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Hard to start after replacing injectors...

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Old 06-18-2017, 10:55 AM   #101
racerseks
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bingo, as mentioned 90 posts ago the problem is not the fuel pressure drop. If you have pressure when you crank the car the pressure drop is a non issue. Most likely the chip needs to be adjusted to the new injectors, or the cold start injector has failed.
Or it could be the injectors, since my oil smells like gasoline now...
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Old 06-18-2017, 12:06 PM   #102
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Put the old ones back in just to rule out your issue.
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Old 06-19-2017, 09:48 AM   #103
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Or it could be the injectors, since my oil smells like gasoline now...
Unlikely since you mentioned that the car is hard to start when it is cold or warm. If the injectors were leaking it would start well when cold (injector leak would have provided the extra fuel for a quick cold start) and hard when hot because it would be flooded by the extra fuel.

As long as you have fuel pressure when cranking the main issue will likely be the injector to chip calibration for base pulse width.

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Old 06-19-2017, 10:17 AM   #104
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Or it could be the injectors, since my oil smells like gasoline now...

​​​​​​​Hard to say since cranking dumps fuel into the cylinder which gets past the rings. You might have flooded the engine. If change oil. If you suspect that the injectors are leaking, test them if they are not multecs
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Old 06-19-2017, 03:13 PM   #105
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Put the old ones back in just to rule out your issue.
Unfortunately, my old ones leak too. That's the only reason I replaced them. Never would have touched them otherwise...thanks.
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Old 06-19-2017, 03:18 PM   #106
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Unlikely since you mentioned that the car is hard to start when it is cold or warm. If the injectors were leaking it would start well when cold (injector leak would have provided the extra fuel for a quick cold start) and hard when hot because it would be flooded by the extra fuel.

As long as you have fuel pressure when cranking the main issue will likely be the injector to chip calibration for base pulse width.
Okay, I'm going to go back and read all this stuff over again...but one thing keeps standing out to me. You say as long as I have fuel pressure when cranking, fuel is not the issue. But did you see the part about how mine drops almost immediately? You referred to it as slow, but it is within a minute....from 43 down to about 18...within one minute. All I see all over the place is how people say the fuel pressure is maintained for hours and hours and hours. Mine just doesn't seem normal with what it's doing.

Is there any test for the injector to chip calibration you mention?
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Old 06-19-2017, 03:19 PM   #107
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​​​​​​​Hard to say since cranking dumps fuel into the cylinder which gets past the rings. You might have flooded the engine. If change oil. If you suspect that the injectors are leaking, test them if they are not multecs
The replacements are Bosch III's from Fuel Injector Connection. How do I test them? Thanks!
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Old 06-19-2017, 03:23 PM   #108
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Outstanding. Now we know it isn't leaking from the pulsator. As mentioned, if the return line is clamped and it does not hold pressure, it has to go somewhere. So, either the pump or the injectors are leaking or the FPR is. If the FPR is leaking, you can see it in the manifold. Take that out of the equation and we have the injectors. Without a bench, we cannot really test it. So we will circle jerk back to that later.

Now we need a couple of people involved. The guy at the pump will give the signal and the guy in the car turns the key and read the hose. A second later (The priming should be about done), clamp off the feed hose. If the pressure drops, it is between the regulator and the clamp. If it holds, your pump is an issue.
Isn't this the same test I did before?
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Old 06-19-2017, 03:35 PM   #109
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Okay, I'm going to go back and read all this stuff over again...but one thing keeps standing out to me. You say as long as I have fuel pressure when cranking, fuel is not the issue. But did you see the part about how mine drops almost immediately? You referred to it as slow, but it is within a minute....from 43 down to about 18...within one minute. All I see all over the place is how people say the fuel pressure is maintained for hours and hours and hours. Mine just doesn't seem normal with what it's doing.

Is there any test for the injector to chip calibration you mention?
bjankuski is right...don't worry about fuel pressure drop off. If the pressure is close to spec when cranking (and I bet that it is, but you could check), then this whole "bleed off" deal doesn't matter one whit.

Checking for bleed off is part of a diagnostic check for other problems, but it really doesn't matter what the pressure is once you shut the car off....if it's close to correct when cranking. Holding pressure for 1 minute is longer than long enough for the purposes of the issue you're having.



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The replacements are Bosch III's from Fuel Injector Connection. How do I test them? Thanks!
There is a tool that you can buy to pulse the injector for a certain (short) duration. You charge the system, then pulse one injector, watch fuel pressure drop for that event, write it down. Move the the next injector, repeat. This will tell you ~how much fuel escapes each injector when pulsed for the same amount of time -do they all flow the same?

Then you can repeat that test w/one or a few of your old injectors...compare data. A bigger drop means the injector is flowing more fuel.

OR you can send the new and old injectors to FIC and have him compare them.
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Old 06-19-2017, 05:10 PM   #110
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Okay, I'm going to go back and read all this stuff over again...but one thing keeps standing out to me. You say as long as I have fuel pressure when cranking, fuel is not the issue. But did you see the part about how mine drops almost immediately? You referred to it as slow, but it is within a minute....from 43 down to about 18...within one minute. All I see all over the place is how people say the fuel pressure is maintained for hours and hours and hours. Mine just doesn't seem normal with what it's doing.
All you need is fuel pressure while cranking, how fast it drops is not really important. (Fuel is non-compress able which means a very small leak will amount in a large pressure drop in 1 minute) Who cares as long as you have pressure when the car is cranking, because that means you have fuel at the injectors when you are trying to start. My car leaks down to zero in 5 seconds and starts and runs fine. The leak is the regulator not sealing perfectly. (I know my pump and injectors are fine so the very small leak to the tank while running does not cause me any issues or concerns)

Go ahead and find the pressure drop it will not hurt, but it will not cure your issue unless you have no pressure while cranking or your injectors are the leak, but then you would have other symptoms. (Like black smoke at start-up when warm)
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Old 06-20-2017, 02:02 AM   #111
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I'd have to agree that so long as the pressure is sufficient while cranking, you have a different issue causing the cold start problem. At least you know your FPR and injectors aren't leaking though!

I know it's not any fun, but I would put the original injectors back on (assuming you didn't toss them immediately like I did!) as suggested by others and see if the hard start persists. If not, then you know it's just the difference in injectors. Chances are the ones you have are fine, they're just a bit different from what the car is programmed for.

Good luck!
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Old 06-20-2017, 09:28 AM   #112
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Have you given Jon a call? Ask him if he thinks you should go to 24pph? Just a thought. If you haven't cleaned the cold start, send it in. Either way, give Jon a call.

Last edited by aklim; 06-20-2017 at 09:29 AM.
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Old 06-27-2017, 12:30 AM   #113
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Have you given Jon a call? Ask him if he thinks you should go to 24pph? Just a thought. If you haven't cleaned the cold start, send it in. Either way, give Jon a call.
I've emailed and left messages, but haven't heard back. When I hit the "sales" option, someone picked up right away. It was not Jon...how do I get in touch with him directly? Any ideas? Thank you.

Last edited by racerseks; 06-27-2017 at 01:30 AM.
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