Fuel Pressure Drops after shut off

[LiquidX]

Lately I've started to notice that it takes about 15 or so seconds start my car. I have a 255 that was installed about 2 years ago and it's worked great. I have an AFPR that was installed at the same time with no issues.

I just installed ECMLink v3 and my FIC Bluemax 1250 injectors. It wasn't until after those that I've been noticing my fuel pressure issues.

Turn the key and the pressure goes to 43psi. After about 5-10min the pressure drops down to 20psi. It then takes about another 20min or more to drop down to 0.

My AFPR is NOT leaking out the drain line since I put a clear line on capped it off to prevent vapors from escaping and it dropped 20psi with that attached with no fuel or vapors.

I have been told that it could be the check valve in the fuel pump or injectors leaking into the cylinder (which is what I'm thinking). How would I go about and test both? I already pulled the plugs and they are all the same white/gray color.

Also the car sat for about a year with no starts if that helps at all. So what should I do to check everything and what would be the appropriate method of fixing the problem?

 

[supravw]

My car does the same thing with a 255 and afpr. I've just come to get used to it taking a couple cranks more to start it.

 

[BogusSVO]

Liquid.... some NAPA stores have fuel injector cleaner/testers... so call around and check with them.

They can run a test to see if the injector is not closing properly

 

[viprez586]

That is completely normal bleed-off. Don't worry about it.

I wouldn't be worried about extended crank either with all the modifications you've done. You can't expect factory like crank time or factory "like" anything once you start modifying.
Does it run like crap?
Does it not start at all sometimes?
Is it really that big of a problem?

If your answer to the first two is no then I'd tell you to just twiddle your thumbs while it cranks over.

 

[LiquidX]

That is completely normal bleed-off. Don't worry about it.

I wouldn't be worried about extended crank either with all the modifications you've done. You can't expect factory like crank time or factory "like" anything once you start modifying.
Does it run like crap?
Does it not start at all sometimes?
Is it really that big of a problem?

If your answer to the first two is no then I'd tell you to just twiddle your thumbs while it cranks over.

Upon start up it does run like crap and I need to work the throttle for a little bit otherwise it will stall out.

It used to crank right over before I put in the 1250 injectos so maybe they are leaking out somehow. I did however pull each spark plug and inspect the piston heads. They were all dry even after turning the fuel pump on and letting it run.


Thanks Bogus, I'll have to look into that. There is a NAPA down the road, I'll ask them what they can do.

 

[viprez586]

Pull the rail with the injectors seated in the rail and turn the key on. Make sure the injectors don't pop out but that's an easy way to see if they're leaking.
Your deadtime values are correct?

Maybe if it was direct injection you would see some fuel on the plugs/pistons, remember there is a valve partially covering the path there.

 

[EagleTSIawd]

Yup, mine drops to zero as soon as I turn off the car too. It used to also take me about 10-15 seconds to start, I thought it was normal because I removed and block off all the bottom part of the throttle body.

I came to find out I installed the rubber on the injectors wrong. You first insert the rubber donut inside the gap on the intake manifold then install the fuel rail with the injectors intalled on it. I didn't know and so I squeezed the rubber on the injectors first, well that failed to make a proper seal and air and fuel leaked.

I fixed that then retuned the maf and deadtime and now she starts everytime In like 2 seconds.

 

[LiquidX]

I doubt I'll be able to pull the rail without the injectors popping out. I pulled the rail the other day to replace a lower seal and the #2 injector came out of the rail so I won't be able to build pressure that way.

I do have a log that I just made. Found out my ISC was unplugged and hoped that would fix partial idle issues and my ISC position and lrndidleadj values but it didn't help.

I came to find out I installed the rubber on the injectors wrong. You first insert the rubber donut inside the gap on the intake manifold then install the fuel rail with the injectors intalled on it. I didn't know and so I squeezed the rubber on the injectors first, well that failed to make a proper seal and air and fuel leaked.

I fixed that then retuned the maf and deadtime and now she starts everytime In like 2 seconds.

How would the lower insulator cause an injector to leak (not onto the manifold)?

 

[jjrock5]

I installed mine over the weekend.

YouTube - Adjustable Fuel Pressure Regulator aka AFPR install - Part 1/2

I have the stock fuel pump and injectors.

Now everytime I start the car, more so when it's a cold start, it takes a few seconds to start. Before, the car used to start within one second.

Is this just something that AFPRs do?

 

[viprez586]

Use zip ties or bailing wire to hold the injectors onto the rail. It will look ghetto as s__t but at least it would be easy to verify through a visual inspection.

Hmm, I don't have link even though I have to program for some reason.

 

[LiquidX]

Won't they want to pop out after turning the fuel pump on though? Will the zip ties hold them on hard enough?

 

[viprez586]

That's why I suggested bailing wire, but zip ties are pretty strong.
It's your "test" so if you feel like it is dangerous: Don't.

In theory if the injectors remain seated in the rail everything will be pressurized, so if one is leaking it's bad. I know what you mean though, a couple of my injectors when installed are "tough" to turn/spin, whereas one it's really easy. But do all of them so they don't go flying out and make a mess/damage the injector.

43/ 4 = 10~psi across each injector, think of when your doing a BLT and that coupler blows off at 20psi...though that is a larger volume to fill. Just be careful.

 

[EclipticalGS]

Do you hear any hissing by the gas tank when the car is on by any chance??

My car got hard to start after i took off the Fuel Pressure Solenoid or whatever it is, it added 5 more cranking seconds on the nose.

 

[LiquidX]

Well I went to try the zip ties but I don't have any long enough to hold the injector in the rail by looping the tie from the injector tip, up around the rail and back down.

1 injector did fall out and a lot of fuel came out with it so could that eliminate leaking injectors? Fuel pressure was at 0 at this time.

 

[viprez586]

No, Get longer zip ties or bailing wire (hell even some thin solid wire) and just kind of go around it in a figure 8 configuration or whatever appears to work best.
You want to do this test with the key on so the pump runs and pressurizes the fuel rail and injectors.

You can "chain" link the zip ties.

 

[LiquidX]

I'll have to give that a go tomorrow though. Any way to test the fuel pump check valve?

 

[viprez586]

I do not believe there is a check-valve in our fuel pumps.
Check out the FSM for the 2G, I'm digging through my 1G FSM to see if there's anything similar.

 

[LiquidX]

FSM? Term I haven't heard before.

What I was reading is that there is a check valve built in the fuel pumps to prevent fuel from going back into the tank when the pump is turned off; keeps fuel pressure.

If I didn't have a SS AN line, I would move a check valve into the line and that would at least tell me if the injectors are bad or if the pump is.

 

[viprez586]

Factory Service Manual, sorry.
Anyway I was reading in mine. If the check valve is bad you immediately loose fuel pressure, so I doubt the check-valve in the pump is bad.
It says to inspect the injectors when the fuel pressure bleeds off after shut-down. It doesn't give a time though.

 

[LiquidX]

Well, the issue did start after the install of my "new" injectors. They sat in a bag for about a year before being installed.

I suppose I'll have to go with Bogus' advice and see if NAPA can test the injectors. Is there any sort of fix with injectors at all to prevent them from leaking?

 

[viprez586]

Potentially send them out to get cleaned.
My denso 720s sat for over a year in a dirty tool box, I'm sure getting slapped around a couple of times. I sent them to cruzin performance to get them flow tested and cleaned. Cost around $65 shipped or so.
Funny thing is greddy sells the same injectors for like $300-$400. All it cost me was the cleaning .

Never heard of a napa testing them, I worked there for a month...maybe I didn't stick around long enough to find out. They probably just ohm test them, .

Anyway yeah on cruzin performance website they say not to let the injectors "sit". They get a varnish built up, so maybe your's are just clogged a little and hanging open perhaps.

Fuel Injector Cleaning and Blueprinting

 

[LiquidX]

All but one were sitting new in sealed bubble wrap packaging. The single one was taken out to get pictures then put back in the bag. Perhaps it was that single one that's being a little funky...

 

[viprez586]

Perhaps, Look at that link i provided.

 

[LiquidX]

I checked it out and it looks promising. However I sent FIC an email regarding my issue and if I'm lucky they'll be able to help me out with this as well.

It is seeming to boil down to the injectors with when this started and what is going on. Good thing I still have my stock injectors.

Thanks for all the help Jake!

 

[viprez586]

No problem, let me know how it goes.