[T3] On and off hard start FI 73 type 3 ?

[Keith Park]

Ya know, and this has been dinner discussions at the invasions, but I never
have ANY problems starting on the first stroke or 2 cold or hot, EXCEPT when
2 things happen,
When the regulator lets the pressure go too high then it floods, and this
was a discussion a month or so ago when Jim figured it out to be the threads
getting corroded and not letting air in the regulator, and the second being
when the backflow valve on the pump leaks down.  When Jim rebuilt my pump
the new bulletproof nylon valve did leak down, at least initially and I
solved the problem with a separate back flow valve, inline with the hose,
that he gave me.  Now, pressure remains up for quite a while and comes up
instantly when  I turn the key on... no problems starting.

Keith


Topnotch Restorations
topnotch at nycap.rr.com
http://www.topnotchresto.com
71 Squareback  “Hothe”
65 Notchback  “El Baja Rojo”
93 RX7  “Redstur”
13 Subaru Outback "Blendin"

-----Original Message-----
From: type3-vwtype3.org <type3-vwtype3.org-bounces at lists.vwtype3.org> On
Behalf Of Jim Adney
Sent: Friday, June 24, 2022 10:25 AM
To: type3 at vwtype3.org
Subject: Re: [T3] On and off hard start FI 73 type 3 ?

The question you never asked was, "Why does this happen now when it never
happened when our cars were new." The short answer is, "I don't know, but I
can guess."

For what it's worth, my startup experience is EXACTLY the same as yours.

When our cars were new, there was grey vinyl sleeving over all the FI hoses
in the engine compartment. My GUESS is that this sleeving served as a bit of
a heat shield, keeping those lines just a bit cooler in the heat soak after
shutdown. When those hoses were replaced over time, the vinyl sleeves were
thrown away, because the new hose was a bit too big to fit inside the
sleeves and the vinyl may have shrunk a bit, too. It's also worth
remembering that even when my '68 was new, I'd sometimes turn the key ON and
OFF a few times to make starting easier. Later FI engines tended to run
richer and cooler, but they had the same thermostat, so I'd expect the heat
soak to be the same.

Back in the day, I bought a roll of the sleeving from VW, but it came in
black rather than grey. I figured that black would not be as good a heat
shield as grey, and the hose I had at the time was still too large to fit
inside it, so I never tried it. I have smaller hose now, so I might try it
next time I replumb an engine, but the primer switches work great, so
there's little incentive to look for a solution that still needs some use of
the primer switch.

Jim

On 23 Jun 2022 at 15:31, William Jahn wrote:

>  I have a prime switch and use it until I hear no more air then cycle 
> the key once pump the pedal once and most of the time it starts fine. 
> Sometimes it will start then quit yet I try the key again and it starts
right up.
> Once it starts I can drive it and shut down and it always starts right up.
> 
>  I drove it yesterday and it started fine , today it quit once then 
> started.
> 
>  I  replaced the fuel pressure regulator back in the mid 90's yet even 
> the original worked fine , never had any issues starting or air in the 
> fuel lines where I needed a primer switch  I just turned the key and 
> it fired right up.
> 
>  I have checked everything and have power to the ECU from the power 
> relay and the pump relay always times out every time. The connector 
> that feeds the ECU from the power relay is clean and tight.  I 
> replaced the fuel pump with a 2 port type and it's been fine. I also 
> replaced the fuel filter and don't have many miles since both were 
> done. Not long ago I took apart the power relay and cleaned the 
> contacts and replaced the ground wire since half of the  1/4 " female
crimp was missing.
> 
>  All I can think of is that the fuel pressure regulator is bleeding 
> down overnight. The fact that once it's started then runs and starts 
> right up every time after tells me it's not a wiring issue.
> 
>  The odd part is usually if it starts and tries to die if I feather 
> the throttle it will keep running. It's when it starts and runs for a 
> minute or so then just quits that has me baffled. This has only happened a
few times.
> 
> William
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--
*******************************
Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
*******************************

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