Difficult starting when cold! HELP!

94' Cherokee: Ok so every time the engine is cold or has sat a few hours it has a terrible time starting. It's like with a carb when you have to get gas into it after sitting a while... Then when it is started the check engine light is on and after driving a few min and turning it off, then on, the light is off and it's all normal running and starting. What is it that's gone bad? Is it a bad fule filter not letting the engine get enough gas when cold or is it some kind of sensor? HELP! This is driving me crazy and on top of that it drains my battery too fast!

I would check your fuel pressure, first.

pete

When was your last tune up? Engines love fresh plugs in the winter.
How old is the battery and when was the last time it's post were cleaned?
Plus as above. Fuel press check. running and keyoff check.
This stuff will fix most hard starting problems. If not then.
Cherokee starters do go bad and drag, Slow turning engine and/or low cranking voltage are sine ofa bad starter. But the battery/charging system should be checked and clean first, before turning to the starter.
How many miles on the engine. Do she burn oil? Check the compression? Tired old engine are just like me. We just don't like getting started on the cold morning.

If you're getting a check engine light, the first thing to do is to see if you can retrieve the code. Key (ignition on, not starting) on-off-on-off-on and then read the flashing light. The codes are two digits each. "12" is a recently disconnected battery, and "55" is normal, end of sequence. Any other codes will have some meaning that can be looked up. Post back here with the code, or look it up here:

http://www.allpar.com/fix/codes.html

If you can't find the code in that site, there's another link within it for another page of codes that may be easier to interpret. The 94 XJ uses more or less standard Chrysler OBD I codes.

If the problem occurs only when it's been sitting a while, try this: turn the key on to ignition, wait about 5 seconds, then turn it off and turn it on again and wait another 5 seconds or so before cranking. If this improves start times it indicates that your fuel pump check valve is leaking down and losing pressure. That can be fixed either with an expensive fuel pump repair or an inline check valve (I seem to recall someone doing this with a BMW part), but if all else works well you can live with this indefinitely - just get in the habit of waiting before you crank. My 95 has leaked down at least a little for the last 100+ thousand miles.

I changed the plugs, cables, and distributer cap and rotor a couple months ago... How do you check the pump pressure? Is that what you were talking about waiting 5 seconds? What it does is just crank and crank until (it seems) fule get pumped in... Is it that it's loosing pressure so it has to pump it back to the injectors? The plugs etc. should be good... It has 240K so I know she's old! I think the compression is prob still pretty decent and I know that couldn't be causing this problem. I'll see if I can check the codes tonight and post up.

simplyXJ said:

I changed the plugs, cables, and distributer cap and rotor a couple months ago... How do you check the pump pressure? Is that what you were talking about waiting 5 seconds? What it does is just crank and crank until (it seems) fule get pumped in... Is it that it's loosing pressure so it has to pump it back to the injectors? The plugs etc. should be good... It has 240K so I know she's old! I think the compression is prob still pretty decent and I know that couldn't be causing this problem. I'll see if I can check the codes tonight and post up.

Click to expand...

Yes, basically what happens is that when you stop, the pressure in the ruel line drains down, and you spend a little time pumping it back up before any fuel comes out the injectors. You can check the pump pressure by getting a fuel pressure gauge and plugging it into the schrader valve on the fuel rail. Unless you have a gauge already though it will cost you something like 30 bucks. Usually the problem with the check valve will not affect running pressure anyway, so it might be worthwhile just to see if cycling the ignition helps. If it doesn't do anything, then you should probably look elsewhere for the problem, and if it does, you can decide at your leisure what to do about it.

If it is only a cold starting problem I would check the air and coolant temperature sensors and the electrical connections on them. Checking the codes first would also be a good idea. Some do-it-yourself parts stores will do the code check for you for free.

I had the same problem last winter, it was the air temperature sensor in the intake manifold. Mine is a 1987 Renix, so it is a bit different than 1994, but I think they still used an air temp sensor in 1994, if not they probably went to a mass air flow meter and eliminated the MAP sensor and air temp sensor. That would leave just the coolant temperature sensor.

Mike McGinness
South Houston

Ok so cycleing the ignition is where you turn the key, wait 5 seconds, and turn it again?