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Hard to start after replacing injectors...

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Old 05-21-2017, 07:43 AM   #1
racerseks
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Default Hard to start after replacing injectors...

This is in regard to an '86. I did a complete tune-up a few months ago, and the car started and ran great, but I noticed a leaking injector. I have since replaced all my fuel injectors with 22 lb. Bosch III's, and my car has been hard to start ever since. It runs nice once it starts, but it starts like a car that's been sitting for 10 years! Any idea where I should start troubleshooting? Thank you.
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Old 05-21-2017, 08:36 AM   #2
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Did you plug the cold start injector back in?
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Old 05-21-2017, 08:45 AM   #3
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Did you plug the cold start injector back in?
Yes, I did...thank you for the comment.
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Old 05-21-2017, 08:59 AM   #4
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Is it hard to start every time you start it or only after sitting and cold? I have 22lb Bosch injectors and didn't have a problem with the stock intake. I now have an edelbrock intake and no cold start injector. It's a little slower to start cold, but fires right up after it's been running.

Do you have a fuel pressure gauge?

Last edited by Dt86; 05-21-2017 at 09:04 AM.
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Old 05-21-2017, 09:04 AM   #5
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the system has to go thru a learn process. disconnect the battery for a short period, connect, restart the car, and let it idle for around 15 minutes. see if that helps....

hey, did you ever get the leaking valve cover issue resolved?
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Old 05-21-2017, 09:17 AM   #6
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Originally Posted by Dt86 View Post
Is it hard to start every time you start it or only after sitting and cold? I have 22lb Bosch injectors and didn't have a problem with the stock intake. I now have an edelbrock intake and no cold start injector. It's a little slower to start cold, but fires right up after it's been running.

Do you have a fuel pressure gauge?
I am pretty sure it's been hard to start every time. If it runs, and I shut it off, I think it restarts okay...but 30 minutes, it's hard again...but I will recheck for a more definite answer.

I had planned to install one on the rail for instances just like this, but it leaked and I decided to keep it off. I had a diagnostic type, but have not seen it since I moved. I plan to buy one to just hook up to the schraeder as intended.

Thank you.
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Old 05-21-2017, 09:20 AM   #7
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the system has to go thru a learn process. disconnect the battery for a short period, connect, restart the car, and let it idle for around 15 minutes. see if that helps....

hey, did you ever get the leaking valve cover issue resolved?
I had the battery disconnected the entire time I was doing this job. I also disconnected the weatherpack connector per the instructions. I've let it sit and idle and driven it around the block a few times, but will try again.

Yes, I did get that resolved. Long story...plan to reply to the last few replies in that post.
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Old 05-21-2017, 10:30 AM   #8
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Have a pic of the injectors?
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Old 05-21-2017, 10:43 AM   #9
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Have a pic of the injectors?
A pic of them on the car? I can make some...or do you mean before the install? I'll see if I do. They are the orange colored Bosch III's, if that helps. Thank you.
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Old 05-21-2017, 11:51 AM   #10
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Did you have the cold start injector checked out? Also what does the ECM say the CTS is reading?
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Old 05-21-2017, 01:38 PM   #11
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Did you have the cold start injector checked out? Also what does the ECM say the CTS is reading?
No,l I didn't. It started really easy before the injector replacement. I changed an o-ring or two. Whatever comes with the fuel rail rebuild kit...I used them all. Sorry, can't recall what "CTS" is. Is it the coolant temperature sensor? The one that's the same as the air temperature sensor on bottom of the plenum? Was a bit suspect of that. It's just about the only thing I didn't replace...though I did replace the connector. Can you elaborate?

Thank you.

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Old 05-21-2017, 01:52 PM   #12
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Coolant Templates Sensor. We will need a scanner to see what the ECM sees for temperature and hit the sensor with an infrared thermometer and see if they are close.

Any chance of getting the cold start injection piece serviced?
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Old 05-21-2017, 03:53 PM   #13
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Let me just jump in here with a theory. I have an 86 with the same problem.

Always started fine for years on the first crank. My injectors were leaking and I replaced them with new. Now it takes and extra revolution or two/three to start. First check that the cold start injector really is plugged in all the way, it's kinda a bear to get seated sometimes. Check for same at the temperature sensor on the front of the manifold. Don't know about you but I take that off when I disconnect the fuel lines. If all OK and no codes I'd bet it's the cold injector. ( I suppose it could be something else but your only change is the injectors)

My theory:
The injectors used to leak down in a matter of minutes-less than 15 usually. New injectors don't seem to leak, it takes hours for the pressure to go down and I think that's mostly past the regulator seat. I think what was happening was the old injectors leaked enough to create a rich condition-always started right up. I'd bet my cold start injector has been clogged for years but was covered up by this rich condition. Now that is not the case anymore so hard start.

Maybe someday I'll fix it by getting the injector cleaned. It's not a big deal for me where i live.
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Old 05-21-2017, 03:58 PM   #14
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Quote:
Originally Posted by Tod Stiles View Post
The injectors used to leak down in a matter of minutes-less than 15 usually. New injectors don't seem to leak, it takes hours for the pressure to go down and I think that's mostly past the regulator seat. I think what was happening was the old injectors leaked enough to create a rich condition-always started right up. I'd bet my cold start injector has been clogged for years but was covered up by this rich condition. Now that is not the case anymore so hard start.

Maybe someday I'll fix it by getting the injector cleaned. It's not a big deal for me where i live.
How will this work? Fuel pools down to the valves and stay there? Won't the engine heat evaporate the fuel?

What has location of your residency got to do with the injectors being dirty? Fuel flows through and it picks up varnish regardless of where you live.
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Old 05-21-2017, 05:01 PM   #15
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How will this work? Fuel pools down to the valves and stay there? Won't the engine heat evaporate the fuel?
Some of the valves are open though so fuel goes into the cylinder though, vaporizes and stays there. Same for closed valves too only it stays in the manifold. Only need a few cc's to get it started. Just my theory can't prove anything.

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What has location of your residency got to do with the injectors being dirty? Fuel flows through and it picks up varnish regardless of where you live.
I'm talking about just the cold start injector. If I lived back North I'd absolutely be getting it cleaned. Here it's mild to hot most of the year, cold start would be off by the time I turned at the end of my driveway on hot days. Couple of extra revs to start aren't a big enough deal to fix right now. Runs great otherwise.
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Old 05-21-2017, 06:52 PM   #16
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Some of the valves are open though so fuel goes into the cylinder though, vaporizes and stays there. Same for closed valves too only it stays in the manifold. Only need a few cc's to get it started. Just my theory can't prove anything.


I'm talking about just the cold start injector. If I lived back North I'd absolutely be getting it cleaned. Here it's mild to hot most of the year, cold start would be off by the time I turned at the end of my driveway on hot days. Couple of extra revs to start aren't a big enough deal to fix right now. Runs great otherwise.
My guess is that it would evaporate it and it would mingle with the air around to not make a difference but that is also a guess.

I thought cold start only comes into play when cranking and once it starts it is off so I would think that by the time it is in gear, it would be long off?
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Old 05-21-2017, 08:35 PM   #17
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My guess is that it would evaporate it and it would mingle with the air around to not make a difference but that is also a guess.
I would say you're right but...
The car always (15 years from the time I first got it) had the very very faint smell of fuel vapor after being shut down for any length of time. Could only smell it in enclosed space. During the course of getting this car back into shape I replaced fuel lines, filters, hoses, emission stuff, etc. Really everything but injectors. Well the car was running fine...and so on. I was the only one who could smell it until the last inspection where I am now, it's just a quick mechanical check, and the tech said he smelled it too. Had no idea what to do. Time goes by and I finally replace the injectors-smell is gone! That's when I started thinking about the whole cold start thing. I feel like a real dummy! Back in the day I was the guy who would get stuff like that real quick used to make the other guys crazy. Oh well I'm going to say it's old age or my planets are out of alignment. Sorry this is long I doubt anybody cares.

Quote:
I thought cold start only comes into play when cranking and once it starts it is off so I would think that by the time it is in gear, it would be long off?
Yep it's on at start but stays on until the temp is 95-100. Theres a bimetallic strip that keeps it on a little longer if it's really cold. That's why the sensor is like a million dollars. or something like that.
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Old 05-21-2017, 09:21 PM   #18
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Cold start injector switch. Fixed my hard start on my 88.
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Old 05-22-2017, 08:05 PM   #19
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Originally Posted by aklim View Post
Coolant Templates Sensor. We will need a scanner to see what the ECM sees for temperature and hit the sensor with an infrared thermometer and see if they are close.

Any chance of getting the cold start injection piece serviced?
What kind of scanner will I need for that?

I could probably get it serviced if need be, but I didn't have any problems in that way before replacing the injectors.

Thanks...
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Old 05-22-2017, 08:09 PM   #20
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Quote:
Originally Posted by Tod Stiles View Post
Let me just jump in here with a theory. I have an 86 with the same problem.

Always started fine for years on the first crank. My injectors were leaking and I replaced them with new. Now it takes and extra revolution or two/three to start. First check that the cold start injector really is plugged in all the way, it's kinda a bear to get seated sometimes. Check for same at the temperature sensor on the front of the manifold. Don't know about you but I take that off when I disconnect the fuel lines. If all OK and no codes I'd bet it's the cold injector. ( I suppose it could be something else but your only change is the injectors)

My theory:
The injectors used to leak down in a matter of minutes-less than 15 usually. New injectors don't seem to leak, it takes hours for the pressure to go down and I think that's mostly past the regulator seat. I think what was happening was the old injectors leaked enough to create a rich condition-always started right up. I'd bet my cold start injector has been clogged for years but was covered up by this rich condition. Now that is not the case anymore so hard start.

Maybe someday I'll fix it by getting the injector cleaned. It's not a big deal for me where i live.
Theories welcomed!

Yea, mine takes many more revolutions that that to start. Once it starts, it runs nice.

I'll check those plugs.

Thank you!
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