gronkX

For the first time in almost 15 years, my 86.5 had to have a trip on a tow truck.

I drove it to the ball field last nite, and when it was time to leave it started fine, and went about 300 yards before simply stopping.

I checked fuel pump fuse, and swapped out the relay for another one, but that didn't help. I don't think I heard the pump running when I turned the key.

Any suggestions as to where to start looking for problems?

ammonman

Verify you have 12VDC at the fuel pump connections when cranking the engine. IF yes, then you need a new fuel pump. If no, look at the crank sensor.

Mike

gronkX

And if it's the crank sensor, jumping the XX relay should run the fuel pump and allow the car to start, right?

Do 86.5s suffer from brain damage?

James Bailey

Yes the LH can fail and not energize the fuel pump. Common initial failure mode.

AO

I was thinking you would post "relay, relay, relay..." and now I hear there's going to be a blue moon this month.

Maybe the world is going to end this year.

Mrmerlin

I would look at in this order.

fuel pump fuse, you have to drop the CE panel down for this test,
get the test light and see if both wires have power to them on the back side of the fuel pump fuse contacts where all the gray wires plug in, if not then the fuse holder is corroded.
removal of an unused fuse spring clip and swapping it to the pump location will usually cure this

Is there power to the pump? check fuse and relay, swap in a horn relay into the fuel pump slot (#53 relay)
Does the pump run if supplied with 12V and a ground? If no replace the pump.

NOTE dont open any fuel lines while working on the pump elex tests


Replace the LH and EZF relays as well as the ignition relay they are all #53 relays,
do one at a time and test.

Inspect the crank position sensor if the connector has crumbled replace the CPS.
Its under the aircleaner behind the MAF at the back of the V

Inspect the throttle position sensor short cable, if the connector has failed, NOTE it cracks at the car harness side next to the bosch temp 2 sensor then replace the short cable, Roger sells em.

Remove the connectors for the computers and see if they are corroded, then install the connectors

inspect the coil wires for shorting and the cables should not be touching any part of their run also remove the cables and look for corrosion.

Remove the battery terminals and clean them all,
also the ground point where the ground wire connects to the chassis.

Inspect the 14 pin connector under the hood, clean the pins ,
use an eraser for cleaning elex contacts,

Please report back what you find,
If possibe with pictures of the engine and the various connectors and the CE panel

Stromius

CPS failure would show no movement of the tach on startup.

gronkX

OK, so I went to visit the car today to see if the tach would move when cranking it, and was planning on jumping the relay to see if the fuel pump would run.

And of course it started right up when I turned the key, and seemed to run fine for a few minutes.

Does the computer store any fault codes that might indicate what the problem could have been? I'm thinking since it died while running that probably eliminates a relay, so it's probably time to replace the crank sensor anyways.

Not really keen on having it die on me again - if it is a flaky sensor, and it dies on me again, will I be able to drive it home by jumping the fuel pump relay, or does it also affect the ignition?

BRB-83-911SC

I had a CPS fail on me, and the symptoms leading up to complete failure were occasional shut down of the engine - as if turning off the key. It would restart a few minutes later, until it failed completely as a no start in my garage.

I don't think jumping the relays will get the car started if the CPS has failed.

AO

Two 928 owners here in the local Detroit area had VERY similar symptoms/ Car would run fine and then just die. In both cases it was a bad LH computer (fuel injection). One died with the usual "clicking injectors", the other did not. Unfortunately, this is a relatively expensive repair. If your LH is original, it very well be going out on you, and the only way to test is to swap in a known-good LH and see if the car runs.

Mrmerlin

FWIW the earlier cars with the LH injection dont seem to suffer the failed computer,
like the 87 and onwards do

John Speake

Yep, Merlin is right. It's rare for an LH2.2 to fail, the EZ-F have proved to be the weaker of the two vital ECUs.

Try the relays first. Intermittant starting is virtually never the LH or EZ-F ECUs, they fail and stay failed.

AO

Sorry, missed the 86.5... carry on.

gronkX

Well, I replaced the crank position sensor and all 3 of the relays (for $5 each, these really should be a regular maintenance item and so far haven't had any reoccurance of the problem.

Bjbpe

I had a similar problem for quite a few years. Every time it lfailed to start I would replace the spark plugs and it would fire right up. Eventually it failed to start even after I replaced the plugs. Turned out that it was the "brain". I'm an aerospace engineer and I hate electrons but I would imagine the "brain" was losing output and could fire clean new plugs until it finally quit altogether.