixed up. I'll try bridging those pins tonight. If that doesn't work I'll check voltage across the pump and swap my spare one in if that comes up good. I'll keep you posted, thanks for the help so far.

[98_s14 0]

I tried a spare air flow meter last night and hey presto! the problem seems to be gone.

Hopefully thats the end of it, thank you for your help

[*Glenn* 854]

All good