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

[Jim Adney]

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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-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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