Vapor locking with FiTech, please help

[Hinmaton]

Over the years of having my FiTech occasionally I would have hot start problems, but they seem to be getting worse. In the past, I was always able to add a little fuel directly to the throttle body and it started right up, I had always assumed the Prime Shot function was fritzing out or something.

On the most recent trip it was happening every time the engine cut off- stall or otherwise (manual transmission). I was able to get it started a few times with the manual gas injection, but it began only running so long as the gas in the throttle body was present. I then noted that I had zero fuel pressure at the inline gauge right before the 10 Micron filter right before the throttle body. I assumed the filter was clogged, so I removed it. The fuel pressure was back and the engine started right up. This seemed to solve it until the engine was hot again (189deg max all day long) and it stalled or I shut it off. Same problem, no fuel pressure = no start.
So clearly it was cracking the lines and letting the vapor out, not the filter.
So I ran the rest of the day this way, if it shut off, I would just crack the line, let the vapor push the fuel back out, then it started no problem. Every time.
I am running 2000 5.0, with FiTech- ECU run timing, a G-Surge with a fresh Bosch intank pump, fed by a manual pump. I have the fuel returning from the throttle body to the accumulator and back to the tank. My tank is vented but gas always had pressure problems, if the tank is filled, it will push back out the cap. So I keep it roughly 3/4 full max (23 gallon BCB tank).

Since the trip, after lots of research, I came across information about the one way check valves throughout modern fuel injected vehicles. So I added one inline after the pump. Did some testing and it seemed like it would only hold pressure for a few minutes. I then decided to change the position of the check valve, removed 10 Micron filter, and then capped the return to the tank thinking that it contain any pressure bled off from the return system (I was assuming that the fuel was not leaking passed the injectors into the throttle body, because it always wanted fuel went it wouldn’t start), the results were identical. The gauge would go down to zero within 5 minutes or so, but if I cracked open a line fuel would shoot out?
I tried testing it by letting it idle and get up to 183 degrees (about as hot as it will get just idling still), shut it off, let it sit and heat soak and restart it. It did fine. I don’t trust it.

Clearly there is some manner of vapor locking going on, but maybe there is something off with the FiTech too? It was never this bad before. It’s 5 years old or so.
Any suggestions or thoughts?

Hh


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[Yeller]

all of those pieces under the hood trap heat, the filter, the Gsurge all of it. I've had no luck running that stuff under the hood, even with mostly open inner fenders. I know that the fuel injection companies even some of our own folks tout all of that stuff like its the easy way, best way and "fixes all issues" in my experience they only induce issues when it gets hot. Any reservoir that holds any volume of fuel needs to be as far away from the engine and as near the fuel tank as possible. I've found it very hard to beat a simple pump on the frame rail and a filter near the tank, always seems to work.

I know not what you want to hear but it is what my experience says.

 

[Hinmaton]

all of those pieces under the hood trap heat, the filter, the Gsurge all of it. I've had no luck running that stuff under the hood, even with mostly open inner fenders. I know that the fuel injection companies even some of our own folks tout all of that stuff like its the easy way, best way and "fixes all issues" in my experience they only induce issues when it gets hot. Any reservoir that holds any volume of fuel needs to be as far away from the engine and as near the fuel tank as possible. I've found it very hard to beat a simple pump on the frame rail and a filter near the tank, always seems to work.

I know not what you want to hear but it is what my experience says.

Fine I’ll do it right…
Not what I wanted to hear, but what I needed to hear.
Thanks,

Hh


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[Yeller]

Fine I’ll do it right…
Not what I wanted to hear, but what I needed to hear.
Thanks,

Hh


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Your welcome.

It’s that or move to northern Siberia, then you wouldn’t have to worry about vapor lock

 

[EPB72]

I agree with yeller on simplifying ,, but on the Siberia comment how about putting a bag of Ice over and around the surge tank and seeif anything changes?

 

[Jdgephar]

Fine I’ll do it right…
Not what I wanted to hear, but what I needed to hear.
Thanks,

Hh


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I found I had similar issues when I was in Denver this summer. I eventually need to move my high pressure pump out of the engine bay.

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[Hinmaton]

Your welcome.

It’s that or move to northern Siberia, then you wouldn’t have to worry about vapor lock

I moved it below the body behind the transfer case protected by the skid plate. The exhaust runs on the opposite side. One way valve just after the pump.

It should be cool, but it’s hot as hell.
With the temp at 186 degrees running fine, if I shut off the engine, the fuel pressure drops from 60 psi to 20 psi, when I try to start it, the pressure goes back up, but it doesn’t start.
Even if I let it sit for 20 minutes it won’t start. If I crack the lines to release any vapor lock pressure (it only seems to release the pressure that was still in the line?), it still won’t start. The only thing that does anything is putting gas in the throttle body.
It is definitely different now, but the results are the same.
Is it possible that the heat soaked FiTech is not sending fuel during cranking?
Or do I need an inline pump?

Pardon me while I go kick something for awhile…

Hinmaton


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[Yeller]

186* engine temp or the surge tank is 186*? 186* at the surge tank it is vapor locking. Now it is also possible that the Fitech is over heated as well….. I’d spray the throttle body down with water and see if it starts when it acts up. Still sounds like vapor lock.

Did you move the fuel filter too? If it is still where it was that is probably your vapor lock point.

 

[.94 OR]

I had issues when I had the sump pump. Went to a 23 gallon with a high pressure pump and all seems better now.

 

[73azbronco]

So pressure drop right after stopping. Is it a pressure check valve or a leaking injector? Hmmmm.

 

[Hinmaton]

186* engine temp or the surge tank is 186*? 186* at the surge tank it is vapor locking. Now it is also possible that the Fitech is over heated as well….. I’d spray the throttle body down with water and see if it starts when it acts up. Still sounds like vapor lock.

Did you move the fuel filter too? If it is still where it was that is probably your vapor lock point.

186 degree coolant temp.
The pump housing is not that hot.

I actually pulled the 10m fuel filter out of the system, it was causing a noticeable reduction in fuel pressure.


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[Yeller]

So pressure drop right after stopping. Is it a pressure check valve or a leaking injector? Hmmmm.

Vapor lock will cause this. so will a leaking injector or check valve.

My guess is heat soak in the throttle body is causing issues, whether it be vapor lock or electronic, potentially both. Have you tried spraying the throttle body with water to see if that causes it to rapidly get better? Duno, guessing trying to help trace down the issue. I'd still be curious of the sump temp.

 

[bmc69]

Fine I’ll do it right…
Not what I wanted to hear, but what I needed to hear.
Thanks,

Hh


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But...I had a nearly identical setup under the hood of my crawler with the 408C and never once had any issues like OPs. ? HP fuel pump mounted near the accumulator which was mounted on driver side fender well.. LP fuel pump always moving fuel from tank through accumulator and back to tank...maybe that's what is missing in OPs setup?

 

[Hinmaton]

But...I had a nearly identical setup under the hood of my crawler with the 408C and never once had any issues like OPs. ? HP fuel pump mounted near the accumulator which was mounted on driver side fender well.. LP fuel pump always moving fuel from tank through accumulator and back to tank...maybe that's what is missing in OPs setup?

That was exactly my setup. Return ran through the accumulator to keep it all cool. Still does.


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[Hinmaton]

Vapor lock will cause this. so will a leaking injector or check valve.

My guess is heat soak in the throttle body is causing issues, whether it be vapor lock or electronic, potentially both. Have you tried spraying the throttle body with water to see if that causes it to rapidly get better? Duno, guessing trying to help trace down the issue. I'd still be curious of the sump temp.

I haven’t tried cooling it with water, yet. Are we talking garden hose to the over heating radiator or splash some bottled water on it and give it a go?
Maybe I’ll try it tomorrow.


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[Yeller]

I’d use a Hudson sprayer lol.

 

[Hinmaton]

Trouble is, this only seems to happen when I’m on the trails in the thick of it. I can’t seem to re-create this in an environment where I have control over what’s happening.

Another data point.
My truck would not start after sitting for over an hour. The engine was still warm, but not hot by any means.
But by adding a tablespoon of gas to the throttle body, it started right up.
Doing this seems to work every time.


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[bmc69]

It will never start on its own with no pressure at the injectors. Do you clearly hear the HP pump cycle on briefly when you first turn the key to "on" when starting the engine? Does the fuel line pressure jump to 40 or whatever its supposed to be for that setup? Its supposed to..and then its supposed to stay there. (duh, I know). Had this same issue with son's '90 Bronco...fuel pressure would immediately sag back down to zero after the initial HP pump cycle and it wouldn't start without a shot of starting fluid. I changed the fuel pressure regulator and fuel pump at the same time and that cured it..but left me wondering which was the culprit...LOL.

 

[BGBronco]

I had similar issues with FiTech. Mine turned out to be a bad injector. They are pricey but solved the problem.

I ended up swapping my FiTech with a Holley Sniper. Sniper isn't perfect but I've had minimal issues.

 

[Hinmaton]

It will never start on its own with no pressure at the injectors. Do you clearly hear the HP pump cycle on briefly when you first turn the key to "on" when starting the engine? Does the fuel line pressure jump to 40 or whatever its supposed to be for that setup? Its supposed to..and then its supposed to stay there. (duh, I know). Had this same issue with son's '90 Bronco...fuel pressure would immediately sag back down to zero after the initial HP pump cycle and it wouldn't start without a shot of starting fluid. I changed the fuel pressure regulator and fuel pump at the same time and that cured it..but left me wondering which was the culprit...LOL.

The pump does discernibly turn on and stays on while cranking.
But I haven’t replaced the regulator yet.


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