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#506407 - 04/30/08 05:12 PM
37 Zephyr fuel problems
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peter_smith
Member
Registered: 12/20/05
Posts: 61
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Hello All
I took the Zephyr for its annual MOT yesterday, all went well till we got to the garage that was doing the test, I left the motor running while I went in to see if I could drive straight in, as the ramp was free, I got back in the car started to drive and it just faded out, I thought it had just doped itself up with ticking over for a while, anyway it would not start off the starter, but fired straight up with a push.(very embarrasing, but doesn't it always happen at the worst possible time)
All went well for the test, but on driving home I was doing about 60 and it started missing the gradualy faded out, there appeared to be a good spark but it would not fire up.
I checked the gauze filter in the top of the fuel pump, it was spotless, no sign of anything blocking it, I eventualy got a tow back to my brothers house which wasn't to far away, after removing the air cleaner and pouring a drop of petrol into the carb it started and continued to run OK, in fact I drove it home no problem, about 12 miles.
When I first got this car it used to fade out at about 60mph, or on steep hills, but if you eased off the gas it would pick up again no problem, obviously a fuel shortage, but would never stop altogether.
At this time I cleaned the tank out, ran a new fuel line up the other side of the chassis, away from the exhaust, stripped and completely rebuilt the fuel pump including, pivots pins and bushes,new spring, diaphragm and valves, and even made up a slightly extended pump pushrod, screwed the diaphragm down with a retaining ring, and without the top of the pump on, so that I could see how much movement there was.
Lastly I rebuilt the carb.
After all this I thought this problem had gone away, there was no overheating of the engine, and the outside temparature was about 15 deg, definately not a red hot summers day.
I think there is some sort of vapourising in the fuel line somewhere, the only alternative I can think of is to try an electric pump at the back near the tank, so that the fuel is being pushed rather than pulled up the pipe.
Any suggestions gratefully accepted.
Regards
Peter Smith
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#506427 - 04/30/08 06:25 PM
Re: 37 Zephyr fuel problems
[Re: peter_smith]
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carbking
Member
Registered: 11/26/04
Posts: 528
Loc: MO
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If the tank vent were clogged, the posted result could occur; as the tank could become "vacuum locked".
You might try a test without the fuel cap, to see if the problem can be reproduced with a known vent.
Jon.
_________________________
Good carburetion is fuelish hot air!
Owner - The Carburetor Shop LLC (of Missouri)
The most expensive carburetor you will ever buy....is the wrong one for the application that you attempt to modify!
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#506428 - 04/30/08 06:27 PM
Re: 37 Zephyr fuel problems
[Re: peter_smith]
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peecher
Member
Registered: 01/04/03
Posts: 507
Loc: Washington
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Peter, sounds like the vent in the fuel tank cap is stopped up.
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#506435 - 04/30/08 07:18 PM
Re: 37 Zephyr fuel problems
[Re: peecher]
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peter_smith
Member
Registered: 12/20/05
Posts: 61
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Jon/Peecher
Thats the second thing I thought about after checking for a good spark, as I had fitted a new cap since the last time the car was out, but there was no rush of air into the tank, so I am assuming thats OK, I did about 20 miles before there was any sign of a problem, I would have thought that a cap vent problem might have shown up before then.
I did about 400 miles in this car last year, with no problems, I always had the tank filled between half and full, on this occasion it was about 1/4 full as I wanted to run the gas off which had stood over the winter.
I can only think that maybe the pump has had to pull the gas from a slightly lower level, and this has shown up the problem.
I will try running it with the old cap on just in case, but I don't think that is the problem.
I will keep you updated.
Many Thanks
Peter Smith
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#506460 - 04/30/08 08:37 PM
Re: 37 Zephyr fuel problems
[Re: peter_smith]
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V12Bill
Member
Registered: 07/02/03
Posts: 469
Loc: Mt. Holly, N.J.
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Peter,
I had a similar problem with my '48 and assumed that it was a vapor lock, because it always happened after the engine was warmed up. My problem was mostly hard restarting when warm. I had an S $ L coil on it on the advice of a friend and assumed that it was rebuilt correctly. Note the number of times I have used the word assume. It turned out to be a bad coil which I replaced with one rebuilt by Jake Flemming. When I replaced the coil the car ran with more pep and got better gas mileage. You could also have a problem with one or both ignition condensors. I have been told that there is no such thing as vapor lock, it is an ignition problem. I tend to agree now.
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#506782 - 05/02/08 06:15 AM
Re: 37 Zephyr fuel problems
[Re: V12Bill]
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peter_smith
Member
Registered: 12/20/05
Posts: 61
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Hello Bill
When I checked for spark, I had nice blue spark on both banks, although I would not totaly rule out ignition problems, I have had the coils rewound by Jake, and the distributor totaly rebuilt and set up on the proper rig, rotor recut, new brushes, new cam, points, and condensers, 400 miles ago, I would not think I am unlucky enough to have 2 condensers go down at the same time, but anything is possible, I am still convinced it is a fuel problem, and I think if a fuel line becomes warm enough a vapour bubble will occur, but in this case as I said It was not a hot day, there was no engine overheating, and the fuel pipe runs up the chassis on the opposite side to the exhaust, so I can't see where it would get too hot.
I am still working through it, and will post the results.
Regards
Peter Smith
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#507863 - 05/06/08 06:56 PM
Re: 37 Zephyr fuel problems
[Re: peter_smith]
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peter_smith
Member
Registered: 12/20/05
Posts: 61
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Hello All
Ran the car again, with the fuel cap off, after about 15 miles the same thing happened, started missing, and gradually came to a halt.
Got the car home, stripped the carb, checked everything, found nothing wrong, stripped the fuel pump, checked and all looked OK, fitted another new diaphrgm and valves, just in case. Disconnected the fuel line front and back, blew through with air, nothing to see.
Removed the fuel sender unit from the tank, temporarily fitted an electric pump to the fuel pipe, pumped the tank out into a drum, as this was happening i was watching through the sender unit hole, hoping that if there was anything in there it would be drawn to the pipe, as the fuel level got lower I thought I could see something floating in the fuel, I got a welding rod and made a small hook on the end of it, what I fished out looked like the corner of a newspaper, about 1" x 1/2", but big enough to cover the hole in the pipe and slow down the fuel supply, this was almost impossible to see floating in the fuel, I continued pumping out until the tank was almost dry, but couldn't see anything else in there.
How this got into the tank is a mystery, although I did not have a locking cap on last year, so anyone might have slipped it in.
This was a common occurance on trucks, when the driver would use a rolled up newspaper as a funnel, when the paper was removed it would tear on the neck of the tank, and some would be left in to be flushed down with the next fill of diesel.
Anyway it's all built up and running, I'm gonna do about 150 miles tomorrow and see what happens, wall to wall sunshine is forcast so it could be a nice day, fuel system permitting, If I still have problems, I think I will leave it in the garage, and take to strong drink.
Regards
Peter Smith
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#507884 - 05/06/08 08:24 PM
Re: 37 Zephyr fuel problems
[Re: peter_smith]
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V12Bill
Member
Registered: 07/02/03
Posts: 469
Loc: Mt. Holly, N.J.
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Peter,
Thanks for posting your findings. It sure helps others when we read of the cause of a problem.
Bill
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#507907 - 05/06/08 10:26 PM
Re: 37 Zephyr fuel problems
[Re: V12Bill]
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simplyconnected
Member
Registered: 11/06/07
Posts: 189
Loc: Detroit (Royal Oak), Michigan
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Kinda makes you wish for a very large screen on your pickup tube.
Believe me, vapor lock exists. Maybe not in the UK, or low-lands, because atmospheric pressure is high. But in the Rocky Mountains, on a hot day, watch out! Gas can boil at 100 degrees F., where atmospheric pressure is low. To make matters worse, the fuel pump, mounted on the engine, sucks gas at least ten feet, making an even LOWER fuel line pressure. Any pinhole in the line will suck air, and leave the gas behind. The fuel pump gets busy pumping more air than fuel.
An electric pump and filter, mounted at the tank, makes very good sense, and it exerts positive pressure on the fuel line (raising the boiling point). Put a motion-cutoff switch on the power wire just in case of a collision. You don't want gas pumping when the engine is stopped. - Dave Dare
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