Help! 89 Won't start when warm. Lets try again plz...

[DallasK]

The car starts and runs perfect when cold. Once warm and parked for a short time, it won't start. I checked with an OHM meter. When warm all injectors are at 18.0 with one at 18.1 and one at 17.9.
Cold the injectors are all at 16.4 with one at 16.2. Is this acceptable or does this variance between cold and warm mean it is an injector issue?

I also assume the fuel regulator is the black diaphragm looking part near the passenger side rail, towards the rear of the rail, that has a few silver bolt heads around it. Is that correct? It also looks like all bolts are in need of a standard star wrench type tool. Is this correct? Can this part be obtained at the local auto parts supply or is it something that generally has to be ordered if needed?

So I am trying to determine if the injectors need changing. Or if they do not should I go ahead and change the fuel regulator, or do I need to buy some sort of gauge to check the pressure on the regulator before replacing it? It would be nice if there were a picture somewhere here describing these parts and their location though I am sure I can figure it out eventually. I still love my car! Thank you.
Dallas

 

[vetteboy86]

You can buy a fuel pressure gauge that connects to the shrader valve that is on the passenger side fuel rail near the back. It screws right on. Connect it then key the ignition on. Should see at least 38 psi I believe. I will have to reference my FSM. Anyways, it should remain at pressure. If it doesn't then you have a leaky injector. If it stays at pressure make sure the connection is good on the valve and start the car. Keep a close eye for gas leaks. Note the pressure. Increase engine RPM's and the pressure should increase. The proper way to check fuel pressure while engine is running is by disconnecting the vacuum line that goes into the pressure regulator. If when you pull the vacuum line off, fuel comes squirting out then you need to replace the diaphragm inside the fuel pressure regulator.

 

[DallasK]

Thanks Vetteboy; OK, that sounds do-able. But first I was hoping someone would tell me for sure if the readings I got for the injectors are acceptable. I guess you would have said something if you thought they were not...

 

[Hib Halverson]

This hot no-start problem...

It is that the engine will crank but will not run?
Or, when you turn the key to start, nothing happens at all.

If it cranks but won't run, what happens when you floor the throttle (ie: force the ECM into clear flood mode) then crank the starter?

 

[DallasK]

Yes it cranks but won't start if it has been recently driven (Warm). Once I let it cool completely it starts and drives perfectly. I was hoping that someone qualified would verify that my voltage test on the injectors means the injectors are OK and then I will move on to the fuel regulator check. Thank you.

 

[vetteoz]

The injector readings appear fine.
I don't see the FPR being a Hot / Cold problem; If it is stuffed it is stuffed

As Hib asks;
will it hot start with the throttle open?
If it does this is a indication the injectors are leaking fuel into the engine making it to rich on not start.Leaving it for a while alows the fuel to evaporate

 

[DallasK]

No it does not start with the throttle open. Sorry I did not answer that question earlier. I certainly don't want to waste anyone's time. It simply will not start until it cools. No matter how long I crank it or how I work the throttle. I am a bit surprised about the regulator response as it seems most believe my problem is either injectors or the fuel regulator. I was just beginning to feel like I was getting a handle on this thing. I just got back from the auto parts store after dropping $38 on a fuel pressure gauge. Hope I did not waste that hard earned money.

 

[DallasK]

Well I just checked the fuel pressure. It was 30. Then I relived the pressure on the gauge and did it again. It was 32-33. I can't start it and warm it up until tomorrow. If I wake up my darling bride of 19 years may be forced to slap me around a bit... Thanks for all your help. Any further advice will be greatly appreciated. Cheers.

 

[vetteoz]

I just got back from the auto parts store after dropping $38 on a fuel pressure gauge. Hope I did not waste that hard earned money.

I was just thinking that if the FPR was faulty it would be fault all the time.
The no start open throttle virtually eliminates the flooding problem
Another tack.
Have you got spark when hot?
Possibly an electronic component is failing / breaking down with heat and only working when cold
Try a timing light when you have the hot start problem

 

[DallasK]

I have no timing light anymore. I guess I can hold a spark plug wire near the head of a spark plug and see if spark jumps the gap. I will heat up the car tomorrow and check the spark hot and check the fuel pressure hot.

 

[DallasK]

Just remember that once started the car can be driven as far as I like. It seems if an electrical component were getting hot it would fail even when the car was in operation. Just a thought.

 

[vetteboy86]

I would agree with the previous statement. Just for sure though, I would pull a plug when it isn't starting and see if spark jumps across the plug gap. I guess it is possible that while working a component would stay working then when shut off could possibly not work. It is a long shot. Verifying spark will get you one step closer.

 

[DallasK]

OK, I will try that today. Thanks.

 

[raidoman]

No Hot Start

My 87 had all the same symptoms. Ohm readings, fuel pressure were all OK. The problem was the injectors were leaking down when the car was shut off. After funning it adn letting it set for an hour or so, I pulled plugs and found wet plugs from leakage. Cold start was great, car ran well until I shut it off. Would start only when cooled down. A new set of injectors solved it. Went with Tomco injectors as they do not use a pintle as do the OEM Bosch units. Have had them in 5 years now without a problem.

 

[muddywaters]

Ditto radioman, Only I used Bosch GenIII injectors and my 88 runs great.

 

[DallasK]

Thanks Radioman and Muddywaters. After all the great help I have received here I had come to that conclusion but I am so grateful for your post because you describe the situation perfectly and I feel very confident you are correct. It was exactly what I needed to hear. I am ordering some today. I have decided on the Bosch3 as well. Giddyup!

 

[badglas]

Hot start

If I read your earlier post correctly, you said you had a max fuel pressure of 32 psi. This is at the very bottom of the spec for this car. Typical fuel pressure on an 89 would be 38 - 42psi. I would start there if you have'nt bought injectors yet. Most 89's won't run with 32 psi of fuel pressure.

You don't mention the last time the fuel filter was changed, could be restricted there.

You need to follow Chart A-3 of the 89 service manual for proper diagnosis before spending your hard earned dollars.

If you need info you can contact me at 217-726-3840 9-5 Mon - Fri

Ron Kane
Benchmark Corvette Service
Bloomington Gold Restoration Workshops Senior Instructor

 

[DallasK]

Actually I have not purchased yet. I was putting jetskis in the water yesterday. I am not sure how a fuel filter fits a warm start problem but it seems you are the expert. The fuel pressure was 32 but that was cold. The car starts and runs perfectly cold. I believe I was using the gauge correctly. I have no service manual and have no idea where to get one here locally. I have tried. Also I have no idea where the fuel filter is on this car. If the minimum is 38 pounds how is the car running? I just went from confident to frustrated again. Bummer. Thanks for your comments though.

 

[muddywaters]

Injectors,injectors, injectors, their 20 years old, were not designed for ethanol, I paid $169.00 for the Bosch GenIII. Your problem doesn't occur when the car is running it occurs after the car is shut off, leak down. Yes, It would be a good idea to change the fuel filter when you change your injectors. Just wondering, Where in Pa. are you located? If your not comfortable with that question, don't answer it. Fuel filter is on pass. side frame, piece of cake.

 

[DallasK]

Hey muddywaters. Thanks for yet another positive post Dude. I live in Pittsburgh. (Fox Chapel TWP. if you know the city.) I am a HUGE Penguin fan and the baby Pens are where you live as I am sure you know. I am calling around now for a fuel filter now. Changing that seems appropriate whether it is failing or not after all its years of being on the car.