hard starting

My '91 caprice wagon that I am working on to get on the road again has developed a hard-to-start situation. After sitting for more than a few hours it spins over a lot before it will start. I plan to replace the fuel filter this weekend. The car has 200,000 + on it , with only 12,000 on a fresh engine, but I don't know if the fuel filter has ever been replaced. It runs fine once it fires up. I hope the filter cures the problem.

Fuel pumps for these rides are notorious for going out.

Andebe wrote:

Fuel pumps for these rides are notorious for going out.

As notorious as the lt1 cars?

Fuel pumps seem to be a "thing" on these TBI wagons (can't comment on LT! since I haven't had one)...I've had several TBI wagons and they have all been a bit slow to prime up and start as they aren't designed to hold "prime" pressure once you stop cranking....... The fuel pressure regulator in my Olds was also holding less-than-spec pressure (9psi) resulting in weird surging after hot starts (vapor lock) so I installed an adjustable pressure kit to the regulator........A mechanical fuel pressure gauge is the best test tool you can buy for one of these cars.....

Ive replaced 3 out of the 4 TBI's Ive owned.

Next time its hard to start,. put your foot to the floor,. see if it makes any difference,.

The filter didn't fix it. I read somewhere that another with the same problem unplugged the temp sensor and the problem went away. I think I'll check the sensor on mine. I ran it hot hot hot once without any apparent damage to the engine except the temp gauge pegged on full hot and has not moved since. I guess it fried the gauge sensor and possibly the temp sensor that communicates with the computer. Maybe the sensor is telling the computer that the engine is hot all the time? We'll see.

Well, the good news is that if it's the fuel pump it will crap out totally soon and provide a positive diagnosis of the problem.

Have you noticed a staggering of the engine on longer trips recently? The pumps seem to fault when they overheat and then recover a bit after they cool.  That's only temporary before they drop dead and won't run the engine at all.

I have not driven the car for several months. It ran fine when I drove it last.

I tried starting the car with the temp sensor unplugged and it starts better, but seems to surge after starting. Plugging the sensor back with the engine running smooths it out and raises the rpms a bit. Tomorrow I will replace the sensor .

papa wrote:

I tried starting the car with the temp sensor unplugged and it starts better, but seems to surge after starting. Plugging the sensor back with the engine running smooths it out and raises the rpms  a bit. Tomorrow I will replace the sensor .

when you unplug the sensor it tells the ecm its -40c,. ecm adds a lot more fuel to start,.
its surges because its too rich,. you plug sensor in, it leans it out and idles up and smooths out,.

Your original post,. was it pertaining to a partly warm hard start?

Now you are dealing with a cold start?

next cold start,. try cycling the fuel pump a couple of times before you start it,..

Actually , ever since the problem started, I suppose any start except for an immediate restart was a problem. I had tried turning the ign switch on and off 3 or 4 times when starting . Is that what you mean by cycling the fuel pump? I plan to replace the sensor this evening after work. I'm anxious to see if it fixes the problem. I wonder what other sensors , besides the sender for the guage , I might have fried when it overheated.

It's pretty difficult to offer internet advice and diagnosis,.

I could write a laundry list of problems that would cause a poor start condition,..

depending just how hot it got,. gaskets might be compromised,.
fuel pressure regulator spring might be stuck/broken

A hard start complaint would be easier to diagnose with a fuel pressure reading and a vacuum reading,.

perhaps you have the famous tbi warped intake manifold syndrome,..

Still stirring the pot,I see...

Replacing the sensor didn't fix the problem. So the car sat from Dec 9 until Dec 24 without being touched. Then yesterday it started fine. I tried it several times today and it starts and runs fine. Elfing magic maybe? Or divine intervention? Some new brake shoes and wheel cylinders this coming week and I'm on the road again!

Strange....

dry environment now?

No, actually we have had a long spell of rainy days and nights for several weeks. I'm going with divine intervention.

water in fuel maybe,.

with a car an intermittent connection is sometimes called divine intervention,.