floorguy

new to the forum so forgive me if this has been asked a million times. i scrolled down through some of the threads, but didn't find anything 83 specific. car has spark and fuel, amm is known to be good. it will occasionally start and run fine until it is turned off, then no start. tach barely moves when cranking. i put a new fuel pump relay in to no avail. i have not yet picked up a service manual yet, so i'm unsure of the location of the crank sensor. any and all help appreciated!



jason zeiner
83 944
87 volvo 245 5.0 e-mod race car
2000 husqvarna sm 610r supermotard bike

jharding

Ahh...the old intermittent start problem. If it cranks slowly it could be a bad battery, a loose positive or negative cable. If all that checks out it could be one of the flywheel reference sensors. Check the wiring to the sensors to see if any insulation had worn through. Also, how did you confirm you have both spark and fuel?

floorguy

brand new battery, cables seem fine. i popped the cap at the end of the fuel rail and cranked her over, and popped a plug to confirm spark. i have a spare good amm. it certainly seems like a wiring prob, which i will investigate next. thanks for the info, jason in ct

Lechto

I had the exact same problem on my 83 944. Peal back the insulation on your sensor plugs (the side going to the DME) and check and see if there are any breaks. That was my problem so it might be yours.

floorguy

thanks lechto. my prob is that i haven't picked up a manual, so i am a bit unsure as to what these sensors look like.

z851@yahoo.com

I'm not sure about your '83, but if it is the same as my '87.... at the back of the engine, near the firewall you should have 2 rectangle plugs, one above the other. Wiggle the plugs and push them together. I just went through this with my car. Try to do this to the top one only and see if the car will start. If not try the bottom one (process of elim.)

Good luck!!!

'87 944
'03 Boxster
'37 Chevy

floorguy

thanks z, i'll check it out tonight....

floorguy

well i think the sensors are okay. the car will usually start when cold or after sitting for 10-15 minutes. i located what appear to be some melted vacuum lines one of which goes to what i think are two fuel pressure regulators. (located on top/back of intake man.) replacement did not help. car is also idling around 2-2.5k rpm. would a bad fuel press regulator cause this perhaps? also any suggestions for good parts sources? thanks again, jason zeiner in ct

jharding

High idle could be caused by a vacuum leak. The fuel rail has a pressure regulator and a damper. If the regulator is bad it usually causes the car to run rich. So starting would be a problem and the idle would be low to non existent.

With all that said, a vacuum leak normally wouldn't result in a no start condition. I still think you have electrical gremlins, like a break in the wiring of one of the flywheel sensors.

You may have a host of problems. Why not remove the intake manifold (not that hard at all), replace all of the vacuum lines, test the idle stabilizer valve, reinstall the the intake manifold with new gaskets, and go from there. Also, don't look over the obvious. You may have a bad spark plug. Plugs are cheap, replace those with a set of regular Bosch (ie; not platinum).

floorguy

i think i'll do that. one thing i did find, is what looks to be some type of insulator. it is in a bracket that is boltd directly to tthe firewall, behind the top clips to the reference sensors. it's orange plastic, with a green wire going in, and a black wire going out.....

Lechto

If I am not mistaken that should be from the oxygen sensor which shouldn't have anything to do with your starting problem.

Start checking the basics like coil, rotor, distributor, wires, plugs. Then I think if everything is checking out to be ok, it is probably a bad DME or something with your reference sensor wires (make sure the sensors are nice and tight).

Only one sensor controls whether or not your car will start and run so turn it on and disconect one of them and see which one shuts her off. Then the one that does turn her off check and see if there are any breaks. I am also struggling with this problem, but this seems to be on the right track. Good Luck

Lechto

Also, if you have a buddy around or maybe someone who is feeling nice (very nice) borrow there DME and plug it into your car for a few days and see what happens.

floorguy

well, put new plugs in, no go. checked the fuel delivery again and found that no power was getting to the pump. no power at fuse box, or at harness underhood. feeling stumped....

jharding

Do you have a service manual for the car (Haynes or factory?)? If yes, check fuses to fuel pump (also in your owner manual). If those are okay then remove the DME relay (relay #2 on the top row (second row above fuse panel), jumper the two pins (Can't remember which two they are) and see if the fuel pump is running. If the fuel pump will not run then most likely the pump is bad. If it does run then your DME relay is bad.

floorguy

i put a new relay in, and i know the pump works. i ran a power line straight from the battery to the pump and it fired right up. for some reason, after the engine has been started once, power to the fuel pump fuse stops. all other fuses will be hot except fuel pump. thanks for your help guys...