Having an issue with overheating my fuel after prolonged idle. I can drive the car no problems, but twice now (after long periods idling), i notice the fuel pressure start to drop from 40 to 35 to 30 to 25, etc. One time it actually killed the car, the other it just started to lean it out. If I let the car sit for 5 minutes fuel pressure goes right back to normal. I thought it was a dirty pre-filter, and there was a lot of crud in the pre-filter, but cleaning it did not seem to fix the issue.

System is as follows:
8 gallon cell
-12 to 85micron filter
pump
-10 40 micron filter
-10 to -8 y block under hood
-8 to each rail
-8 from each rail to reg
-8 from reg to fuel cell

Now, a couple of issues I see currently (trying to get a grasp on what, if any/all, should be addressed first).

1- small fuel cell, 8 gallons means less fuel volume to dissipate heat, pump moves over 3 gallons per min, thus it is flipping the tank A LOT

2- 40 micron post-pump filter. not sure how this one slid through the cracks, but i looked at my parts sheet and that is what I am using some how. aeromotive calls for a 10 micron. not sure if this could introduce enough restriction though (hell, it's been fine for over a year and 2500 miles). figure it needs to be changed anyway so i'll buy a 10 micron

3- no turbo blanket and lots of under hood heat. not sure if it'd make that much of a difference, but with no turbo blanket + a/c it gets hot under there. figure the fuel is picking up a decent amount of that ambient heat.

4- no pump speed controller, this is by advice given to me as these can fail you at the WRONG time and cost a motor (plus they are expensive).

5- very slight leak in suction line (right at the cell where the -12 bulk head comes through), it is VERY slight, like just enough to attract dirt on the sump of the cell. i have replaced the seal at the bulk head but it still has this very slight leak. could this be constantly aerating the fuel causing cavitation in the pump?

 

i do know with large pumps, a speed controller is ideal if you drive the car and see a lot of idle time or stop and go traffic

 

I would work on the suction leak. Also, for $50 you can add a fuel cooler to dissipate the heat - cheap, easy solution to NPSH issues from temperature.

 

could the suction leak really cause this issue?

 

I doubt it. My guess is the fuel is just getting too hot.

But, I figured I would mention it being it doesn't take much of a suction leak to cause issues.

 

This is typical of the big fuel pumps... They heat the fuel when running at full speed. I ran a Magnafuel 4303 for a while and it did the same thing, and that was with a 14 gallon tank. if it is a street car, you are going to have to run a controller or a large cooler.

 

Any reasonably priced coolers?

 

I was wondering why you weren't making any new passes

 

meh, just got married/honeymoon.

in other news i did just put all new tires on her, so i'll hopefully be out there this weekend doing some T&T before our "cruise" race on the 26th.

this problem isn't debilitating, it is just annoying. i can drive it 20 miles without a problem, it just doesn't like long periods @ idle.

 

Did you go to the M/T 28x10.50 ET Drag? You had radials right?

 

nope, still on radials, going to give them another try. if i can't get them to work i'll buy a second set of pro-stars and mount some et drags on them for the track. i just like driving the car, esp. driving to the track, whoopin up on some trailer cars, then driving past them on the way out.

i did manage 2 120mph passes but the tires were done. had to ramp in the boost over 2.3 seconds, it was painfully slow out of the hole to keep the tires stuck.

 

I run dual pumps. 1 pump runs under normal loads with no boost. The 2nd pump runs when boost kicks in with a hobbs switch with a relay. I'm pretty sure with my 12 gallon fuel cell and running a big pump or 2 somewhat large pumps constantly like I'm running would boil the fuel. I also keep all piping wrapped and blankets on the turbo's.

I've never tried a fuel cooler and that might be the way to go. I just don't like the crazy sound of the huge pumps. Way too loud when I'm cruizing.

 

1. This is the issue
2. 40 micron is larger then 10 micron, thus less restriction not more
3. This could play a roll, but unless all the hot side parts are coated I dont know if this will make a huge difference
4. this is part of the issue
5. Your tank does have a vent on it correct? while it could be a small leak i dont think it will affect your issue.

 

Damn 2.3? Did you try leaving on like 2-3 pounds instead of 6-8 like we talked about?

I think some of it was in your suspension also, but the boost leash should of helped.

Is the timing table still working for you?

 

i am still on the timing table we built. i left on like 5-6psi and it'd hold that, but i had to bring it up to 16 SLOWLY and even then it'd spin them at the top of low gear. i figure the timing table is working fine if i am doing 120mph in the 1/8th, the tires were SHOT though. i went ahead and put another set of the radials on since the car see's the street so often.

as for this problem i wired my fuel pump speed controller back in but the tach signal isn't working on it but the manual switch is so i decided to just buy a second pressure switch (currently have one wired for the meth injection @ 10psi) but with this one have it speed up the pump at something low like 1-2psi. i figure this actually makes more sense then using a rpm threshold for activation since with the glide i see some pretty high rpm's cruising on the highway and don't want the pump speeding up just cruising down the highway. seems manifold pressure would be a better activation anyway. what do you think?

 

you need an expensive an unreliable controller for your expensive and unreliable race pump


OR use street pumps? i run 3 walbros'.

everything is designed with criteria. the parts you are using were not built for what you are doing / trying to do with them.

how much power are you trying to make anyways? and whats the brand of the pump.

please dont say aeromotive, and please don't say you got it used. thats a double whammy of *it aint gonna work*

 

Put a 100+ micron filter pre pump. Had the same issue. Putting a more free flowing filter in fixed the problem.

 

Sorry 10 micron. Not 100 lol been a while

 

it is an aeromotive eliminator. it's used in the since that i've run it on the car for the past 2500 miles over the course of a year. no idea on what kind of power the car makes, it has gone 5.85 and 120mph on 275's in the 1/8th and it's not gutted, has a/c, heat, radio, etc. maybe 700rw

you had it right, a 100 micron is "free-er" flowing then a 10. i am running an 85micron pre filter so going to a 100 would increase flow slightly.

 

Well I'm just glad I could be of some help with the timing and boost.

Hope you get this fuel situation squared away.