Hot starting problem

[dwvw]

I have a problem with my 87 325e not starting after it warms up. I originally thought it was bad gas as the problem happened after filling with a brand I never used before (Mohawk, up in Canada), so I drove that gas out, and filled with Shell V-Power, and changed the plugs as well. The problem was still there. I have since changed the fuel filter, and the vacuum line for the fuel pressure regulator.

The car also seems to be idling at 600-700 rpm, and it does vary, but not as much as I have read about for most vacuum line leaks (800-1800).

I am going to get some more vacuum line and change the rest of them when I have a chance, but is there anything else I should be looking for?

[jlevie]

Have a smoke test run to see if there are intake leaks. Other possibilities exist, but it is pointless to investigate them until there are no intake leaks.

[dnguyen1963]

I suggest that you check the fuel pressure and the FPR.

[sayed ali]

Bad fuel pump?

[Gregs///M]

"Hot starting problem"

Most people with hot starting problems have symptoms of their starter not cranking during hot days and recently been driving it. Go to start the car up...and nothing. No crank, no nothing.

However you have not listed exactly what your problem is? Does it try to start up? Does it crank at all?

[E30Gus]

^ Yes because everyone knows that bad gas will make your starter stop working...:razz:

[dwvw]

It does crank no problem. The hot starting problem actually started after the slightly erratic idle problem, or I did not notice it as I figured the car needed plugs and fuel filter done anyways, then sat for 6 or so hours. I didn't notice the hot start problem till the next day.

Also I did push start it once no problem, after it wouldn't fire with the key.

[dwvw]

I am going to test the fuel pressure this weekend, but since I have two other cars it isn't a real emergency to get it running, just want to have what I need this weekend and not have to run around for parts or tools.

[mrgraphics]

My 86 ETA did that. Cold, it would start right up. Drive it around, and once it got warm would shut down. Wait for a while and let the engine cool, it would start back up.

Turns out it was the crankshaft position sensor - it was on it's way out, and when it got warm no longer sent the signal. The ECU didn't know when to fire, so it shut it all down.

[Gregs///M]

^ Yes because everyone knows that bad gas will make your starter stop working...:razz:

Way to contribute something knowledgeable to this thread, leave the technical troubleshooting to people who actually have answers. Answers that are backed by people with electrical and mechanical experience.

I have a problem with my 87 325e not starting after it warms up. I originally thought it was bad gas as the problem happened after filling with a brand I never used before (Mohawk, up in Canada), so I drove that gas out, and filled with Shell V-Power, and changed the plugs as well. The problem was still there. I have since changed the fuel filter, and the vacuum line for the fuel pressure regulator.

The car also seems to be idling at 600-700 rpm, and it does vary, but not as much as I have read about for most vacuum line leaks (800-1800).

I am going to get some more vacuum line and change the rest of them when I have a chance, but is there anything else I should be looking for?

I would certainly check the electrical specs of the CPS per the Bentley manual or ETM. Also check the electrical specs of the Coolant Temperature sensor which provides ECM signal based on engine temp. Your AFM also has a temperature sensor. Measure its resistance between pins 1 and 4, should be 1k ohms to 3k ohms.

Be sure your TPS is adjusted properly and working via electrical testing. good luck.

[UserError]

Best test for a crank position sensor is to turn the engine over with a DMM hooked up to the terminals and make sure it's producing an AC voltage signal. Having the resistance be correctly in spec has little to do with actually producing what the DME is expecting, signal-wise. With your eta, you'll have two sensors, one that senses the teeth on the flywheel, and one that senses a pin that marks #1 cylinder. The one that senses the flywheel teeth is the more important of the two, and switching them (don't forget to also swap the connectors!) could highlight that one sensor is bad.

The coolant temperature sensor would be a rather long shot, as would the temperature sensor in the AFM, since it runs while warming up, and also while warm. If either of those sensors were out, the car wouldn't run even remotely right while cold or warm.

[dwvw]

Going to test the CPS, Cold Start Valve, and Coolant Temperature Sensor tomorrow.

For the CPS, what sort of AC voltages should I see, 1-5v or so when running?
Cold Start Valve should basically not leak fuel when disconnected, and spray fuel when connected?
The Coolant Temperature Sensor should read read 2100 to 2900 ohms cold, and 270 to 400 ohms at operating temp, correct?

Should I also test the Idle Air Stabilizer Valve?

Also for a 1987 (12/86 build date) 325e my car should have Motronic right?

[dwvw]

Oh and I am also going to go through and clean up all the grounds, they have probably never been looked at. How many are in the engine compartment?

[rares]

let me know how it goes... i have the same exact problem... i am also starting to suspect the fuel pump relay under the hood. possibly in the relay coil, once temps reach hi levels, the coil might not start the pump until it cools a little...

thanks

[jlevie]

Going to test the CPS, Cold Start Valve, and Coolant Temperature Sensor tomorrow.

For the CPS, what sort of AC voltages should I see, 1-5v or so when running?
Cold Start Valve should basically not leak fuel when disconnected, and spray fuel when connected?
The Coolant Temperature Sensor should read read 2100 to 2900 ohms cold, and 270 to 400 ohms at operating temp, correct?

Should I also test the Idle Air Stabilizer Valve?

Also for a 1987 (12/86 build date) 325e my car should have Motronic right?

Those should be checked, but only after proving or eliminating intake leaks. Which means a smoke test(s). I don't see where you say you have done that. Only when a smoke pressure of 2-4psi can be achieved and held for at least 5 minutes do you know that there aren't any intake leaks. If on the first test leaks immediately show up, those have to be fixed and the test repeated.