Misfire/ won't start
Moderator: martauto
Hi, it's a m20 2.0 been running fine. But had a loss of power misfiring. Tried to get it home but just got worse pulled over then it cut out, and now won't start. Getting spark from the plugs. Undid the fuel line to the rail n cranked it fuel came out. I've Changed the distributor cap. Don't know what to do next?
Thanks
Thanks
- Brianmoooore
- E30 Zone Team Member

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- Joined: Mon Jan 10, 2005 11:00 pm
Not 100% conclusive that the pump is good. With the supply pipe undone the pump has a far easier time than when it's working under a couple of bar pressure.Eddypunch wrote: Undid the fuel line to the rail n cranked it fuel came out.
- Brianmoooore
- E30 Zone Team Member

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- Joined: Mon Jan 10, 2005 11:00 pm
Fuel will come out at quite a rate from an open supply pipe, but this is at zero pressure, not the pump's working conditions. You need a fuel pressure gauge to check under those conditions.
Check whether the spark plug tips are wet with fuel after cranking. If not, assuming the pump IS good, the problem could be the DME relay not providing power to the injectors.
Check the relay by removing it, identifying pins 30 and both 87s of its socket, then using two short lengths of wire to link together these pins of the socket.
Check whether the spark plug tips are wet with fuel after cranking. If not, assuming the pump IS good, the problem could be the DME relay not providing power to the injectors.
Check the relay by removing it, identifying pins 30 and both 87s of its socket, then using two short lengths of wire to link together these pins of the socket.
- Brianmoooore
- E30 Zone Team Member

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- Joined: Mon Jan 10, 2005 11:00 pm
?? How do the relays make a noise when they're not fitted to the car??Eddypunch wrote:I've linked the both the terminals on the ralays. The dme made a clicking sound and the fuel pump was making a noise.
Nearly starting could well still be fuel pump, with the pump cutting out under the reduced voltage while cranking. The first time I encountered this was while I was away from home, and it took me some time to work out what was happening.
Cheap fuel pressure gauge required - ebay for under 20GBP.
- Brianmoooore
- E30 Zone Team Member

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- Joined: Mon Jan 10, 2005 11:00 pm
Fuel light not on? This is normally reliable and accurate.
- aimlessrock
- E30 Zone Squatter

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- Location: Manchester
if your tank is on the dreggs i would use this chance to empty it out before putting fresh fuel in. Also checking the fuel filter would be wise.
just my two cents
just my two cents
E30 320i Convertible (1989)
190 Mercedes (1988)
"there is nothing more expensive than a cheap E30"
190 Mercedes (1988)
"there is nothing more expensive than a cheap E30"
Is it now working ??Eddypunch wrote:Gonna sound like a massI've idiot here, didn't have any fuel a™„. The fuel gauge is saying it's got some in.
Thanks for the help!!
If so what the hell eh ?, shit happens yeh?
Mart.
Only the E46 cab left now.
Just got too old.
Just got too old.
- Brianmoooore
- E30 Zone Team Member

- Posts: 49358
- Joined: Mon Jan 10, 2005 11:00 pm
Ah! That probably explains things!Eddypunch wrote:Well it goes up n down all the time. The bloke I bought boy off said when he changed the fuel pump bad it's been doing that since.
Fuel level sensor has to be removed from the fuel pump assembly before the pump assembly can be removed from the tank.
The uninitiated don't know this in advance, but the portion of the uninitiated who are also terminally clueless just go ahead and try to remove it complete anyway. This results in creases and dents in the aluminium tube that contains the level sensor, writing it off.
In my post further up the page, I mentioned a time when I had a fuel pump fail while I was away from home. I eventually found a scrapyard that had an E30 in it, and in that E30, the rear seat and cover over the pump had been removed, the pipes and wires removed from the pump, and the pump twisted loose from the tank. At that point, they had found that the pump wouldn't come out of the tank, and had given up. All I had to do was to undo the four nuts securing the level sender, pull out its mangled remains, and then lift the pump out.
On the subject of 'breaking down' that turns out to be just an empty tank - that happened to me twice in the space of two weeks with my E39!
The first time was late at night in Germany, when I ended up being recovered on the back of a flatbed. This car normally runs on LPG, but, as a result of a fault with the ECU, it had switched to running on petrol while still indicating that it was running on LPG. The low petrol light was on, but that's not unusual, since petrol is only required for starting and emergency use, and every litre carried is unnecessary ballast. It was showing plenty of fuel on the LPG gauge, so I didn't even think of carefully looking at the petrol gauge.
The second time was partly as a result of work done after the first breakdown.
Since I didn't fully understand at the time while the car had used petrol instead of LPG, I decided to run with a full petrol tank, which uncovered a leak from the petrol tank. This turned out to be a badly fitted seal around the fuel pump retaining ring, so the pump was duly removed and refitted in a German car park, before returning home.
A few days later my wife was out with the car, and rang me to say the car wouldn't restart after being parked for a few hours.
This time, I had all the symptoms of no petrol again, but a petrol gauge reading exactly half full. 5 litres of petrol got the car going again, and on further inspection, I found that one of the twin level sensors in the tank had become caught up in the fuel pump wiring when it had been refitted in Germany, keeping that sensor at full.



