Intermittent starting problem with 2009 Hyundai Accent

1.6 liter engine cranks but didn’t start. Mechanic replaced fuel pump. Car
starts good for a couple days then does not again. Towed to shop and then
started fine. Tried switching horn relay with the fuel pump relay but still did
start. Day later started fine. What can I try next?

Try getting a better mechanic.

How do you know for sure it was a fuel pump? Was the pressure checked? Did someone spray starting fluid into the intake to see if it would run to prove it was not an ignition issue? did the car light the check engine light? Were there any errors stored? If your mechanic did not do all this, see the advice above.

The symptoms sound like it might be a failing crankshaft position sensor which may or may not set an error code.


Thanks for the info. Definitely going to a different shop. I didn’t know there was a place to spray
starting fluid on fuel injection systems. Coils,wire harness and plugs were done a year ago. Is the crank
shaft senser fix an expensive thing? I think the mechanic is competent but don’t know if he did
all of what you suggested.

Starting fluid is sprayed into the throttle body intake. Usually requires removal of the intake hose to gain access.

I don’t know where you crankshaft sensor is so, could be an easy swap, could be difficult. The sensors themselves are usually $25 to $75 USD or so.

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For cranks ok but won’t start and run, the most important step towards the solution is to determine with certainty whether the problem is spark or fuel. Once that is known, the solution usually quickly follows. Is your mechanic absolutely certain this is a fuel system problem?

As far as what you can try next, suggest the first thing is to have another talk with your mechanic, and ask him to explain why he thinks this is an fuel system problem. For example, were there diagnostic codes? Was the fuel-rail pressure measured? Was the input power voltage at the pump connector measured? Both with the pump plugged in, and not plugged in?

Mechanic determined pump was bad. He replaced it and after 2 days had same problem.
Took it back and he said new pump was bad and replaced n/c. Again ran 2 days and same
no start again. A day later it started so drove it back to shop and they found no problem.
Ran 2 days again and now wont start again. Another car talk member posed the crankshaft
position sensor is a possibility. The part is about 20 dollars. It appears the labor would be
no more than an hour. It seems to me it would take that long to get at it and test it so wouldn’t it
make sense to replace it anyway. Car has 103 thousand on it so I wasn’t surprised when
they replaced the pump. Should I go to a different shop?

Yes …

I wouldn’t replace the crank position sensor just b/c it might be the problem. It might be a lot of things. Easy to run out of money before running out of guesses. A good shop can determine if there’s a problem with the CPS. If the CPS is faulty, at the time it isn’t working there will be no visible sparks at the spark plugs during cranking for example.

Based on what you say, it sounds like there is some problem w/the fuel pump or fuel system, but I’m guessing it probably isn’t the pump itself. The electrical connection at the pump is where I’d be looking. It could be burned or corroded. That means that the voltage the pump receives is less than the voltage the harness going to the pump delivers. When the pump is replaced, disturbing that connection makes it work for a while, but then the bad connection problem resumes. Sort of like jiggling your broken stereo system’s wires, the sound returns for a while, but quickly returns to it faulty ways.

Thanks for the advice. I think it is located on bottom side near the starter
but I will have to check that out with the mechanic. I have not decided if
I will go back there or find a new shop. I have used this guy a couple times
and was satisfied. The shop I have gone to for years was sold when the
owner retired so I tried this one. I have 2 others that have been suggested by

Thanks for the suggestions. I think it is on bottom side by starter. Will have to ask
mechanic. Had 2 previous jobs done at this shop with no problems. The shop I
used for years closed when the owner retired. Friends have suggested 2 other
shops so I am not sure if I will go back to this one or not.

Thank you for your advice. I am undecided as to whether to go to the same shop.
Will decide this weekend.