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Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 3 Series / 4 Series > E30 (1982 - 1993)

E30 (1982 - 1993)
God's Chariot. The E30 was produced primarily from 1982 through 1991. The cabriolet was the one exception which was produced through 1993.

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  #1  
Old 04-06-2013, 12:46 PM
Sk8Mafiya Sk8Mafiya is offline
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BMW Hard cold start

Hello!
I'm having difficulties pinpointing a problem with cold starts. The engine will take 5-7 seconds before turning over. I've hooked up a fuel pressure meter directly to one of the hoses and it stays steady at 40psi. The plugs have been checked, injectors cleaned, fuel filter changed, cap and rotor, as well as many other shot gunned parts. Recently I took off the air intake boot to replace it (the old one had a nasty tear) and I noticed a build up of fuel. I know there is a blow back valve that re-emits the emissions back into the engine, so I unhooked that temporarily to see if fuel would still build up, and it did. I was wondering if it could be a problem with my Fuel pressure regulator? Or maybe a worn O-ring that leaks into the intake boot, then to my MAF unit. THANKS
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  #2  
Old 04-06-2013, 01:45 PM
Sk8Mafiya Sk8Mafiya is offline
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Also, I just pulled out my dipstick and it smells slightly like fuel, and I discovered a decent crack in my ICV hose.
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  #3  
Old 04-06-2013, 02:52 PM
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downhiller downhiller is offline
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could be fpr, the vacuum line that is cracked, other vacuum lines. it sounds like you found the problem, being running rich. change out what hoses you can since thatll be the cheaper fix and it doesnt hurt to do that, then go to the fpr if the hoses doesnt fix it.
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Old 04-06-2013, 02:54 PM
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What year and model is the car? I believe the earlier cars had cold start injectors which in your case could be bad.
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Old 04-06-2013, 03:20 PM
Sk8Mafiya Sk8Mafiya is offline
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It's a 1991 325i, 2 door. I don't believe it has a cold start injector, I read somewhere that you should hold the pedal half-way down in substitution of the non-existing cold start injector. Ordered an ICV vacuum hose for now, since it was practically split in half.
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Old 04-06-2013, 03:42 PM
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you have a fuel injected car. you shouldnt touch the throttle during start up.
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Old 04-13-2013, 01:15 AM
Eenbal Eenbal is offline
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Quote:
Originally Posted by Sk8Mafiya View Post
Hello!
I'm having difficulties pinpointing a problem with cold starts. The engine will take 5-7 seconds before turning over. I've hooked up a fuel pressure meter directly to one of the hoses and it stays steady at 40psi. The plugs have been checked, injectors cleaned, fuel filter changed, cap and rotor, as well as many other shot gunned parts. Recently I took off the air intake boot to replace it (the old one had a nasty tear) and I noticed a build up of fuel. I know there is a blow back valve that re-emits the emissions back into the engine, so I unhooked that temporarily to see if fuel would still build up, and it did. I was wondering if it could be a problem with my Fuel pressure regulator? Or maybe a worn O-ring that leaks into the intake boot, then to my MAF unit. THANKS
40psi? That seems rather high mate. Petrol injection should be around 3-4psi iirc. Might be over fueling on start-up?

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  #8  
Old 04-13-2013, 09:43 AM
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No 40 psi seems correct.
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  #9  
Old 04-13-2013, 09:50 AM
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I think you are referring to The transfer pumps which are rated at around 4psi
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  #10  
Old 04-13-2013, 01:46 PM
Sk8Mafiya Sk8Mafiya is offline
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ICV vacuum hose replaced, problem persists. Going to try a compression test on each of the plugs.
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  #11  
Old 04-13-2013, 05:34 PM
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when your starting you car, and your on the "start" portion having the starter engaged, does it seem to be turning the motor at a fast pace or does it seem to be slow like a dying battery?

reason i ask, if it cranks quickly, you most likely have a fuel bleed back problem causing an air pocket in the fuel filter and long crank times when cold (very similar to vapor lock)

if it cranks slow, the battery doesnt have the power to rotate the motor for it to catch and run by itself and part of the problem is the ignition doesnt have the juice to light the air/fuel mixture in the combustion chamber.
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Old 04-24-2013, 06:40 PM
Sk8Mafiya Sk8Mafiya is offline
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The battery is fine, but it just seems like a normal crank time. I don't understand the build up of fuel in my Air Intake boot. I've temporarily re-rigged the fuel blow back hose so the fumes can't even get back into the engine, but somehow fuel is still there. After turning the car off, it will start right up; but only with in a 10 minute time-span. The problem is driving me mad!
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  #13  
Old 04-25-2013, 10:53 AM
gamma gamma is offline
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Me too!! And i've changed my fuel regulator pressure before yesterday, 80$.. And nothing.. Same problem.. I changed barely everything..
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  #14  
Old 04-25-2013, 06:41 PM
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are your injectors stuck open?
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  #15  
Old 06-29-2013, 10:52 AM
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BigBoy740il BigBoy740il is online now
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Re: BMW Hard cold start

OP,
First off, get a Bentley manual and check chapter 6, section 5.5. Remember, vacuum leaks would cause a high fuel pressure at idle, but by now you should have replaced all vacuum/intake hoses and boots. The FPR is rated at 3 bars (42.4 - 44.4 psi). There are a few checks you should perform. First, connect a fuel pressure guage to the fuel rail input. With the engine running, check the pressure level. A high reading indicates a blockage in the return line. If the reading is ok, remove the vacuum hose from the FPR. The pressure should increase, if it doesn't, squeeze the fuel return hose. If the pressure increases, the FPR is bad. Next, shut the engine off and note the pressure reading on the guage. Wait 30 min. Pressure levels shouldn't drop more than a few psi. Excessive drops indicate a bad FPR, leaking injectors, or a bad fuel pump non return/check valve. Since you stated you have fuel in the intake booth and possibly oil, I would lean towards leaking injectors or high fuel pressure.
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Last edited by BigBoy740il; 06-29-2013 at 11:05 AM.
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bmw 325i 1991, cold start, fuel pressure regulator, hard crank, long crank, mass air flow, mass air flow sensor, rough start


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