[urq] Continued Fuel System Woes

[Frank de Kat]

Hello Jon:

>> Any ideas/BTDT appreciated, thank you!

Well, here's my idea..
I'm wondering if you have done an actual 'flow test', up at the front  
of the car?
Not sure on the 3b, but in the red 4k manual they have you disconnect  
the fuel line up front, force the pump on,  and see if the pump  
delivers a set amount of fuel in a set time.

You may want to check that, before going to pull the tank?  If flow is  
good, may be that the pump is flowing well, but not putting out enough  
pressure under load, or supply voltage at the pump has gone bad?

If  you do decide to pull the tank, it's not *that* hard. You can  
again force the pump on to get most of the fuel out (with a line to a  
gas can, up front).  Probably the hardest part is dealing with the  
fuel line, right where it comes out the bottom of the tank, and the  
rubber 'gasket' that the line (and the rear diff lock lines?) goes  
through..

Other than that, it's pretty well straightforward unbolting the tank..

http://www.motorgeek.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=56887&g2_GALLERYSID=d03c7596a37d1a051932c05854f4831b

=Frank=



Message: 1
> Date: Wed, 7 Oct 2015 14:48:02 -0700
> From: Jon Archibald <archibald.jon at gmail.com>
> To: "urq at audifans.com" <urq at audifans.com>
> Subject: [urq] Continued Fuel System Woes - Thoughts Appreciated

>
> Hey all,
> Patient is '85 3B transplant.
> After installing my new fuel pump (Bosch 69430) the car seemed to run great
> for a day or two, then one morning after some spirited evening driving with
> my son I tried to accelerate onto the freeway and found power leveling off
> at just a touch of boost. The ECU seemed to be limiting boost and timing,
> and a glance at my Halmeter showed that things were leaning out under boost
> whereas the mix usually gets noticeably rich.
>
> I've disconnected various hoses to check if the pre-filter (sediment
> canister) was clogged or if any lines seemed clogged to no avail. Fuel
> poured out of the tank feed line smoothly and rapidly when disconnected,
> likewise through the pre-filter. I cross-checked the part number on the
> fuel pump and it appears correct for OE. I previously used a 944 pump the
> PO put on, but I had read that a stock urq fuel pump will do just fine with
> a tuned 3B. I also changed the fuel filter, no difference.
>
> So at this point it seems the issue is either with the tank screen
> (although again gas really came pouring out smoothly and quickly), or
> potentially the pump. I really doubt the pump is responsible since it seems
> correct for the car and I can barely get into boost as it sits.
>
> I'm really hoping if it is crap in the tank that I can somehow get it
> cleared out with the tank in the car, at least for the time being. I'll
> probably open the tank access port on top and see if I can see anything
> with a flashlight this weekend, possibly siphon some gas out and try to
> pick up some debris in the process like when I clean fish tanks. I am
> somewhat nervous about what can be accomplished with the tank in the car,
> both in terms of visibility through the small opening and what unclogging
> might be possible.
>
> Any ideas/BTDT appreciated, thank you!
> -Jon