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Slow start when hot

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Old 05-03-2018, 06:17 AM
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Slow start when hot

Hello,

I have Pontiac Firebird 2.8 V6 MPFI from 1988 with 100k miles on the clock (manual). I have noticed a strange issue and I was wondering if you could help me.

Every time when I get into the car when it is cold, it starts rapidly and smoothly and quickly - as it should.

When I drive it for some time and the engine gets warm (it reaches its normal operating temperature) and I park it, get out and come back to start it again, it feels much different. When I turn the key the starter reacts right away but it takes a few seconds until the engine kicks in. For these 3-6 seconds it sounds as if the starter was trying to start the engine and the engine struggled to come back to life.

After these few seconds it starts normally, but it is not a lively start. It only happens when the car is warm. Sometimes it starts the second time.

There is no lack of power of other symptoms. It runs like new, very stable rpms etc.

Spark plugs, cables, pickcoil where replaced 6 years ago and since then the car did approximately 13k miles.

Does it have anything to do with fuel injectors?
Old 05-03-2018, 07:21 AM
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Re: Slow start when hot

Injectors are probably leaking down after warm and giving you a "hot soak" condition. If original injectors, they're 30 years old. The TPI V-8's are notorious for this. I would think the same for the V-6 also.
Old 05-03-2018, 08:45 AM
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Re: Slow start when hot

This is what I though. Yes the injectors are original.

I spoke with a local shop and they told me that they could order AC delco ( a bit pricey) and replacement which I believe is by Standard Motor Products or Airtex. Are these ok brands or should I stick to AC Delco?

(I have always imported original parts by GM/AC Delco from US, because I am based in Europe, but the local guys tell me that the replacements are also ok).

How many injectors are there ? I guess it is 6, should I replace all of them in one go or check which is leaking first and replace the faulty one?

What else would I need? Any seals, rubber ?
Old 05-03-2018, 09:16 AM
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Re: Slow start when hot

You can get those if you like...but pricey. Yes 6. And here is a thread to guide you through it all. You will need gaskets and such. Read this thread:
https://www.thirdgen.org/forums/v6/6...tors-step.html

Check out:
SouthBay Fuel Injectors
566 Merrick Road #3
Rockville Centre, NY 11570

877.772.2965
Frank Juhl
info@southbayfuelinjectors.com



Hope all this helps you out over the pond!
Old 05-03-2018, 12:00 PM
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Re: Slow start when hot

The injectors are made by bosch. They have a 4 spray pattern and come with a 3 year warranty. We'll be more than happy to help you. TGO members still receive 10% off however the code is not working at this time on the site. You can give us a call if you like
516-442-4707
Old 05-03-2018, 12:47 PM
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Re: Slow start when hot

Besides replacing the injectors due to age. You might want to check your timing. You will need to do this warm with the est disconnected.if the timing is overly advanced the starter will sound like it’s struggling.
Old 05-03-2018, 06:40 PM
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Re: Slow start when hot

I’ve seen tired timing chains do this...
Old 05-03-2018, 07:16 PM
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Re: Slow start when hot

Originally Posted by Galaxie500XL
I’ve seen tired timing chains do this...
With that mileage though??
Old 05-04-2018, 04:30 AM
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Re: Slow start when hot

Hi there,
maybe check the positive battery cable. If it is original, over time it can get corroded internally, and when the engine warms up it can get heat soaked. That can raise the resistance enormously, make it very hard to start.
The cable may look perfect on the outside, but you cut it open, and it is all chalky dust on the inside. Worth checking the resistance of the cable, and if it is bad, they are not very expensive, and fairly easy to replace.
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