2004 Hyundai Accent 1.6L Having Trouble Starting- Help!

Hey guys,

About 6 weeks ago, I started my car and it started, but when it did it shook really hard until I turned the engine off. I started it again a few minutes later, and it started just fine; it was a little rough at first, but smoothed out after about 15 seconds. I drove it without any further issue until about 3 weeks ago. It cranked and shook like hell again, without starting. A few minutes later, I tried again, and it started up smoothly. A week ago, I got in the car to come back from the store, and it cranked, didn’t shake, but wouldn’t start. When the tow truck guy told me my overage for a tow was going to be 105.00 for 12 miles, I told him he was insane and cancelled my tow and then magically, thankfully, my car started up. I figured it’s a fuel or spark problem, and changed the plugs and wires since it’s about time to do that anyway. A few days go by, damn car won’t start again.

So this is the pattern: Car starts and runs totally fine, except occasionally when it doesn’t want to start and only cranks and shakes, and then you leave it alone for a random amount of time (from 5 minutes to a half hour), and it eventually starts. I thought it was only when it was at 1/4 tank or below and was thinking maybe the fuel pump, but today I have 2/3 of a tank and it happened again. Check engine light is only on when it won’t start, when it starts up fine the light is off. It’s happening more frequently now and I can’t afford to keep swapping parts only to find out it’s not fixed, so I need to get it figured out. Someone point me in the right direction?

My first suspect is a sticking egr valve. Not all cars have egr valves these days, but if yours does, ask your mechanic to check it for proper operation.

Since its getting more frequent, get into the habit of making sure the fuel pressure is all primed up before turning the key. To do that turn the key to the run position - where all of the dash lights come on, but one click short of cranking it. Don’t crank it at all. Turn the key back to off. Then back to run - off - run - off about maybe 5 or 6 times. If you listen each time you should hear the faint hum of the fuel pump behind you. After doing that 5-6 times crank it. If doing that makes the problem go away, then you probably need a new fuel pump. Someone with a fuel pressure gauge should check the fuel pressure including what it does on a shut down and then on a start.

If that does nothing, and you are having one of those no-start episodes, floor the accelerator pedal and hold it to the floor (no pumping) while cranking, easing up on it steadily if it does fire up. If that reliably works you need someone to check for things like leaky fuel injectors.

If you try those things and it doesn’t work, report back - including much more info on the car (e.g. mileage, full state of maintenance info), and have someone scan for error codes even if the engine light isn’t on. Many auto parts stores will do that for free. If you get any codes (even “pending” codes) report back with the exact code, like “P0123”.

I probably can’t check most of this til Saturday when I get off work, because I work 24 hour shifts til then, but I can add a few things here now. It has about 165,000 miles, no major work needed except a used transmission with 80,000 miles and a new clutch, both put in about 10,000 miles ago. I do try to stick to the basic maintenance schedule as well as possible. Flooring the gas pedal on start up doesn’t seem to work reliably…sometimes the engine starts to kick over a bit before dying, but other than that, starting up doesn’t seem dependent on flooring it. Starting fluid seems to help the engine start to kick over too, but more often it only almost starts and then dies, so that’s not reliable either. Also, that could just be coincidental, since it’s more or less the same outcome as not using it at all. I was thinking about it and I have previously noticed a humming sound after turning off the engine and getting out, and it seems to come from where the fuel pump is located, at the rear driver’s side quarter panel under where the gas goes in, behind or maybe slightly above the tire. It sounds kind of like one of those antennas that goes down by itself, but my antenna doesn’t do that.

I’m pretty mechanically capable in terms of being able to put back together anything I can take apart, but I don’t know enough to diagnose much more than the basics with cars, so I appreciate you guys’ help. I’ll add more info as I get it.

Might want to check the fuel pressure regulator. Sometimes they can spring a leak, could cause this symptom. Fuel pressure regulators typically have a rubber hose going to the intake manifold. Remove that hose and see if there is any signs of gasoline in it. There shouldn’t be.

It was the crank position sensor. Which I was going to replace, but I sent the car to a mechanic first, so I ended up having to pay him to put it in, to rule it out in case it was something else. Of course. Thanks for the help guys.

I once trouble shot a 1996 Hyundai Accent with a similar problem. Every now and then it would crank and just not start. So I went with the owner/driver on her errands with the appropriate tools. It took a few stops but when it failed to start, I noticed that the ignition timing appeared to be way off. After I connected a timing light, the fool Accent cranked and started perfectly. So I priced the Crank Position sensor and the Cam Position sensor. But, the prices were so high I decided to try everything simple before I threw a part at it. So I uncoupled the sensor plugs; swabbed the contacts with contact cleaner; applied a swab moistened with WD40; and reconnected the plugs. The problem has not resurfaced as of this date.

I was wondering what the cost of your Crank Position sensor was? Do you know if your sensor is a Hall Effect type?

Not being nosy – just curious.

I don’t know about the Hall Effect, but it cost about 50 bucks for the part. A little online research while I was trying to diagnose the issue suggested that the crank sensor on Accents fails pretty frequently.

Thanks for posting the result OP, glad you got your car running well again. I’m surprised the faulty cps didn’t result in a diagnostic trouble code indicating cps problem displayed by the code reader. Was your mechanic using the Hyundai specific scan tool? I guess the car’s diagnostic software isn’t able to determine there’s a problem when that part’s operation is just marginal. Maybe it has to completely fail before it reports a DTC. Anyway, glad you got it solved.

I’ll add to this . . .

I’ve replaced many crank sensors over the years

The vast majority of them did generate a code

But a few did not