The car starts fine when it's cold but after it is warm it will just turn over and not start. Since it will turn over I assume it has nothing to do with the battery and since it turns, then the starter must be good. So what could cause a car to start when cold but not when warm?

 

Either low compression, flooding, or some combination of the two. Do a quick search for "hot start problem".

Brandon

 

Hello Samps,

There are a large number of things that can cause hot starting problems, and unfortunately, I've had the thrill of having most all of them happen to my car.

The most common are poor compression, leaky injectors, broken vacuum lines, and ignition problems. Here is a list checks to do starting from the lesser expensive tests on up. (Note: If your pretty sure its a flooding problem, then just skip down to having your injectors cleaned or replaced).

The first thing to do is check your compression.

After that, check your vacuum lines.

If this is ok, check out your igniters when they are hot. Hook up a non-inductive timing light, and verify that all the plugs are firing. I suggest a non-inductive light, because I spent half a year trying to find one of my starting problems after an inductive timing light strobed correctly on all four plugs. I found a post where someone said how an inductive timing light had strobed correctly, even when the coil was not putting out enough voltage to fire the plugs. The non-inductive (direct connnect) timing light will not strobe unless it gets a pulse of at least 25kV as it is supposed to. After making tons of other repairs (and blowing a lot of $$)trying to fix my problem, I tested the coils with a non-inductive timing light, and sure enough one of my trailing coils was bad after all.

If that doesn't do it, and you still have your cats on the car, you should then have your exhaust system tested for back pressure (plugged cat(s)). As the converters get hot, they get more restrictive. So, in cases where this is the problem, the car will still start when cold, but not when hot. If you have a lot of miles on your car, you may also want to get rid of your pre-cat, just to get that extra heat out of your engine compartment.

If all that checks out, then it is time to check out your fuel injection system. Check the fuel pressure, then move on to the injectors. If you haven't had the injectors profesionally cleaned and balenced in 80k miles or so, its probably time you had it done anyway. If one or more of them are still leaking after cleaning, then you'll need to replace them. Fuel Injection Warehouse ( http://www.fuelparts.com ) has Cobra remanufactured injectors for $40 each. When I serviced my injectors, I just skipped the cleaning and bought 4 remanufactured ones to save time. They look and perform just like new ones, and I've been very happy with the set I got.

If none of those things pan out, holler back.


Good Luck,
Douglas

88 Turbo II,
Melbourne, FL

 

Thanks for the info. The car in question is not mine and not a RX-7, . One of my buddies here at work said that his Saturn was doing this over the past month or so. He said he took it to the dealer and they ran a diagnostics test on it and came up with nothing. He says it starts fine when cold but not when hot, the funny thing is that when it does get started it runs great.

The reason I posted in this section is because it is a co-worker and I told him I would try and find out some info, and I didn't want to take forever. I tried to ask using a general automotive style question but I had a feeling I would get rotary specific answers.

Thanks again for the info but I'm guessing his problem lies in some odd Saturn devise that was probably designed to go bad after 50k miles.