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View Full Version : My 78 FJ40 is running out of gas


Pdwight
10-06-2010, 01:09 AM
Hello new to this forum. I am getting my 78 FJ back on the road for short trips and hops around town while I work on the old girl. I bought this cruiser from a dealer in 1980 and New Old Stock, it was a demo and kept around until I bought it......skip ahead many years....lost my wife to Breast Cancer 7 years ago after a 4 year fight with this horrible disease. At the time I was really trying to get the cruiser back going....had put a Weber on and had it running...it has just sat in my driveway since. I retrieved my old Carb from the box I put it in and did a rebuild using a ultrasonic cleaner and it came out nice. I reinstalled it and it cranked on the 6th turnover with a little gas in the butterflys. I did a tuneup new plugs, distributor cap, wires, rotor button, changed oil..etc. It runs great but after a mile or so it stutters and dies....no fuel in the sight glass...it will idle for 10 to 15 minutes...no problem. The gas level is exactly on the frosted dot on the sight glass. I was very careful to set the float to the specifications in the 2F manual. I am used to working on precision equipment, handguns etc so this seemed to go well. I replaced the fuel filter, drained the gas tank, used a air hose to blow back pressure from the "in" side of the fuel filter with the tank empty and not much resistance. I didn't get much gunk or particulates out of the gas tank. I hooked everything back up and same problem. I had a new spare fuel pump and replaced the one in the cruiser (BTW the old girl only has 85K original miles on her) same problem. I changed the fuel filter to a generic one that you can see through....good gas movement...not too much "stuff" in the filter, when I disconnect the filter gas siphons freely from the tank...so no obstruction.

I even replaced the original needle valve assembly and reset the float...same problem....now to my long winded question. On the Weber I did not use the return line all those years, if it were stopped up could it cause this situation ??

I am running out of Ideas to try.

Thanks
Dwight

PS is Jeff and Pinhead still around.....used to talk to them years ago on the board from Texas.
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SteveH
10-06-2010, 09:52 AM
You could do some more diagnostic testing - when it begins to sputter, can you back off the throttle and see if the fuel pump can 'catch up' and refill the carb bowl? Also, drive it with the gas cap loose (or off) and be sure you're not pulling a vacuum on the tank. A plugged return line would tend to increase the pressure at the carb.

If none of this works, you might try temporarily installing an electric fuel pump (a decent one - Carter, perhaps - not a Holley performance type one) and see if that fixes it. I did that on my '78 after a new OEM fuel pump still wouldn't keep up with vapor-locking and fuel flow issues.

Pdwight
10-06-2010, 10:04 AM
I did the last tests with the gas cap removed, I can stop and feather the throttle and usually get it going again but I have to drive like there is an egg under my foot or it will stall. Once it would not start and i Poured a little gas in the carb and it started instantly but we just made it up a hill in my neighborhood to coast back home.

What would happen if the fuel return line (Banjo fitting on the Carb) were stopped up....would this increase in pressure cause this ??

Thanks
Dwight
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Air Randy
10-06-2010, 01:13 PM
Pinhead is still around on the IH8MUD forum, haven't seen him here though.

I did have a similar problem with the stock carb on my 40 when I used some black silicone gasket sealer on my fuel tank sending unit. I sucked some of the silicone into the fuel filter and restricted it but didn't block it completely. The engine would run fine until I went up a hill or accelerated hard, then it would act like it was running out of gas. I installed a new fuel filter but had the same issue. Turns out a very small piece of the silicaon made it's way into the carb somewhere. Since I was in Moab at the time I tried the "Oklahoma Rebuild" approach = Remove your air cleaner, rev the engine by hand to about 2,000 rpm then slam your hand over the top of the carb. It kills the engine but causes a huge vacuum spike inside the carb so it can suck particles through that are causing issues. Amazingly it worked fine for me and the carb has worked perfectly ever since. It's a long shot but its worth a try.

Did you try disconnecting the fuel line at the carb then cranking it over to check the fuel pressure you are getting delivered to the carb? You could have a restriction between the fuel pump and carb. It's not very common but I have seen cases where the lobe on the camshaft that operates the fuel pump lever is worn enough to not get full pressure/volume from the mechanical fuel pump. In that case it is usually easiest to just install a good quality electric fuel pump.

Pdwight
10-06-2010, 01:20 PM
Thanks , going to try that today....I know there is nothing in the carb...cleaned every piece in a heated ultrasonic cleaner and blew out all the passages with air......then had it back apart yesterday and installed another needle valve and screen....clean as a whistle.

I am going to measure the fuel flow this afternoon at the carb and see what I get.

Thanks for responding.............I like the do or die carb cleaning method for the trail.

Dwight
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nattybumppo
10-06-2010, 04:35 PM
I think I'll try that Oklahoma Rebuild method on my 60.

Pdwight
10-06-2010, 08:03 PM
I measured the gas output at Carb today for 15 seconds.....only about 1 inch deep in a fruit jar.....it should have been more. So I started at the gas tank...pulled it and found a split hose on the "Out" of the gas tank where it goes through the floor. I have the tank pulled so I am painting it while it is out....not much rust thanks goodness.

Should get it back together by this weekend.
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Pdwight
10-06-2010, 09:35 PM
What would be wrong with running a new flexible fuel line from the gas tank directly to the fuel filter and by pass the metal lines that have been sitting idle for many years ??
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74fj40
10-06-2010, 11:04 PM
no problem I did that on my own 40. but rubber deteriorates much quicker than metal, also a kink can be created very eaily if there is too much slack. although mine has been all rubber lines for about 5 years now.

Air Randy
10-07-2010, 02:03 PM
Bypassing the metal lines will probably work OK. However, in the past, I have seen problems where the rubber line can suck closed due to a weak spot in the wall of the line or if it gets really warm and softens up too much, etc.

Its possible the split line is sucking in some air and reducing the fuel flow. Let us know if that turns out to be the solution.

Pdwight
10-08-2010, 05:14 PM
I pulled the gas tank, replaced every inch of rubber line with brand new. I bypassed the metal line to the fuel filter from the gas tank with brand new gates flexible line. Washed the tank put again.....nothing out of it, the supply nipple on the side of the gas tank is not restricted.....put it all together and cranked it up. Ran like a champ....gas right on the mark in the sight glass. I warmed up took it for a drive and at the same point it almost died....I feathered the gas and got it running but barley got it home. I do not know what to do at this point. Getting just over 8 ounces of gas at the carb for 15 seconds of starting. The only thing I have not replaced is the float.....please if anyone has any idea.......Help !!!

Thanks
Dwight
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Air Randy
10-08-2010, 05:29 PM
When you washed out your tank did you pull out the sending unit so you could look inside the tank? I'm wondering if there is a flexible line on the fuel pickup inside the tank that is collapsing or kinking?

Next, I would buy an inexpensive electric fuel pump and install it as close to the fuel tank as possible. You can jury rig a bypass to your mechanical fuel pump or leave it in the fuel circuit, it shouldn't make any difference. Check to see how much volume you get in that same 15 second period versus the stock pump.

If none of this works, try putting your weber carb back on and see what happens. If it runs out of fuel too you know its in the fuel system somewhere, if it runs OK you know the problem is in the OEM carb.

Did you ever hook up the return line from the OEM carb to the tank? I can't imagine that would cause your issue but were sort of grasping at straws now.

Pdwight
10-08-2010, 06:10 PM
"When you washed out your tank did you pull out the sending unit so you could look inside the tank? I'm wondering if there is a flexible line on the fuel pickup inside the tank that is collapsing or kinking?"

I never thought about that, I just poured the gas through a cloth to check for particulates....this makes perfect sense.....does the gas tank have a flexible pickup line ??
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