Jump to content

Photo

Why is my fuel hot?

- - - - - fuel hot regulator pump

  • Please log in to reply
13 replies to this topic

#1
quan3165

quan3165

    Junior Member

  • Members
  • Pip
  • 2 posts
  • Location:Houston
  • Region:Texas
  • Car Year:2000
  • Car Number:70

This race weekend I was having some issues with fuel and I hope someone on here may be able to help.

 

The symptoms may have separate causes, but here's what it's doing:

- Gas fume smell in the car. Not vaporizing gas fume smell, but almost smells like I'm breathing through the filler neck. Suspect it's coming from under the hood, as I still smell it when I put my face up to the NACA duct.

- I can go race a full session, even the 45 minute race, and when I shut it down in tech, it will not fire up again. Have to wait 30 minutes or more to start when the engine (or whatever) cools.

- Lines going to & from the regulator in the trunk are warm/hot to the touch after a session. Not sure if this is normal.

- After a couple dyno pulls when things heat back up, I lose 3-5 ft. lbs. below 5300 RPM or so. Hp from 5300 to the limiter is the same both ways.

 

Again, maybe not all related.

 

This is on a '99, we are using an Aeromotive 13129 regulator, we replaced the fuel pump and pickup sock, and rebuilt/cleaned the regulator to no avail. We use a fuel pressure of around 55psi. The stock regulator has been removed and we replaced it with a hose that dumps returned fuel on the pickup sock. I don't think anything changed on the car since the last time we raced it in June. Was hotter and didn't have these issues.

 

Any help is much appreciated.

 

Tyler Q



#2
ChrisA

ChrisA

    Veteran Member

  • Members
  • PipPipPipPipPip
  • 582 posts
  • Location:Richmond, VA
  • Region:NCR
  • Car Year:1999
  • Car Number:58
Gas smell could be a minor leak at nearly any connection point. It evaporates quickly, so could be little difficult to spot. Or it could be gas permeation through the hoses used for the FPR. I have had this issue before, could not locate a leak then smelled the hoses and they reeked. Replaced them and they still do it, but to a lesser degree. Today fuels are tough on hoses. Fuel temp could be from the exhaust heating the tank.

Chris

 

Happiness is a dry martini and a good woman ... or a bad woman.
- George Burns


#3
quan3165

quan3165

    Junior Member

  • Members
  • Pip
  • 2 posts
  • Location:Houston
  • Region:Texas
  • Car Year:2000
  • Car Number:70

I forgot to mention I have a Springfield Dyno exhaust, and it's far enough away from the tank that I don't think the exhaust is a likely culprit. Thank you for the reply.

 

I will likely be looking at hoses and injector seals before Sebring to find a leak if one exists... I want to preserve the few brain cells I have left. Just a little too coincidental to have all these fuel related issues at once. Would rather diagnose than throw parts at it.



#4
av8tor

av8tor

    Member

  • Members
  • PipPipPip
  • 180 posts
  • Location:Ybor City
  • Region:SouthEast
  • Car Year:1999
  • Car Number:121

that's a tough one.  I was thinking it was your Kooks exhaust heating it up, but you busted that theory.



#5
MPR22

MPR22

    Veteran Member

  • Members
  • PipPipPipPipPip
  • 2,005 posts
  • Location:Houston
  • Region:Southwest
  • Car Year:1999
  • Car Number:22
Fuel tank temp might be from the fuel pump, we ran an aero motive for a while but it was too high capacity, it would get hot trying to push the fuel through a regulator eventually fails. We are back to stock pumps.
Shattering - For those who cant drink tequila NASA Champs Winner - NASA Champs Winner Majors Winner - Novel Approach - When a paragraph simply won't do... We have a Winnah! - Won their 1st race... Congratulations! Bona fide - A bonafide Spec Miata driver Donor - Made PayPal donation

#6
TylerQuance

TylerQuance

    Member

  • Members
  • PipPipPip
  • 16 posts
  • Location:Houston
  • Region:Texas
  • Car Year:1999
  • Car Number:70
I had the same thought Michael... replaced my Walbro 190 with a stock capacity piece and same issue :/

#7
TylerQuance

TylerQuance

    Member

  • Members
  • PipPipPip
  • 16 posts
  • Location:Houston
  • Region:Texas
  • Car Year:1999
  • Car Number:70

I have 2 usernames...



#8
Brandon

Brandon

    Veteran Member

  • Members
  • PipPipPipPipPip
  • 650 posts
  • Location:North Jersey
  • Region:NNJR
  • Car Year:1996
  • Car Number:48SM

Is your SD exhaust clamped or welded at the joint of the two pieces?

What about the FP cover in the interior, is that installed too (direct sun on the tank through the window for example)?

 

Hot fuel can logically only come about from two (three) sources: pump, exhaust, sun.


Bona fide - A bonafide Spec Miata driver

#9
TylerQuance

TylerQuance

    Member

  • Members
  • PipPipPip
  • 16 posts
  • Location:Houston
  • Region:Texas
  • Car Year:1999
  • Car Number:70
The exhaust is clamped but no leaks as far as I can tell. Is that where you are going with that?

I do have the metal cover installed.

#10
dstevens

dstevens

    Veteran Member

  • SMembers
  • PipPipPipPipPip
  • 1,403 posts
  • Location:Vegas
  • Region:LVR

A way to diagnose heat soak related issues is with an infrared thermometer.  You can get one that will work at Harbor Freight.    https://www.harborfr...ting-61894.html

 

Hot exhaust gas can absolutely make it out of the clamp and any gaps where the tubes join with a clamp can become heat sinks.  Like Brandon says, the heat has to be coming from somewhere.  Unless you have some sort of coating or thermal barrier the heat will transfer into the surrounding components.

 

To get an accurate baseline you may need to measure a known working car.  Even without that you can still get an idea of what may be happening by looking for hot spots in places like the top access panel of the tank, fuel lines, fuel rail, areas near the exhaust or header.  The get the fuel to a temp where it's noticeably hot it's likely an outside source causing heating.  Once you confirm there is or isn't an outside source heating the fuel you can start diagnosing other areas.



#11
TylerQuance

TylerQuance

    Member

  • Members
  • PipPipPip
  • 16 posts
  • Location:Houston
  • Region:Texas
  • Car Year:1999
  • Car Number:70

Thank you all for your guidance so far. I'll start with welding up the exhaust instead of counting on the clamp since that's free and probably should happen anyway. I don't see evidence of leaks however.

 

These are returnless systems and the lines to & from the regulator are hot, so it must be something before fuel gets to the engine compartment.



#12
TylerQuance

TylerQuance

    Member

  • Members
  • PipPipPip
  • 16 posts
  • Location:Houston
  • Region:Texas
  • Car Year:1999
  • Car Number:70

LOL. I wonder if this could be it???

 

 

Attached Files



#13
Jeff Wasilko

Jeff Wasilko

    Member

  • Members
  • PipPipPip
  • 233 posts
  • Location:Boston, MA
  • Region:NER
  • Car Year:1995
  • Car Number:08

kwality!



#14
Brandon

Brandon

    Veteran Member

  • Members
  • PipPipPipPipPip
  • 650 posts
  • Location:North Jersey
  • Region:NNJR
  • Car Year:1996
  • Car Number:48SM

Bingo!

 

Glad you found it!


Bona fide - A bonafide Spec Miata driver





Also tagged with one or more of these keywords: fuel, hot, regulator, pump

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users