legacycentral bbs

So, here's a mystery to me. I'm hoping someone has some insight into this.

My car (the 91 SS) starts no problem when its cold. I can get in it, and take it anywhere. After driving it a long distance, and shut off the car, it won't start. It is almost as if a. the engine is flooded or b. it's out of gas. It will turn over, and just stutter out, stalling. and will not start, not at least after waiting 2 hours and trying again. This has happened to me at 2 different occasions where I actually had to have the car towed back home.

So, a few things I have looked at. Crud in the gas tank, there really isn't anything inside of the gas tank that looks bad that could be clogging the pump. I also replaced the fuel filter, cleaned the fuel pump out. I have not tested the pump, but when the car is cold, it works perfectly fine.

This is where it gets frustrating. I had to have the car towed home lastnight after I shut it off, and it would not start again. I just went down this morning to check the car. It started right up. No problem. I checked the ecu for codes....and there's nothing. Which is good, but bad. I have no idea where to go from here, and I certainly don't want to drive this car anywhere because of the current state of unreliability. What gets me, is the car is fully functional up until a point, and then it just refuses to start.

Josh, if you could move this to Engine please. I put this in the wrong place. Sorry.

Sound like a injector is leaking basically flooding it out. Could be the o-rings on the injectors or one that is leaking under pressure when you turn off the car.

Temperature related starting issues can be related to the coolant temp sensor. How is your gas mileage? If you have an unknown age sensor, it might not be a bad idea to replace it. They're about $20 from one of the online subaru dealers.

The car's mpg has not changed at all since this problem began. I did measure the fuel pressure, and that was okay.
Checking with a few other people, they have told me either crank or cam sensor. Which, seems like it may be making sense. If it is faulty, and throws a code when the engine hits a certain temp, it is telling the ECU to not start the car.
Well I just looked up the parts, and holy crap Crank sensor is $271 and a Cam sensor is $145. yikes.

If you replace them (which honestly I don't think they are the problem) try and find a used one you can use for testing purposes.

Coolant temp sensor is a much cheaper alternative. Now, how can I test if they are bad? The car isn't throwing a code, so will this mean if the car is operational, everything will read okay? This sucks, because I will never know if I fix this issue until one day I'm somewhere, and the darn thing won't start.

The issue with the coolant temp sensors are that even if you test them, they may test ok, but still cause the issue. The best way to test them is to check their resistance against the factory manual when they are in a known temperature.

It's honestly just easier to replace it than pull it out, test it, and not be 100% sure whether it's bad or not. My suggestion is to pick one up from one of the online subie dealers and replace it.

So, I unplugged the Coolant Temp Sensor to see if I could replicate the problem, and the car was acting the same way when it was hot and gave me the no start issue. So, lets see if replacing it does any good.

Ok, sounds like a plan. Let us know how it turns out.

So, it's not the coolant temp sensor. Next steps are replacing cam and crank sensor. Darn those things are expensive.
While replacing the CTS I had noticed a lot of oil blow by had dripped onto the harness under throttle body. Perhaps its possible that is making it act up? I haven't cleaned the connectors just yet, but I cleaned and fixed the blow by from throttle body earlier this month.

You can check the wiring with a multimeter and checking the resistance from the ECU connectors to the sensor connectors. You can try and find used cam & crank sensors to swap in to see if they change anything before you go and buy new ones. That'd probably be a cheaper/better route to go.

So, Im awaiting the sensors to arrive still. I went to move the car the other day, and it wouldnt start. Car was sitting for a couple days. I check to see why it wont start, and discover the fuel pump isnt priming.
So, I check under back seat to see if it was the harness that burns out. Come to find out, at some point in this cars life, someone already re_routed the wires.
I took a multi meter to the fuel pump harness and upon startup its getting power. So, I pull pump out, clean it up, clean all connectors inside the pump assembly with electrical cleaner. Put it back together, and the car fires up.

Coincidence? I have no idea. Im still going to replace the sensors, but a bad ground or short in the fuel electrical system is looking like the issue.

Yeah, it could be a bad connection. If it happens again, I'd try and determine whether it's a connection or possibly the pump may be on its way out.

The car not running has been bugging the heck out of me for the past month. It's bugging my girlfriend too, because all I'm doing is fiddling with the damn thing every free moment I get. haha.

Before I decided to throw in the sensors from another engine, I took one more attempt to take the harnesses apart under the throttle body for the cam and crank sensors. It looks like I didn't get to do the crank sensor because I was being too gentle with the harness earlier (small screwdriver helped that out) So, after I got it off the post, I pulled the cam sensor harness apart, and inside the harness and contacts were soaked in oil from the blowby issue I had previously. I cleaned it up, checked all my grounds fiddled with that, and took the car for a nice spirited ride.
Now, this was just a butt dyno, but with cleaning the fuel pump contacts and harnesses, and the cam and crank harnesses, the car feels like it has its life back to it.
I'm knocking on wood something was just not making constant contact, and I found it. All this, and I spent just about $160 to get it back running again (this includes the towing fee). However, I think I spent 5 or 6 hours taking stuff apart, cleaning it, re-installing.

Hopefully that was the problem.

Drove the car around for a while on Saturday without any hiccups. I go to pick up lunch, and it starts acting up again. Same exact symptoms as before. Thankfully I have gotten smart, and bring my toolbox with me on my trips just in case that would happen.

I listen for the fuel pump making noise, and all I got was a couple clicks. I crack open the door hiding the fuel pump harness, I give her a small tap, unplug the harness and plug it back in. She fires right up, and I drive it home.
So, I just bought a Walbro fuel pump. I don't know if its the pump, perhaps the plastic top of the whole unit that has a short in it. But, I will see if it acts up again after fuel pump install.

How does the connector under the rear seat look? Does it look burnt at all?

It looks like it had shorted out at one point in time, and the harness has already been spliced up. It also has had the fuel pump replaced by the looks of the wiring.

Hmmm....I wonder if that wiring was not done properly.

I was thinking the same thing. I put the new Walbro pump in today. Installation was easy with the proper fit kit this one came with.
There was a small servo that was attached to the pump housing that the Walbro didnt need. Someone spliced it up with the old pump and some wiring was exposed. This certainly looked like an area where a short or loss of power could happen.

Car has been running great. Love the new pump, the car starts the second I turn it over, and accelerates without any issue. Warm startup is great as well. I should have just replaced the pump in the first place, but I'm glad I ended up doing some research and going with the Walbro. Thanks Josh for the help as well. Diagnosing this was a PITA.

Glad it's running well. Can you take a pic of this servo thing.....I don't believe there should be any servo thing in the tank.

Well, looking for the pump it appears I can't find a picture of one anywhere on line with what was on my pump. Very strange. Here is a picture of one I stole off Google Image search...on the metal brace, you can see where the fuel line comes right up, there is a small dimple on the photo. On that dimple on my fuel pump is a very small servo of some type. It was strange, I'm not sure what exactly it did, but I just snipped the wires and used the suppled Walbro harness.

Hmm....that's weird. That photo shows a pretty standard fuel pump setup, and that is how mine were.