paragon
Member
Posts: 118
Loc: Sonora, California
Reg: 12-11-05
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07-09-12 03:11 PM - Post#2246248
ZZ4 engine - 4 barrel, electric fuel pump - appears to have vapor locked, re-started fine after waiting 1 1/2 hours. It was hot outside and I was running the air.
Is there a sure way to fix this problem?
I've heard that ELECTRONIC FUEL INJECTION eliminates vapor lock issues, is that correct? Of course, that route is expensive with the Edelbrock kit over $3K!
I'm not a mechanic, just looking for some input.
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retiredrich
Contributor
Posts: 792
Loc: NE
Reg: 10-05-07
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07-09-12 04:03 PM - Post#2246276
In response to paragon
Does the fuel line run near a header, muffler or touch the radiator hose? Just a thought. Along with the heat under the hood from the hot day could possibly cause a problem.
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 Rick_L
Honored Member
Posts: 24738
Loc: Katy, Tx, USA
Reg: 07-06-00
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07-09-12 04:11 PM - Post#2246278
In response to paragon
Electric pumps don't make much suction pressure, some not any.
Gravity feed between the tank and the pump is the best way to overcome this. This means two things - your pump inlet must be below the tank, and the line must run downhill to the pump.
Unfortunately this is a bit of work, you really need a sump in the tank and a pickup at the bottom of the sump. Then the pump must be mounted low and that may make it vulnerable to road debris or even scraping the pavement.
EFI systems in OEM installation get around all this by putting the pump in the tank - and that's also a lot of trouble.
You may be best off to go back to a mechanical pump unless you have a clearance issue mounting one.
I know that a lot of guys get away with an electric pump without doing the sump/gravity feed deal. If you want to try to stick with that, make absolutely sure your tank is clean, that the sock on the pickup is not obstructed with rust debris, and that you don't have any kinks in fuel line between the tank and pump. Also you absolutely don't want a filter between tank and pump, only the sock on the pickup. If you have a filter it must be 100 micron or larger and you need to be sure it's never loaded up with junk.
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 62chevy427
"7th Year" Silver Supporting Member
Posts: 1499
Loc: laurens sc
Reg: 04-13-06
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07-09-12 04:17 PM - Post#2246281
In response to paragon
my truck does this and i installed a electric pump near the tank. the pump should be below the tank,but i have found that by running something like a p trap on a sink enough fuel stays in the pump so that there is no problem. i only use the pump when the truck sits a while or when it vapor locks. been on there for several years without a problem.
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Bruces 57
Frequent Contributor
Posts: 1663
Reg: 01-03-07
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07-09-12 06:10 PM - Post#2246339
In response to 62chevy427
Hello;
It all boils down to boiling! Gas now a days is way more volatile and because of the ethanol boils at a much lower temp.
Fix: Install a pressure regulator with a return line (FI uses return lines) plumbed back to the tank, this way the overheated gas can be deposited back in the gas tank and re fed to the engine at a cooler temp.
Bruce
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62chevy427
"7th Year" Silver Supporting Member
Posts: 1499
Loc: laurens sc
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07-09-12 08:40 PM - Post#2246395
In response to Bruces 57
that works most of the time. one of our church vans-85 dodge with a 360- will boil the gas out after being driven and then sitting for a couple of hours. i can crank it most of the time,but others cannot.it has the filter with the built in bypass.
we have 2 more with the same set up that do not do it.
56 bel air ((since 2002)
62 impala ss (since 1965)
65 el camino (since 1969)
66 nova (since 1987)
67 malibu convertible (since 1981)
72 el camino ss454 (since 1985)
83 gmc 4wd (since 1991)
95 impala (new)
11 malibu (new) |
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retiredrich
Contributor
Posts: 792
Loc: NE
Reg: 10-05-07
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07-10-12 03:45 AM - Post#2246453
In response to Bruces 57
I don't use ethanol in mine, but todays gas could certainly be a contributor to the problem. Living in Nebraska, it get's very warm here like CA. I use a metal line from the tank for a short distance and then a rubber type pressure fuel line from there on to the fuel pump and up to the carb keeping it away from the mufflers, headers etc. along the way. I've always done it this way on any of my cars. I drive 7,000 plus miles each Summer and have never had a problem. I think a metal line allows heat to get to the fuel easier.
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5Larry7
"11th Year" Silver Supporting Member
Posts: 1673
Loc: Dallas, TX
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07-11-12 04:22 PM - Post#2247139
In response to Bruces 57
I had a vapor lock problem, so I installed a return line as described above, end of problem.
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