UPDATE Re: re. is this bad gas?
porter_dog at hotmail.com
Fri Dec 13 08:01:41 EST 2002
Just a quick one on my maybe bad gas- I no longer think it's that. Using
the bently, I made it through several diagnostic sections last night before
it got too dark/cold to work (car is [naturally!] on the street and not in
1. Fuel pump delivery volume within spec (CSV line into graduated
cylinder, jumper fuel pump. 10sec of run time got 415ml of fuel, spec is
~1200ml/30 sec.) Also, I believe that this test would have shown water in
the gas if it were present, there was none.
2. System pressure good at 80 psi.
3. Both 'after start' and 'warmup' enrichment DPR current good.
4. The kicker so far: The second pressure (can't remember what Bently
calls it- differential pressure I think?) is supposed to be 3-7 psi LOWER
than the system pressure. It's exactly the same as the system pressure.
(This is measured with the pressure gauge valve closed and the thermo sensor
and differential pressure regulator unplugged).
I'll run through the rest of the checks tonight/tomorrow; leading
contender is a failed pressure regulator at this point, according to Bently.
Anyone have any thoughts on that?
>From: Ben Swann <bswann at worldnet.att.net>
>Reply-To: "bswann at worldnet.att.net" <bswann at worldnet.att.net>
>To: "'porter_dog at hotmail.com'" <porter_dog at hotmail.com>
>CC: "'quattro at audifans.com'" <quattro at audifans.com>
>Subject: re. is this bad gas?
>Date: Thu, 12 Dec 2002 23:28:43 -0500
>It could be bad gas. If the gas has water, and it is/has been freezing,
>you could be getting ice, possibly even jamming the pump. So I guess don't
>rule out bad gas.
>Now, on the several of these cars I've messed with lately, almost all of
>them had to have the FI thermo sender replaced. The symptoms you describe
>are right in line with what happens when they go bad. This seems to be the
>common fault I've dealt with lately, but certainly not the only possible
>culprit you can nail down.
>IMO, replace it - thepartsconection has them so cheap, I just check them
>for the fun of it, and even if they seem close, put the new one on anyway -
>problem usually got fixed with the new one. These things are amazing for
>the trouble they can cause when not working right. Also, the problems
>reared up with the colder weather, as the cars were running great up until
>So, have you replaced your sensor lately?
>[My 86 4kq, while ugly and rattly and noisy, runs PERFECT. Or it did until
>I tried to leave for work this morning.
> Yesterday I got gas at the usual place (less than 1 mile from my house),
>checked the oil and found I needed a top up. Got home and parked. Popped
>the hood and added about 1/3qt oil. Put the filler cap back on (checked ;)
>). Decided to top off the battery as well, as cold morning starts were a
>little slower than normal. Nothing major there- cells were down a bit but
>plates weren't visible. Sealed everything back up.
> Go to leave this morning, and as usual it started right up but then
>stalled. WTF? It did that about 10 times, starting fine then stalling
>immediately. If I crack the throttle while starting, it revved up then
>stalled. A couple times it would 'idle' for 10-15 seconds, but it might
>have been firing on 1 cyl every 4th rotation...
> To me bad gas is the obvious answer, but if that's the case why did it
>start well? Still good gas in the CSV line? 10 starts worth?
> Could I have gotten Something Important below the battery wet when
>water? (it was done rather sloppily, but there was no electrolyte spilled,
> Suggestions for diagnosis/remediation gladly accepted.
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