Curing Vapor Lock in a 5.7 Vortec FJ60

[Kurtis]

Don't you have a TBI Kurtis? The pressure is much lower (below 20 psi right?) and generally people do not have issues with inline pumps in those systems.

A quick google search will yield several pages of results where typical inline pumps have failed on the high pressure (Vortec) systems.

Yup only 13 psi at stock horsepower. With the vortecs the inline pumps last a very long time as long as the fuel system is set up correctly. A lot of guys run them on motors running way past 60 psi. I know a lot of guys with over 50k and a few years and their still going strong on LS1 swaps into various cars and trucks. Some of these are pushing a lot more than 260 hp as well. You want a filter around 50 microns before the or less and 5-10 after and it will last a very long time.

The two main things are
1. MSD in line pumps die quick.
2. For some crazy reason a lot of people put a very restrictive filter in between the pump and the tank which kills them or no filter before which also kills them. You need something to keep the large particles out of the pump but not restrict it.

 

[dcoy]

This is why I'm doing an in-tank pump for my vortec swap. I have heard from several people that live here in AZ, that cavitation is a real issue with 60+ PSI inline pumps. One remedy might be to use an in-tank booster pump, to ensure the inline high pressure pump is adequately supplied at all times. A FJ62 tank and pump might be the ticket for this 2 pump setup...

Your experience seems to bear out my concern; that the heat, and to some degree the elevations in Arizona and the Southwest in general, create perfect conditions for cavitation even though TLC had not seen that in any of their other conversions (given that most of their conversions stay in California or go all over the place). We did try, once, when we broke down in Las Vegas, to place inline low pressure, then high pressure pumps on the rail. This was a total bust. We couldn't even get out of town (temps were in the low 100s). Do you think there is an advantage to putting a booster in the tank as opposed to just placing a single, regular, high pressure pump there? I have a 42 gallon, aftermarket tank that I am told there should be no problem with putting it in there.

I have the same engine in my 85 with the 4l60e. I have some of the same symptoms you do, mine acts up after a long elevation gain, doesn't stall, but when I shut it down it won't restart until I pull the fuel cap for 15 minutes...That may just be our pumps behaving differently.

My engine with the AC engaged has never gotten over 220 degrees, it generally runs right at the thermostat temp of 195. I'm not sure it's a temperature related issue as much as a pump cavitation problem. I haven't had any problems since we have been out of the 90's either, so it could be temp related.

How is your cooling system set up? I'm assuming you have the chevy mechanical fan as there is a shroud in your pic.

I'm running the walbro 392 inline external pump, with identical pluming to Elbert's. It doesn't get hot at all. The tank doesn't pressurize either.

What components in the PCM do you have operational? Does it have a BAR sticker? Curious where they put the charcoal canister, and which one they used. I have the stock C1500 unit right where I want a second battery.

Mine still has the fuel tank pressure sensor programmed, along with the fuel level sensor. I have a CEL, but I'm not concerned with it as I don't have the components hooked up.

My next step is to drop the tank and install a walbro submersible to eliminate the fuel pickup issues. I've seen similar problems on Geman cars with external inline pumps where slight cracks in the pickup pipe caused the pump to cavitate.

That's interesting that it doesn't stall. I haven't found opening the tank to have a consistent effect on the situation. It is usually a matter of time. In fact, I have never had to be towed because of this. I can limp along in absolute misery, driving 40 mph and having to stop intermittently; I drove all the way from Kingman Arizona to Southern California this way once.
That is correct about the GM mechanical fan. We have considered an electrical fan and coolant pump to deal with the increased core temps that occur immediately after failure, however that really would not address the primary problem (cavitation/vapor lock).
Sorry but I'm not familiar with the computer nomenclature (bar sticker, charcoal cannister). I believe the C1500 is what is sitting on the left wheel well in the picture?
I believe there is no fuel tank pressure or level input into the computer.
I am beginning to think that the in tank route may be the way to go unless if anyone has any experience/success with low pressure booster pumps between the tank and the high pressure pump.

Thanks guys for the feedback/info

 

[dcoy]

A couple of things:
A) Not all modern EFI fuel systems have a return line back to the tank from the engine.

B) The odds that the vapor lock is occurring downstream of the pump are pretty slim.

I would concentrate on the section of fuel plumbing between the fuel tank and the fuel pump. I would also suggest trying one of the GS392 fuel pumps.

a) This does have a return line
b) Interesting. I guess that goes along with the "Ideal Gas Law" way back from Physics class.
I'll check into that pump. Walbro pumps seem to also be getting a good review here and the MSD (what I have) generally poor reviews.

 

[dcoy]

What kind of hose do both of you have between the tank and the pump?

We have 3/8th inch diameter stainless.

 

[dcoy]

The two main things are
1. MSD in line pumps die quick.
2. For some crazy reason a lot of people put a very restrictive filter in between the pump and the tank which kills them or no filter before which also kills them. You need something to keep the large particles out of the pump but not restrict it.

Hmmm. Now that I was thinking about going in-tank, all I really need to do is change my pumps from MSD to Walbro and add a pre-pump prefilter? Is it also possible that some pumps are less likely to cause cavitation than others? Because what I believe to be seeing here is that the pump does'nt die, in fact once I stop assaulting it with high demand at high temperature it is just fine. I can also push a nearly brand new pump to "failure" as well in these conditions.

Thanks

 

[dcoy]

More pics

Just to help visualize my fuel system better, the site is now letting me upload the rest of the pictures now.

This is a view towards the back of the rig with dual fuel pumps on the left and the Barry Grant Heat sink to the right of center (with the cool "wings"). The fuel tank is behind the heat sink.


This is a closer view of the dual fuel pumps mounted inboard to the passenger side rail

I did forget to clarify that there are some interconnections that you can see here that have rubber hose (i.e. it's not all stainless fuel line).
The hose clamp that is left of center here is the one I used to "vent" the fuel system, presumably venting the vapor that was formed by cavitation. Then we got our fuel pressure back. The DPS/Highway Patrol Officer stopped by and noted "what's that smell of gas?". I said, "Oh, that was just me".

 

[ntsqd]

It was interesting to me to note that an increase in pressure of 25.3 psi only raised the boiling point by 30 degrees, but a decrease in pressure of 4.7 psi reduced the BP by 10 degrees. The reduction has nearly twice the effect on BP as the increase.

The reason that I asked about the hose type(s) is that some hoses will collapse under vacuum, particularly as they age. Not all pressure rated hose is also rated for vacuum.

Those MSD pumps don't look much if any different than the Walbro pumps. Curious, was expecting them to be completely different.

I don't know where Kurtis got that 50 micron pre-pump filtration number, but it seems a bit restrictive to me. I have seen a typical carb application filter, even new, be too restrictive to be in the suction line and cause cavitation. In building my pre-pump filter (since 60's don't have a fuel pick-up sock) I attempted to duplicate the opening size of my sample GM fuel pick-up sock. I've no idea what size particle it will pass, but I figured that GM did and that their pumps would be OK with whatever size it was.

 

[dbleon]

If you have an oversize tank, then what the HE L L are you still worrying about??? Just spend the $150 for a Delphi in-tank pump, a corvette 33737 regulator/filter and call it a day. If you still have issues after that, you know it's not fuel delivery.

Here is what you need: Vetteworks

 

[dcoy]

If you have an oversize tank, then what the HE L L are you still worrying about??? Just spend the $150 for a Delphi in-tank pump, a corvette 33737 regulator/filter and call it a day. If you still have issues after that, you know it's not fuel delivery.

Here is what you need: Vetteworks

Yeah, that's probably the way to go. Just trying to get as much info about different options as possible before I jump in.

Thanks

 

[rover67]

OK, it looks like you might have an LRA Tank in there like me. That made me think a bit..

My history:

I had several inline pumps on my rig when I had the stock tank. They lasted a while, were kinda noisy. they did work though.

I then switched tanks. I started having more fuel issues. It seemed to be impossible to keep the fuel pump from cavitating. It'd pull a hard enough vacuum that the fuel would boil on the suction side. I verified this by putting a clear filter (with no element in it) on the suction line. After trying everything I could think of I decided it'd be a good idea to go with an in tank pump. I did that and ALL of my fuel related problems went away.

Hotter fuel made the problems exponentially worse.

you can try removing EVERYTHING from the inlet side of the pumps to see if they run better. Of course you'd be risking that they suck stuff up and fail sooner. You can also get a cheap glass exterior filter from NAPA or something and place that inline with the pickup on the suction side of the pumps to see if there is solid fuel flowing or if there is vapor as well.

Running both pumps you have set up there at the same time would create a large amount of suction on the single line coming out of the fuel tank, and seems like it might make things worse.

I have wondered if all these aftermarket higher flow inline pumps just move too much fuel and create these cavitation issues as a result. So I'm wondering if maybe a lower flow pump would work better.

Anyways, I guess what i'm saying is I felt like I had more issues with my LRA tank than with my stock setup. Maybe it is more restrictive on that fuel pickup.

might be worth just doing in tank like dbleon is suggesting.

here is what I did:

https://forum.ih8mud.com/60-series-wagons/394565-tank-fuel-pump-conversion.html

 

[dcoy]

Running both pumps you have set up there at the same time would create a large amount of suction on the single line coming out of the fuel tank, and seems like it might make things worse.

Oh no, I don't run them simultaneously. I have in-dash switching to go from one to another. Nevertheless, I am getting alot of cavitation (apparently) from just one pump and having the switching mechanism has proved to be an expensive, but effective diagnostic tool to show that the pumps are not simply overheating or burning out, since switching to a fresh pump after failure has occurred does not fix the problem.

It has been helpful to know of your and other people's experiences that the in-tank setup has been a consistent cure to fuel supply issues, so I am 99% sold on taking that approach at this time. I would have to sacrifice my cool in-dash on-the-fly pump switch, but it doesn't work when the chips are down anyway.

Thanks

David

 

[Elbert]

fixed or still working on it?

if fixed what was the solution?

 

[dcoy]

fixed or still working on it?

if fixed what was the solution?

Thanks for the followup Elbert.

Unfortunately, now that the late summer heat has ended, any changes we make to the Cruiser would be sort of "blind"; the problem would be "fixed" either way because the critical inducing factor (heat) is gone. The plan at this point is to pursue the in-tank fuel pump but we will have to do some research into how to do this, what pump to get, etc. We are also considering whether we should do some sort of "mock-up" to simulate an in-pump system before we do it but I am personally in favor of "just doing it" based on the amount of feedback, especially of people located in the Southwest who have had similar problems that were essentially fixed with an in-tank pump.

I'll post up on the thread when we have more news, probably next Summer.

Thanks

 

[Elbert]

if you do the in-tank pump...why not replicate the GM setup and use a GM pump?

I've run the same external pump (Walbro) from day one on my engine swap without issue, with a simple setup using the stock tank.

All your issues go away with cool weather?

A nice in-tank fuel pump setup is nice and quite, but I think you had better understand your problem before jumping off into that. Maybe it will solve the issue.

You never said if your fuel lines were away from heat soureces and if the gas tank had adequate clearnace from exhaust.

I just think that a vapor lock induced issue from heat is not probable, unless you have something wrong with clearnce from heat sources or wrong fuel hose etc...

my fuel pump and 1st fuel filter are in the same general location, and my primary fuel filter is betwen the engine and the fuel pump.

in my mind vapor lock on a fuel injection systems takes some obvious exposure to a heat sourece....which you should be able to easily see. THe obvisou place this would take place would most likely be at the passenger side rear of hte engine...espically if you follow or use the stock fuel line or routing...as the exhaust manifold of the pasenger side is fairly close to that area.

If you go with an in-take pump....I would use the stock GM pump from a 97-99 GM pickup/SUV, if external pump I would use Walbro. Rover's post above shares a link where he setup an in-tank pump.

 

[lcwizard]

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

 

[ntsqd]

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.

 

[lehiguy]

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.

 

[rover67]

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.

 

[MANUCHAO]

When I ran an inline pump.. it worked fine but it was too damn 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 bitch 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.....

 

[dcoy]

if you do the in-tank pump...why not replicate the GM setup and use a GM pump?

I've run the same external pump (Walbro) from day one on my engine swap without issue, with a simple setup using the stock tank.

All your issues go away with cool weather?

We're at the early stages of planning, but we're considering the GM pump, although the whole experience of this conversion makes me want to avoid GM parts as much as possible (I've had numerous, relatively new, GM parts (not related to the fuel system) just spontaneously decide to die without warning).

Yes, high ambient temperatures (90 plus) seem to be the critical component here. Of coarse, you seem to need sustained highway speeds, mountains, and moderate altitude as well. But without the heat I have never had a problem. TLC in Van Nuys, the guys who did the conversion, say they have never had a problem like this with any of their other conversions, although few of them go to the desert Southwest. It seems that there is something special about this set of conditions since several other respondents to this thread that have had problems are in the Southwest, and the problem was rectified by an in-tank system. Interestingly, TLC did mention to us that they are going to in-tank pumps in their conversions, but the reason for this was not stated.

So it seems that you can get away with an external pump if your vehicle is not exposed to these somewhat specific conditions.

A nice in-tank fuel pump setup is nice and quite, but I think you had better understand your problem before jumping off into that. Maybe it will solve the issue.

I think that the way my system behaves along with what others in this thread have seen are pretty good evidence that cavitation (I think of this as a form of vapor lock) is occuring at the level of the pump. That would explain why placing the pump in tank would cure the problem (the in-tank pump eliminates the resistance of fuel line between the tank and the pump which I think of as the substrate for the cavitation). Beyond that, another poster did place a clear filter inline and was able to visualize lots of vapor (bubbles) in the fuel lines. I, personally, did also have a filter that was clear as well a number of years back. During one of these episodes, I saw the same thing although I wasn't sure how to put this observation into context and I subsequently moved to a non-clear filter.

You never said if your fuel lines were away from heat soureces and if the gas tank had adequate clearnace from exhaust.

I just think that a vapor lock induced issue from heat is not probable, unless you have something wrong with clearnce from heat sources or wrong fuel hose etc...

my fuel pump and 1st fuel filter are in the same general location, and my primary fuel filter is betwen the engine and the fuel pump.

in my mind vapor lock on a fuel injection systems takes some obvious exposure to a heat sourece....which you should be able to easily see. THe obvisou place this would take place would most likely be at the passenger side rear of hte engine...espically if you follow or use the stock fuel line or routing...as the exhaust manifold of the pasenger side is fairly close to that area.

If you go with an in-take pump....I would use the stock GM pump from a 97-99 GM pickup/SUV, if external pump I would use Walbro. Rover's post above shares a link where he setup an in-tank pump.

As far as a localized heat source, I believe I did mention above that the whole fuel system is along the passenger rail and the exhaust is along the driver rail. Therefore, we can't really substantiate a localized heat source as a problem.