injectors not fireing

[jaysee]

hey i have a 1986 bmw 325 and after changing the head gasket the fuel injectors
will no longer fire, i have 12v to all injectors and i do have spark
i thought maybe there was a fault in the wiring but i can fire the injectors by grounding pins 14 and 15 from the dme connector.
the car will start for half a second off of the fuel from the cold start injectors
and the reference sensor is within spec but the engine speed sensor is out of spec by around 3ohms
i got a used dme from someone on e30tech thinking that was the problem but it didn't change anything.. ecu has power at all the proper connectors..
i dono what else to do..
the car was having problems dying sometimes before i changed the head gasket..
and sometimes would have to sit for a few hours b4 it would start again

[jaysee]

anyone have any idea what the problem is and wanna chime in on this?

[HPMotors]

What is the fuel pressure? Is this an i or an e? Sure you got all of the bits back on right? Cam timing, electrical timing, ALL connections? Just last week we did a valve job on an 07 Suzuki Reno and it wouldn't run after we got it back together. Checked it every which way - getting extremely annoyed - and finally found a loose ground connection hidden under the intake manifold that we had failed to tighten. This took us a bit to find as it passed visual inspection - but not a wrench check. When you do a job like a head replacement, as you know there are LOTS of things to put back just right. Little things missed can bite you on the but big time.

If all of the above is correct, then move on.

You certain none of the injectors fire when the car runs briefly? Mazda has an extremely similar, flapper style air flow meter (which this car has). Mazda has a run inhibit if the meter doesn't move off closed - a safety to keep fuel pump from running if motor quits. Looking at the wiring diagram BMW does not seem to have this feature. Can someone verify? Is there some other type run inhibit BMW uses?

If you are certain the injectors aren't firing at all then this would not be the problem anyway. I'm just suspicious of this since you say it runs momentarily.

Another thing the wiring diagram shows is that the 325 only has six injectors. Where is this cold start injector you referred to? The diagram I am using is for a 1987 3 series - supposedly 86 would be the same.

Car dying before you pulled head? Fuel starvation? You need to elaborate on that a bit as most likely what was going on then part time is now full time.

Wish I could tell you more but these types of problems just take troubleshooting procedures - and they are tougher to do remotely.

cheers & good luck - Henry

[markdas]

Agree with Henry thought process.....

Earths make a big difference on the E30, check there is a good earth on the top of the engine, I put an addtional one on one of the rocker cover bolts to the bulkhead on the exhaust side just to make sure!

Crank sensor could still be a culprit, check the toothed wheel is clean and the sensor too at both ends, check it carefully for cracks in the insulation at both ends.

Fuel can be a big issue too......not sure if you have the 2 pump set up, but check each one is running. Again, we ran new wires to the fuel pump to get better reliablity. Check the fuel pump rely too and the main relay which is next to it in the engine bay! You can force the fuel pump to run using a small length of wire, then try starting the engine?

ECU at fault maybe?

[jaysee]

i used noid lights to verify the injector are not fireing. and cold start valve is in the middle on the intake manifold twordes the side the valve cover is on
there is a fuel line going directly to the sold start injector
also being a eta fuel psi is 2.5 bar and i teasted and got between 40-45 psi

86 uses a "200" casting head
and 87 is different, it was a major update and used a different intake manifold
as well as different pistons and the "885" casting head same as the 325i
87-88 was called a super-eta
i have a Bentley manual for my car as well as a wiring book for my specific year
and when i say it momentarily starts i mean it catches for half a second and dies by the time i release the key. and thats after cranking for 10-20 seconds.
allowing enough fuel to build up from the cold start injector.

i can fire each bank ( its set up in 2 sets of 3) of fuel injectors by manually grounding the 14th and 15th pin of the ecu connector (wich is the pins for the ecu that connect to the fuel injectors) so i would gather that the harness to the injectors is in-tacked
also the ecu has power and the right connectors and all the ecu grounds have continuity to the chassis

[markdas]

Have you done a compression test post head gasket change? Sounds like you are pretty competent at all this, but there is always the chance of an error in terms of timing marks, compression leak etc?

[jaysee]

and i thought the ecu was bad. and got a new used one from someone on e30 tech
hooked it up and car still does the same thing.
the cps ohms out as in spec per bentley manual. but the engine speed sensor that counts the flywheel teeth does not
also i was under the impression that if the cps was out i would have no spark

i have heard that the engine only needs the cps out of the 2 to run. (out of the crank sensor and engine speed sensor)

im going to the salvage yard today to try and find some referance sensors
im to broke to buy new ones and out of work due to a bad head injury

[markdas]

Sounds like the crank sensor.......I think you can still get a spark and not have the injectors firing?

If you had no spark and no injectors, then I would have said immobiliser?

[jaysee]

well i should find out soon, im going to the salvage yard to look for reference sensors (crank sensor and engine speed sensor are identical.
but this will be fun. day before yesterday it was 50 degrees and sunny. today theres 8-12inches of snow accumulated and its almost a blizzerd ( gotta love west michigan lake effect)
but this is the only day i have a ride out to that salvage yard witch is 45mins away, (probably an hour and a half in this weather)

[jaysee]

well i replaced that sensor and now the car runs.. it runs like **** but it runs
turned out to be the engine speed sensor that was the problem