'87 325 turns off when coming to stop, starts after 20 mins

[plasmaboy]

Allrighty,

I've got an 87 325, very nice condition, something over 150k miles on it. Just got it 3 weeks ago, and brought it to Brooklyn on a 700 mile drive. No problems, whatsoever.

However, first time out in the city, while slowing to a stop light, the car stops running. Very gracefully just turns the engine off. All lights/electricals seem to be okay, and when you try to start it it sounds great, but just doesn't fire up. Wait 15-20 minutes, starts on the first crank. This has happened 4 times, each while coming to a stop at an intersection, each requiring at least a ten minute waiting period before it'll start again. The most recent 2 occured within just a few minutes of each other, each still requiring a decent wait. Some days it has run flawlessly, other days the dying thing.

I've got the 2.7 liter with the Motronic fuel injection (not 1.1), so possibly a cold-start valve problem?

I'm hoping someone out there has simply had the exact same symptoms before... yeah right.

Any ideas appreciated, especially with diagnosing the real problem.

Thanks in advance.

-ben

[plasmaboy]

so, last night i pulled the transfer pump+float unit out of the tank just to be sure that there wasn't too much sediment, and there wasn't. i'm going to try to replace the fuel filter next. The pump sounds just fine when the car is running and since it's was driven 700 miles before it came to brooklyn without a problem i'm ruling out the pump.

-ben

[jeffreyb4me]

the transfer pump isn't likely with the symptoms, first make sure the intake boot (the big elbow) is good. next most likely cause is the Main Relay or/and the Fuel Pump relay(s). they're both under the small black cover on the L/F shock tower. Replace the both.....the pump relay has one pin with 2 green/purple wires coming off it, that 3rd relay in there is for the vapor purge control.

[plasmaboy]

yeah,
i didn't really think the pump would be the problem, just thought maybe sediment moving around could clog the intake. in any case thanks for the advice. the elbow does have some cracking in the bellows area, that can really cause it to not start? interesting. i guess i should check all the other air/vacuum lines as well. they're probably not too costly to replace.

thanks,
ben

[jeffreyb4me]

that bellows will need to be cracked through to be the problem...big air leak. with it idling, move it around and see if it stalls or changes the speed a lot....if you just squeeze it & release, a little speed change is normal.....the only other 'air' hose to creck is the breather hose from the valve cover to the throttle housing.

[plasmaboy]

Thanks for the tip, I didn't get a chance to test it yet, but it's a great idea. As for no other "air" hoses to check, what about the fuel regulator vacuum?

i'll try the squeezing out tonight.

-ben

[jeffreyb4me]

sorry 'bout that one, i thought it was too obvious to miss. besides the short idle valve hoses, thats all there are.

[plasmaboy]

so, i found out this weekend that the real problem is flooding. when you come to a stop from anything above an idle, within a certain temperature range that is, the car will still out and not start again for hours now. unless, as i figured out this weekend, you pinch the main fuel line before the fuel rail with a pair of pliers. that stops the flow of fuel and gets the cylinders dried out quickly, and the car starts in about 15-20 secs of turning.

the air hoses don't seem to make a difference.

more ideas?

thanks,
ben

[plasmaboy]

so,

finally gave in and took it to a mechanic. it was a crank/speed/reference/pick your terminology sensor. they switched them around and sure enough, it's running great.

anyone know where i can pick these up for cheap?

thanks,
ben

[jeffreyb4me]

a note a forgot about, if your car is a manual trans, the reference pin on the flywheel may have broken off. this isn't uncommon and cause bizzare symptoms. the engine won't start or keep running without both sensors working BUT if it's running and you unplug the rpm sensor, it will run 'til it's shut off. [won't restart] silly point i guess but the problem might also be a sticking fuek pressure regulator or the DME control unit and they're 'fiddling' was just a fluke. this does happen!

[plasmaboy]

i completely believe that flukes happen. it did run great for the 20 mins i ran it after getting it back though, so i'm crossing my fingers, and digging around for some new sensors at a reasonable price, they're $95/per from bavauto.com.

i've got another computer on the way (used, salvage, obviously not the new $600 part) and i may just order a new fuel regulator to be safe. there's supposedly a little window on the bell housing of the 325 that lets you see if the pin is still there or not so i'm hoping they check that the pin is intact.

thank you for your help though, and i'll keep you posted if anything changes.

-ben