Vapor Lock

[erik88lr]

First post here, though while waiting for my registration to become active I've looked at all 408 pages of previous postings over the last ten years, and read many with similar issues. The last was some five or six months ago, so maybe time to beat the dead horse again. :p

1973 Series III 88" w/ 2.25 petrol engine. All original with original Zenith carb (rebuilt several times, new float recently).
Restored the truck some 20 years ago, rebuilt the original AC fuel pump then, and have had no running problems for those 20 years, even living in the hot Atlanta, Georgia area.

Ordered one of the $39.50 ProLine pumps from our host a year or two ago, as the price seemed right, thought it would be nice to have a spare. A month ago the Landy died following a hot restart. No fuel delivery at the carb until things cooled down. Put on the ProLine pump and all seemed well for a week, then experienced fuel starvation at high RPM and load. Engine would die unless I let it idle awhile to build up some more fuel in the carb.

Ordered and installed a second ProLine pump. Also checked filter at base of dip tube in tank, found it partially clogged so removed it. That may have been the high RPM/high load problem. Two days later again experienced the engine dying after a hot restart. No fuel delivered to carb, no suction on suction side of pump. Dumped cold water on the pump and it started working again. Later ran the engine with some clear plastic hose temporarily installed on both sides of the pump and saw many air bubbles coming from the pump, none coming from the tank.

I'm tempted to condemn the ProLine pumps, but suspect that the 10% ethanol in the fuel may also be a factor. Have others experienced this? Are you buying ethanol-free fuel? I've found a station near home that sells it, but it sells for more than high test gas at the 10% Ethanol pumps at the same station.

Today I received a Carter electric fuel pump that I ordered from Amazon a few days ago. My intent is to mount it between the tank and the mechanical pump, and switched so I can turn it on only when needed. I'll also fill up with the ethanol free fuel when I next need gas. Just don't understand why I've gone 20 years without a problem.....

I still have the original pump, and will rebuild it if I can find another kit.

~erik~

[Contractor]

No disrespect to our host, but their fuel pumps suck.

I went through 3 pumps before I finally gave up and bought a NOS AC pump from Ike. I know several other people that have experienced the same issue ( I will say that we were made whole).

Put a pressure gauge on it and see what you have. Your fuel pump probably puts enough fuel in the carb bowl to allow it to idle and then once you give it a little pedal, it can't keep up and you basically run out of gas. You should see at least 2.5lbs at idle, closer to 3 would be better.

Again, no disrespect to RN….but it is what it is.


There is a very unlikely chance that your cam lobe is worn so much that it is making poor contact with the fuel pump, but I doubt that is the case given my experience.

[cedryck]

No disrespect to our host, but their fuel pumps suck.

I went through 3 pumps before I finally gave up and bought a NOS AC pump from Ike. I know several other people that have experienced the same issue ( I will say that we were made whole).

Put a pressure gauge on it and see what you have. Your fuel pump probably puts enough fuel in the carb bowl to allow it to idle and then once you give it a little pedal, it can't keep up and you basically run out of gas. You should see at least 2.5lbs at idle, closer to 3 would be better.

Again, no disrespect to RN….but it is what it is.


There is a very unlikely chance that your cam lobe is worn so much that it is making poor contact with the fuel pump, but I doubt that is the case given my experience.
I might add, Sadly, I had the same experience with a cost effective, Proline pump. Fuel starvation symptoms under load. I went back to using an AC pump. and in the future will add an electric pump. No offence intended to our gracious hosts,,,

[slowmo]

Oh boy. I fought this for quite a while. Went through two new yet crappy mechanical fuel pumps. Gave up. Went to a Carter electric fuel pump...which is quite loud BTW, but problem solved. I left the mechanical pump hanging but it is disconnected. Need to get it off of there one day. LaDeDa.

My truck would start OK and run until the carb bowl was empty and then die. I would disconnect the fuel line, pump the fuel pump lever like crazy and no fuel. I did get some good burns though. I tried priming it by filling the line and pumping like crazy with no results, until eventually it started working...magically. With one of the new yet crappy mechanical pumps, the sediment bowl gasket had swelled to twice its original size and of course was leaking like crazy (they apparently used neoprene which is great for wet suits, but terrible with gas). However, this gave me the opportunity to dig through a nearby trash can to find some proper gasket material, make a new gasket and blah blah blah.

I used the word "crazy" a bunch of times here...and I think installing one of these new yet crappy mechanical fuel pumps is...crazy.

[erik88lr]

Spent the day installing the new Carter electric pump on top of the chassis rail that runs beside the fuel tank. Put a toggle switch on the front of the seat support, next to the latch that would hold the cover under the center seat if there were a center seat. It's now the base of the cubby box.

Anyway, too early to tell if that has fixed my problems. I ran the truck around the block with the pump off to be sure the mechanical one would draw fuel through it, ran the electric pump with the engine off to be sure the pressure (3 psi) wasn't too high to cause the carb to flood. All looks fine.

I'll give it all a good test this weekend.

~erik~

[timc930]

I went with a little Facet. I mounted it on the frame next to the tank. I bypassed the manual pump,left it in place, just connecting a fuel hose to inlet and outlet, in the event I needed to use it in an emergency.

[slowmo]

I went with a little Facet. I mounted it on the frame next to the tank. I bypassed the manual pump,left it in place, just connecting a fuel hose to inlet and outlet, in the event I needed to use it in an emergency.

I hadn't even thought of that. Good reason to leave it there. Thanks.

[erik88lr]

Drove about 100 miles on the highway. Unless the electric pump were switched on the engine would buck and miss as it suffered fuel starvation whenever there was an incline on the road and I had to floor the throttle to try to keep up with traffic. Once I felt a power loss begin I'd switch on the pump and within a few seconds the engine was running strongly again.

I filled the tank with ethanol-free fuel, but that made no difference in the power loss. I need to get an OEM fuel pump or good rebuild kit. Sorry ProLine, but your pumps just aren't keep up...

~erik~