Curing Vapor Lock in a 5.7 Vortec FJ60 (2 Viewers)

[dcoy]

I would appreciate anyone's feedback if you wouldn't mind taking a few minutes to read through this minor tome. I have an '86 FJ60 with a 5.7 Vortec Conversion. It has had fuel supply issues from the beginning (2004). A fairly specific set of conditions will lead to failure: Running at highway speeds, usually with a significant load (a trip load out or a trailer), high ambient temperature (90-100+ degrees F.), usually a sustained grade, running for about one hour, and usually some altitude (usually around 3000 to 4000 feet). Failure comes abruptly, usually while ascending a grade. There are only a few seconds warning. It stops and fails to restart. Plenty of voltage from the battery and the starter turns over but the fuel pressure is consistently under 50 psi (Vortec require >50 psi) . Often I don't have time to leave the traffic lane, or often there is a two lane road with no shoulder so I am stuck in the middle of the road. Engine temperature is fine. The usually remedy has been waiting for the vehicle to cool, then restarting and limping along to a point where I can change the fuel pump. Invariably, that takes care of things for the rest of the trip, although the severity of the stated conditions are usually not repeated (for example, we get to Moab or wherever our destination is and driving around town and trail goes without incident). We finally decided that the problem must be fuel pump overload/overheating (in the GM setup, it is supposed to be in the tank). We installed an inline fuel pressure gauge, an inline heat sink, and two pumps in line that can be switched on the fly. A cool setup, only it doesn't work. I gave it the definitive workout this summer in 90+ degree heat driving through the Navajo Reservation and some local mountains and found that switching to a "fresh" pump does not give me fuel pressure back. The key maneuver I performed which, I believe, has clinched the alternate diagnosis (vapor lock) is that I vented the fuel system as if I was changing the fuel pump and instantly restarted the vehicle and drove home. The next step (fixing the problem), is less clear. But given that, we think that, the key, remediable factor generating the vapor lock is heat therefore we believe that a critical temperature in the engine compartment is likely creating the vapor lock. Therefore, my plan is to take a drive in characteristic conditions with the hood off, which should drastically cool under hood temps. If this prevents this phenomenon (and thus proves our hypothesis) the next step is not so clear. We are considering insulating the fuel line within the engine compartment to prevent the relatively sudden increase in temperature around the fuel lines that occurs as it enters the engine compartment. Beyond that, I am looking for any other ideas or experience with this problem that any of you might have with this, or similar problems.
For those of you who have finished this discourse I appreciate any feedback you may have. It is a cool truck. I have put an incredible amount of time and energy (and money) into this project but we really need to get to the bottom of this problem so we can drive it and trust it to get to our destinations; it has ruined more vacations than I care to count.
Sorry this is only my second post. I've been lurking for a long time though.
Thanks
David

 

[Elbert]

What are your engine temps when this is happening? What brand and model number is the fuel pump? What type of fuel filters do you have.

Fuel injection vehciels normally don't have issues with vapor lock.

do you have the vent line that use to connect to the charocal cannister capped or is it open? Your fuel tank must be vented. You do have both the supply and return fuel hoses connected?

What is the location of your fuel pump and fuel hoeses....hopefully you don't have them routed near exhasut (heat source).

I have a 1999 GM 5.7 vortec in my truck so we should have pretty identical setups.

Assume the check engien light is not flashing.

I have run walbro fuel pumps from day one (I'm still using the same fuel pump I installed at day one).

I ran rubber hose (approated type to the metal tube of the fuel tank and bascically replcated what was OEM over to the passenger side frame. then down to a non restrictive russell fuel filter, then walbro fuel pump.....then about a foot forward I have a GM fuel filter (off a 99 SUV/Pickup GM), then the fuel hose runs up to the engine.

Your fuel pressure has to be right on the money or its just not goign to run right. I'll asnwer any questions you may have about what I've donw. I'll be out of the loop tomorrow but I'll check the board sometime Sunday. On the low pressure side of the fuel system I'm running fuel injection rated rubber hose, on the high side of the fuel system I'm running braided fuel hose.

 

[rover67]

How hot is the actual fuel in the fuel tank getting? How much pressure is building in the tank?

I had similar issues when my exhaust was heating up my fuel tank to ridiculous temps and would essentially cause the fuel to boil.

Is the inlet to the pump fairly clear or do you have a filter or something that could be restricting it? Sounds like the pump might also be cavitating, that's why I mention that.

 

[torfab]

I have run into similar situations, where the fuel filter was restricting the flow adthe ngine would cut out. What kind of filter do you have? And where is it located?

 

[dcoy]

What are your engine temps when this is happening? What brand and model number is the fuel pump? What type of fuel filters do you have.

Fuel injection vehciels normally don't have issues with vapor lock.

do you have the vent line that use to connect to the charocal cannister capped or is it open? Your fuel tank must be vented. You do have both the supply and return fuel hoses connected?

What is the location of your fuel pump and fuel hoeses....hopefully you don't have them routed near exhasut (heat source).

I have a 1999 GM 5.7 vortec in my truck so we should have pretty identical setups.

Assume the check engien light is not flashing.

I have run walbro fuel pumps from day one (I'm still using the same fuel pump I installed at day one).

I ran rubber hose (approated type to the metal tube of the fuel tank and bascically replcated what was OEM over to the passenger side frame. then down to a non restrictive russell fuel filter, then walbro fuel pump.....then about a foot forward I have a GM fuel filter (off a 99 SUV/Pickup GM), then the fuel hose runs up to the engine.

Your fuel pressure has to be right on the money or its just not goign to run right. I'll asnwer any questions you may have about what I've donw. I'll be out of the loop tomorrow but I'll check the board sometime Sunday. On the low pressure side of the fuel system I'm running fuel injection rated rubber hose, on the high side of the fuel system I'm running braided fuel hose.

Thanks for the detailed response. I'll try to answer in order.
The engine block temp was 120-130 on my last run when I was monitoring through the OBDII port. This, we thought, was not particularly high but still could be heating the engine compartment to the degree where vapor lock could be caused.
The fuel pump is an MSD 2225 which is a high pressure, high performance pump. I'm trying to find the filter specs but I'm not having success yet. I believe it to be a GM item.
My reading says the same, that vapor lock is not common in fuel injected vehicles, but when I read about the conditions creating vapor lock (with or without cavitation) it seemed to fit my situation (high temps plus altitude, in particular).
We have checked the venting of the tank and appears to be okay. I don't know about a charcoal cannister. We also replaced all fuel lines to remove any constrictions that could increase resistance and increase workload on the pump. There was a fitting at the take off from the tank that was 1/8th of an inch. We changed to a 3/8th inch fitting that was consistent with the rest of the fuel line.
The fuel pumps are rail mounted on the opposite side from the exhaust.
We're running metal fuel line the whole way.
We also put a Barry Grant Heat Sink inline upstream from the fuel pumps. These, by their specs, have a pretty impressive ability to cool the fuel, and by extension, the fuel pump.
No check engine lights when this happens, and oh yes, this engine is exquisitely sensitive as I've noted with my fuel pressure gauge on the dash => if the pressure is less than 50 the engine will not play.
Thanks for helping me to work through this problem. I, unfortunately, did not do this myself, and I am a novice mechanic but I am learning alot (probably more than I want to) from this process.

 

[TobyB]

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

 

[dcoy]

How hot is the actual fuel in the fuel tank getting? How much pressure is building in the tank?

I had similar issues when my exhaust was heating up my fuel tank to ridiculous temps and would essentially cause the fuel to boil.

Is the inlet to the pump fairly clear or do you have a filter or something that could be restricting it? Sounds like the pump might also be cavitating, that's why I mention that.

There isn't an actual fuel temperature sensor (not that we couldn't make one). We have addressed fuel temperature issues by putting the Barry Grant heat sink inline (upstream from the pumps). That has been shown to decrease fuel temperature almost 100 degrees (Barry Grants data), although it obviously couldn't cool it any lower than ambient.
As I mentioned in my other reply, the fuel tank appears to be venting appropriately and the fuel supply is located away from the exhaust as well.
The fuel filter is post-pump, it is GM-spec and we have checked it (and replaced it) frequently to assure there is no debris increasing resistance to pump flow.
I do wonder about cavitation by the pump and my reading has said that cavitation is essentially one form of vapor lock (it is a way of generating the vapor). My ability to vent the fuel delivery system right at the level of the pump and instantly restart after waiting on the side of the road for about 45 minutes I think supports that. That is why I am concerned that dealing with under hood temps may not fix the problem if the source is at the level of the fuel pump (cavitation). The pressure transducer, by the way, is about 4-5 feet forward of the pumps/filters on the rail as well. If, when this is happening, I force the pumps to run (we rigged a direct circuit to the pumps because the ECU normally shuts down the pumps after 5 seconds if the engine doesn't start), the fuel pressure at the transducer will actually go down. But when I vent the fuel line the pressure goes back up without even giving the pumps a rest, meaning the pumps are continuing to work like champs but they're just pumping against vapor until it is vented.

I have run into similar situations, where the fuel filter was restricting the flow adthe ngine would cut out. What kind of filter do you have? And where is it located?

Oh yes, I believe this was responded to above. Briefly, we are using GM spec fuel filters that we have checked repeatedly. I will recheck with my mechanic about their identity and their flow characteristics.

 

[dcoy]

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

Hmmm, I'm going to have to let your reply digest a little bit.

Thank-you and thanks to everyone for their replies so far.

 

[Elbert]

easy way to see about fuel tank pressure is this.... do you get a lot of pressure release when you open the gas cap to add fuel, if so the gas tank most likely is getting over-pressurized or not vented properly.

Are you saying the engine temp is 120-130F when this happened last? That's not even warmed up. What is your normal operating temp..I assume something like 180-195F?

It sounds like you have a fuel line near a heat source potentially (check the full length of the fuel line), or simply a fuel pump issue. You said you have swapped out fuel pumps...are you installing the same one multiple times? I can't overstate that the fuel pump is critical and the walbro brand is the one to get.

YOu can't have a restrive fuel filter between the tank and pump (not clear what you have), you certainly need a filter between the pump and engine. Assume you have replaced the fuel filter. I only run a GM type filter between my fuel pump and engine as its easly replacable and well proven (GM pickup/suv from 1999 model year).

my exhaust gets warm/hot....I have not had an issue with my fuel tank getting hot but you can't rule that out if your exhasut is very close to the fuel tank. I think I have 2 to 3 inches gap or so (maybe less) I'll look at Sunday to see.

I would start by making sure that you have no heat sources that are impacting the fuel tank or fuel hose. I would change the fuel filters, making sure you have ones designed for high pressure fuel system, and I would consider going with Walbro fuel pump. I have forgotten what size fuel hose we used but on the low pressure side (between tank and electronic fuel pump) I'm simly running fuel injection rated hose the same size that fits the OEM fittings at the fuel tank or very similar...then from the fuel tank forward to the filter and engine we used high pressure braided hose along with AN fittings.

If you guys used metal line (hoep its new...not the factory toyota line) I suspect its very close to the passenger side of the engine...I would look to make sure you have clearnace from the exhaust there.
You want to run at least the same ID hose that a GM SUV/Pickup ran on their trucks so you have enough fuel volume. I assume you are ok on that but just noting.

YOu need to make sure that the hose I'm spoke about earlier that ran to the charcoal canister is not capped off. I'll take a picture of the hard line on the firewall where the hose use to connect to. I removed the OEM charcoal cannister when I swapped engines, I assume yours was probally removed as well.

make sure you have no kinked fuel hoses the full length of them....from the tank forward all the way to the engine.

 

[dbleon]

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...

good luck

 

[dcoy]

Are you saying the engine temp is 120-130F when this happened last? That's not even warmed up. What is your normal operating temp..I assume something like 180-195F?

Whoops! Duh! Meant to write 220-230F. Normal cruising temp is under 200F.

I'll go through the rest of your responses and get get back with you after I check afew things under the Cruiser.

Have a nice weekend.

 

[ntsqd]

A couple of things:
A) Not all modern EFI fuel systems have a return line back to the tank from the engine. I know that GM uses a Pulse-Width Modulation (PWM) scheme to control fuel pressure on some of their systems with returnless (single direction) fuel plumbing. It would behoove you to look into how the original vehicle for your engine was plumbed and make sure that your FJ's fuel system plumbing is as much of a clone of it as is possible.

B) The odds that the vapor lock is occurring downstream of the pump are pretty slim. At ambient pressure fuel boils between 80*f and 437*f. Raising the pressure to just 40 psi moves the boiling points to 110*f/572*f. (Fuel isn't one type of molecule, it is a mixture of different molecules - each with it's own unique boiling point.)
However, reducing the pressure on the fuel will reduce it's boiling point. Reducing the pressure on the fuel, as does happen in the sections under vacuum between the pump and the fuel tank, will cause the fuel to boil at a lower temperature. Reduction from ambient (14.7 psi) to 10 psi reduces the boiling point range down to 70*f/396*f
(Boiling Point Calculator)
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. Those are a OEM pump and will have a much higher MTBF rating. Some guys have gone to a suction pump to supply the HP pump. I did this, but more to head off the kinds of issues that you're having than anything else. The key to a suction pump (I used a Carter ~5-10 psi carb application electric fuel pump) is to place it as low as you can and as close to the fuel tank as you can. The trade-off will be how protected it is in the location. I mounted mine in a compromised spot. It's not as low as it could be, nor is it as close as it could be. It is in a fairly protected spot though. More on what I did and why here: https://forum.ih8mud.com/60-series-wagons/336261-my-84-60-build-wallace-5.html#post6295933 and here: https://forum.ih8mud.com/60-series-wagons/336261-my-84-60-build-wallace-5.html#post6321809

 

[dcoy]

Supporting photos

Before I respond to some of the above questions and ideas, I thought it would be helpful to provide a little more background info and a few photos.

First, the 1999 5.7 L Vortec installation in the Cruiser. It had about 50 miles on it upon installation:

The conversion was performed by TLC in Van Nuys. I bring this up to point out this was performed by professionals who have done this conversion multiple times in the same manner, apparently without the same problem. Unfortunately, TLC has been unable to help me with this problem although I have been in contact with them from the very beginning (literally at the time of the very first breakdown). They have seen the Cruiser and have checked the venting of the tank (a 42 gallon aftermarket item). The other work addressing my fuel supply issues has been done here in Flagstaff, AZ by Accubrake 4x4.
Here is my in-dash digital fuel pressure gauge :

and my in-dash switch for my pumps:

I'll continue the photos in the next post.

 

[dcoy]

More photos

:whoops: , I've exceeded my (pathetically low) online storage capacity. I guess I'll have to figure out how to fix that problem before I continue posting.

 

[505 crusher]

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.

 

[ntsqd]

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

 

[dcoy]

Boy, lot's of specific technical issues coming up. I'll have to sit down later to address them all (and also deal with the photo issue).
One interesting theme that I found to be particularly provocative so far is the several references from the Southwest (places with heat plus altitude) regarding fuel pump cavitation that has been addressed by placing in-tank fuel pumps. I think that would be consistent with what is happening to me. In fact, when we decided to go to a dual fuel pump system we also considered the in-tank pump but opted for the dual pumps on the rail plus heat sink because we felt that pump work and overheating was the primary issue not cavitation. We also didn't like the idea of having to drop the tank for pump access. Perhaps we should have gone that way in the first place.

 

[Kurtis]

Like Elbert said absolutely do not put a high pressure filter in between the tank and the pump. It will fry your pump over and over. Only use a larger less restrictive filter between the two and the high pressure filter between the pump and the engine. aztpi.com sells a nice walbro complete setup with some good filters.

The other thing like everyone says Walbro pumps are much much better than the MSD ones. I've had a inline walbro in my setup for 2.5 years. I don't see a need to put it in the tank personally and I live in AZ and sit in traffic at 115 degrees with my a/c on.

Read the link I posted below it pretty much sums up what has worked for others with similar setups and pressure requirements.
https://forum.ih8mud.com/60-series-wagons/471535-5-3-fuel-pump-wtf.html

 

[dbleon]

I've had a inline walbro in my setup for 2.5 years. I don't see a need to put it in the tank personally and I live in AZ and sit in traffic at 115 degrees with my a/c on.

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.

 

[dcoy]

easy way to see about fuel tank pressure is this.... do you get a lot of pressure release when you open the gas cap to add fuel, if so the gas tank most likely is getting over-pressurized or not vented properly.

Are you saying the engine temp is 120-130F when this happened last? That's not even warmed up. What is your normal operating temp..I assume something like 180-195F?

It sounds like you have a fuel line near a heat source potentially (check the full length of the fuel line), or simply a fuel pump issue. You said you have swapped out fuel pumps...are you installing the same one multiple times? I can't overstate that the fuel pump is critical and the walbro brand is the one to get.

YOu can't have a restrive fuel filter between the tank and pump (not clear what you have), you certainly need a filter between the pump and engine. Assume you have replaced the fuel filter. I only run a GM type filter between my fuel pump and engine as its easly replacable and well proven (GM pickup/suv from 1999 model year).

my exhaust gets warm/hot....I have not had an issue with my fuel tank getting hot but you can't rule that out if your exhasut is very close to the fuel tank. I think I have 2 to 3 inches gap or so (maybe less) I'll look at Sunday to see.

I would start by making sure that you have no heat sources that are impacting the fuel tank or fuel hose. I would change the fuel filters, making sure you have ones designed for high pressure fuel system, and I would consider going with Walbro fuel pump. I have forgotten what size fuel hose we used but on the low pressure side (between tank and electronic fuel pump) I'm simly running fuel injection rated hose the same size that fits the OEM fittings at the fuel tank or very similar...then from the fuel tank forward to the filter and engine we used high pressure braided hose along with AN fittings.

If you guys used metal line (hoep its new...not the factory toyota line) I suspect its very close to the passenger side of the engine...I would look to make sure you have clearnace from the exhaust there.
You want to run at least the same ID hose that a GM SUV/Pickup ran on their trucks so you have enough fuel volume. I assume you are ok on that but just noting.

YOu need to make sure that the hose I'm spoke about earlier that ran to the charcoal canister is not capped off. I'll take a picture of the hard line on the firewall where the hose use to connect to. I removed the OEM charcoal cannister when I swapped engines, I assume yours was probally removed as well.

make sure you have no kinked fuel hoses the full length of them....from the tank forward all the way to the engine.

Thanks Elbert

I thought I felt a pressure differential once when pulling the gas cap after this happened but it did not happen again.
All of my fuel lines are on the opposite side of the vehicle from the exhaust (the inline heat sink is a little closer (it's midline) but it's still about a foot from the exhaust.
Based on your recs and others, will put the Walbro on the wishlist.
We put new, stainless 3/8th inch diameter (GM spec, I understand) throughout.
The fuel lines run much more cleanly and direct than before (TLC, I believe used the stock fuel lines that had many more transitions that I think could add resisitance).
We have a GM spec fuel filter between the pump(s) and the engine, about 1 foot downstream.
I will check on the status of the charcoal cap just to be sure.

David