Author Topic: M42 weird starting issue (Read 8487 times)

longms · « **on:** October 26, 2009, 01:22:23 PM »

So my m42 is finally running and logging some miles. There is only one issue. When I turn the key the engine turns over for about 4-5 seconds but then fires up every time. The car does this every time. It will not fire right up upon turning the key.

What could be some possible reasons for this issue? What should I be checking? Could MAF sensor do this? Could the fuel lines be losing pressure and that is how long it is taking to build it back up?

Thanks in advance.

Sophia69IS · « **Reply #1 on:** October 26, 2009, 04:43:55 PM »

my car does this too! I haven't been able to figure it out, I replaced the starter and it worked for awhile and then right back to doing this.

longms · « **Reply #2 on:** November 09, 2009, 08:42:01 AM »

Still have not found a fix...fuel sensor has been pressure check and everything and that all seems to be ok.

Yea, my starter is working fine. It turns the motor over strong but it is like the motor has to wake up and build up before it decides to fire. Ignition maybe?

?

AcSchnitzer318is · « **Reply #3 on:** November 09, 2009, 09:01:14 AM »

New plugs? Wires? I was thinking starter, but you say not that. Fuel pump was my other guess... but you pressure checked fuel system.

kowalski · « **Reply #4 on:** November 09, 2009, 12:51:50 PM »

check valve on your fuel return line. Keeps the fuel line pressurized for re-start.

You can just put in a fuel line check valve, call bma and describe what you need.

I paid less than $15 to fix this problem.

enildeR · « **Reply #5 on:** November 09, 2009, 03:15:41 PM »

are you referring to the pressure regulator? because that is not $15. that is expensive.

where was the part you replaced, if it isn't the regulator? was it near the fuel rail or near the tank?

would you be able to look on realoem and see if they have it listed?
Real OEM VALVES/PIPES OF FUEL INJECTION SYSTEM

cjshelley · « **Reply #6 on:** November 10, 2009, 02:44:08 PM »

My E30 does this as well, but there have been one or two occasions where it didn't start in the moderately cool weather. I cranked it for quite a while and the motor almost caught every few seconds - it would burble like it's about to start and then go back to cranking. 9/10 times it has trouble starting (cold only), it cranks, burbles, and then fires up. I was told I should check my fuel pressure at various places along the lines, but not only am I lazy but I also lack a pressure gauge (and my last experiment with fuel lines ended with gasoline shot down my ear canal... OH the pain). I looked in the Bentley and with the fuel pump working and the ICV mechanically functional (the jury's still out on whether or not it's getting a signal), I decided that the cold start valve might be shot. Granted, the Bentley I have covers my body but no the M42, so I haven't investigated yet.

longms · « **Reply #7 on:** November 15, 2009, 01:22:00 PM »

Everything electrical (wires, plugs, fuel pump, etc) on the motor is brand new with only about 200 miles of run time.

Will check pressures more extensively.

longms · « **Reply #8 on:** November 21, 2009, 09:41:08 AM »

Quote from: kowalski;81155

check valve on your fuel return line. Keeps the fuel line pressurized for re-start.

You can just put in a fuel line check valve, call bma and describe what you need.

I paid less than $15 to fix this problem.

Where is this said check valve???

longms · « **Reply #9 on:** November 23, 2009, 11:00:15 AM »

We also installed brand new fuel lines into the system. Could the new lines have anything to do with it?

Andy_Casey · « **Reply #10 on:** November 23, 2009, 11:44:22 AM »

Most EFI systems prime the fuel system when you put stage 2 on the ignition. You'll hear the fuel pump whirr a little then stop...

longms · « **Reply #11 on:** December 01, 2009, 10:03:31 AM »

Explain to me what you mean by putting stage 2 on the ignition???

And I want to know how you got your M42 to 160bhp?

?

DesktopDave · « **Reply #12 on:** December 01, 2009, 10:56:32 AM »

He's talking about key position II, where the key is in running position. Position III turns the engine over.

I heard about this check valve to fix warm start problems on my e34. I'm thinking it's installed in the fuel supply line after the high-pressure pump to prevent fuel from bleeding back into the tank.

IIRC it's normally integrated into the pump, but when it goes it's much easier & cheaper to just splice a new one in on the fuel supply side.

cjshelley · « **Reply #13 on:** December 02, 2009, 10:09:31 PM »

From what I read somewhere on the M42, the fuel pump is only actuated once the starter turns the motor at 125 RPM or something like that. My fuel pump doesn't make a peep with the key in position 2 (in an E30, maybe it changed with the later models)

DesktopDave · « **Reply #14 on:** December 03, 2009, 08:32:13 AM »

Let me double check that. I thought the pump primed the lines on pos II, then started running when the engine spins. I'll re-post later today with my findings.