1995 850 Starts Fine, weak Restart. MVSOLVED FIJ

DoriDori · Post by **DoriDori** » 16 Jun 2015, 17:22

I've read several previous threads on here and begun chasing the rabbit down the hole to solve this issue! My 1995 850/auto/non-turbo runs awesome until last week. Wife left in the AM to go to class, calls me after class and tells me car will not start. Calls me right back and says, "Nevermind, just got it started!". What happens is after car sits overnight and is able to cool off it starts and runs like new like it always has. Starts without hesitation and idles, drives at all RPMs without ANY HICCUPS. But if you turn car off and run into store, by the time you come back out to start the car then engine just cranks and cranks and cranks without starting. After about 10 attempts it will start and then drive like nothing ever happened! Strange!!!

After browsing several threads I have:
-replaced Fuel Relay
-replaced Fuel Pump
-Have jumped the fuel pump relay and still the problem persist.

This leads me believe, according to other threads, the problem is ignition related. So, which of the three parts should I buy and test first: Coil, Camshaft pos sensor, or crank angle sensor? OR which of the above parts can I test for failure?

Thanks for help!

Post by **jblackburn** » 16 Jun 2015, 19:01

Try disconnecting the EVAP purge valve line to the intake manifold. Tape it off at both ends so fuel vapors or a vacuum leak don't exist. Try a few hot starts.

I had a bad one that was flooding the intake at hot starts with fuel vapors.

Beyond that, I would test resistance on the coolant temp sensor when the engine is hot.
2800 ohms at 68 degrees F
1200 at 105 degrees
300 at 180 degrees

If that checks out, my next shot would probably be either camshaft or crank position sensors. The cam sensors are more common for all-out no-start conditions, but either can be flaky under heat soak conditions.

DoriDori · Post by **DoriDori** » 16 Jun 2015, 20:52

jblackburn wrote:Try disconnecting the EVAP purge valve line to the intake manifold. Tape it off at both ends so fuel vapors or a vacuum leak don't exist. Try a few hot starts.

I had a bad one that was flooding the intake at hot starts with fuel vapors.

Beyond that, I would test resistance on the coolant temp sensor when the engine is hot.
2800 ohms at 68 degrees F
1200 at 105 degrees
300 at 180 degrees

If that checks out, my next shot would probably be either camshaft or crank position sensors. The cam sensors are more common for all-out no-start conditions, but either can be flaky under heat soak conditions.

Very interesting! Could be heat soak related because if you drive, lets say, 45 minutes, and then turn engine off and then immediately turn the engine back on it will start as normal. It's only when the car has set for several minutes, still hot, that it has trouble starting. But this past Saturday the wife and I went out on a date for dinner. We drove the 850 to the restaurant. Sat and ate for about 45 minutes, and then left and the car started just fine. We drove straight to grocery store, spent about 10 minutes, and as we restarted the car it wouldn't start again. Took about 5 minutes of starting to get it to start, and then BAM runs and drives like new again.

I'll try bypassing the evap line and report back. Thanks for feedback.

mika · Post by **mika** » 17 Jun 2015, 14:53

Off topic, does anyone have a good guide on how to test a sensor or resistance (ohm?)?

Never had to do this, would like to learn

DoriDori · Post by **DoriDori** » 18 Jun 2015, 08:47

Ok, Drove for 35 miles yesterday, half highway/half city, and when I parked I disconnected the EVAP hose and did not smell any fuel fumes. Also, I monitored the coolant temp via OBD2 port on my phone and coolant acted normal: 192 on highway (75mph@2,900rpm) and about 185-190 around city driving. I'm buying a new coil today for $30ish.

ALSO NOTE, the engine will always start after about 7-10 attempts after a heat soaking. And I have no CEL on at all. Sometimes the ABS light will come on intermediately during the day driving when conditions are hottest, but it usually always comes on when it is raining. This has been happening for years lol.

Post by **abscate** » 19 Jun 2015, 04:40

I think you are in the right track with the coil

How old and what brand are cap, rotor, plugs, plug wires??

DoriDori · Post by **DoriDori** » 23 Jun 2015, 12:13

abscate wrote:I think you are in the right track with the coil

How old and what brand are cap, rotor, plugs, plug wires??

Entire head and everything attached was rebuilt with new parts in 2012. Like I said, no problems until temps starting reaching upper 80s and 90s here in Ga this year.

Update: replaced the coil and wrapped fuel lines from fire wall up to the fuel rail in oem grade heat shielding. No difference in problem! ugh.

Here's a scenario from yesterday: Started car for first time around 2pm and drove 15min mainly on the interstate. Stopped for fuel for 5 minutes. Started the car fine and drove another 25 min to Home Depot mainly city driving. Spent 10 min in Home Depot and came out to start the car and no start. Just cranks. I tested the fuel rail valve with the pump on and fuel was spraying out under pressure. After about 5 cranks with about 60 seconds in between cranks she finally started. Drove to work no problem. It's only after things have heated up and if it has sat for more than 10 min. Just ordered a cam position sensor.

Post by **abscate** » 23 Jun 2015, 22:42

I believe this car has the vacuum operated fuel pressure regulator. When these fail, fuel can get sucked through it and cause a rich condition and hard warm starting. Search for FPR here ..it easy to test without cost.

DoriDori · Post by **DoriDori** » 24 Jun 2015, 12:19

abscate wrote:I believe this car has the vacuum operated fuel pressure regulator. When these fail, fuel can get sucked through it and cause a rich condition and hard warm starting. Search for FPR here ..it easy to test without cost.

This 1995 850 has a supply and return fuel lines. Would the test still work?

And when it wouldn't start yesterday I pressed the shreader valve and the rail had plenty of pressure.

Post by **jblackburn** » 24 Jun 2015, 13:00

Yes, his test should still work. There's a vacuum line to the FPR right between the 2nd and 3rd (or is it 1-2?) cylinders on the fuel rail. Disconnect it and see if it's wet or smells strongly of gas.

Aside from that being the culprit, maybe you can help us narrow it down. If you can get it to where it won't start next time, can you:

-Check for (strong) spark by disconnecting a spark plug/distribtuor wire and grounding it to the top of the head (thinking being cam/crank sensor)?
-Depress fuel schrader valve briefly until it spurts a little bit of fuel (vapor lock?)
-Unhook line to purge valve @ intake manifold.