Jump to content

91 V6 engine shuts off then turns on intermittently


Recommended Posts

:confused:While driving or some times at a stop, my engine will just quit... sometimes (while driving or moving) it will restart on its own, but most times (while stopped I need to try to restart it with the key (put it in nuetral). Problem is intermittent. I am worried it is the auto shut down relay... but that would make me think it would always be on or off vs intermittent... that then points to some kind of fuel sensor (ASD is supposed to shut off the engine when no fuel is detected) or it is the ECM.

Any thoughts? car runs fine most of the time and can drive for 20 miles with no problems, then just out of the blue... shut off. I could get some kind of fuel guage to see if preassure is gone, but dont think that is the problem... dont know what would monitor fuel flow? to cause an automatic shutoff... and dont want to just swap the ECM as I dont know it is the culprit.:confused:

Link to comment
Share on other sites

Guest My TC Toy

Ironmike, I cannot comment on the car restarting itself after shutting down, I will have to think about that some more. But, what I will mention is that some years ago I had a LeBaron that used to shut down at no specified interval. It used to drive me crazy. What the dealer finally found was a 3V wire from the ECM that had a rotten in-wiring connection. The wire used to make and brake at its own whim. How the dealer found it was, while the engine was running, they tugged, bent and otherwise disturbed the wiring harness out of the ECM. When the found the correct spot the engine died. They tested it a couple of times and cut the harness open to expose the wiring fault.

I don't know if that is your problem, but it is an easy test with no cost.

Good luck, and if I think of something on the automatic re-start, I will post.

Bob

Link to comment
Share on other sites

thanks, I will give that a shot... I am thinking a ground somewhere or something that is given a messages to the autoshutoff ASD that there is not gas... then it is like you say... a loose wire that loses connection for a second... shuts off (asd in run position with no gas) then connects again and the asd relay opens again and it starts running again... it only turns on itself if the problem is immediate vs shuts down completely.

Link to comment
Share on other sites

Guest StudeDude 01

Ironmike---check the coil wire both at the distributor cap and the coil for corrosion. Also check the coil electrical connections. Most of these are 20+ years old and I have seen some crumble because of heat and age.

Link to comment
Share on other sites

Guest My TC Toy

OK Ironmike, I sat down with a glass of Shiraz and pondered your automatic re-start after a shut down. I got nothing that makes any sense. It could be an ignition switch but it would never restart itself. You mention a loose wire, etc, but the starter and ignition are two separate systems. I can't see it happening.

Then it accured to me- does your car have a remote starter? It is possible, only possible mind you, that the control box for the remote start is malfunctioning. If yes, cut the power to the remote starter control (cut the wire or disconnect the fuse). Then see if it happens again.

You may not have installed the remote starter yourself, but it could be an old system originally installed. The best wat to find out is remove the panels below the steering column and search for a control box or check single wires in the engine compartment. I know one goes to the coil and two go to the starter switch on the tranny.

Let us know.

Bob

Edited by My TC Toy
add info (see edit history)
Link to comment
Share on other sites

I think it is a gas issue... it shuts off my rpm goes to zero, the fires back up... only happened once or twice, mostly it stays off. think it is because of the way the asd works when in run position and getting gas. fixed a gas leak so hoping that solved the problem.

Link to comment
Share on other sites

Guest Jim_McNally

I think there's some confusion here - I'm assuming when you say it "restarts" you mean the engine stops, and then, while it's still turning over due to inertia or the car still moving, the engine catches again and continues making power. Otherwise you would be saying that a completely stopped engine suddenly spontaneously powers the starter by itself, which would be both nearly impossible and highly dangerous...

In the former, I think it would need to be more than a fuel leak, at least a small one, since a leak big enough to drop the fuel rail pressure enough to stop the delivery of fuel would have the entire engine compartment awash, and possibly start a fire. Good thing you found the leak before you got a fire! A short interruption sounds more like electrical to me.

When you say the "rpm goes to zero" does it really or is that just on the tach? If the tach goes to zero with the engine still turning, that would point to an electrical or ignition supply issue too.

Unfortunately, intermittant things like this are the devil to find - can't fix it unless you can see it when it's broken...

Jim

Link to comment
Share on other sites

You got it Jim... I am thinking it is because the motor is still moving and somehow the gas or spark cut, then come back? Remember I am going 75 down the freeway... so I am thinking it is still spinning the motor when either the spark or gas or ASD comes back.

On the RPM it is just the tach, so not reliable... probably shuts off because of loss of elec vs the motor is not spinning. So yes agree someing electrical or ignition.

Link to comment
Share on other sites

  • 2 weeks later...

An update... read some past posts and saw others had this same problem. It turned out it was the optic sensor in the distributor not reading correctly... but also I did some fuel preassure tests and it looks like my preassure is bad (too low)... going back through posts on that.

Link to comment
Share on other sites

Guest Jim_McNally

Makes sense, since the tach is driven by the same signal from the sensor in the distributor - many people actually drive around with an extra one in the trunk just in case it fails...

Fuel pressure - three likely things - fuel pump, regulator, filter. Filter is easy to replace, regulator costs more than the filter, fuel pump is hardest as you have to drop the fuel tank to do it, and it costs the most. The pressure should be 48psi on a V6 - if it's low, you can try blocking the return line from the regulator (with the engine not running but the fuel pump powered). You can do this carefully with a pair of vise grips on the rubber hose - if you clamp it too tight, you will need to replace the hose after you're done. I prefer to pull the hose off the return line to the tank and plug the hose there with a solid metal rod the same size as the fuel line, and a clamp. If the pressure goes way up, then the pump is OK, the regulator bad.

Good luck

Jim

Link to comment
Share on other sites

Jim thanks, my tach does all the sudden go to zero, then jumps around usually when it dies... more confirmation that the distibutor sending unit (optic sensor assumed) is the culprit... then I definitely have a fuel issue because when I turn on the key I get 10psi... then sometimes shoots up to 40psi... then drops fairly quickly (believe it is the regulator).

My approach... change fuel filter, change regulator (about $100), find the optic sensor or replace the distributor with reman one... and thenpray the fuel pump is good.

Also replaced all the rubber hoses as the previous owner put on regular fuel hoses vs high pressure ones.;)

Link to comment
Share on other sites

  • 2 weeks later...
Guest TC4FREE

Hi. Just saw your post and we had similar problem; ignition cutting out intermittently, sometimes while on freeway at 65 mph! It was a Hall effect module, or hep. Had never heard of it, read about it here and got tips from forum members. Replaced and VOILA, fixed problem. Hope it helps.

Link to comment
Share on other sites

I am going for the fuel pump now... replaced the distributor, replaced the regulator... problem seemed to be better, but it still cuts out. It now appears to cut out more when it is hot outside. In the morning when it is cool it runs no problem, on the way home from work in 100+ phoenix, it cuts off... wait 2 mins... starts up again.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...