Discussion:
low fuel pressure

Hi, Everyone.

Serial # A809N05165U

I have a possible fuel issue that only occurs first thing in the morning. Symptoms are either very long crank time, or crank, no start. After I get it running with a shot of propane in the intake, it starts fine for the rest of the day. Fuel pressure is 1 psi at the vaporizer. I think the spec is 1.5 psi. I don't have much experience with LP systems, so any direction you all can give me would be great. Maybe tar in the vaporizer? If so, can I drain it from somewhere, or do I have to take it apart?

Thanks, guys.
  • Posted 22 Jan 2015 08:27
  • By autotech500
  • joined 26 Jun'14 - 6 messages
  • Ohio, United States
Showing items 1 - 4 of 4 results.
No vacuum leaks as far as I can tell. Although the gauge reading was fluttering quickly between about 19 and 20 in.Hg which I don't like. It did smooth out some at higher RPM. Hopefully, not a valve problem. Replaced carburetor diaphragm, and no change. I'm going to check the ignition system tomorrow. Still need to check regulator too. I might have multiple problems here.
  • Posted 23 Jan 2015 09:30
  • By autotech500
  • joined 26 Jun'14 - 6 messages
  • Ohio, United States
Yep, Impco system. It doesn't have that button on the vaporizer, though. Maybe it's aftermarket.

Choking it did work, so I guess I'll be looking for a vacuum leak next. Haven't had a chance to do that yet because it's been in use.

Thanks!
  • Posted 23 Jan 2015 08:12
  • By autotech500
  • joined 26 Jun'14 - 6 messages
  • Ohio, United States
1.5 w.c. output pressure is correct, even at 1 w.c. it should run

First check inside the vaporizer and make sure it is not gummed up, clean it out of necessary.
then...
i would go to the mixer/carb and check the diaphragm and make sure it is not torn or leaking by the bullet button seat.
And of course check for any vacuum leaks too.
  • Posted 22 Jan 2015 23:00
  • By swoop223
  • joined 23 Mar'12 - 3,691 messages
  • North Carolina, United States
You've been swooped!
swoop223@gmail.com
That has an Impco regulator, right? Sounds like there may be low vaccum. Maybe check for a vacuum leak. The regulator and the lock valve need good vacuum to operate properly or it could be any of the fuel system items being dirty or needing replacement because they are not allowing the fuel to turn on or flow when cold starting. Try "choking" the carb with your hand instead of shooting propane in there, when cold, and see if that makes it start.
  • Posted 22 Jan 2015 11:37
  • By mrfixit
  • joined 11 Dec'08 - 1,434 messages
  • New York, United States

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