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Discussion Starter · #1 ·
I need help. I would like to drive the car – it’s the perfect time of year to do so, but now I can’t.

Let me know if any of this makes sense and if I’m headed the right or wrong direction.

I’m having problems with my ‘57 210 stick with a 265, 2BBL Rochester carb, and mechanical fuel pump.

I have a transparent in line fuel filter between the fuel pump and the carb and am running regular – which has Ethanol added (the pump says “at least 10%”).

When I start the car up, with the engine cold, the fuel filter fills to about half way and the car runs smooth, with no problems.

After about 5 minutes of running at idle, the fuel level in the fuel filter drops to barely nothing and if I rev the engine long enough it starts running rough and will eventually die – I suspect because of fuel starvation.

I then shut the engine off and watch the carb for about 15 minutes to see my next problem: fuel leaks at the side seals in the body of the carb. Not much – but enough to smell up the garage with raw fuel odors.

Initially I thought it was a problem with the fuel pump and that the carb needed rebuilt – so I replaced the fuel pump and had the carb rebuilt.
No change.

Next I thought I may have a leak in the tank side of the fuel pump, so I disconnected the line to the tank from the fuel pump and ran a new line from the pump into a fresh can of gas and started the car.
No change.

Next I replaced all of the lines from the fuel pump to the carb and replaced the fuel filter.
No change.

I next checked to see if any of the fuel lines from the fuel filter to the carb got hot – they didn’t (I could touch them with my hand easily.)

After searching this site, and seeing many suggestions, I decided to check the pressure out of the fuel pump.
Between the fuel pump and the fuel filter I put a “T” fitting and ran a pressure gauge off of the T. I then started the car, after letting it cool down over night.

At start up the pressure was about 5.5 lbs and the fuel filter was about half full.

After a minute of running the engine was warmed up and I bumped the carb to reduce the idle speed. The pressure increased to about 5.9 and remained constant.

After about 4-5 minutes of running, the fuel level in the fuel filter started dropping, but the fuel pressure remained constant at about 5.9.

After about 7 minutes the fuel level in the fuel filter was barely visible, but again the pressure was constant at 5.9.

I shut the engine off and waited a few minutes but noticed that the fuel pressure remained constant at 5.9 – even after 4-5 minutes.

I was convinced by this time that if I waited another 10-15 minutes I would again start to see fuel leakage out of the car, so I decided to vent the pressure by disconnecting the line from the fuel filter to the carb. This of course released 6 lbs of spray (which I cleans up) – but after 30 minutes I had no leaks out of the carb.

Here’s what I suspect so far:

Carb leaks: The leaks out of the crab are caused by the gas sitting in the hot carb after shutdown, under 6lbs of constant pressure, and swelling as it absorbs heat from the hot carb body.
The carb only has a thin (1/8 inch) paper gasket between it and the intake manifold, which will normally be at 160 +.
Since the gas is in a closed space it has to go somewhere, so it seeps out. I think this problem may also be related to the ethanol, but I’m not sure how.

Fuel Starvation: This is where it gets tricky and my thoughts are only half-baked.
Lots of what I read and hear indicates that the ethanol gas increases the vapor pressure of the mixture and thus vaporizes at a lower temperature.
Since I am using a mechanical fuel pump that is attached to the side of the block, the guess is that the fuel pump gets hot and is less efficient in pumping fuel – thus less fuel gets to the filter and hence the carb.

I next plan to test this.

I plan to get 2 gallons of regular gas, with no ethanol additive. (it costs about $4/gallon here now – but you can get it.)
I will run a line directly from the gas can to the fuel pump and, starting from a cold engine, rerun the tests, but this time use a laser temp gauge to monitor the temp of the fuel pump, carb and lines.

If the fuel filter stays full then I guess I need to stop using Ethanol fuel.

If there is no change in the results then the only other things I can think of as possibilities are to:

Replace the mechanical pump with one that is not attached to the block and that doesn’t get hot (assuming that the temp readings indicate that the mechanical one does).

Somehow reduce the temp of the carb – possibly by putting a thermal break between it and the intake manifold – a thicker gasket maybe?

Beyond this, I’m open to all ideas – Do you have any? Please help -- I'm getting tired of this and want to go for a ride.....
 

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Dennis, sounds like a stumper. Lots of folks have chased the elusive, low fuel level in the clear filter phenomenon. I had an issue where when the engine got warm, it ran like garbage... The filter did look low at times but I was convinced the ethenol fuel in my Rochester quadrajet bowl was getting too hot because the carb sat directly on the stock manifold. It ran horrible once warm and stalled constantly. I just couldn't tune it when warm and restarts were difficult or impossible. So without breaking the bank, and because I wanted to retain the stock manifold, I decided to install a phenolic spacer between the carb and manifold. After installing the below listed spacer and forming a new choke control rod out of a piece of metal coat hanger, the car starts cold, hot and tuned with no issue. I then was able to drive the car to work, 60 miles round trip a couple times a week with no issue.

http://m.summitracing.com/parts/mrg-3406

Unfortunately I don't see a complete kit for a two barrel but here is a link to the two barrel spacers. I would suggest it as a possible solution.

http://m.summitracing.com/search/Part-Type/Carburetor-Spacers/Carburetor-Mounting/2-barrel/

Good luck!
 

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Have you tried completely removing the fuel filter? Where's it located? I've had filters get warm enough to do the same thing, with the gas lines being cool to the touch. Other then that I'd try to find a phenolic spacer, really sounds like vapor lock imo.
 

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Discussion Starter · #5 ·
As a follow up.
During all of my testing so far, once the fuel level in the fuel filter goes down to nothing, I have rev'ed the engine to see if the level changes -- it doesn't -- no matter what I do the level remains low and I end up using all of the fuel in the carb bowl up and it dies.

Today, I hope to run my next tests.
Sure hope they tell me something.
More later.
 

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It sounds to me like the problem is in the filter. If you're using one of the cheap plastic inline filters these things rarely fill up completely. If you're maintaining fuel pressure and the fuel apparently isn't getting to the carb, the filter must be blocking it. Something is either swelling up or breaking down. If you have the AC glass filter, the element inside might be plugged up. The obvious test is to remove the filter.
 

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I had a similar problem as you are referring too, the car would die (no fuel) even left me stranded, all I needed to do was wait 5 - 10 minutes then was good to go for a short run. This is what I did to fix the problem.

I tried replacing fuel pump, fuel filter, fuel line etc etc no fix so next I:


Drained what was left of existing fuel.
Removed fuel sender, let fuel filter dry then blew out all of the fine dust.
Disconnected line to fuel pump, blew line clear from sender to pump.
I added a new glass bowl fuel filter at carby.

Now the gas at the fuel filter is alway full, no breakdowns, happy cruising :)
 

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I'd pull the sending unit and clean the filter on the fuel pickup. I went through the same thing on my Dad's 55. It was plugged solid with fine black dust.
It's worth a look but he said he's run a new line from the fuel pump intake to a fresh can of gas and it still happened. Everybody loves a mystery unless it's happening to them! Can't wait to hear what it was.
 

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As a follow up.
During all of my testing so far, once the fuel level in the fuel filter goes down to nothing, I have rev'ed the engine to see if the level changes -- it doesn't -- no matter what I do the level remains low and I end up using all of the fuel in the carb bowl up and it dies.

Today, I hope to run my next tests.
Sure hope they tell me something.
More later.
I realize you had the carb re-built and am assuming
that it was thoroughly cleaned before re-assembly???

I'm thinking that the float needle valve might be sticking
shut intermittently.Other cause could be in the idle circuit.
 

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I had the same problem a few years ago. After doing all that everyone has suggested, which still did not cure the problem, I sucked it down, and pulled the pump pick up out of the gas tank. the screen looked fair, not terrible, but what I found was when i removed the screen and inspected the tube, the intake line for the pickup had been accumulating varnish, a little bit at a time over the years, until the tube was nearly closed. It was just open enough to let some fuel in, fill the lines, but could not keep up with the demand after running for a bit because of the restriction. I replaced the pickup and screen and had no further issues, and I was using one of the inexpensive clear plastic fuel filters, as I have for 35 years so maybe not the filter after all. Worth a shot.
 

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Discussion Starter · #15 ·
Been having to work since my last post.
plan to run tests over the weekend.
I have a can of Ethanol free gas ready -- will run a line directly to it, to eliminate the tank and fuel line.
Also have laser temp gauge on my hip.
 

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My 57 was doing the same thing youre describing. We put a new tank and sending unit on it, and problem solved. The old tank was so full of crap, it just wouldn't let enough fuel in.:anim_25:
 

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Discussion Starter · #18 ·
Update 2/3/13
Okay, the problem has not been solved but I know more.

I ran the car directly out of a can of Ethanol free gas – I connected a fuel line from the fuel pump into a gas can so I could rule out the line to the tank and the tank.
Results: No change. The fuel level in the fuel filter still drops to nothing after a while.

So this says that, at least for my problem, having Ethanol in the gas makes no difference. Just to double check though, after about an hour (to let things cool off), I re-hooked up the gas line to the tank and ran the same test off of the Ethanol gas in the tank – with the same results.

I was a little more methodical this time though. I kept track of the time and measured the surface temp of the intake manifold, carb float and the top of the fuel pump.

I was surprised how hot everything got. After 15 minutes of idling, the intake manifold was at 290, the fuel pump at 155, and the front of the bowl of the carb was 160.

The fuel pressure, measured between the fuel pump and the fuel filter, remained constant at 5 lbs – a little lower than I had seen in earlier tests, but constant.

Through all of the tests, the engine was purring though – very smooth.

I did note a few things:

First the carb leaks have stopped – don’t know why this happened, except to guess that the carb body gaskets have seated themselves with the repeated heating and then letting them sit for a week while I had to work. This has allowed me to concentrate on the dropping off of fuel in the filter.

The drop does seem to be temperature related and not just time.

The 2nd and third tests I ran took less time because the engine was warmer starting out, but the drop in fuel level, as seen in the fuel filter, happens about when the body of the car (around the float) goes above 130 – at this time the fuel pump body is about 120 and the intake exhaust is about 270.

This is leaves me with a few possibilities.

Bad fuel pump (even though I had it replaced) – Even though the fuel pressure was constant, this only means that the check value in the pump was working. It doesn’t guarantee that the intake check value was working, or that the baffle was.

Carb problem – even though I had it rebuilt.
Have no idea what this could be though.
I thought that the carb was getting too hot and causing the vapor pressure in the bowl to increase such that the pump wasn’t able to push the fuel to the fuel filter, but since the fuel pressure remained constant, that didn’t make sense.


My guess is that the fuel pump is not working after it gets too warm.
I hate to shotgun problems though.
I would really like to know what the problem is before I just throw another fuel pump at it.
I also don’t think I would be able to recognize a problem with the fuel pump by just taking it apart.

So I plan to next measure the input vacuum that the fuel pump pulls and see if it changes as things heat up. That should tell me exactly whether the pump is the problem.

Does anyone have an idea how much of a vacuum I should expect?

I don’t like the fact that the carb body is getting so hot.

After I rule out the fuel pump I’ll next try ways of reducing the cab body temperature – possibly by getting better (or thicker) gaskets between it and the intake.

Oh by the way: To ensure that the fuel lines were not overheating, I put a heat shield sleeve around the line both between the fuel pump and the fuel filter and the fuel pump half way back to the tank (well beyond the muffler). After I did this I reran my tests – no change.

I also changed the fuel filter (again) - even though the one in the car through the last tests blew clean and had no blockages. Again – No change.

More later.

Hope I solve this before summer arrives and it’s too hot to enjoy to drive.
 

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SUGAR CANE ETHONOL.

i have read what you are talk'in about and all i can say is be very carefull of using ETHONOL fuel ,it is from sugar cane and can eat gaskets and rubbers like there is no tomorrow im an Aussie and its done some nasty damage over the years mate.
 

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as so many guys know, i`ve chased a fuel problem, very similar to yours, for all last summer. that clear filter drove me nuts. long story short, you cannot say one thing that i did not try. as a result, GENERL MOTORS PERFORMANCE PRODUCTS [GMPP] fuel pump. they make 2. don`t need the 15 psi one. well, anyway, that pump cured my "disapearing fuel pressure". hell, i started out at 6, cold, dropped to 1, 1.5 at times. just a thought, good luck.
 
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