Prolonged cranks to endless cranking.. Relays?

[Z06&E30]

86 325 auto

Up to date on all normal maintenance, just finished driving the car from SE Florida to SW Texas, ran like a champ!

Once in Texas, we had some cooler days, car started to have a little issue with starting, crank for 5 seconds, let it sit for 5 seconds and try again. Complete that cycle 3 or 4 times and the car would fire up and run normal. Drive around town to do errands car was fine, no prolonged cranks after being up to temp.

Drove the car on a work trip about 500 miles round trip, prolonged cranks, given the car only had to start twice, departing home and departing work.

Following morning, head out for errands. Extremely prolonged cranking, rest, cranking. Finally got it start up and it ran fine. Go to leave the store, car will not start, just cranks and cranks. Did not want to burn the starter up so after about 10 minutes of cycling the crank, rest, crank ordeal the car fires up and idles as normal. Drop her into drive and I am making my way through the parking lot the car dies. Cold dead, no sputtering, no bucking, straight dead like the key was pulled out. Stop the car, put it in park and try to re start, after about 30 seconds of fussing around it starts and we are on our way, sorta. Get about half a mile down the road at a light, same thing - dead stop, no bucking no sputter. Go to restart before the light changes, it wont even crank. I pull the key and try again, finally get it to start. I race it home and instead of shutting it down, I let it idle and open the hood to try to see if there is anything I can wiggle or move that will kill the car. I couldn't find anything. Car is idling away as it should. I turn the car off and restart, fires up right away. Following day, jump in the car and it just cranks and cranks. No start at all. What is going on?

Relays? Fuseable link?? Coil?

New plugs, wires, cap, rotor... Coil is not new though.

New fuel pumps (in tank and high pressure)

New fuel filter

I think its electrical, since when it does die its instant.

[Z06&E30]

No one...?

[RobDog]

Sounds like leaky fuel injectors, Crankshaft position sensor, or maybe a vacuum leak. Check the metal 90* elbows that connect to the throttle body and make sure they are not loose. If you can pull them out or wiggle them they are a vacuum leak that could cause stalling and hard starts. Ohm the CPS and check for any cuts or Knicks in the wire. Check that the fuel rail is holding pressure after you shut the car off with a fuel pressure gauge.

[superj]

since you are driving an eta, check the temperature sensor that effects the cold start/starting system.

my sons 86 325 also has a long start but I think his is the check valve in the fuel system because his cranks about 5-8 seconds before starting and I swapped all his sensors with the ones on my 86 325 with no change in either car (mine starts perfectly on the first crank, each time) but his fuel pump/check valve is who knows how old and mine is a year old.

I would definitely also day you have something loose that bumps around and looses/gains connection. like maybe one of the sensors in the transmission bell housing, by the starter. one of those tells your fuel pump to come on when cranking so if its got a loose/bad connection, you will just crank and crank.


where are you at? the valley? not many places down there can help you out, either? there are a few nice e30s that the owners do all the maintenance on and some that are chopped and hacked pretty badly.

if you were in corpus, there are a number of guys who are great at e30s and could help.

[Z06&E30]

since you are driving an eta, check the temperature sensor that effects the cold start/starting system.

my sons 86 325 also has a long start but I think his is the check valve in the fuel system because his cranks about 5-8 seconds before starting and I swapped all his sensors with the ones on my 86 325 with no change in either car (mine starts perfectly on the first crank, each time) but his fuel pump/check valve is who knows how old and mine is a year old.

I would definitely also day you have something loose that bumps around and looses/gains connection. like maybe one of the sensors in the transmission bell housing, by the starter. one of those tells your fuel pump to come on when cranking so if its got a loose/bad connection, you will just crank and crank.


where are you at? the valley? not many places down there can help you out, either? there are a few nice e30s that the owners do all the maintenance on and some that are chopped and hacked pretty badly.

if you were in corpus, there are a number of guys who are great at e30s and could help.

Sorry for the delayed response but thanks for the input everyone. 7 on 7 off makes it tough to find the downtime. I've got 7 off right now so my goal is to get it figured out.

I'll look into those!

I am in Corpus! Went ahead and ordered some relays but unfortunately sent them to my address in SoFlo. Regardless, headed out to mess with the car. Will report back with any finds/progress.

[Z06&E30]

FINDINGS -

Messed around with the relays, took the horn relay and fog light relays and swapped them in for the Fuel pump and O2 sensor relay. Made no difference. Removed the fuel line feeding the cold start injector and hit the key, did not get any fuel gushing out.

With that, it leads me to believe that the high pressure pump is out again. I have the one that came with the car which is older but will swap in to see if that makes a difference.

Does this make sense? I wasn't able to find a relay that was compatible for the main relay from the fuse box... Does the main relay send any signal to the high pressure fuel pump or even the low pressure pump?

[Maggiolone]

Might have leaking injectors.

[Z06&E30]

Round 2 of FINDINGS -


Went out this morning to swap out the high pressure pump, figured I'd try one more time to see if I could get it to run. Hit the key and it fired right up and purred. Ran good until it go to about opearting temp and it cut out like the key was hit off. I attempted to restart and couldn't get anything.

Went ahead and placed my multimeter and some gator clips to the terminals on the high pressure pump. Nothing 0.00 volts when the key was in the crank position.

Checked the fuseable link near the battery - Good.

Went ahead and pulled the relay for the fuel pump, placed a jumper in there and tried to start the car. I could hear the pump running but the car still would not start, only cranking.

Checked voltage on the terminal for the fuel pump relays, read 12.0 or something near right.

Checked the crankshaft position sensors on the bell housing (drivers side)..... this is where I find a few 'could bes' both sensors are in poor shape where they are plugged into the loom. I pulled on off, the gray one and the sensor pigtail basically crumbled in my hand, and read around 1050 ohms(?), plugged it back in. Tested the black one and it also broke down in my hand, showing the wires for the 3 prongs to open air and losing the actual plastic fitting on the end.

This would make sense, if the DME does not see the correct timing or position for the crank it wont fire the injectors or will batch fire them in the wrong order. So even with the fuel pump relay jumped it still is in the wrong order and if the DME does not see the timing or has no reference or signal from the CPS then the fuel pump will not be energized?

[RobDog]

The DME has to be able to see timing data from a rotating engine before it will fire the injectors, spark, or turn on the fuel pump. I have had cps and engine speed sensors go bad before and act temp sensitive. They read the correct olms and work until warm or cold. My dads 325es would not start cold but would start if pushed started. Then once warm it would start with the starter for the rest of the day. That ended up being the engine speed sensor, the forward/upper sensor. My dad's sensor crumbled in my hand also, leaving me with metal pins. If they are crumbling in your hand then they are older than shit and should be replaced. The cps and engine speed sensor are the same sensor, so they share the same part number and are interchangeable. I think you are on the right track. I would start with changing those 2 sensors and go from there.

[Z06&E30]

The DME has to be able to see timing data from a rotating engine before it will fire the injectors, spark, or turn on the fuel pump. I have had cps and engine speed sensors go bad before and act temp sensitive. They read the correct olms and work until warm or cold. My dads 325es would not start cold but would start if pushed started. Then once warm it would start with the starter for the rest of the day. That ended up being the engine speed sensor, the forward/upper sensor. My dad's sensor crumbled in my hand also, leaving me with metal pins. If they are crumbling in your hand then they are older than shit and should be replaced. The cps and engine speed sensor are the same sensor, so they share the same part number and are interchangeable. I think you are on the right track. I would start with changing those 2 sensors and go from there.

Ordered two CPS sensors, they both were toast. Crumbling in hand and the sensors themselves were grimmy.

I agree, with everything you stated. Hoping this is the problem here. Reading last night, does the position of the two sensors matter once they are plugged in? like the orientation in relation to each other? For example, the fwd female plug is for the lower sensor and the more aft female plugs is for the higher location? I was too excited to pull them off to remember the orientation, not that it would matter. Try it one way, if it doesnt run right, switch the plugs?

Fixed the drivers side wheelbearing, thing was toast. Came off in several pieces. Hope it rids of the humming at 55mph +...

[RobDog]

The CPS goes to the rear/lower hole in the trans and reads off the single metal pin on the flywheel. The CPS plugs into the gray harness plug.

The engine speed sensor goes to the forward/upper hole in the trans and reads off the teeth on the flywheel. The engine speed sensor plugs into the black harness plug.

I am doing the rear wheel bearings on my brothers car and have hated life for the past day. The half shafts are rusted in the hub and do not want to come out easy. I have the SIR tool so everything should be easy if I could get the dam shafts out. I can move my brothers rear driverside tire a half inch in every direction when the wheel is in the air.

[Z06&E30]

The CPS goes to the rear/lower hole in the trans and reads off the single metal pin on the flywheel. The CPS plugs into the gray harness plug.

The engine speed sensor goes to the forward/upper hole in the trans and reads off the teeth on the flywheel. The engine speed sensor plugs into the black harness plug.

I am doing the rear wheel bearings on my brothers car and have hated life for the past day. The half shafts are rusted in the hub and do not want to come out easy. I have the SIR tool so everything should be easy if I could get the dam shafts out. I can move my brothers rear driverside tire a half inch in every direction when the wheel is in the air.

Had a work week. So didnt get a chance to drive it really.

I'm off now, car drives prefectly (knock on wood) today. Did about 100 miles of driving to ensure we're stable. No problems to report.

Wheelbearing replacement seems to have fixed the drone/humming at 55+, slightly tighter steering too.


Messing with the good relays and the the middle relay in the cluster of 3 seems to have solved the cranking issue as well as replacing the 2 sensors on the bellhousing.

I ended up chewing up the allen heads on the bolts for the sensors, had to go to lowes to get some new ones. All is well.... So far but looking at swap kits... Drove into 35 knot winds at 75mph.. could not accelerate with it at WOT... needs MOAR POWA!!

[Fuggly Stick]

I would definitely also day you have something loose that bumps around and looses/gains connection. like maybe one of the sensors in the transmission bell housing, by the starter. one of those tells your fuel pump to come on when cranking so if its got a loose/bad connection, you will just crank and crank.

Is this the same for a 88 325is with an auto? I have same problems where the engine turns over 5+ time before i hear the fuel pump kick on. Engine aslo randomly dies at a stop or driving around. I've changed the cps in the front of engine but still same thing.

[Z06&E30]

Is this the same for a 88 325is with an auto? I have same problems where the engine turns over 5+ time before i hear the fuel pump kick on. Engine aslo randomly dies at a stop or driving around. I've changed the cps in the front of engine but still same thing.

Could be. I never had an cut outs over bumps or anything. But thinking back I definitely should've.

Fuel pump doesn't pre-pressurize like on other cars. It will only energize if it sees the signal from the computer, the computer only sends the signal if it gets the reading from the CPS sensors down on the bell housing.

Use a jumper wire and see if you can get the high pressure pump to energize, if you can then try using the key to start the car. If it doesn't start then its not seeing the cranks position correctly. If it does start, its likely that relay causing the problem.

[Z06&E30]

Problem seems to be back.

Get in the car after putting over 1500 miles w/o a problem and it decides to prolong crank. Car fires up and runs fine. Following morning I load the car and hit the key, just cranks. So I take a jumper wire and see if its the fuel relay, I hit the key and the car fires up. So i swap the relay out for a new one. I test it out in the parking lot, start and shut it down 3 or 4 times no problem. 20 minutes later I am actually leaving for work and I go to leave, car cranks and cranks but finally starts.

Driving down the highway, smooth road at 65mph car completely dies. Again, like the key was pulled. No bucking or anything, totally dead. I go to pull over and drop it into neutral, car fires up and I make it to work. Once at work I pull in and let it sit for about 20 minutes with the car off. I hit the key to move the car and it only cranks and wont fire up, tried the jumper wire on the fuel pump relay and it only cranks.

I'm in my off week from work so I got off the boat and figured I'd be towing it home today. I went ahead and pulled the fuel line off the rail and had good pressure, no fuel in the FPR vacuum line either. I swap the relays around and the car fires up and runs great. Not sure which relays, but the three that sit on the wheel hub drivers side, the two closest to the drive i have swapped around with new. I have not messed with the most forward one, which has a metal casing? Regardless, I make the 45 minute drive home without any hitches.

Once in the parking lot of the complex, I figured I'd do some testings. Turn the car off, and try to restart. Prolonged cranking, try this 3 or 4 times and never get a start. Let it sit for 2 or 3 minutes, hit the key and it fires right up no problem. I was unloading the car and letting it idle. I jump in the car and increase the rpms to 2k, car instantly dies like someone pulls the key. So I pull the key out and restart, only cranking without any starts.

Where to look?

CPS on the bellhouse/tranny are new and were the fix last time this went on. worked for about 2.5 months. But now I'm fighting the same issue again.