hard starting after it sits

[Duke901]

after i let the car sit over night or just for a while like when im at work it takes it a while to start. what could cause this. the car is a 92 2.0 non turbo 5 speed.
Thanks Mike

 

[femmeDSM]

Most common reasons for this include low fuel pressure or a bad ECT (coolant temp sesor).

Low fuel pressure could be caused by any number of things -- a worn o-ring on the fuel pump, a pinhole leak in one of the lines, or a 'sticky' fuel pressure regulator would be a few things to look at.

Are you getting any CELs? Any other symptoms that might be related? Did you change out any parts, or add any mods prior to this?

 

[jackstandracer]

My friend has the same problem with his car when it sits for a little bit and it wont start on the first key over but it always does on the second, his mods are walbro 255, SS lines from tank-fuel filter, new fuel filter. were probably goin to check his fpr tonight see if its sticking and ill let you know how it goes.

 

[Duke901]

Nope no mods, the car is all stock. i have put in new plugs and wires, im also not getting any codes. Also the temp seems fine.

 

[femmeDSM]

The coolant temp sensor is the first sensor the ECU looks at when starting the car. It tells the ECU what temperature it is outside, and the ECU uses this information to judge how much fuel to shoot to the injectors. So it really has very little to do with the actual "temp" of the car. Just FYI

These usually throw codes when they go, but I would check it out anyway, just to be sure.

Just for the sake of asking...are you sure you wired the plug wires correctly? I've done this before by accident. The car will run like crap and will be hard to start.

Check/verify your post-filter, pre-rail fuel pressure (buy or borrow a fuel pressure gauge, they are not expensive). Also, when's the last time you changed your fuel filter? Could be getting clogged.

 

[Duke901]

ya i have the wires right. the car runs great after it does start. I havent changed the fuel filter or i havent looked at its pressure. Where on the fuel line can i test it. After the car has ran and i only let it sit for just alittle bit, it will start right up. its only when i let it sit for hours will it do it.

 

[femmeDSM]

You can hook up a fuel pressure tester on the line coming from the top of the fuel filter (the line that goes into the rail). In a n/t, the FPR maintains approx. 48 psi in the fuel system.

What kind of service manual do you have? Most will demonstrate the proper way to test fuel pressure. If you need help doing this, let me know.

 

[Duke901]

my friend has a talon and the repair manuals so i can look for it there. Do i need any special fitting to fit on top of the filter.
Thanks Mike

 

[Old Mitsu Tech]

Looks like this thread is handled.

Good Job

 

[Duke901]

well im still having the problem. Its even worse when it is really cold outside. The fuel pressure was ok.

 

[femmeDSM]

It's your coolant temp sensor.
This is located on the front/bottom of your thermostat housing, and has two wires connected to it via a black plug. One wire is green, the other is yellow (on my car, at least). Verify that the wires aren't split, corroded or broken, then follow the Service Manual's instructions on testing. You'll be testing resistance with the engine cold, and then again with it warm.

If your car will not start, you can remove the coolant temp sensor and simulate the engine temperature via a bowl of hot water. (be careful when you remove the sensor -- coolant will spill everywhere if you don't drain it first).

If you need resistance specs, let me know and I'll dig them out for you.

 

[oldman]

Looks like this thread is handled.

Yes, it's good to sit back and just relax for a change.

 

[Duke901]

femmeDSM- Ya if you have the resistance specs that would be great

I will check it out and see what i come up with.

 

[femmeDSM]

Sure thing.

The basic info comes from the Hayne's manual, with some tips thrown in by me where necessary.
First off, the sensor you are looking for is on the lower part of the thermostat housing. (refer to pic attached -- it is labeled Engine Coolant Temp Sensor).

Unplug the black plastic clip and turn the key ON (do not start the car). Connect the negative probe of your DVOM to a good ground on the car, and the positive to one of the plugs in the clip (forget which one it is, but IIRC it is the one that has the GREEN wire going to it - in my car at least). With key ON you should see approx. 4.5-4.9 volts.

Assuming this checks out okay (99% of the time it will), we will now move on to resistance.

Basically speaking, as the temperature of the coolant INcreases, the resistance value will DEcrease.

With the engine cold and the sensor unplugged, turn your DVOM to resistance (ohms) and connect the probes to each of the two prongs on the sensor. The prongs on the ECT will form a sort of "T" shape: kind of like this: | \

With engine cold, resistance should read somewhere between 2,200 to 2,700 ohms (if it's a little higher, it is due to extremely cold ambient temperatures. Somewhere close to this range is okay though).

Now, plug the sensor back in and start the car. Get the engine up to operating temperature, and turn it back off. Unplug the sensor again, and repeat the resistance test. (BE CAREFUL, it is VERY HOT down there now). The resistance should now read approx 280 to 350 ohms.

If it is extremely cold where you are, or if you can't quite reach the sensor (it's in a weird place, so it's hard to get to the prongs sometimes) you can unbolt the sensor and remove it. If you do this, have a rag handy to plug the hole you make by removing the sensor -- lots of coolant will come out. You can drain the coolant if you want, to avoid this.

Put the bottom of the sensor (gold metal part) into a dish of room temp water (50-80*) and measure resistance. Then, heat the water to approx. 180-200* (not quite boiling), and repeat, using the same resistance values stated above.

If resistance is not within specs, replace the sensor.

You can find a replacement here: http://www.diamondstarmotorsport.com/maintelectronics.shtml

Good luck, I think I covered everything. If you get stuck, let me know.

 

[femmeDSM]

Yes, it's good to sit back and just relax for a change.

Don't get too comfortable! Before I know it, you guys will leave me here all alone to fend for myself, .

 

[Duke901]

thank you very much

 

[Doug99RS]

Don't get too comfortable! Before I know it, you guys will leave me here all alone to fend for myself, .

What are you talking about? We already have.

Back back on the topic, it's not just an issue of having good fuel pressure while running or at initial key on. If the fuel pressure is bad it could allow fuel to drain back in to the tank. Fuel pressure should drop maybe 1-2 lbs a minute. It shouldn't hold pressure over night either but it certainly shouldn't drop all the way. The lines aren't supposed to have pressure on them all the time but should still have VOLUME in them at key off. Leaking fuel pressure regulators can lose pressure and volume causing long crank times and poor drivability.

If you've got a logger you may want to check fuel trims and see if there's a trend there indicating the engine needs more fuel across the board.

But... Femme, you've been very helpful here. Thanks.
Doug

 

[femmeDSM]

What are you talking about? We already have.

I knew it! I thought I was seeing less and less of you Wisemen around here lately!

It shouldn't hold pressure over night either but it certainly shouldn't drop all the way. The lines aren't supposed to have pressure on them all the time but should still have VOLUME in them at key off. Leaking fuel pressure regulators can lose pressure and volume causing long crank times and poor drivability.

Yeah, I know all about that, believe me .
I'm still thinking ECT in this case because, as he stated, the problem is worse when it's cold. I suppose we can't completely rule out fuel pressure, but he did indicate that he tested it and it was good......Which led me to the ECT.
Tricky things, those Coolant Temp Sensors. When they go, they mimick low fuel pressure almost exactly

I'll have to count, but I think I've answered about 15 ECT questions in the past week. What's going on? Is it "DSM ECT Failure Week" or something.........?

 

[Doug99RS]

Definitely could be ECT. ECT sensor is alot easier to just swap out than fuel pressure is to check unless the car has a shader valve on the rail. I don't think the 4g63's do though.
Doug

 

[Duke901]

Well i haven't had the chance to check the ECT with it being cold out, but i have noticed it i feather the gas while trying to start it, it will start easier.

 

[femmeDSM]

Well i haven't had the chance to check the ECT with it being cold out, but i have noticed it i feather the gas while trying to start it, it will start easier.

Further proof that it's either fuel pressure or ECT. Gotta be one of these two things
My money is still on ECT, but with DSMs you can never be 100%

 

[Duke901]

Once the weather gets alittle warmer i will find out if the resistance is high on the ECT.

 

[Doug99RS]

Once the weather gets alittle warmer i will find out if the resistance is high on the ECT.

Resistance is going to change with temperature of the block. Just crank up the car and see if you're resistance starts changing gradually until it's at full hot.
Doug

 

[Duke901]

ya i know, i ment its just to cold to mess with it, so im going to wait till the weather is alittle warmer hopefully it will be some time soon.

 

[1g4g63pwr]

Most common reasons for this include low fuel pressure or a bad ECT (coolant temp sesor).

Low fuel pressure could be caused by any number of things -- a worn o-ring on the fuel pump, a pinhole leak in one of the lines, or a 'sticky' fuel pressure regulator would be a few things to look at.

Are you getting any CELs? Any other symptoms that might be related? Did you change out any parts, or add any mods prior to this?

Thank you for the answer(coolant temp sensor), Just fix my problem today and check engine light went off .