Crank no start

[slipknot51]

so i am newer to the subaru world and i just bought myself a 1991 subaru legacy ss for 350 bucks as a project car and i have been having issues with the starting of the engine, once in awhile it starts up right away and then when i go out there a week or two later and try to start it cranks but doesn't start i do have a good amout of knowledge about cars and i checked the basics and i got fuel but no spark i replaced all the plugs and wires. still no spark i have also check the resistance on the coil and the resistances were all with in spec. i am wondering if any one else could help throw me into the right direction to figure out what i need to do to fix the issue i'm having.

[Legacy777]

I'd suggest checking the ignitor and wiring from the ignitor/coil pack to the ECU.

If all that is good, I'd look at crank/cam sensors or possibly an ECU.

[slipknot51]

I have checked the wiring and that seems to be in hood shape I have also checked the voltage out put on the crank and cam sencors and they are both with in spec. I just recently replaced the igniter and I have spark but it doesn't seem to be getting any fuel. The weird this and I don't know if this is commen in subarus but when I disconnected the cam sencor I don't get spark which I found weird. I have checked the codes and I got 11,13,and 22 which I know they are crank cam and knock sencor but all the harnesses and connecters are in good shape. One thing I tested for theory sake I unplugged my tps and turned the key on and tried to start it and see if I got a code for it which I did I repligged it in to see if it when away which it didn't. So I decided to clear the memory and it for some reasom came up with all the same codes even for the tps so I'm wondering of maybe my ecu might be bad

[Legacy777]

How did you clear the codes?

If you're not getting fuel, I would check to see if the fuel pump is turning on. I'd recommend putting a gauge on the fuel supply line, and then connecting the green tee diagnostic connectors. With the ignition in the "ON" position, the fuel pump relay will cycle on and off, and you should have good fuel pressure at the gauge. If you do not, I would look at the fuel pump relay, wiring, and the fuel pump.

[slipknot51]

I know that the fuel pump is turning on I can hear the relay click and I also hear the fuel pump turn on and off when I have the green connector plugged on the one thing I haven't done is check fuel pressure which I shouldn't of assumed that I had it since the pump was turning on. I used mitchal on demand to look procedures to clear the codes on the ecu.

[Legacy777]

I have instructions on my site on how to clear the codes.

www.surrealmirage.com/subaru/engine.html

I would first start by pulling the EGI/TCU fuse, fuse 14 for about an hour. If that doesn't work, you can try the green and black connector method mentioned on my site.

[1994LT]

i had the exact same problem and it was a dirty crank sensor and cam sensor then a couple bad grounds

[Jessekrs123]

When my ignition system was failing, it was a bad ECU ground on the engine. Drivers side right next to the rocker cover. The ground was loose, and the bolt that held it down would not bolt in all the way so I moved the ground and it fixed my problem.

[slipknot51]

Well I have a new crank angle sensor in the car Now but I haven't check out the can sencor yet I have done a resistance and voltage test on it and the sencor was in range at the connector I was going to t into the ecu and check voltage there and see if I get the some thing if not I got some wiring to do lol

[slipknot51]

Intresting development on the subaru project I fixed the crank,cam,and knock sensor code and tried to start it still nothing so i check for spark had spark then checked to see if i had fuel no fuel, so i did some diagnosis and figured out that the fuel pump was bad so i bought a new one and replaced the fuel filter while i was at it to. So i now have fuel and fuel pressure at the fuel rail but still nothing. So i check to see if my injectors had the right resistance value also checked to see if they were getting power and if they were pulsing like they should. Resistance was good, I had power to the injectors and finally checked to see if the injector was being grounded by the ecm with a diode tester and the diode did not pulse at all so im wondering if you might know what i should try next. I checked the wiring from the injector's to the computer and measured the resistance and there was no abnormal resistance value like .01 which is normal in my book. Im thinking that maybe i might have a ECM problem. Do you know if there is any way that I could take the ECM apart and maybe replace the transister that control that driver for the injectors

[Legacy777]

Good diagnostic work! I would agree with your assessment that it sounds like an ECU issue. As for trying to repair the ECU, you might be able to do it if you can determine what part/component needs to be replaced. That's something I do not have the expertese for.

There is a member on here, rob He has been working with modifying/tweaking these ECU's, and he may be able to help point you to the proper component.

[slipknot51]

Would you know what the guys user name is so that i could send him a message and see what he might say about what parts i might need or if i should just swap out the ecu

[mike-tracy]

his user name is..... rob

[slipknot51]

Intresting development i went home and was checking pins out of the ecu i got resistance/voltage from the crank and cam sensor when the car was cranking also i had power and ground to the ecu both constant and key hot. i check power going to all my sensors and grounds for the injectors and they were fine and check resistance and they were with in spec. my dad kind of threw a wrench in the works he mentioned something about a map sensor i know the car clearly has a maf and i thought i had a map to and he was talking to one of his friends that was having the same issue that i am happening and he said that the map sensor when out on his car and he replaced it and the car started and ran great. I was wondering if anyone know if there was a map sensor and if a map sensor was shorted or not being detected if that would cause a crank no start issue. I know that alot of turboed car usually use the map is a secondary and is used for when your under boost and the maf is normal used for load and fuel control. If any one know if they do have map or might be able to point me in the right direction. The car does now pop a little but still wont start

[Legacy777]

I'm pretty sure the car would still start if the MAP sensor was bad. The ECU would just not allow the engine to boost.