Curing Vapor Lock in a 5.7 Vortec FJ60

[dcoy]

The competition guys run nothing less than this

Aeromotive 11101 - Aeromotive A1000 Fuel Pumps - Overview - SummitRacing.com

anything less fails when you don't want it to

Looks cool. I know that even stock GM vehicles have a tendency to need pump replacement freqently, so it makes some sense to me to put a beefed up one in-tank to minimize the frequency that you have to drop the tank.

 

[dcoy]

As I tried to point out earlier, you don't need heat to have vapor lock. All you need is to lower the pressure on the fuel low enough and it will boil at room temperature. So you can not confine your search to heat sources, you also need to look at where restriction(s) upstream of the pump can or do cause a vacuum in the supply line to the pump. It is entirely possible that one or the other, or a combination of both are the source of the problem. Replacing the existing pump with a killer pump without addressing the true problem is asking the killer pump to die too.

That point was defintely taken. We did do some work upstream. In particular, we found a 1/8th inch fitting on the tank at the of takeoff of the fuel lines. We thought the time we found that was a "eureka" moment and we had found the source of the problem. Unfortunately, after changing this to 3/8th inch, consistent with the rest of the fuel supply, it was not the instant cure we had hoped for.

 

[dcoy]

I have run a single external pump from day one and I have never missed a beat, although I operate at about 20 PSI, the HP is high and I do not have volume or pressure issues. It seems to me that the idle pump would possibly create a return path to the supply side, increasing, not helping, your problem.

I think that, amongst other things, the Vortec need for high pressure and a high pressure/cavitating pump on the rail are key elements in this problem. It is not 100% clear to my why some people can get away with a rail pump in some circumstances that you would'nt think they should though.

If I understand you correctly about the "idle" pump, I would say that the way the dual pumps are set up, the alternate pump does not (or should not) allow any return flow because of its check valve.

 

[dcoy]

I believe the LRA tanks are worse off than the stock config with an in line pump placed outside the tank pulling from the stock outlet of the tank.

If you want to try and see if it is the tank causing the issues you could temporarily plumb the pump inlet to the drain on the sump of the tank. careful with sediment though. That'd give it good solid fuel flow and eliminate most of the restrictions the LRA tank might have on the pickup line. Mine ran OK with an inline pump BEFORE I did the LRA tank.

I agree that putting a killer pump in there is only going to make things worse. I think like a few have said above the issue is on the supply side.

Yeah, we are thinking about trying the drain-to-pump-inlet approach as a way of simulating an in-tank pump just for fun before we drop the pump in the tank.

 

[dcoy]

When I ran an inline pump.. it worked fine but it was too **** loud...
I swap to a second (same brand) pump "MSD, but the problem still persisted...
I then ran a stock FJ62 fuel tank (this have the pump in the tank) but I swap the pump to a walbro pump. It ran great and very quiet...

Until, I got the bigger tank... It has a GM pump which is even quieter than any other pump I have used !!

I know everything fails but I really dont see or hear of many people having issues with their intank fuel pumps failing (Hype perhaps?).....
Yeah I know its going to be a ***** having to swap the pump when it fails..but, where is your sense of adventure I ask ????

I think what you should do since you got the LRA tank you ought to get an fj62 in-tank fuel pump and put a walbro pump in it.

Its probably the cheapest way to do it.....

My fuel line runs 1"or 2" over the exhaust pipe and I have never had any issues with fuel delivery under the heat.. running across NV, AZ or UT.... during the summer.....

Funny, at this stage of the game I sort of like a noisy pump. That way, I know it's running.

I don't even want to think about the "adventure" of swapping an in-tank pump in the field. I understand that some people (not necessarily in Cruisers) cut an access port in the rear compartment to allow access to the in-tank pump. I think, with my storage drawers, it would probably be easier to drop the tank.

I don't really understand why more people don't have any problems with the out-of-tank pump (although I'm not sure if the conditions your'e exposed to are identical to mine. For instance I've had pretty good luck with driving in the flats around Phoenix in 100 degree plus temps). I'm assuming your engine is a similar Vortec; I couldn't tell what it is from what I saw of your build thread.

 

[ntsqd]

That point was defintely taken. We did do some work upstream. In particular, we found a 1/8th inch fitting on the tank at the of takeoff of the fuel lines. We thought the time we found that was a "eureka" moment and we had found the source of the problem. Unfortunately, after changing this to 3/8th inch, consistent with the rest of the fuel supply, it was not the instant cure we had hoped for.

It may not be one particular detail or feature that is the problem, but a series of small problems that add up to be big enough.

With domestics I have found that good, working JY parts can easily be better parts than new "OE replacement" parts. I don't know that I'd deliberately use a JY fuel pump, but I have used JY electronic ignition parts, that were clearly OE and not replacements, on various low buck projects with great and long term results. Unless the failed parts came from a GM dealership I wouldn't count them as a strike against GM parts. Even if one of them did come from a GM dealership I wouldn't count all of them against GM parts.

The replacement auto parts industry is shooting themselves in the foot. Instead of maintaining quality and charging an appropriate price they are chasing the lowest possible cost supplier, whose parts are junk. It's a downward spiral that may not be recoverable. If it is recoverable it will be painful to the consumer.

 

[lehiguy]

Random Thoughts...

Perhaps you should keep one of the external pumps and run a Walbro in-tank much like a Ford setup that they used on everything for years and years. My external pump is for a Ford. I figured it would be easy to find and if it can feed a 460, it shouldn't struggle too much with a 350. Your fuel tank may be low enough that the fuel, or at least a portion of it, is always going to be lower than the pump. WIth the stock tank, that doesn't occur.

 

[TS888]

I know very little about the Vortec setup, but here's my thought-

all modern EFI engines run a 'full flow' fuel system- the regulator is on the return line
to the tank. Gas is always circulating, and the injectors pull what they need before the
regulator bypasses everything over 50 psi AND MANIFOLD VACUUM back to the tank.

This makes traditional 'vapor lock' impossible- any vapor in the system's just vented back to
the tank, where it recondenses.
The in- tank pump prevents any vporization on the intake- since the pump's IN the liquid, it therefore
pumps liquid out.

If your EFI's NOT full- flow, I think job 1 is making it so. It's not hard with the
appropriate pump. Everything stays cooler.

Now, if a line's too close to the exhaust, sure, the fuel will boil continuously, causing real problems.
Or, as above, if you have a gas tank heater, that'll do about the same thing- if the fuel's really close
to its vapor pressure, the extra heat of being pumped AND the engine heat can do it. It's easy to
test with a thermometer in the tank. Or even one of those IR guns...

fwiw.
t

X2 on this advice. I've never seen a properly set up fuel injection system vapor lock.

 

[dcoy]

Taking the Plunge: In-tank Fuel Pump

Now that it's Spring, Summer is close behind. And along with Summer, we'll have more high ambient temperatures ready to induce my fuel delivery problem (let's not call it "vapor-lock"). Not to rehash the above discussion, it has become the time to move forward and frankly, the In-tank pump is the only thing that has not been done on this Land Cruiser over the years of dealing with this problem. So we purchased an In Tank Fuel Pump Module from Fuel Pumps (Tanks, Inc), and we found the largest unencumbered space between baffles. We cut the hole and it's ready to go in:





After we button it up we'll do the rest of the plumbing (including removing the rail pumps and the cool switching circuitry) and we'll be ready to roll. Overall, we're surprised at how straightforward the whole process seems to have worked out to be. Of course, the proof will be in the pudding; I'll have to make number of runs in the heat to know that this is the final solution.

 

[dbleon]

It's probably too late..... but I think a better option is to run the OEM GM pump assembly. Looks like an aftermarket tank you have there, there is certainly enough room for it. All needed to run the GM assembly is a vettworks ring. The cartridge desgin of the GM pump is better than that small sump of the Tanks Inc assembly. Plus it includes the fuel level, and pressure all in one clean unit.

That's my two cents.

 

[Clonestocker]

My swaps not finished yet but I stuck a replacement Chevy pump in the Toyota pump holder. I have pics on my swap thread. matt

 

[dcoy]

Yeah it's sorta too late.

I did think about the GM setup although we shied away from it because we wanted to avoid the GM pump. GM pumps have a fairly well-established legacy of short life, even in GM vehicles. Not that it wouldn't work; I just would rather minimize any GM components as much as possible. I know that seems strange given that we're dealing with a GM Vortec engine. But then, of course, the GM engine is sitting in a Toyota, a brand that is on the other side of the spectrum of reliability, IMO.

 

[dbleon]

You can use the GM canister with any pump you want... To my knowledge they are made by Delphi - (the OEM ones at least) - a quality manufacturer.

Hope it works out for ya!

 

[dtemple]

dcoy,

this is my first time reading your post, but I struggled with seemingly identical issues about a year ago on my jeep.

i have an 89 YJ with a 5.7L Vortec from a 1998 suburban. Everything on the motor that was replaceable was replaced up installation (injectors, sensors, seals, etc). I installed an E8248 inline pump back by the tank (within 2 ft), and that worked fine until my first trip on the highway in the summer.

I was driving in West Texas in the summer, and when it got over about 100 degrees, the jeep just died on the freeway and would not start. it started back up after sitting about 30 min, but then it would consistently die every 20 min or so. I filled it with fuel and the issue went away for about an hour (nice cool fuel in the tank after fillup).

I tried clothes pins ont eh fuel lines, insulation, changing the pump out, and nothing would work.

I continued to struggle with that issue for 6 mo, and it even started happening in colorado when it was only 80 degrees.

I was at my wits end and finally installed a ford (2000 ish F150 I think) pump in the tank, and that has solved that issue "for good."

I am fairly sure that the issue was cavitation/vapor lock behind the fuel pump. I guess the extreme vacuum right behind the pump lowers the boiling point of the fuel enough for vapor lock? I really dont understand it 100%, but I could just never get the truck to run with that inline pump. My lines were run nowhere near the exhaust either.

Hope everything works out ok for you.

 

[rover67]

Sweet!! How'd it work?!

dtemple glad to hear you got yours fixed!!

 

[Elbert]

I've not experienced this and in general I think vapor lock ...is not very common on fuel injected vehicles. Given that you don't run your fuel line/hose near heat sources and you have a good fuel pump that is rated for the engine/pressure you have to run. GM fuel injection engines are very sensitive to fuel pressure...you don't have to be off the mark by very much and the engine will run like crap.

I wanted to just send out another note saying that I'm still on the same walbro external fuel pump I installed at day one of my engine swap (Details in posts above). Engine is a 1999 5.7 Vortec.

I've had some issues but not with the fuel pump or plumbing.

 

[dtemple]

rover67,

My pump in the tank has worked flawlessly so far. It is much quieter than the one I had mounted on the frame, and the only issue I had was a kinked fuel line in the tank (the short rubber piece used to connect the pump to the Jeep sending unit housing-100% my fault).

I tried 3 different pumps, several different positions(above tank, below tank), fuel line insulation, spraying water on the pump to cool it down (though it did not feel unreasonably warm), etc. None of that worked. the jeep was fine 99% of the time- it just seemed like when I drove it a long ways the fuel must have heated up enough to cavitate behind the pump.

I really liked the idea of the external pump, for ease of access, but I just couldnt make it work.

 

[ntsqd]

I'm becoming more and more convinced that the problem is vapor lock when reading of these problems, but that it is caused by the vacuum created between the pump and the pick-up. Moving to an in-tank pump does two things, it considerably shortens the length of line under vacuum, and it surrounds the pump (& suction line) with coolant (fuel).

If you've ever felt the bottom of an EFI fuel tank after a long run in hot country you'll notice just how hot the fuel gets. I don't know how much of that is self-inflicted (fuel being heated by recirculating thru the pump) and how much of that is from heat radiating off the pavement.

 

[dcoy]

I am fairly sure that the issue was cavitation/vapor lock behind the fuel pump

Thanks dtemple (and everyone else). Your problem, and your assessment of it, seems to closely mirror the behavior that I've seen with my Cruiser. I'm hoping the in-tank pump will resolve the problem. With the temps cranking up this week, I should be able to get the Cruiser back and take it on afew test runs. I'll let you guys know how things go.

 

[dcoy]

I wanted to just send out another note saying that I'm still on the same walbro external fuel pump I installed at day one of my engine swap (Details in posts above). Engine is a 1999 5.7 Vortec.

Thanks. I'm currently operating on the assumption that the rail-mount pump system that you have and TLC says has worked for "all" of their Vortec conversions works fine in the majority of circumstances. The minority, (myself included) that I've seen in this thread are in people who drive their vehicle in conditions of high heat, high elevation, and high engine load (up mountains), have problems with fuel supply based on "vapor lock" or cavitation in the fuel system. An in-tank pump seems to have fixed that issue for many in this thread so we'll see if that approach works for me soon.