Question: best fuel temp

Mike L.

Got Sheep?
Staff member
Vendor/Sponsor
Aug 12, 2006
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Fullerton CA
I will start some testing again in a little while since I have so much info and am still curious enough to finish this project. Now that my buddy Guy at SoCal has a dyno we can play around.
Casper has had one of my fuel coolers for a couple of years.:D
 

jmaz268

Lead from the Front
May 20, 2010
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Springfield IL
I will start some testing again in a little while since I have so much info and am still curious enough to finish this project. Now that my buddy Guy at SoCal has a dyno we can play around.
Casper has had one of my fuel coolers for a couple of years.:D

So does that mean you are going to start selling the coolers again as well?
 

lotsofmiles

Father of the Van
Dec 4, 2008
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Michigan
And I just saw the same thing on the way home today.
Ran the factory tank down to 1/4. started putting in fuel from the aux tank and had an instant drop in temp.

I just dont know how accurate the temp reading is and how much heat is 'soaking' into my temp probe from the engine area.

I installed 2 temp gauges this week. One for the fuel, and one for the oil temp. I didnt install the probe for the oil temp yet because I wanted to search on where to put it. So for the next trip I will zip tie the loose probe right next to the fuel temp probe. Should give me an engine compartment temp reading and the fuel temp reading. I'll bring efi next time and moniter the factory temp reading too.

going to order to valve tommorow to choose which tank to pump the return fuel to.
 

Mike L.

Got Sheep?
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Aug 12, 2006
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Fullerton CA
If you have a lift pump and run your tank down to 1/4 you will lose power as there won't be enough fuel in the cup to keep enough volume flowing to the CP3. Hard acceleration with low tank level will also rob you of power. The cup needs to be submerged and that won't happen below 1/3 level. Return fuel is dumped back into the cup which is important if you run tank level low. It doesn't matter if cup is submerged.
 

lotsofmiles

Father of the Van
Dec 4, 2008
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Michigan
Just pulled another one of those park models. 10,700 pounds 39 ft and tall. Pulling thru some hill on the highway I would watch all the temps climb going up the bigger hills except the fuel temp. The harder I got on the go pedal the more the fuel temp dropped. I think the engine heat is heating the fuel under normal driving. I wonder if, with my factory fueling, it would work putting a cooler behind the grille after it leaves the filter
 

lotsofmiles

Father of the Van
Dec 4, 2008
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Could be


I was thinkning might be from needing and use more so it wasn't sitting in the filter and lines cooking as long.

Tank was on F
 

MFDinosaur

New member
May 20, 2009
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I've added fans to my factory fuel cooler and also added another cooler in front of the radiator to gain any benefits I can from cooler fuel. It's the factory cooler, which Mike has pointed out is not nearly as efficient as his probably is. To be honest, I never noticed an appreciable gain in mileage. I never did monitor my fuel temps after adding the front cooler. Maybe one of these days I'll do a before and after test and report back.

To add a cooler up front is relatively simple. I had an old transmission cooler with 3/8 (I think) hose ends, bought male and female quick disconnects and about 12 foot of fuel injection fuel line. I disconnected the return line and used the new disconnects to insert the front mounted cooler. You can run the lines along side the radiator , no problem.

With a single cp3, there is very little pressure in the return line.
 

lotsofmiles

Father of the Van
Dec 4, 2008
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Michigan
I just added a fuel cooler too. And yea, I think an upgrade on the return line cooler would help too.

I bought a Dearle oil cooler with fan and 1/2 inch lines. Its a 6 tube. Mounted behind the grille.

Didn't wire up the fan yet.

But I did put the sensor in and was watching fuel temps before and after this cooler.

I saw fuel temps after the cooler stay 3-8 degrees above the outside air temp on my mirror. The temps pre cooler ranged from 10-30 degrees higher.
The cooler really 'shined' when in ANY slow or stop and go driving where pre-cooler temps would climb fast, but after cooler temp stayed steady even without the fan hooked up.

I goofed and should have ran the factory tank down below half while towing (to try to duplicate the conditions that gave me the 0087 6 times in one trip). But I didn't think of it until the ride home, not towing. Running empty I did run the factory tank below half and as it went below 1/2 the temps pre- cooler started climbing.

No 0087s this trip.

Next trip I will run the tank down below 1/2 while towing to see what the temps do
 

66impala

Gear head, bus driver
Aug 20, 2010
48
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Kalamazoo, Mi
i placed on my cooler a 4 inch electric fan puller and a pusher. i have it hooked to the run mode on the ign. switch. but i have a toggle switch for the winter i like it little warmer than 30* or less. i say my last time i check my fuel temp was about last year and it was down about 89* with out side temp 97* in florida when i was there in Sept.

oh yeah i used a b&m trans cooler and just fitted the fittings to make it work. spent maybe $300 on everything even a bracket to mount it in the same place where stock was. forgot to mention that i just start the truck and only drove it like 20 miles when i checked it.
 
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66impala

Gear head, bus driver
Aug 20, 2010
48
0
0
43
Kalamazoo, Mi
sorry about that i ment 89* i used two 4inch electrc fans one a a puller and the other a pusher. back to back with cooler in the middle.