It seems to me that most of the proposed solutions address the problem from a flow point of view and don't really account for the fact that it works fine before it's hot. Do most of you just expect the heat problems to go away if he increases the size of the return line?

I have no answers, my only proposal got pretty summarily dismissed as being absurd a few pages ago, and I cant help but agree with their reasoning.

So what causes a flow problem only when its hot? I dont think fuel tank air pressure is going to be heat related. You guys seem to think that an undersized return line wont overheat the pump enough to cause it to overheat and therefore slow down.... I tend to agree with that too. So what's left? Is the fuel line itself getting hot? Have you put a temperature gun on the line itself? On the regulator?

To me, if the return line is too small and overheating the pump, wouldn't that problem happen ALL the time? Again, Im no expert, but perhaps my layman attempts at understanding will help someone else have a eureka moment. I understand the regulator is boost-referenced, so the pressure increases as load increases, putting more load on the pump. But also if the motor is using almost everything that the pump can provide at load, then doesn't that almost isolate the return line from the system? So a return line restriction becomes less of an issue in high demand situations, right? And wouldnt the return line restriction be a problem that causes the pump issues at times when the engine ISN'T using much fuel? When msot of it is having to flow back through the return line instead of going into the cylinders?

Is it safe to assume that since the problem is heat related, something is getting hot? If so, how can we track down what is getting too hot? Is there some way we can monitor the temperature of the fuel pump?

 

I think the return line and or regulator, if too small, will cause pump to work harder and produce more heat. In time this heat builds up to a point that effects delivery of fuel. The issue takes time and when cold it doesnt show.
If it is a return issue then eliminating that could possibly delay the onset of fuel overheating. Less heat from pump gets transmitted. Is it a cure? I dont know. It may take 1 hr to overheat now but new return the issue may come back in 2-3 hrs this time.
The fact that 3 pumps did this while maintaining same return system shines light on a possible area to improve. Feed line changes did not help so the backside is all there is left to test.

It also very well could be the design and position of rails in the tpi system that absorbs engine heat and eventually cooks fuel tank. If there was a way to monitor fuel temperatures and track down where this issue occurs, that would be a huge help. Maybe it needs a fuel cooler? Maybe a better rail design? Idk but i have seen my rails get over 170 deg and never had a fuel issue. I also dont know what size stock rails are and hp potential stock rails have. I doubt you are sucking them dry if the 340 pump is on a 18 volt booster

I'd love to see aftermarket rails and external regulator tested along with temp monitoring. Lastly if fuel temp is causing cavitation and vapor lock issues then jack up the fuel pressure a ton and see if it goes away. That however is not good on pumps and the 340 or walbros may not perform well. Well dual walbros should support 700-800 on 70-80 psi pressures. After 60-64, power potential is suppose to drop off alot. I do know at 64 psi they hold 1000 wheel

 

wonder how a 5.9 cummins turbo would work on a tpi motor? or a duramax turbo.... similar displacements and rpm range..... ?

 

Hard to say. Some might work well but gas vs diesel hotsides could be different and the boost pressures of diesels is alot higher than most would run in a tpi motor

 

20 InHG comes out to 9.823062 according to a handy dandy internet calculator I found. With a base of ~45 that would indicate it should drop to ~35. That being said though, I'd think it quite possible 2-3 PSI difference would be within the realm of combined error of the gauges being used and the reading of the gauges themselves. Just saying.

A simple test would be to pull the return, run it to a 5 gallon gas can/drum/whatever, and then see if the base FP drops and if the FP drops at idle. If you have parts around it's not mortifyingly expensive to try by any means except perhaps the time.

ED:Why not monitor fuel temps? GM 90 ohm CTS sensors are easy to get and metal, all you'd really have to do is "T" a block into the fuel line if this was external regulator maybe even use one in the reg. Throw a gauge on top of it, and you're in business.

 

You can buy a t block and put AN fittings on it to install in your feed line and buy the 40$ transmission oil temp gauge kit from b&m or whoever. I have that setup in my trans cooler lines but same could work for fuel. Thats an interesting idea i never thought of

 

You guys keep thinking heat and return, I'm thinking it's duration..

The longer the car runs, the more vac builds in the tank.

This exact problem has happened to just about every speed boat I've ever owned when the tank vent crapped out.

The theory of a pump heating up because the return is too small is nonsense. The operating range on the pump is up to 100psi. If it can run at 100psi regulated (since we know reglulators work by RESTRICTING RETURN FUEL), it sure can run at 45psi without overheating. We know the line isn't bottoming out his adjustibility on the regulator since he has different fuel pressure under vac than he does at baro.

-- Joe

 

wire in a 2bar map sensor into the tank with some vacum hose somehow and measure its output on a spare input on the megasquirt
hell u could plumb the line from the map sensor into tthe line that used to goto the evap can with a rubber hose
simple and cheap and a guaranteed way to know if the vent is the issue


while ur at it do orr's idea and put a temp sensor in the fuel line and datalog it to the megasquirt then u have both angles covered and a final answer once and for all

 

Even though he's got gasoline sloshing out of the filler neck?

 

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I mean if you had to you could get a cheap replacement gas cap that's not vented and just drill a hole and put a fitting in it for a vacuum gauge. Would be pretty easy and cheap I bet. Would be a waste of time if you run the gas cap that loose all the time, but it would at least rule that out. Or just tee into the pressure relief valve line. Whatever.

 

.......or just install an appropriate size vent on the tank while they are installing the new pump setup.

 

Updates?

 

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make sure heads are pressure checked.

also, pay close attention to intake gaskets or the throttle body if there is coolant running through it still. those are areas coolant could get into the intake tract.

 

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i agree, its most likely not the pump causing this. but, if you can put together a complete fuel system that is correct by the rules, you can move on to the next thing. no more "wondering".
denmah really is a smart guy on this stuff. he knows exactly how everything works and has enough experience pushing the limits with the different parts to know just how much he can get away with. i've watched most of his vids, and he has WAY more drive than i do. havent had that much energy/drive since i was 18 years old. doesnt mind going to the junkyard and rolling around in the dirt pulling gears out of a rearend or engine/transmissions out of a u-pullit yard. he's got my admiration for sure.

 

Where are you getting 044 bosch's for 60$?? They are are 150-170$ pump

 

just watched the hitler vid where he rides in the back of the iroc. holy hell that one had me rollin!!

 

Totally off topic, but I was curious if your tpi throttle body was stock or the 58mm?

 

I thought he usually did a pusher such as a 255 in tank then fed the 044 that way. Also as said they are way closer to a $200 pump and if you go look up the pressure curve i believe they outflow even a 340 at higher pressures.

 

The knock off's are as cheap as $50. Here is one:

http://www.ebay.com/itm/External-Electric-Fuel-Pump-044-for-Bosch-OEM-0580254044-Poulor-300LPH-Adapter-/271310205591?pt=Motors_Car_Truck_Parts_Accessories&hash=item3f2b593297&vxp=mtr
The actual bosch (if you can trust the ad) seem to go for around $140.

-- Joe

 

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the vids are hillarious. reminds me of how i've felt with my camaro over the years. 12 years ago i swapped the LS1 stuff in place of the LT1. had troubles all over the car after that and it made me hate the car. put cnc ported patriot heads and 230/236 cam along with huge exhaust in it and only laid down 376rwhp. clutch never would disengage correctly, and i pulled the trans out 6-7 times swapping one component at a time trying to fix it. to this day it still isnt right. lol put a 12 bolt rearend in there and it kept leaking. replaced the axle seals several times and finally got it right just before i sold it. then i swapped the stock rearend out of my donor car in there and it leaked at the pumpkin/tube welds. go figure.
had some issues with getting it tuned correctly, and finally said screw it, ill just drive it. so i drove it for 2 years or so before realizing my intake silencer plug had come loose and was causing a huge leak between the maf and throttle body.
i put a nitrous setup on it, and on the way to the track to test it for the first time i hit it on the highway. blew both headgaskets and covered every square inch of underhood area with coolant.
i could go on and on.

 

I would have given up

 

engine has 85k on it now and its on its 4th set of heads and 4th cam. lol

 

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kickass! i like to see the culprit when im repairing something.
might want to spray the new cometics with copper coat before installing them this time, too. i think cometic actually recommends that on blocks/heads that don't have their recommended finish. i did this on the set on my camaro, and i reused them. they seem to be fine.

 

I'm at like 2K miles if that and already on 2 heads 2 cam 2 rears 2 trans, 2 diff turbos, 2 hoods lol

 

dang, you know exactly what i mean. lol my swap had 55k on it in '01 and now it has 85k. for a mild car that is supposed to be a driver, that is pathetic. why i still have it is beyond me. i kinda still love it, but also hate it.

 

So what causes something like that?

 

Awesome man ... shizz is hilarious

 

Damn only 376hp with a built LS1 ?!?!? That sucks ... mabey u will find the problem and get it right ... cars are funky sometimes .. everything has to match up just right to make a fast car .. I'm thinking (as well as others here on this forum) my little 305 build is gonna make somewhere between 350-370 after tuned right ... "IF" I ever get it tuned right

 

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wow! thats awesome service!

loved your hitler video. it made my night.

 

Your head guy rocks. Will be interesting to see what the comp does. Here is to a quick recovery.

 

The heads should handle plenty. 10 plus years of hard, boosted abuse, mine are good. Just saying. Some how, my original build is still in one piece.

 

hey i just watched some of ur vids , and i noticed a few things

first off ur air filter is way way to small , when u use such a small filter u create very high vacum in the turbo inlet, this causes it to pull oil from the front seal

it can also cause premuture wear on the bearings , though i dont belive the air filter caused ur bearings to go bad , but it is more then likley the source of ur smoke issue

 

wow, $100 is fantastic for all that!!! i think some head shops would charge that for the resurfacing alone.
machine shops very rarely finish your stuff when they say they will, and this one did. that is awesome too.
i wouldnt worry about the compression, you have to mill a boatload to make a sizeable difference. like .050" or more. i had a set that needed .025". they had been run hot a few times and were shaped like bananas.
very anxious to see it pick up some power once the fuel issue is fixed!

 

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Walbro 255 in the tank with a Kenny Bell Boost-A-Pump. Everything else is factory aside from the injectors.

 

So you support 600rwhp with a walbro 255 simply by increasing voltage to the pump?

-- Joe

 

That be good news to me. I want 1200 whp and normally would need 3 255 pumps but curious if a booster could help. Or twin 340's with booster

I have heard 550-600 before with boosters in single 255 systems

 

I know a single Walbro 255 wouldn't do it for me, I went with the DW300 instead...

 

According to Kenny Bell, the boost-a-pump on the highest setting will make the pump flow 100% more. And its not supposed to shorten pump life. Hell, I have 10 years on mine. All I know, is it supports enough fuel to power my combo that moves a 3500lb third gen to 130mph in the 1/4 mile.

 

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mercy.....