In general my engine starts fine... hot or cold.

Every once in a while I have trouble, only when cold the engine is cold. I go to start it up, it just cranks, doesn't even act like it wants to fire, I crank for 5-8 seconds, then let it sit, I can hear the fuel pump running and running...

I then try to start it again, crank it for another 5-8 seconds, it spudders a little, like it wants to start, but doesn't. again the fuel pump runs and runs.

I then crank it for the third time, and she ususally fires up but not always. I don't have a fuel pressure gauge, so I can't see how much pressure my pump is putting out, but I pushed the little schrader valve in, and fuel came out like crazy, so I assume I have pressure.

I don't think it's Ignition, since I have new plugs, new cap/rotor, new coil, new ignition module.

After it does fire up, it runs a little rough for a second, then it runs fine. I don't think it's flooding either.

Any ideas?

 

Faulty CSI (cold start injector) perhaps... Could also be a worn/dirty IAC valve if you have had any searching/jumping idle symtoms too. Possibly could use a full tune up too if you haven't done so.

The fuel pump running after you try to start it and let off is just repressurizing the lines and is totally normal.

 

I have a brand new IAC, and did the ECM relearn on it, the idle is fine, although a tad high.

As for a bad cold start injector, I really dunno if it is good or bad, If that is the reason I'm having trouble starting, then it works fine sometimes, cause I have no trouble starting most the time.

Full fuel tuneup? What would that include? New pump/regulator? or Injectors and stuff? I have a new fuel filter I need to put on.

Thanks!

 

I'm not so sure it's the cold start injector. Since the CSI, as well as the Smog Pump solenoid, is not ECM controlled.... removing them (which is what I did on my 86) will not cause an error code, nor does it (well, nor 'should' it) cause any starting or driving problems.

Curious though, what's you're timing setting? BTW, how old are you're fuel injectors? They might be getting clogged up.

 

Not sure how you're saying that a bad or removed CSI wouldn't hamper starting. The '86 ECU doesn't have enough crank fuel pulses to start the car without it. Without chip changes, my '86 cranked for 5-6 seconds before firing until I added .50 pw in the 0-8 crank trigger table values.

A faulty CSI will crank for several seconds before starting when it's not working (similar condition to removing or disabling it), and fire right off the bat when it happens to be working correctly. That was my main reason for disabling mine...

You are correct that it did not set off an error code though.

 

No no... I'm not saying that his car will start faster without the CSI. Judging from his symptoms, and of how long it's taking to turn over and start (not to mention his problem being tempermental, happening only every now and then), I seriously doubt it's the CSI.

As far as crank fuel pulses, he can simply disconnect his fuel primer, along with the fuel pump relay, then see if it starts after an extra couple of seconds (about 5-6)...being that the oil switch/fuel primer sends the pulses to and fro to the ECM (to ensure that the engine get's primed before start up, as well as to ensure that pressure cuts off in case of an accident).

The car will run fine without the CSI, it will even run fine without the fuel pump relay.... however, it will take a few more seconds to start.

 

But that's just it though... a faulty CSI will give his exact symtoms... 5-8 second cranks before starting, sometimes it starts normal... I had the exact same symtoms...

 

Just so everyone reading realizes ahead of time, we're discussing, and not arguing.

Once the engine reaches a certain crank speed, the fuel pump is activated by the ECM.... and the relay and CSI is no longer needed, agreed?

Okay, but.... he claims that not only is it taking a very long time to start (on a couple of tries not to mention), but that it idle's rough for the first couple of seconds, then smooths out. This cannot be caused by the CSI, it sounds like dirty injectors (remember, he installed a fresh ignition, on top of, possibly, old & dirty injectors).

Once the primer, primes.... and once the engine is cranking for more than 3-4 seconds (even if it's not officially started yet), then the pump is triggered. If anything, the problem might even be by the primer switch itself (which in essence, might be blocking voltage sent to the ECM). He might need a new Oil Primer Switch.....

But this can't be.... as he states that he's getting fuel pressure.

 

Agreed, discussing, not arguing. There aren't any bleeped words anywhere. Heheheheh

Agreed that the primer switch and injectors could also be involved. In my case though, it was the CSI with the same symtoms.

Come on MysticWizard, go buy some parts and tell us which one wins!

 

Also don't forget about the cold start switch that is in the coolant passage on the intake.

 

That one makes the most sence! I did replace my intake about 3 weeks after I got the car, before I replaced the intake I had no problems with it starting ever. After I did the intake it started acting up. The replacement Intake I got had all the sensors on it already so I decided to just leave them on and put the intake on.

I still have the sensors off my old intake, so I guess I could just swap them for the ones in the new intake, and see if that solves my problem.

 

Are you sure you don't have a vacuum leak? Did the intake seat right?

As for the original Cold Start Injector (CSI) and sensor, try it out. However, on my 86 TPI... I literally took mine off, and it ran like a dream regardless. But if you think that it might be the culprit for yours, and if indeed it is, then let us know.

 

No vacuum Leaks, It runs like a dream once it starts up. The intake went together easily and seated down nicely. Everything was torqued to specs in the correct order, and then checked over again.

 

That's good.

Now, if the fuel pump is working constant (which you already confirmed), then every injector is getting fuel. The cold start injector doesn't block fuel to the other injectors, it just switches 'on' to prime the motor.... it's not meant to run it.

But even so.... GM scrapped the cold start injector 'idea' for the TPI engine in 1990, but of course they maintained the fuel primer (which turns on, and allows the injectors to function momentarily). Once the engine reaches desired crank speed, the ECM triggers the fuel pump to pump constant.

If you turn the key in the 'on' position (without starting it), you'll hear the pump running.... but then will shut off after a few seconds (because the ECM didn't sense crankshaft rotation, and cut off the feed to the pump). The cold start's only objective is to help prime the engine, especially in a colder climate.... but the car will certainly run and drive the same without it.

 

Timing is set at 6* BTDC as the little tag under the hood specifies. I was having problems with Detonation/knock with any higher timing.

As far as the Injectors... I really dunno how old they are. I bought the car with 170K on it, and the seller didn't know the history on it, as it had been bought used by him also.

When I had the intake off and looked in the top of the engine, it looked as if it had someone in there before. Although I'd say it's been a while, I found some slight metal shavings in the valley, but I'm not worried about that right now. I am assuming the injectors are either original, or pretty old, They had some carbon on the metal tips, which I tried to clean away.

I know I need to replace them eventually I just don't have the money! I don't know if anything can be determined by gas mileage... I get about 14 around town and 17 on the highway.

I need to swap those sensors on the front of the manifold. and see what that does for me. Thanks for the help guys!