I am certain the problem of fuel pressure loss is not the tank vent. I now have it vented well, and when you take off the cap entirely, the problem still exists.

If I can trust the electrical fuel pressure gauge, the pressure is still dropping off after it gets warm. I ordered a mechanical gauge from Summit, but it leaked, and did not register, so I sent it back to be replaced. Until the new one shows up, I cannot verfiy that the pressure is indeed low. For now, I will do nothing further until I can verify the actual pressure, but I would like to at least think about alternatives if the mechanical unit shows the pressure is indeed dropping off.

It has to get really warm before it shows up but it does show up. This would suggest either the fuel pump or the pressure regulator is at fault. . While it is expensive and difficult to change this pump, it might be cheap and simple to change the pressure regulator if some one could recommend an OEM application for a turbo charged engine. It would need to have a vacuum reference,and be something I could plumb into a 6 AN line. I looked at a regulator for a ford 5 liter engine, which was only $39 bucks at Pep Boys, but it required a special mounting fitting it gets screwed to.O looked one for a Corvette, but could not tell what was supposed to plumbed to what on it. It was not obvious which end was in, and which was return. I could go to a junk yard and get the fitting from a Ford in the yard, but am hoping maybe this has already been researched here on the forum. I am hoping there is a GM or Chrysler regulator out there that is a simple in and out style with nipples or fittings on each end.

This particular pressure regulator, unit is the second expensive after market regulator I have put on this set up, and am not at all convinced expensive after market ones are better. The first failed in a different way. It failed to hold pressure after shut down, and I was told this was why the car would not start when it sat for awhile. Looking back on it, the ACcel ECu might have been a bigger part of the problem. But, that is behind me. The Mega Squirt has not failed to start so far, and I suspect it will do its part of the job flawlessly if I can stabilize the fuel pressure. I no longer have the first pressure regulator, so it is not an option to put that one back on and try it.

Any thoughts here? Thanks.


Sam

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The best advice I can ask for is how to diagnose this problem since it does not show up until the engine is too hot to open the fuel line on. It would be best to know for sure which part is defective, but if I have to throw parts at it, I want to throw the cheapest ones first.

Sam

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Slow the <expletive deleted> down! Wait until the mechanical gauge comes THEN worry about things like the regulator or pump. Your mind is racing as fast as your dumping $$ out your wallet

Regulators are fairly simple devices. If they hold vacuum (you can use something like this or even your mouth on the vacuum port to test) then they are likely good.

Do me a favor - feel how hot your fuel rail is after running / driving and this symptom develops. I'll let you know where I'm going with this once you come back with an answer.

Thanks Pierre.It is great to have your bright mind thinking about this. I have already vowed not to do anything until I get a better handle on this. Although, that has not been my pattern in the past, I have recognized my impulsiveness as a problem to work on.

How should I judge the hotness of the rail? Can I put a spot temp gauge on it? I have access to one. Right now, everything under the hood gets blisteringly hot. You cannot stand to touch most of the stuff.

As I see it there are three challenges on this car currently, and they are somewhat related:

1. Management of under the hood temperatures.
2.Stabilizing fuel pressure.
3. Get better boost control

Thanks again.

Sam

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Sure would like to see some pics of your set up..........hard to visualize just what is what.........where is your fuel rail ,your return line, etc etc.
hope I could help then.
best regards .......max

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1966 barracuda 360
1964 signet conv. 170 turbo
Bonneville or Bust 2012

I'll write more tonight. Thanks for the offer.

Sam

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Too hot to touch? Hot enough to hold for 10 seconds but not more? Warm to touch? Cool to touch?

Pierre:
Are you thinking fuel boiling problem? Caused by mechanical fuel pressure drop off, or pressure drop due to fuel boiling because the pressure is not high enough to prevent a phase change?

Any thermal guys out there that can shed some light on fuel boiling temperature vs. pressure.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

If the fuel rail is running hot, you might wind up fixing it by increasing the volume of fuel flowing through the system. This would practically entail reworking the regulator setup so as to have a higher flowrate through the return side of the system, thus continually cooling the supply side with fresh fuel from the tank. But the point about not buying any new parts til you've put an actual gauge on the line is an excellent one. While you are waiting to do that, check the routing of your fuel lines all the way along the whole supply side, especially in the engine bay and near the exhaust system. Find ways to insulate and/or isolate the lines from heat sources.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

This kind of discussion is priceless. I will check it out soon. There is much to do today. The fuel rail is right over the manifold, of course, and the turbo exhaust flange is a mere 7" from the fuel rail. That can't be good. I was tinking it might help to construct an aluminum heat shield between the turbo and the entire manifold and fuel rail. If I had it to do over again, I would move the turbo further out by a few inches, and forward by 4 or 5 inches to get it away from the intake and fuel.

I originally thought the order of fixing things was:
1. Fuel supply
2 Heat handling
3. wastegate.

Now I am thinking heat handling is an essential component, and must be addressed earlier on. Once I get the time to start it and run it a bit, I will do the hands on test, and let you know what I find. Of course, the AN lines are rubber with stainless around them, which will not give a true sense of the heat there. But the fuel rail, and the FPR will. Thanks again to all.

Sam

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Pierre, I let it idle for 30 minutes while I worked on putting new brake lines on a friend's Miata. It never got as hot as it would have had I driven it and then checked it out, but the fuel pressure did drop from 43 to around 34, in stages. I checked the temperature of the FPR and the fuel rail in two ways. Measured with a spot gauge it was 135 for the FPR, and 235 for the Fuel rail It went up in stages of course. When the fuel rail was 175 the pressure was around 37psi. I'm sorry I forgot to look at the temp gauge. It was raining cats and dog at the time, and I was running out in the rain to check it out, and leaning under the hood to stay dry while I was checking it out.

Using your measure, I could not stand to touch the fuel rail for more than a second or two. And, I could only hold onto the FPR for 4-5 seconds if that. I did a spot check of the turbo flange and it read 350 for a bit, and then went off the scale of the measuring device. I will do this again after I drive it. I am still waiting for the pressure gauge from Summit. I have received notice that it has been received as a return.

I am wondering if the intercooler is worth while. The plumbing takes up so much room under the hood, and the intercooler sits in front of the radiator, which has got to be a bad thing. I am wondering if the gains are outweighed by the loses. There are bound to be loses in all the piping as well. Every time the tube takes a corner, that supposedly causes heat to build up.

So Pierre, you have some idea to share here about keeping the fuel cooler? ARe you thinking something like a tranny cooler tied to the frame?

Sam

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235F? Whoa! x 2. Your not burning fuel mist, your burning fuel vapor. Sam take some fuel and poor it on your driveway during a hot day. It's almost instant vapor. Now imagine 235F.... There is no way you can expect consistency with that much heat in your fuel. Injectors don't expect steam coming into them.

Let's start with a pic with the hood up so we can see the routing of everything. Throw a ruler or tape measure in there for a sense of scale. Show the filter as well if you can.

A fuel cooler is an option but if the fuel is being heated up under the hood itself then it really doesn't matter if you cool it before.

The opposite way to look at it - how cool is the input fuel? The fuel doesn't spend much time in the rail, couldn't be more then a second or two for it to go from one end to the other. Even with a high under hood ambient, if you have sufficiently cool fuel input, you will have cool fuel coming out (and a much cooler rail). IIRC you got a tank with an integral sump / pump. Warm fuel is being put into the sump, and sucked right back into the pump. It may not have sufficient time to cool. How hot is the return line at the pump? It may make more sense to put a cooler on the return line, or dump the return into the tank not the sump. This will let it it mix with a much larger volume of fuel, letting it cool itself.

Learned from experience. When I was running my TBI setup, I didn't dump the return into the tank. I t'd it back into the pump input. Now that was a quick way to heat up fuel.

Increasing volume should only be done if you are actually going to use it. The more volume a pump produces, the more work it does. More work = more heat. Ideally a pump is matched to the engine it's mated with. Sure a bigger pump won't necessarily hurt things, but if your already running into heat issues....

Pierre, I will get more careful readings today. This spot reader is pretty specific, but I was in a hurry, and there is a lot of other hot stuff under there. I know the regulator measured 135, which also seemed pretty hot to me. The fuel rail measured 185 degrees at partial warm up. I could see the fuel pressure drop as the temp went up on the fuel rail, for sure.

I am thinking about getting rid of the intercooler. It sits in front of an AC condensor, which sits in front of the radiator. It is not a flow-through,which means a 180 internally, and there is about 8 feet of 3" tubing and coupling that clog everything up, which has to add to the heat under the hood. Also, there are 8@ 90 degree bends, plus an additional 180 near the TB. In the end I think it does more harm than good. I can keep all the parts if, in the end, I want to put it back. But, I kind of think everything here should be re-engineered at some point anyway.

And yes, I was thinking a cooler on the return line.

If you will send me your e-mail, I can send you photos of the under hood set up. I may be trying to do the impossible here, as the turbo itself is only 7 inches from the fuel rail. There really is not much space between the driver's inner fender and the TB opening on a slant's intake manifold. Might be a good set up for way north in Manitoba.

Sam

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Sam, remember the one thing after another principle. I imagine removing the intercooler is not a 10 minute task. If your jonesing to remove it, I can't stop you. But lets figure things out here first.

We'll do like what we did with your gas tank pix. I'll PM you my email then when you send the pix I'll post.