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Subeast-EA81

Vapor Lock after fill up? had to call for a tow

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Did a search, didn’t find much info on this issue, so here goes. That past two times I have filled up, the car seems to get some sort of vapor lock, bear in kind this is only when I fill it up, I use only non-ethanol premium due to the advanced timing. The first time it did it I was able to nurse it along until it cleared up, however yesterday I had to get towed home from the gas station. My assumption is that it is vapor lock, but I may be wrong. I know I will need to check fuel pressure tonight when I get home. Anything else I should be looking for? The car will idle around 2000rpms (lean?) but lack all power.

Edited by Subeast-EA81
grammer

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Sound like a problem with your charcoal canister. Try disconnecting it from your intake (and capping the intake side only) to see if that fixes it.

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What car with which engine and fueling setup?

 

I've seen this issue in Carbed cars swapped to EJ FI. The return line is very small, and comes into the bottom of the tank. Full tank(above the vent in fillneck), plus pressure from evaporating fuel= no where for the fuel to return to.

 

Ussually simply popping hte gas cap off, and waiting 5 mins gets it working right again.

 

If this sounds like your issue.... and you've got an EA82 body car,......I recommend installing an FI gas tank. Solved the problem in my 86.

Edited by Gloyale

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So here is the latest, I got home, and had left the gas cap off all night hoping it would vent out, anyways tested the fuel pressure both prime and standing, hooked the vacuum gauge up, retarded the timing to factory (had a mark on the disty) bypassed the vac line from the charcoal canister,… and,… Nothing. Cranks normaly until it pops out the intake then all vacuum disappears (what little you get when cranking) and the engine takes on a lack of compression or unbalanced cylinder sound. Turn the Key off, wait a minute and try again, the starting sounds we are all used to return until the next pop (backfire thought the intake). Work Done – Checked cleaned and re-gapped plugs, removed the injector and cleaned it, resealed the t-body, reset the timing, cycled power to the ecm. Initial prime fuel PSI=20~ Standing=12-15 Cranking=10-12. I don’t think I slipped a T-belt as they are both new, and the fact the after setting the natural sounds of the engine return. Any thoughts? Stuck EGR? I know its getting fuel as the throttle plate is damp with fuel after fiddling with it. I’ll review the FSM prior to be and see if anything jumps out at me.

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So i may be dealing with low fuel pressure? that would explain the backfiring through the intake due to a lean condition would it not? Aside from the obvious fuel filter change, what other components might i question? furthermore what should the cranking pressure be? Thanks again all for the input.

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Every time Ive had backfire thru the intake its been timing related. I would make certain the timing, both valve and ignition are Ok. That really doesn't follow with 'no starts' after filling up the gas tank, but maybe worth a look anyway.

 

Maybe the rotor under the distibutor cap lost its screw and is flopping around trying to fall off.

Edited by markjw

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So i may be dealing with low fuel pressure? that would explain the backfiring through the intake due to a lean condition would it not? Aside from the obvious fuel filter change, what other components might i question? furthermore what should the cranking pressure be? Thanks again all for the input.

 

Looks that way.

Slow burning end gases from a very lean mixture can indeed give intake backfires.

Fuel pump and voltage supply to and grounding of same.

Pressure reg. too.

20-24psi

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good luck... agree... that is an odd issue after a fill up or just coincidence, very odd as why would filling a gas tank effect operation?? hmmmm....

Read the final cause... that is like crazy... interesting event...

 

For my own personal opportunity to learn I took this Post and final cause/effect and talked to a family relation who is a VW mechanic (years of other vehicles) and he went into great detail regarding the flooding of the charcoal housing in the older and newer cars, what can happen, what he has seen etc... .

 

After rattling on he talked of the N-80 valve on the newer auto's that can fail/foul and cause thousand of dollars of damage on the higher end cars. He said one of the worst things a driver can do is over fill the gas tank... when the gas pump goes "clunk" and shuts off, don't continue filling.. etc.. He even went into detail how he just finished working on a newer car with the exact same issue, had to change various parts, vent line as they are damaged by raw fuel and traced back to the owner always filled her tank to the tip-top every time.

Edited by Indrid cold

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Thanks to all who helped with info, I checked everything just to find the evap line from the fuel tank was full of gas (confirmed by lightly blowing compressed air into it with the gas cap off) Charcoal can was full too (thanks @presslab) so I drained the gas tank down below whatever level the evap line enters the tank and capped it off, as-well as the charcoal can after getting the gas out of it. Now the car runs like a dream. My only question is what is the down fall of not having a functional evap system other than emisions?

Edited by Subeast-EA81
I cant read

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Charcoal can was full too (tthanks @Gloyale)

 

Ahem...And to thank someone on my $hit list... :dead:

 

My only question is what is the down fall of not having a functional evap system other than emisions?

 

It only affects emissions. Keep in mind however that the charcoal canister reduces emissions as much as a catalytic converter does.

 

evap soilniod stuck open ?

 

A stuck closed solenoid could cause this problem, stuck open would probably just make it idle weird.

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Sorry about that Presslab, i guess more coffee is in order when writing replys first thing in the morning. I gracefull reasign my thanks accordingly :drunk: no hard fealings i hope.

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