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gdea73 Samba Member
Joined: January 31, 2013 Posts: 39
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Posted: Thu May 12, 2016 6:30 pm Post subject: Stalling during sustained (warm) idle |
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I recently bought a 1971 Ghia with a 1641 and dual Weber IDFs. I have driven it a fair amount and had no issues until recently—the other day, it stalled while I was sitting at a red light for a while. It was over 90 degrees that day. Started back up without much difficulty, but then it became increasingly prone to stalling when idling on my way home.
The idle RPM would suddenly lower, and the generator light would flicker, until either I gave it some throttle or let it stall.
I've read many threads about this type of issue, but I was hoping to get some help troubleshooting as I investigate. There could be many causes to this problem.
Since it began suddenly, my first guess was that the fuel filter was clogged. The PO had installed it in the engine compartment, between the fan shroud and the T junction of the fuel hoses. Not the worst location, but I wanted to move it out of the engine compartment. I've yet to complete this job (which has included installing new fuel lines), because I realized that it was to be extremely difficult with the car on the ground. Hopefully, when I get my jack, I can pull apart the rubber line just front of the firewall and get a new filter in there.
However, I may be looking in the wrong place. Once I rule out that filter, I'll see if setting the points may have helped, and adjust the valves and change the oil.
Is it likely that one or both idle jets are clogged, and if so, how much of the carb linkage must I disassemble, if any?
Thanks in advance! |
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Danwvw Samba Member
Joined: July 31, 2012 Posts: 8892 Location: Oregon Coast
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gdea73 Samba Member
Joined: January 31, 2013 Posts: 39
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Posted: Thu May 12, 2016 7:11 pm Post subject: Re: Stalling during sustained (warm) idle |
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I believe so. It appears to be mechanical. I'll have to check to see if there's a VW emblem on it. |
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Danwvw Samba Member
Joined: July 31, 2012 Posts: 8892 Location: Oregon Coast
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Posted: Thu May 12, 2016 7:21 pm Post subject: Re: Stalling during sustained (warm) idle |
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Probably what is going on is now that the weather is warm the fuel is boiling and the pump is vapor locking. The ethanol fuel we get these days is not too good in these engines so see if you can get non ethanol fuel for it until you can get an electric fuel pump installed perhaps up front under the fuel tank where it's nice and cool. You may want to run the electric fuel pump off of a relay so it shuts down if the alt/gen light comes on. They make some pretty nice electric fuel pumps that will work with your carbs. CB Performance Electric Fuel Pump and Electric Fuel Pump Relay Circuit. It should be a pretty easy installation as all the wires you need are already up front. Key on power and gen/alt light wire perhaps add an override switch. _________________ 1960 Beetle And 1679cc DP W-100 & Dual Zeniths! |
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Mellow Yellow 74 Samba Member
Joined: October 14, 2014 Posts: 1615 Location: Sydney, Australia
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Posted: Thu May 12, 2016 11:12 pm Post subject: Re: Stalling during sustained (warm) idle |
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gdea73 wrote: |
Once I rule out that filter, I'll see if setting the points may have helped, and adjust the valves and change the oil. |
Also check the timing - if it is too retarded it will stall at idle but go ok (but will run hot) at higher revs. _________________ 1962 Karmann Ghia
1974 Deluxe Microbus
1985 Caravelle (Vanagon) |
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gdea73 Samba Member
Joined: January 31, 2013 Posts: 39
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Posted: Fri May 13, 2016 7:34 am Post subject: Re: Stalling during sustained (warm) idle |
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Thanks for the suggestions! I will check timing after I adjust the valves and see if that may be the cause. I'll also consider getting an electric fuel pump (and pressure regulator), while in the meantime seeing if Shell 91 makes a difference (supposedly has no ethanol). |
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thruhiker74 Samba Member
Joined: June 09, 2014 Posts: 118 Location: Tucson
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Posted: Fri May 13, 2016 8:33 am Post subject: Re: Stalling during sustained (warm) idle |
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Danwvw wrote: |
Probably what is going on is now that the weather is warm the fuel is boiling and the pump is vapor locking. The ethanol fuel we get these days is not too good in these engines so see if you can get non ethanol fuel for it until you can get an electric fuel pump installed perhaps up front under the fuel tank where it's nice and cool. You may want to run the electric fuel pump off of a relay so it shuts down if the alt/gen light comes on. They make some pretty nice electric fuel pumps that will work with your carbs. CB Performance Electric Fuel Pump and Electric Fuel Pump Relay Circuit. It should be a pretty easy installation as all the wires you need are already up front. Key on power and gen/alt light wire perhaps add an override switch. |
Does ethanol affect the boiling point? My '61 does this as well, out here where temps can easily climb over 100. Most of the time it's fine, but when it gets hot, I get unreliable idle. If it is somehow related to the ethanol in the fuels (can't get straight gas in Tucson), do you know if the additives for dealing with ethanol might have a positive affect on this? |
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Danwvw Samba Member
Joined: July 31, 2012 Posts: 8892 Location: Oregon Coast
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Posted: Fri May 13, 2016 10:25 am Post subject: Re: Stalling during sustained (warm) idle |
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Well it used to be that regulations only allowed Ethyl Alcohol to be added to gasoline in the winter and at only levels 10% or less and gas sold at higher elevations did not have it because it vaporizes easer at high altitudes.
Back In 2005 I took my 67 beetle out to Colorado, it had a hot running 1641cc single port with the non-dog dog house fan system with the stock steel oil cooler, W-100 cam etc, Pict-28 and stock fuel pump mounted to the block. It would start stalling on me anytime I got ahold of ethanol gas. I could get gas in the mountains and it was ok but get gas in town at stations that sold low elevation gasohol gasoline and it would begin it's stalling behaviour. But I installed an electric fuel pump. Just one of those Facet 2.5-4 psi ones up front under the tank away from the engine heat and that solved the problem.
By the way, quick fix for a vapor lock is to dump a cup of Ice Water on your stock Fuel Pump!
Found this, it looks like gasoline could have various boil points depending on the mix.
_________________ 1960 Beetle And 1679cc DP W-100 & Dual Zeniths! |
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bhartwell59 Samba Member
Joined: December 28, 2014 Posts: 788 Location: dallas, tx
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Posted: Fri May 13, 2016 10:52 am Post subject: Re: Stalling during sustained (warm) idle |
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curious, if it is indeed vapor lock, isn't there a simple way to reroute the fuel line/s?
Or would vapor lock happen no matter where in the engine bay? _________________ '74 Zambezi green Ghia vert, autostick, 101k
'87 Jeep Wrangler, 4.2, 330k |
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Danwvw Samba Member
Joined: July 31, 2012 Posts: 8892 Location: Oregon Coast
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Posted: Fri May 13, 2016 11:14 am Post subject: Re: Stalling during sustained (warm) idle |
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You could probably run some of the fuel back to the fuel tank and solve the problem. _________________ 1960 Beetle And 1679cc DP W-100 & Dual Zeniths! |
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gdea73 Samba Member
Joined: January 31, 2013 Posts: 39
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Posted: Tue May 17, 2016 4:56 pm Post subject: Re: Stalling during sustained (warm) idle |
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Danwvw wrote: |
You could probably run some of the fuel back to the fuel tank and solve the problem. |
If you could elaborate on how that might be done, I'd really appreciate it.
I also do not have a fuel pressure regulator right now, though it had been running fine with the stock fuel pump directly attached to both carbs.
I guess the question is how I would route only excess fuel back to the tank. |
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gdea73 Samba Member
Joined: January 31, 2013 Posts: 39
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Posted: Sat Jun 18, 2016 3:02 pm Post subject: Re: Stalling during sustained (warm) idle |
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Since last time, I changed the oil and removed the post-pump fuel filter. I installed a new one between the hard line from the tank and the hard line to the engine. I got some 92 octane gas, which (I think) couldn't contain ethanol, or at least not E10 like 87 octane. It had been running well in moderately warm weather 70-80°F, but today after driving around the city in 90 degree heat again, the idle would drop too low to sustain without prodding the gas.
Perhaps this is still vapor lock, but I still need to adjust the valves and check the timing. Before the stalling began, it did feel like it hit redline faster in a given gear (and thus was slower). |
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