I’ve been dealing with an intermittent issue that has me a bit boggled. I’m assuming outside heat affects it but I can’t guarantee it. It’s happened now 4 times out of 16 starts. All 4 times it was hot outside but it’s been hot and started too.
When the issue happens, it will always start right up on the second attempt. Troubleshooting this has been tough. No codes stored and everything looks good on live data. The car runs great and whatever it is, is related to starting only.
My assumption is a failing check valve regulator on the fuel pump. Perhaps it’s not closing properly and it’s allowing fuel to drain back to the engine. Being heat soaked just adds to this issue. Unfortunately I can’t control the weather to test if heat actually makes a difference. Just the normal operating temperature doesn’t but that’s not really much help because if my theory is correct, I would need to leave it off to see if it causes the issue and by then the engine would have cooled. The car can be parked over night and no start problem in the morning.
I was going to do a fuel pressure test but the car doesn’t have a Schrader valve on the fuel rail. So I would need some specialty tool to test it.
I’m hoping maybe you can offer some additional tests or theories on what my problem could be. Maybe some ideas on how I can reproduce the problem. I don’t want to just toss a fuel pump in the car in hopes it fixes it. I’d rather know for sure but it might be my only option.
I’ve tested the battery and it’s good- I scanned for error codes and none present- I haven’t pulled the plugs yet but because it starts on the second attempt and runs great I don’t expect them to be bad- I checked air filter and it’s clean- fuel pump relay is also on my possibility list, I’ve considered swapping it with the horn relay put at the same time with it being so intermittent I don’t know how I could test that. At least I could heat it when testing to see if it makes a difference. So if you have a good test for that let me know. I’m hoping to get this fixed this weekend. So I’m gathering all the info I can to help me diagnose this. If you have some tips or suggestions I would greatly appreciate it. Thank you!
When the issue happens, it will always start right up on the second attempt. Troubleshooting this has been tough. No codes stored and everything looks good on live data. The car runs great and whatever it is, is related to starting only.
My assumption is a failing check valve regulator on the fuel pump. Perhaps it’s not closing properly and it’s allowing fuel to drain back to the engine. Being heat soaked just adds to this issue. Unfortunately I can’t control the weather to test if heat actually makes a difference. Just the normal operating temperature doesn’t but that’s not really much help because if my theory is correct, I would need to leave it off to see if it causes the issue and by then the engine would have cooled. The car can be parked over night and no start problem in the morning.
I was going to do a fuel pressure test but the car doesn’t have a Schrader valve on the fuel rail. So I would need some specialty tool to test it.
I’m hoping maybe you can offer some additional tests or theories on what my problem could be. Maybe some ideas on how I can reproduce the problem. I don’t want to just toss a fuel pump in the car in hopes it fixes it. I’d rather know for sure but it might be my only option.
I’ve tested the battery and it’s good- I scanned for error codes and none present- I haven’t pulled the plugs yet but because it starts on the second attempt and runs great I don’t expect them to be bad- I checked air filter and it’s clean- fuel pump relay is also on my possibility list, I’ve considered swapping it with the horn relay put at the same time with it being so intermittent I don’t know how I could test that. At least I could heat it when testing to see if it makes a difference. So if you have a good test for that let me know. I’m hoping to get this fixed this weekend. So I’m gathering all the info I can to help me diagnose this. If you have some tips or suggestions I would greatly appreciate it. Thank you!
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Sep 3, 2026 at 8:44 AM