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Aeration

Factory systems take this stuff into account so it's not so common there. Back when carbs were the **** it was somewhat more common because of no return line so if the fuel got hot it didn't get pushed back into the tank to cool. On Maulers setup every component of his system is getting hot. The engine comp is cramped, the fuel lines are attached to coolant (hot) tubes running through the frame, the tank is wedged between a hot radiator and exhaust pipe. The fuel just doesn't have a way to cool down once it gets hot.......Don't confuse this with getting air in the system, that's something completely different with simillar results. In this case the fuel is simply going past it's boiling point at pump regulated pressure so it turns to vapor. When the vapor goes past the injector it goes lean because liquid fuel is much more dense than vapor fuel...
 
Binder said:
Factory systems take this stuff into account so it's not so common there. Back when carbs were the **** it was somewhat more common because of no return line so if the fuel got hot it didn't get pushed back into the tank to cool. On Maulers setup every component of his system is getting hot. The engine comp is cramped, the fuel lines are attached to coolant (hot) tubes running through the frame, the tank is wedged between a hot radiator and exhaust pipe. The fuel just doesn't have a way to cool down once it gets hot.......Don't confuse this with getting air in the system, that's something completely different with simillar results. In this case the fuel is simply going past it's boiling point at pump regulated pressure so it turns to vapor. When the vapor goes past the injector it goes lean because liquid fuel is much more dense than vapor fuel...
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On jeffs rig--that may very well be whats going on.. But the boiling point of gasoline can vary from 100-400 degrees from what I am able to find...


And there is a VERY easy way to find out---take some hose, coffee can and some dry ice and run it that way for the day and see what happens...

Everything is just a guess until some kind of diagnostics are actually done....
 
crash said:
Everything is just a guess until some kind of diagnostics are actually done....
Click to expand...

Very true. Believe me we have gone round with this thing. I actually did hook it up to a wide band O2 sensor to it and logged for a bit. It showed a couple lean spikes but at the time seemed like not enough to be the problem. Only thing were sure of at this point is it seems to be a temperature related issue.
 
Binder said:
Very true. Believe me we have gone round with this thing. I actually did hook it up to a wide band O2 sensor to it and logged for a bit. It showed a couple lean spikes but at the time seemed like not enough to be the problem. Only thing were sure of at this point is it seems to be a temperature related issue.
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Lean spikes--would certainly not worry about that at all--you can get that after a hard accel and then off the gas for a bit....
 
Jobless said:
How hot does gasoline have to get before aeration occurs?
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Given a boiling point between 100* and 400* F at atmospheric (what a crazy spread), I'm getting between 174* and 509* F at 36 PSI.

I don't believe that 400* number. That's crazy. But if you've got the low temp stuff, 175* is no real stretch at all if you're fuel is surrounded by exhaust and radiators and engines and such.


http://www.ch.cam.ac.uk/magnus/boil.html
 
If you have AC, running a line from the interior along the fuel rail will cool it significantly. That's how they cleared up vapor lock with LPG MPFI.
 
As Rick stated,the fuel pump is below the cell. So I have drained the entire fuel system of the fuel from MOAB,dissasembled-cleaned contacts-reassembled the fuel pump,purchased insulation/installed on fuel lines(were appropriate),figured out the gas cooler I want and were to put it.I had planned on doing 24# injectors with 24# MAF from get go but now i will doit as one of the last major pieces of the puzzle that hasn't been changed out.More conversations with Conover really makes me think it is the injectors being fubar from sitting for three years on the engine stand.From the very beginning of the car being a runner we fought with varnished fuel in the injectors and being that $ and time was tight we just "fixed" what i had (stock 19# injectors) and "hoped" for the best.Well..............It sounds like that has caught up with me and now it's time for some fresh nozzles.

The car after re-boot basically go's into limp mode and doesn't read/see the MAF or the O2's.At sea level the car runs "OK".......gain any elevation,even up to the OM and it takes a ****......Moab was off the hook,didn't want to run/accelerate at all.
 
hmmmmmm...

What do you mean it doesn't read the maf/o2 sensors?

As for injectors thats possable. I don't think they are plugged--but it boils down to a shitty spray pattern. With those style of injectors--you can have an injector thats bad, and still flows the same as a good injector--but instead of a good mist/spray pattern you get dropplets.

But then you throw in the elevation change--which would not make alot of sense on the injectors. Noe granted I am no ford guru--but the basic logic of how that injection system (from doing a few now) is setup is really close to the gm setup--same basic principal...
 
crash said:
hmmmmmm...

What do you mean it doesn't read the maf/o2 sensors?

As for injectors thats possable. I don't think they are plugged--but it boils down to a shitty spray pattern. With those style of injectors--you can have an injector thats bad, and still flows the same as a good injector--but instead of a good mist/spray pattern you get dropplets.

...
Click to expand...

This precisly what Conover is saying about the injectors.

If you unhook the MAF or O2's at any point(after re-boot or at the end of a trail) it has NO effect on the motor performance.Brad and rick tested the circuit/signal to and from the MAF and 02's and the computer should be seeing them according to the ohm meter.We put the sensors in Brads car and they work fine(kill the motor when unplugged) stick'em back in mine and nuthin.....as if in limp mode/closed loop
 
FWIW I've had issues on a few different rigs when the rubber lines from the tank to the pump have weather cracked and sucked air. I haven't had this issue on this yota though, the pump is in the tank so if there is a leak there will be fuel leaking so its easy to spot..
 
jeepmauler said:
This precisly what Conover is saying about the injectors.

If you unhook the MAF or O2's at any point(after re-boot or at the end of a trail) it has NO effect on the motor performance.Brad and rick tested the circuit/signal to and from the MAF and 02's and the computer should be seeing them according to the ohm meter.We put the sensors in Brads car and they work fine(kill the motor when unplugged) stick'em back in mine and nuthin.....as if in limp mode/closed loop
Click to expand...

You could always have the injectors cleaned--but if you can upgrade then why the heck not...

have you tried swapping ecms?

And I suspect when in limp mode it stays in open loop--GM never had a limp mode..
 
crash said:
hmmmmmm...

What do you mean it doesn't read the maf/o2 sensors?
Click to expand...

It acts as if it's in open loop at all times and it very well could be. Without the proper test equipment it's hard to tell for sure. I only know so much about this system too but as you said it's very simillar to a GM system. In that case if it's running excessively rich or lean it would stay open loop due to the O2's not being in range to cycle. Vapor lock and/ or bad injectors could do this.
 

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