Fuel system insulation

Lateer · Post by **Lateer** » Tue Oct 25, 2005 9:19 pm

My poor Tercel is having a few problems.
This is the first time this has happened since I had the radiator repaired. I might be taking the car back to that repair shop and asking them to have a look at it. The car is running a little hot for my tastes.

Basically what I think is happening is that as the fuel runs through the line past the block, it's getting too damn hot. This is in turn hitting the hot Weber carb and then boiling. I can hear it after climbing hills. A little *pop* sound coming from the float bowl.

This is causing me no end of headaches. The car doesn't run right, pinging and stuttering and carrying on.

Anyone got any ideas to insulate the fuel line/carb?
I've noticed that some of us have huge insulators between the exhaust and inlet manifolds...

Typrus · Post by **Typrus** » Tue Oct 25, 2005 10:10 pm

Bypass the mechanical fuel pump.
Potentially---implement reflective insulation tape (assuming can be found with enough heat tolerance)
Get some air flow past that area- Hood scoop flowing donw onto the carb area (not necessarily into the carb, just around)
Thin steel plate formed and placed halfway between the block and line.

Gasoline Fumes · Post by **Gasoline Fumes** » Wed Oct 26, 2005 2:16 am

Check the heat valve in the exhaust manifold to see if it's stuck open. I'd just jamb it permanently closed somehow.

gus · Post by **gus** » Wed Oct 26, 2005 3:20 am

On the used 86 I bought used some one had put a black foam pipe covering over gas line from fuel pump to carb.
It looks like the black foam used on water pipes.

takza · Post by **takza** » Wed Oct 26, 2005 4:28 am

In the US you can buy a 2" wide roll of tape that has an alum layer and a thin foam layer that is used to insulate plumbing...could wrap the line with this.

With heated fuel...that raised the fuel temp up to 150F vs the usual 110F...while crawling...I never saw boiling fuel in the OEM carb...still got the sheet steel heat shield?

Lateer · Post by **Lateer** » Wed Oct 26, 2005 4:54 pm

No, and that's what I think is causing the problem.
There's no sheet steel heat shield anywhere near the carb.
Whoever did the conversion thought that it was making the carb too high, I guess.

I put on a new radiator cap and had a good look at the old one. The old one was buggered. Completely. Rusty and covered in goop.
Since then, things have been much cooler, as the system wasn't pressurised so high.

When I replaced the fuel line, I didn't put the insulation back on. Not so much of a problem in winter, but now it's getting into summer, it made a bit of a difference.

I've also got a can of Clean-R-Carb, by CRC. I'll give the Weber a jet or two of that in choice locations, such as the idle circuit, down the emulsion tubes, down the air jets and into the main jets at the bottom of the float bowl. Then we'll see if the car runs any better. By the by, does anyone have a preference between WD-40, CRC 5.56 and Selleys' RP-7? They all do the same job, but can anyone tell me any difference between them?

Where's the heat valve in the exhaust manifold? I had a look at the workshop manual and didn't see it...

Gasoline Fumes · Post by **Gasoline Fumes** » Wed Oct 26, 2005 11:18 pm

Lateer wrote: Where's the heat valve in the exhaust manifold? I had a look at the workshop manual and didn't see it...

Right at the top of the exhaust manifold. It opens up at low temperatures to heat the intake manifold.

shogun · Post by **shogun** » Thu Oct 27, 2005 2:56 pm

fabricate a cool can, coil up some aluminum o r copper tubing put it inside an old lunchbox or some sort of insulation cork will do also, and plug it to your system

Lateer · Post by **Lateer** » Thu Oct 27, 2005 7:02 pm

Well, the Tercel went into the Almighty Mechanics this morning.
This is the last resort for me and my car. I only take it to the mechanics when either I haven't got the tools to fix whatever the problem is (like a press, wheel balancer, gas analyser, oscilloscope) or when I have no idea what the problem is.

When I described the problem, the mechanic said he'd put it on the oscilloscope, as I'd already gone through the things he would have tried first.
Hence, that falls into both categories.

So, I'm thinking something wrong with either the armature or rectifier within the alternator. That's the only reason I'd put something on an oscilloscope.

I'll let you know what happens when I get it back.

Oh, and the car ran cool as a cucumber when I replaced the radiator cap. The old one was hard as a rock, no compression on the spring at all. The new one compressed fine and allowed the system to depressurise and everything.
I'll still check out the heat valve. Maybe that's stuck shut, or open or whatever. What's it actuated by? Vacuum or temperature?

Gasoline Fumes · Post by **Gasoline Fumes** » Thu Oct 27, 2005 11:23 pm

Lateer wrote: I'll still check out the heat valve. Maybe that's stuck shut, or open or whatever. What's it actuated by? Vacuum or temperature?

Just temperature, I believe. There's a heat-sensitive clock spring-type thing that loosens or tightens based on temperature.

Lateer · Post by **Lateer** » Fri Oct 28, 2005 12:01 am

Do you need to disassemble the manifold to access it or can you see it from the outside?

I've looked at my manifold from underneath, behind, in front and above and not seen something that looks like this before.

But then, I don't know what I'm looking for...

Post by **ARCHINSTL** » Fri Oct 28, 2005 1:20 am

Chris and takza helped me on this one back in June...
It is invisible unless the heat shield under the carburetor is removed. You can barely see it from underneath. It is really hard to get your fingers in to feel it with the heat shield in place. It is on the exhaust manifold directly below the "gap" in the intake manifold branches.
It is a weight and a spring. There is a pix on Autozone's site, in the emissions control section of Repair Guides, after you type in the auto you have. The site is http://www.autozone.com. I presume it is available to you in Australia.
Just thought - maybe it's not on the cars sent to Australia - excuse my ignorance, but it does not really get COLD there, does it?
Tom M.