Fuel pressure question

Post your E12 technical questions and comments here. Please, no off-topic posts.

Moderators: Mike W., Pierre

User avatar
Mike W.
Posts: 2889
Joined: Wed Aug 30, 2006 12:12 am
Location: Sonoma County

Post by Mike W. »

No, it should hold pressure overnight. I've cut into junkyard cars to find them fully pressurized months after they last ran. There is a check valve in the fuel pump that can go bad, but on a new pump I would expect it to be good. Injectors can leak down, but I'd expect you to be seeing smoking if they were leaking badly enough to bleed off all pressure. Start doing things like clamping off the supply, then return line with a vise grips overnight to pinpoint which side is bleeding off pressure.
Mike W.



02 525ita. Wife's, aka grocery getter
02 530i. New to the fleet, 3 pedals.
03 QX4, AKA the Datsun. Finally got the 4WD vacationmoble to stop smoking.
07 Xterra. Still on the DL, a purchase from hell.
CBradio
Posts: 283
Joined: Fri Apr 06, 2012 12:03 am
Location: Brooklyn

Post by CBradio »

OKAY!!

I did the clamp test on the delivery line since I also replaced my FPR it should be working. Fuel pressure still dropped slowly.

First, of course, I checked the cold start valve for the millionth time. Not a drop is coming out of it.

I pulled off the intake, and pulled out my "new" rebuilt injectors.
(Boy did I find a lot of gas in the intake and around the gaskets).

Sure enough, when I put the screwdriver in the AFM (why is it always a screwdriver anyways? Cant I use a wrench? :P) the injectors all starting weeping a little gas.

Two more than others, but they are all weeping.

Between my "new" remanned AFM which runs extremely rich, and my fuel injectors, I'm starting to think that the "remanufacturers" do just as good a job on their remans as the "mechanics" that worked on my car way back when. Or maybe it is just the closeout deals on rockauto (SMP) with their super limited warranty because they know the items are not working right. I mean, I'm doing my part!
:shock: :shock: :shock:

Maybe a little weepage is normal?? BUT, two are definitely weeping faster than the others. I expect, they should not weep even a drop. Am I wrong?

Looks like I'm in the market for injectors.....FROM WHERE?

Also, I suspect that I'm not getting smoke because my ignition wires definitely need changing and either way are not exactly compatible with the electronic points I put in. I also think if my ignition system was functioning correctly, I might not notice the weeping injectors, save for smelly oil and maybe hard starts.
1977 530ia
CBradio
Posts: 283
Joined: Fri Apr 06, 2012 12:03 am
Location: Brooklyn

Post by CBradio »

PS:

I have read that Peter wrote:

"....You could remove the 'C' runners and peek at the injectors to see if they 'drip'. Should be less than 2 drops per minute I think."

SO I guess a little weepage is normal?
1977 530ia
User avatar
Mike W.
Posts: 2889
Joined: Wed Aug 30, 2006 12:12 am
Location: Sonoma County

Post by Mike W. »

They should not leak a drop. If they're "rebuilt" and they are still under warantee return them. A hint of moisture is less than ideal but tolerable, but they should not drip.
Mike W.



02 525ita. Wife's, aka grocery getter
02 530i. New to the fleet, 3 pedals.
03 QX4, AKA the Datsun. Finally got the 4WD vacationmoble to stop smoking.
07 Xterra. Still on the DL, a purchase from hell.
CBradio
Posts: 283
Joined: Fri Apr 06, 2012 12:03 am
Location: Brooklyn

Post by CBradio »

Completely off topic but:

Actually I'm not sure they are even rebuilt, they may be New Standard Motor Product Injectors- but they were offered on closeout from Rockauto, as a "private label" item, with a 30-day warranty. Same with that weird AFM I got, for a really good price, on "closeout." Being that I bought the injectors in november, unless I file a suit, I don't think they will replace or refund them.

After doing some googling, it seems a number of people have had similar issues with these "closeout" "private label" products.... The problem I believe is that rockauto basically allows these third party wholesalers to drop ship and offer steep discounts on closeout, I suspect many of these wholesalers take advantage and just ship out garbage. I did email them about it, we'll see.

In the mean time, CAVEAT EMPTOR -
1977 530ia
User avatar
wkohler
Posts: 1063
Joined: Fri Jul 11, 2008 7:25 pm
Location: Phoenix, Arizona

Post by wkohler »

I bought a rebuilt set from Five-O Motorsports for the M535i and was quite happy with them. New hoses and everything.

Do you still have your old injectors? Send them to someone to have them serviced. Between that and replacing the hoses, that's all you need. None of the reman AFMs seem to be any good. Fuel Injection Corp, Python, etc. I don't know what they do to them. There's a good writeup on making adjustments to the AFM centered around the Porsche 944.

http://www.the944.com/afm.htm

Give that a shot with your old one.
Post Reply