Vapor lock solution for carb cars

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330GT
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Vapor lock solution for carb cars

Post by 330GT » Wed Nov 28, 2018 8:39 pm

I've had lots of issues with vapor lock in my 330 GT. The general consensus is that the vapor lock occurs in the un-pressurized line between the tank and filter/auxiliary electric fuel pump. So adding a second electric pump or higher capacity doesn't really address the issue as the fuel is already a vapor by the time it reaches the pump. This causes my original FISPA auxiliary pump to loudly click and bang as it tries to pump the vapor. Of course, E85 fuel with its lower boiling point doesn't help at all.

One thought that just came to mind would be to add a modern in-tank electric pump. That way, the fuel from the tank would already be pressurized and less likely to vapor lock. In a quick online search, I found several universal fit pumps, designed for use by hot-rodders who drop a modern EFI engine into a vintage car. These put out too high of pressure (~60+ PSI), so would need an adjustable pressure regulator for our cars.

Has anybody tried this?
Regards, Kerry
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tim
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Re: Vapor lock solution for carb cars

Post by tim » Thu Nov 29, 2018 3:59 am

Greetings... You are using E85? That's 85% ethanol. Unless you've done some real serious re-working of your carbs, your car will run poorly or not at all. If you are using E10, the stuff at the vast majority of stations it like running your car 5% lean but it will work. If you are using your auxiliary pump in the rear, I don't think you can get vapor lock. The length of the fuel line between tank and the auxiliary pump is short and not exposed to enough heat to cause a lock. A further list of symptoms would help.

Tim
1964 330GT 5769 -the big yellow taxi 61&66 Morgan +4's Daimler SP250 and some other dull stuff plus a brand new Mini Cooper S Clubman JCWS

afwrench
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Re: Vapor lock solution for carb cars

Post by afwrench » Thu Nov 29, 2018 8:48 am

H I Kerry, two questions come to mind.Are you unable to source non ethanol fuel and have you tried and failed to address the cause of the vapor lock itself? Best,Mike
72,365gtc4,14681,2007 599 GTB

DWR46
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Re: Vapor lock solution for carb cars

Post by DWR46 » Thu Nov 29, 2018 11:51 am

All of today's fuels will more easily boil than those of 50 years ago. I don't think the line from the tank to the filter is the main culprit in this problem. It remains cool all the time. It is most likely the lines that run along the chassis near the exhaust are the cause as well as the lines within the engine compartment. That is why, if you get the electric pump running early before the chassis lines get hot, it will continue to provide fuel, as it has then pressurized the line and raised the boiling point of the fuel within that line.

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330GT
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Re: Vapor lock solution for carb cars

Post by 330GT » Thu Nov 29, 2018 12:30 pm

Sorry, I didn't mean E85. Instead, I mean the standard gas that has ethanol added.

As far as measures I've already taken:
1. Second electric fuel pump in parallel w/original FISPA pump.
2. Heat shield between exhaust and filter/pumps in the rear.

I have found that keeping the tank full (more head pressure) seems to help. This usually occurs on hot (80+) days during a long drive.

Note, my 330 GT is a late model with the return line from the rear of the fuel log to the tank. This is supposed to keep fuel flowing even when the carb float bowls are full, i.e. when stopped in traffic at an idle.
Regards, Kerry
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Lowell
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Re: Vapor lock solution for carb cars

Post by Lowell » Fri Nov 30, 2018 2:42 am

All you have to do is to live in Santa Fe, New Mexico. Some years ago, a large, four lane road was constructed: The Santa Fe bypass. That way trucks carrying all sorts of dangerous or radioactive or whatever material could be shipped south from Los Alamos with out going through downtown Santa Fe. I have no idea if this road is still used for such trucks --- maybe, but not very often. What has happened is that many housing developments have blossomed near the bypass. AND, if you get on the bypass and turn right about a mile before it ends, go a couple of hundred yards, and stop at a completely unattended gas pumps, you may fill whatever you have to your hearts content with regular high octane gasoline that has, however, not a trace of alcohol. This is the reason one lives in Santa Fe.
Lowell Brown
1966 Gold 330 2+2 Series II

mark
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Re: Vapor lock solution for carb cars

Post by mark » Tue Dec 18, 2018 9:22 pm

If Memory serves: Kerry lives near Issaquah; if so then simply fill up at the grange: Non-ethanol fuel every day all day.
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330Jim
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Re: Vapor lock solution for carb cars

Post by 330Jim » Fri Feb 15, 2019 11:06 am

Some things I would try.

1 Make sure the ignition timing is correct and the points are phased correctly. Retarded timing will put more heat into the exhaust.
2 Make sure the mixture is correct especially the idle mixture jet. Most of your driving is on this jet. A lean mixture will put more heat into the exhaust and ethanol enriched fuels lean out the mixture.
3 Make sure the heat sheild is in place on the muffler. I know GTCs have a heat sheild. I do not remember if GTs do to, but I would expect them to.
4 Check the mufflers to see if there is any sound deading in them. If all the fiberglass is blown out, more hot gasses inside the muffler will come in contact with the outer casing causing it to run hotter therefore heating up the fuel lines.

The goal is to keep the fuel lines cool as possible. If all the above fails I have seen where wrapping the mufflers in heat sheilding has worked. In that case both sides had to be wrapped because it changed the exhaust sound. I have also seen a GTC that had the fuel lines inside the frame instead of outside.

Cheers Jim

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michaelbalk330
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Re: Vapor lock solution for carb cars

Post by michaelbalk330 » Sun Mar 10, 2019 9:56 pm

kerry
I run an electric pump all the time, and have insulated my pump with some good stuff to keep heat from the fuel lines and pump,
even in atlanta I don't have any vapor lock issues, my mechanical pump is there but doesn't supply enough flow so I just use bendix style for continuous flow..
Michael
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peterp
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Re: Vapor lock solution for carb cars

Post by peterp » Sun Mar 10, 2019 11:17 pm

I've tried wrapping the fuel rail feeding the 3 carbs with insulation and it seemed to help a lot. I just did it as a not very clean temporary test, haven't had time or decided whether I will put something in more permanent, but it did seem to help a lot. I'm surprised nobody has mentioned wrapping that rail.
Peter P
1966 330 2+2 series 2 #8169

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