Fuel getting hot
Thread Starter
Heel & Toe
Joined: Jul 2008
Posts: 20
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Fuel getting hot
Ive got a 98 coupe, with the very early vortech setup (which mounts the SC on drivers side). My fuel system consists of FAST 60 lb injectors and a lingenfelter (i believe 225 lph) fuel setup. This was professionally tuned. I am running about 4-5 psi of boost, car runs great. I have open tracked and auto crossed the car several times this year, sometimes with back to back heats because my wife and i run the car in seperate classes. I have been having problems with the car "overheating" the gas in the tank. Case in point, we were at Putnam park in indiana a few weeks ago, and she ran right after i did. We noticed a "foghorn" sound coming from the car as it ran. upon further investigation, it was the fuel tanks, i slowly removed the gas cap, and ALOT of pressure was released. Also, one could feel that the fumes coming out of the tank were very hot. This has happened again last weekend after a single day auto x event. Does anyone have any idea what is causing this?
Melting Slicks
Joined: Jul 2004
Posts: 2,844
Likes: 144
From: Northern Ireland
Fuel gets hot from two things ( ignoring ambient heat )
The pump itself, and getting fed to a hot engine bay/rails and then back to the tank ( if it's a return system plumbed that way )
As to what temperature it needs to be before there is a problem, that's still open to debate. But pressure in the tank is quite normal on a modern car.
You would need to establish what temperature the fuel is, before you can actually say it is a problem.
Ive tested on my own car, although generally weather here is pretty cool. Ive never seen any temperatures that have caused me concern when the engine and pumps are running.
Although I do run a cooler on the return line, the cooler is very badly located and wouldnt have great airflow.
The pump itself, and getting fed to a hot engine bay/rails and then back to the tank ( if it's a return system plumbed that way )
As to what temperature it needs to be before there is a problem, that's still open to debate. But pressure in the tank is quite normal on a modern car.
You would need to establish what temperature the fuel is, before you can actually say it is a problem.
Ive tested on my own car, although generally weather here is pretty cool. Ive never seen any temperatures that have caused me concern when the engine and pumps are running.
Although I do run a cooler on the return line, the cooler is very badly located and wouldnt have great airflow.
Melting Slicks
Joined: Jul 2004
Posts: 2,844
Likes: 144
From: Northern Ireland
Thread Starter
Heel & Toe
Joined: Jul 2008
Posts: 20
Likes: 0
stevieturbo
yea its a return style system, 97-98 cars were that way. And no, im not getting any check engine light at all, but it seems like its building an awful lot of pressure in the tank. also the vapors are literally hot, you can hold your hand in front of the filler neck and its hot enough you dont want your hand there long!
yea its a return style system, 97-98 cars were that way. And no, im not getting any check engine light at all, but it seems like its building an awful lot of pressure in the tank. also the vapors are literally hot, you can hold your hand in front of the filler neck and its hot enough you dont want your hand there long!
Supporting Vendor
Joined: Apr 2012
Posts: 2,671
Likes: 369
From: Forney TX
You need to put a gauge on the evap line or something to gather accurate data. So far, you're assuming that you have pressure, when in fact you could have vacuum in the tank. I understand the hot vapors and the expansion from that, but it could still be vacuum from evacuating the fuel from the tank so quickly during your races.
Melting Slicks
Joined: Dec 2003
Posts: 3,315
Likes: 17
From: Near Jacksonville Fl.
Hot fuel has been a known problem for a long time even back in the C4 days.
Why do you think they put a warning on the cap to remove it slowly?
I would bet the foghorn sound you heard was the tank venting itself through the evap solonid.
97&98 were unique in the fact the PCM controls the vent.
Why do you think they put a warning on the cap to remove it slowly?
I would bet the foghorn sound you heard was the tank venting itself through the evap solonid.
97&98 were unique in the fact the PCM controls the vent.
Last edited by corvettebob1; Jun 22, 2012 at 03:13 PM. Reason: spelling
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Le Mans Master
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From: Vacaville Ca
St. Jude Donor '13
I experienced this EXACT thing last year on a road trip.My Coupe is a 98. The pressure was SCARY!!! not just a whisp but mine shot hot fuel out at me. The fuel pump was screaming because the fuel was just vapor.
It did it all day one day and I just kept stopping and topping off the fuel trying to keep it cool.
It has not done it since and I think the return system was to blame and was constantly circulating fuel and heating it up. Perhaps a stuck return regulator valve at the fuel rail, I don't know.
I bet you could change that return regulator valve on your fuel rail and fix it, I have gone to a complete RSI Dual pump setup so I never figured mine out, but it was BIG pressure, I was afraid for the plastic tanks and my own life.
Good luck fixing it.
Steve
It did it all day one day and I just kept stopping and topping off the fuel trying to keep it cool.
It has not done it since and I think the return system was to blame and was constantly circulating fuel and heating it up. Perhaps a stuck return regulator valve at the fuel rail, I don't know.
I bet you could change that return regulator valve on your fuel rail and fix it, I have gone to a complete RSI Dual pump setup so I never figured mine out, but it was BIG pressure, I was afraid for the plastic tanks and my own life.
Good luck fixing it.
Steve
Melting Slicks
Joined: Jul 2004
Posts: 2,844
Likes: 144
From: Northern Ireland
Hot fuel has been a known problem for a long time even back in the C4 days.
Why do you think they put a warning on the cap to remove it slowly?
I would bet the foghorn sound you heard was the tank venting itself through the evap solonid.
97&98 were unique in the fact the PCM controls the vent.
Why do you think they put a warning on the cap to remove it slowly?
I would bet the foghorn sound you heard was the tank venting itself through the evap solonid.
97&98 were unique in the fact the PCM controls the vent.
Pretty much every modern car Ive seen the ecu always controls a small solenoid to re-circulate/vent fuel tank vapours via a charcoal canister back into the intake.
I cant think of any that dont, as pretty sure it is a legal requirement as far as emissions go.
Nothing has been routinely vented to atmos for years.
Melting Slicks
Joined: Apr 2005
Posts: 3,418
Likes: 1
From: Chicagoland Area IL
So what controls the vent on other cars ?
Pretty much every modern car Ive seen the ecu always controls a small solenoid to re-circulate/vent fuel tank vapours via a charcoal canister back into the intake.
I cant think of any that dont, as pretty sure it is a legal requirement as far as emissions go.
Nothing has been routinely vented to atmos for years.
Pretty much every modern car Ive seen the ecu always controls a small solenoid to re-circulate/vent fuel tank vapours via a charcoal canister back into the intake.
I cant think of any that dont, as pretty sure it is a legal requirement as far as emissions go.
Nothing has been routinely vented to atmos for years.
Yup looked at that PID before, don't remember exact values, but think anything over 1/2 throttle and duty cycle was 100% or damn close.
Melting Slicks
Joined: Jul 2004
Posts: 2,844
Likes: 144
From: Northern Ireland
Although...depending on exactly where they vent, a boosted setup could mess that up as when the OEM ecu opens the solenoid, there could be boost in the intake tract, so it would never be able to vent.
It might be ok on a light use daily drive
But on a race car that sees a lot of boost for extended periods...it's feasible the tank may not vent for some time, or could even have boost applied to it ( although it is via a very very small pipe )
Melting Slicks
Joined: Apr 2005
Posts: 3,418
Likes: 1
From: Chicagoland Area IL
Normally they vent somewhere around mid throttle and full throttle.
Although...depending on exactly where they vent, a boosted setup could mess that up as when the OEM ecu opens the solenoid, there could be boost in the intake tract, so it would never be able to vent.
It might be ok on a light use daily drive
But on a race car that sees a lot of boost for extended periods...it's feasible the tank may not vent for some time, or could even have boost applied to it ( although it is via a very very small pipe )
Although...depending on exactly where they vent, a boosted setup could mess that up as when the OEM ecu opens the solenoid, there could be boost in the intake tract, so it would never be able to vent.
It might be ok on a light use daily drive
But on a race car that sees a lot of boost for extended periods...it's feasible the tank may not vent for some time, or could even have boost applied to it ( although it is via a very very small pipe )
A slightly pressurized tank is what all my corvettes had on hot summer days, well at least when I went to fill up (yes supercharged).
Given the age of OP's setup, wonder if it couldn't be as simple as a plugged inline filter and vapor pressure issues with hot fuel?
Melting Slicks
Joined: Dec 2003
Posts: 3,315
Likes: 17
From: Near Jacksonville Fl.
So what controls the vent on other cars ?
Pretty much every modern car Ive seen the ecu always controls a small solenoid to re-circulate/vent fuel tank vapours via a charcoal canister back into the intake.
I cant think of any that dont, as pretty sure it is a legal requirement as far as emissions go.
Nothing has been routinely vented to atmos for years.
Pretty much every modern car Ive seen the ecu always controls a small solenoid to re-circulate/vent fuel tank vapours via a charcoal canister back into the intake.
I cant think of any that dont, as pretty sure it is a legal requirement as far as emissions go.
Nothing has been routinely vented to atmos for years.
Unless my memory is failed me he told me ther was no place to pin the wire to on the new PCM.
One would think a simple ball check would be more reliable and less expensive then an electric solenoid.
