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Car will only start with starting fluid, then runs fine once going

I recently had a problem with my car stalling when warm and not starting at all until cooler. This was the crank position sensor.

Now the car will not start without starting fluid. When starting fluid is used, the car will start and then run fine. Once you shut it off then try to start it, same thing. The fuel pump turns on when key is in on position. Holding pedal down to try and clear flood does nothing. Car just cranks and cranks but doesn’t start until starting fluid is used.

So there is either not quite enough pressure at fuel rail, pump is not getting enough draw from battery, several other things could be suspect. Car is a 2003 Hyundai Accent. Battery tested borderline ok. It does the same thing with donor battery attached. I have a fuel gage but need an adaptor for it that I don’t currently have to fit on this fuel rail. Stumped because the car runs beautifully once starting fluid gets it going.

The first thing I can find that makes sense is fuel pressure regulator is not working properly.

Is the check engine light on? If so, what codes are stored? Does the car idle fine?

Something to check if you have access to a scan tool that will read real-time data: Check to see what the incoming air charge temperature is (ACT sensor on some vehicles) and what the coolant temp sensor reads. If the car is ice cold, they should pretty much agree. If the computer can’t accurately tell what temp the air is that’s coming in, it may not be enriching the mixture enough.

Of course the vehicle should still start okay when warm even if the sensor is flaky…

Look closely at the crank position sensor. Make certain that it is fully seated.

I understand the CKS controls cranking and therefore is involved with spark (?) but is it possible if it wasn’t fully seated or there was some issue the car would start and run fine with starter fluid with that being the issue? That will be first thing I check today then start following wiring diagrams but just curious.

So a weak ignition component/spark can cause a no start that would be be “fixed” with starting fluid or is this purely a fuel delivery issue

If it starts with starter fluid, then it’s a fuel issue.

You stated that the fuel pump seems to work okay when the key is turned to the ON position. I wonder if that is true in the START position. I suggest you try to verify that is true by checking the voltage after the fuel pump relay. Another check you might try is to make sure the injectors are working okay and getting power in the START mode.

Alright. I have a feeling this would be an easy diagnosis if I had the correct adapter for my fuel gage.

My car battery tested 505 CCA out of 540 and borderline “ok”. It had been discharged a few days ago so this is my first suspect. Perhaps the battery can only support the starter and is not providing enough fuel pressure. Devil’s advocate though, wouldn’t priming the pump a few times before starting put enough pressure in the lines to avoid this?

If so, the line isn’t holding pressure. Fuel pressure regulator or check valve? Regulator is in pump on these cars.

If the battery can run the starter then it can support running the rest of the electrical systems of the car. This problem isn’t due to low battery voltage. Either the pump isn’t working in the START mode or the injectors aren’t working in the START mode.


I advise you to hold off on throwing parts at the car until you get that fuel gauge adaptor

Well, yes, I wasn’t going to throw parts at it. Like the last fix I researched here and elsewhere and gathered informed opinions then tested out each thing before buying anything and I hit it right. I have that adaptor coming my way, in the mean time I am just fishing for the could be to give me ideas. I do appreciate all input.


Let us know if you need the fuel pressure specs for your car

I can post the specs, if needed

Does it fail to start like this even when the engine is fully warmed up?

If so, the rail fuel pressure test is the place to start.

If it starts ok with a fully warm engine, and fails to start when cold, then I’d tend to suspect something wrong with the cold-start enrichment function. How this works varies from car to car, but one way or another extra gas will be injected on cold starts. The problem would most likely be either that the cold start condition isn’t being detected (some kind of sensor problem) or something is preventing the extra gas from being injected (ECM or injector problem or fuel pressure problem).

It does the same thing warm or cold on this one. Even if you shut it off and go back at it you need a shot of starting fluid to get it going then it’s fine to leave on.

The coolant temp sensor would be a viable culprit then? I just replaced my crankshaft position sensor which remedied my stall, no crank, no start (when warm). It works great now (besides not starting at all now). I see people posting about putting the car in “learn mode” after changing the cks. I don’t have experience with that.

Since your engine fails to start hot or cold, the fuel pressure is where to start. If you are waiting on the fuel pressure gauge adapter, testing the coolant temp sensor is worth a try. I don’t think you’d even have to remove the sensor. All you’d have to do is measure the resistance when the car has sat overnight, then compare the measurement to what it should be at that temperature. Make sure you are testing the correct coolant temp sensor. Many cars have two, one is only used for the dashboard gauge. It’s the one used by the computer that you should test.

Learn mode is what happens when some component is changed or the battery is removed. When this condition is detected, the ECM often goes back to some basic parameter list to use, parameters that will assure the car will start and at least run, but maybe not perfectly at first, until the correct parameters are re-learned for the new configuration.

Why? As a car ages stuff like the throttle body gunks up, various passages don’t pass fuel and air quite as freely over time, so to keep the fuel air mixture and idle rpms to spec the ECM learns and compensates. It might have to boost the amount of gas, or decrease the amount of gas compared to when the car was new. Or increase the amount of air or decrease the amount of air.

Learn mode is a good thing. It works great as long as nothing changes. But it can cause the engine to run – esp idle – poorly immediately after changing something, or just disconnecting the battery.

In an ideal world even in learn mode, the car should still start. But alas this is not an ideal world. There’s talk here of some cars, if you disconnect the battery which resets the computer to learn mode, then the car won’t start, and has to be taken in to the dealer for reprogramming. I’ve never personally experienced that, but something like that could happen I suppose.

I have one temp sensor that feeds both the computer and dashboard. I will check this tomorrow. I really need a better ODBII scanner to see live data. It would make diagnosing things a bit easier.

Check ECU fuse 1, 10amp under the hood to see if it’s blown. If the fuse is good, then the problem might be with the engine control relay

When you turn the ignition switch to start, power is supplied to the engine control relay to open the injectors. Once the engine starts and ignition switch goes into the run position, this power is cut off from the ignition switch. The computer then closes the contacts in the relay and the computer then takes over and fires the injectors.


In the latest twist the car no longer starts with starting fluid either. It cranks and cranks but no start. I didn’t touch it as I am waiting on fuel pressure gauge adaptor. Does this latest development lend itself to anything?

There is no spark from plug wires.Battery is new and fully charged. Car only started with starting fluid a few days ago, now it does not start at all, only cranks.