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Fuel pump questions

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sparkydave

sparkydave

Jedi Knight
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Hopefully this wouldn't make me a DPO, but I've been having some bad luck with fuel pumps. When I got the car, the original fuel pump was working, but suddenly stopped pumping. I assumed the diaphragm might have expired, so I ordered a replacement. When the replacement arrived, I found out the old one was still good; the fuel line had broken. I put the new one in anyway, which worked until it started seeping air in it for some reason, which led to unexplained stalls on the road. I put the old one back in, but it started doing the same thing and left me on the side of the road last summer. So, I made a new gasket for the screen cover, sealed it with some Permatex, and the vapor locking is gone, but now it has a problem where it starts, runs for a few seconds, then dies abruptly. I have to crank for a few seconds again to get it running, but then it runs fine.

Any thoughts? I'm inclined to add an electric fuel pump (Moss #377-420, unless this sounds like a different problem. The other reason I thought of an electric pump is I found a long hill on a highway nearby where it can't seem to deliver enough fuel to keep it tooling along on the hill. About 2/3 of the way up at 55 MPH it starts stumbling, but once I slow down to about 35 it keeps going.
 
I would just go with an electric pump and solve all those issues!
 
Dave,

The issue with only being able to run around 35 mph sounds like a fuel starvation problem. The "sucking air" issue you were dealing with earlier makes me question whether you have an inline fuel filter before the pump that may be plugged. The pickup in the tank could also be blocked by scale or debris. If either of these are the source of the problem, fitting a new pump (mechanical or electric) won't fix the problem.
 
I don't think there's any problem with fuel blockage. I've had the tank out, cleaned it, and replaced all of the fuel line. I put a filter in after the pump, and it's still clean. The screen around the pickup in the tank and the screen inside the fuel pump have stayed clear.
 
I should think it is a fuel line prob as well. However, nothing wrong with an elec pump. Mr. Donald would have used em but they were expensive, he did use them on his race cars.
 
Down here in Johannesburg

Several years ago I had what sounds a similar problem. I bought a new fuel pump and still the car kept on dying on me. I had to rev to keep the engine going. I put the old pump back, sort of an expensive elimination logic approach. This problem kept going for a few more years but fortunately the car wasn't used that much. Eventually I got the total zig with heel/toe/revving/stalling/choke on and off I took it the best MG mechanic in SA IMHO (Roger Pearce). The issue - totally knackered carbs - leaking carbs, wrong mixture that I had played with. He overhauled the carbs, analyzed the exhaust gases etc and it runs like a dream.

Cheers,
Mark
 
When my Midget developed this problem,it was caused by a kinked fuel hose. Straightened the kink and,- - "hey presto" problem gone.
If the fuel supply is restricted,vapour locks occur and cause stumbling,hesitation and complete stalling.
And as has been said,a new pump,electric or not,won't resolve the issue.

Stuart. :cheers:
 
I went with an electric pump Dave. I'm glad that I did now that it is done. I was having nothing but trouble with the mechanical pump. I also used a Holley low pressure fuel regulator. The pump I bought was putting out around 4.5psi. I think it was fine for the Zenith carb but once I switched to the Weber, it over drove it a bit.
JC
 
I'll shoot some tonight. It isn't the prettiest in the world. I mostly just put stuff where I could fit it for now. Planning to disassemble the whole tub at the end of this summer.
JC
 
Here is what I have right now. It is just a work in progress. Mostly trying out things to see what works best. It is in no way ready for pictures that I would consider showing off but since you asked. I didn't expect the fuel regulator to be so large. You can see the regulator and kind of get a reference of the size based on the stuff around it. Also you can see the top of the fuel pump just peeking out past the heater hose. I mounted the fuel pump on the inner fender well and fabbed a quick heat shield to protect it from the header. I'm making a bracket to put the regulator deeper under the fender but didn't have the metal at the time.
 

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sparkydave said:
Hopefully this wouldn't make me a DPO, but I've been having some bad luck with fuel pumps. When I got the car, the original fuel pump was working, but suddenly stopped pumping. I assumed the diaphragm might have expired, so I ordered a replacement. When the replacement arrived, I found out the old one was still good; the fuel line had broken. I put the new one in anyway, which worked until it started seeping air in it for some reason, which led to unexplained stalls on the road. I put the old one back in, but it started doing the same thing and left me on the side of the road last summer. So, I made a new gasket for the screen cover, sealed it with some Permatex, and the vapor locking is gone, but now it has a problem where it starts, runs for a few seconds, then dies abruptly. I have to crank for a few seconds again to get it running, but then it runs fine.

Any thoughts? I'm inclined to add an electric fuel pump (Moss #377-420, unless this sounds like a different problem. The other reason I thought of an electric pump is I found a long hill on a highway nearby where it can't seem to deliver enough fuel to keep it tooling along on the hill. About 2/3 of the way up at 55 MPH it starts stumbling, but once I slow down to about 35 it keeps going.
Click to expand...

I would check for bad hose and or a loose fitting at the tank. If you have a cracked hose beforethe pump it may be allowing air in allowing fuel to siphon back to the tank causing the pump to lose its prime. Sounds like it may fit some of them problems you describe...
 
Scott, that is one neat photo.
 
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