I think I have leaking injectors. With the AFPR set to 43psi it lost to 17psi in 30 min. & to 10 psi in 60 min. Then I repeated the test and it went to 10 psi in 5 min. What's the normal drop?

Sorry I should have said after shutdown.

 

That doesn't seem abnormal. My '86 will hold pressure for a day. I've worked on other EFIs that lose all pressure in a n hour, and they run just fine. I've also found regulators that leak down pressure after about 30 minutes and lose it all through the diaphragm, partially flooding the engine.

 

Run the engine for a minute.. Pull the injectors with fuel rail and all still attached.. Wipe them dry with a cloth and let them sit for 15 to 30 min.. Come back and if any of the tips are wet again then its leaking.

 

Basically what Vader said.

Ideally, nothing is supposed to leak down :-)

But in real life, none of that quite holds water. lol

Basically from what I find, you should hold some type of decent pressure for 30 min to 1 hr after shut down and your fuel system is in pretty good shape.

Depends on how good of shape your regulator, pump and injectors are in and which one is actually causing the leak.

Lots of times, the quick bleed down is the fuel pump check valve failing and not holding pressure, usually the case when the car is fine other than wont hold pressure after shutdown.

Slow leaks or drops can be any of the above mentioned

later
Jeremy

 

One possible exception is if you're using the Holley AFPR with teh large disk for the adjuster part on top. According to what Holley has said, that regulator has a "safety feature" where it bleeds off the pressure fairly quickly (down to 10-15 PSI in less than 20 minutes). DOn't know if that was an actual planned safety feature or something that was "discovered" after they were made, but mine works just fine in all other ways. No restart problems, either.

Just thought I'd add that little tidbit.....

 

After this happened, did you start the car? That would be a good indication if they were, because the car probably would start/idle poorly for a bit.

Heres my leakdown test when I had leaky injectors:



If you car starts and idles fine, I would not worry about it.

 

Thanks for all the responses. My complaint is that it's hard to start. One time I had to get a jumpstart to get it going and I pulled #1 plug and it was wet with fuel. Yes I do have a Holley AFPR and I just replaced it because it would not go above 37 psi. Once I get it started it runs preety good except for a stumble if you open the throttle quickly from idle. The wet plug and quick leakdown time make me think it's an injector leaking.

 

Call Holley tomorrow and ask them if their AFPR has a safety feature that causes the pressure to drop off like you, me, and countless others have seen. I think your problem is something else....

 

my truck lose's pressure instantly when you shut her off. the injecters i had cleaned and #7 leaked but apparently when they tested after cleaning it didn't leak anymore. the fuel pumps brand new. i've seen some sort of "pulsator" kind of deal between the intake pump and line coming from the top of the sending unit? i don't have one of those. would that be my problem?

would there be a way to tell if my regulators not working right without taking anything really apart? i kinda need this truck for work and all

can those small clamps they use on the rubber connecting the pump and sending unit not be clamping enough?

 

My tpi conversion did this to .... cause hairline very small cut in that rubber line between the fuel pump and and sending unit.

after replacing car started alot quiker and holds pressure for a long time

 

hehehehe

My Holley AFPR started leaking past the diaphram. Strange part was it wouldn't leak (out the vac line nipple) with just the fuel pump on. However, when eng was started, it started shooting fuel all over the dist. :0

Called Holley. The rep said he couldn't sell me a diaphram since he couldn't find a part# for it,,, so he just sent me one for free.
That was abt a year ago and no problems since.

I lose abt 1/2 of my fuel press after 30 mins. No problems with hot starts. I suspect the fuel pump check valve is responsible.

 

Jproz1167- if your repsonding to me, then alright when i take the bed off to paint her i'll stick on some 3/8 fuel pressure line and double up on clamps just in case...thanks