Fuel System Randomly Primed

[Proshop]

@Proshop thanks for the details. Perhaps the only bad thing about living in FL is boiling your E85 occasionally..

I’ve always stated that there are positives and negatives to anywhere you live… no matter where it is and yes this is one of those situations where I have positives and obviously negatives. Hopefully this is all it is and I can just chalk this up to RACECAR problems! Lol

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[Proshop]

@LOL WUT and @Cory S just an update.. preliminary conclusion is a vapor lock situation from the heat of the pumps and components in the system. Started the car this morning and ran for 15 mins till up to temp and fuel pressure only dropped 2 psi vs 10 like yesterday. So pulling the fuse for the third pump to help keep the heat down and will be ordering a Hobbs switch to turn that fuel pump on at 5 psi of boost. Fingers crossed this fixes the issue!

 

[Exploded_Muffin]

@LOL WUT and @Cory S just an update.. preliminary conclusion is a vapor lock situation from the heat of the pumps and components in the system. Started the car this morning and ran for 15 mins till up to temp and fuel pressure only dropped 2 psi vs 10 like yesterday. So pulling the fuse for the third pump to help keep the heat down and will be ordering a Hobbs switch to turn that fuel pump on at 5 psi of boost. Fingers crossed this fixes the issue!

Are you using VCM Scanner to monitor your fuel rail temps?

 

[Proshop]

Are you using VCM Scanner to monitor your fuel rail temps?

I don’t believe that is one of the channels that mine records. I’ll have to turn it on and see what they are. I never had issues last summer but I also have bigger pumps now.

 

[Angrey]

I asked this in another thread that was crickets (presumably because no one else knows) but what sort of fuel temps are you observing? I just wanted some data for crude reference. I have a dedicated ethanol sensor and bluetooth module where I can read the alc% and the temp. Would be curious to know the temperatures at which you start to observe vapor lock. (I realize it's going to be different for E85 than pump 93).

Have you considered a different solution than the Hobbs switch?

Whether it's valid or not, a lot of tuners/builders and experienced enthusiasts don't like relying on the Hobbs switch as a potential failure point and risk to lean conditions or lack of proper fuel.

I'm wondering if something like the JPC fuel max where you can reference it to throttle position wouldn't be a more reliable solution. You can ramp in the voltage boost and probably get away with 2 pumps rather than staging with 2+1.

 

[Exploded_Muffin]

I don’t believe that is one of the channels that mine records. I’ll have to turn it on and see what they are. I never had issues last summer but I also have bigger pumps now.

Yes you'll have to add that channel to your channel config.
For reference my rail temps are usually 110-120F in 90F Houston weather (Twin Walbro 274 pumps running full time on E85)

 

[Proshop]

Yes you'll have to add that channel to your channel config.
For reference my rail temps are usually 110-120F in 90F Houston weather (Twin Walbro 274 pumps running full time on E85)

Appreciate the information sir!

 

[Proshop]

I asked this in another thread that was crickets (presumably because no one else knows) but what sort of fuel temps are you observing? I just wanted some data for crude reference. I have a dedicated ethanol sensor and bluetooth module where I can read the alc% and the temp. Would be curious to know the temperatures at which you start to observe vapor lock. (I realize it's going to be different for E85 than pump 93).

Have you considered a different solution than the Hobbs switch?

Whether it's valid or not, a lot of tuners/builders and experienced enthusiasts don't like relying on the Hobbs switch as a potential failure point and risk to lean conditions or lack of proper fuel.

I'm wondering if something like the JPC fuel max where you can reference it to throttle position wouldn't be a more reliable solution. You can ramp in the voltage boost and probably get away with 2 pumps rather than staging with 2+1.

Unfortunately no data as to the temps at which this started. I have triple ti 285s which is way overkill for my 900 or whp setup so even if the Hobbs didn’t work correctly I would more than likely have enough fuel to no go lean. I also have an AEM fuel pressure gauge in the dash that I have set to go off if I drop below 40 psi. I might research other options besides the Hobbs switch thou.

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