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Discussion Starter #1
Hi All,

I have a 03', OBW, H6 with 180k miles on it. The last month or so the car has an issue starting when the engine is hot. Some times it starts right up but most of the time I have to crank it over 3 times to get it to start. There is no CEL and the engine runs great once it starts. I have replaced the fuel filter and pump with no change. I tested the volts on the TPS and they are fine. The spark plugs have about 40k miles on them but because it runs like new when it starts I ruled them out as an issue. I have owned the car since new and it is well maintained and haven't had any other issues.

I've read possible causes could be Crank or Cam sensors but I don't want to spend the money for them if they are good. Any ideas on fow to test the or other possible causes?
Rich
 

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Afternoon,

If the temperature sensor is telling the ECM that the car is hot, it will prevent starting. You would have to have an ohm meter or scan tool with live data to see it.

If the crank or cam sensor is failing, the ECM will pick up on it in majority cases and set the MIL light. Without and ohm meter or scan tool for live data, you could check to insure they are connected tight and no loose wires on the plugs.

If the idle control motor is sticking, hard start will occur. You can remove it, clean it with throttle body cleaner and re-install and see if it improves.

High alcohol in the gas will cause poor starting when warmed up as well. NO E85 GAS, especially in cold weather conditions.

Check your grounds and battery output.

Other than that, it would have to be hooked up to a scan tool that reads live data to see what it is.

The crank sensor should be between 800-1300 k-ohms testing between the pins; camshaft, no ohms measurements, you have to look at the waveform pattern.
 

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Discussion Starter #3
I have changed the temp sensor and it didn't help. I removed and cleaned several very dirty ground connections on the firewall and that didn't help. I know there are probably a few more grounds and I will seek them out and clean them. I will unplug and clean the crank and cam sensor connections. Which one in the idle control motor? I assume on the throttle body and will check it out. Battery output is good.
Thanks Rich
 

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If you always fill up at the same station, I would try a different one. Not recent, but I had this problem years ago with a honda civic. It would take 20 seconds or longer to light off. I checked/tried almost everything. Then it occurred to me to switch brands. To my amazement, it lit off instantly, every time. Fuel can really make a difference.
 

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I have changed the temp sensor and it didn't help. I removed and cleaned several very dirty ground connections on the firewall and that didn't help. I know there are probably a few more grounds and I will seek them out and clean them. I will unplug and clean the crank and cam sensor connections. Which one in the idle control motor? I assume on the throttle body and will check it out. Battery output is good.
Thanks Rich
The idle control motor is opposite the cable actuator for the throttle.

There is a group ground on the back of the motor almost directly under the throttle body, a ground strap that runs from the ABS to the Injector cover, another on the driver side bolted to the injector cover and a few more scattered.

When you checked the battery did you check the base voltage or amperage output? There is a difference and you want no less than 450 amps at the engine block.
 

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Discussion Starter #6
THanks for the diagram. I checked the battery voltage but I didn't test it using the block for ground. I'll try that and see if it shows lower voltage which should indicate the various grounds need cleaning. I cleaned a few already but not where they attach to the block.
Rich
 

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Rich, if you don't have a meter or a way to check "amperage" output, drive over to a parts store and ask them to check the amperage output. The battery can show 12 volts but still not put out the correct amperage. Ask to check at the battery post, then check again with the negative side connected to the block and see what the amperage difference is. That difference is the loss through cables and connections.

If the battery is above 450, and the loss is less than 100, the battery isn't the issue.
 

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Discussion Starter #8
Turns out it was the fuel pump assembly that was bad. I had installed a new pump in the assembly but there is a crack in the metal cap that caused the issue. Bought new assembly and all is well.
Rich
 

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whoa!

that's a well know problem, but usually prevents starting/running completely.

did you buy the filter with the large cap, or another entire fuel pump assembly?
 

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Discussion Starter #13
I knew of the cracked metal cap problem others had but didn't notice a crack in the cap when I replaced the pump in the assembly. Even now the crack is very small. I replaced the entire fuel pump assembly and the problem is resolved. I had the hesitation and hard starting when hot problem for the last 9 months.

I still have the old assembly with the new pump in it and the original pump.
Rich
 
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