to have owned an 84 vintage GM V8 engine in a 1500 truck with the mechanical fuel pump on the front RH side of the block that would starve the carberator for fuel after a quick stop, like a hamburger or a fuel pit stop. The vehicle would move at a max of about 20-30 mph for 10-20 miles before full power returned to normal. In my case I changed out the genuine GM fuel pumps twice before a auto parts store sold me a 3rd party pump that resolved the problem. Turned out as the "genuine GM fuel pump" (c/w a fuel return line to the tank) warmed up to the block temperature it would pump fuel internally between the high pressure chamber (output) and the low pressure chamber (inlet) via a rubber washer that would become "uncompressed" when the pump housing expanded with the heat. Or was this all just a bad dream?
I been mechanic'n on chevs all my life, never heard such a thing. My ole 84, 454, Taska did seem to vapor lock a bit after running hard in hot weather and then shut it down for a short time. When getting back on the freeway, it would starve out and skip a beat a couple times while accelerating to the speed limit, and then was fine...nothing serious. It did that for 12 yrs.
Rich
'98 Flair, 454, Onan Microlite 4k, Intel PD 9155 w/ wizard, Sta-power 1500 watt Inv, 2 6v batts, ammeters, KingDome/sat, Oly Catalytic Heat, hauling 2 Bent Bikes and sometimes towing a Tracker F&S boat.
Had a '78 with a 305 cu/in V-8... the starter would get hot from the engine heat, and not work after stopping. Have to let it cool off, then it'd work again. Heat shield finally fixed it.
SAR Tracker wrote: Had a '78 with a 305 cu/in V-8... the starter would get hot from the engine heat, and not work after stopping. Have to let it cool off, then it'd work again. Heat shield finally fixed it.
That, and I've bought Fords since!
This is what prompted me to start this thread, reading about this starter issue on the Class A forum.
RJsfishin wrote: I been mechanic'n on chevs all my life, never heard such a thing. My ole 84, 454, Taska did seem to vapor lock a bit after running hard in hot weather and then shut it down for a short time. When getting back on the freeway, it would starve out and skip a beat a couple times while accelerating to the speed limit, and then was fine...nothing serious. It did that for 12 yrs.
I will open by betting two slightly used "Genuine GM Fuel Pumps" that we had the same problem.
I had a similar problem with an old 1968 Ford I used to drive. turned out the steel tube fuel line was partly kinked and made the pump work too hard to draw fuel to the engine.
The return system was to avoid vapor lock and over pressuring the float valve in the carb (Quadrajet). A few things can happen. The drilled chamber plugs in the body of the carb can leak fuel; either flooding or starving the engine during start up. The insulation block under the carb was missing on some shade-tree serviced trucks we'd see, causing hard start from fuel percolation. There was a small filter in the input of the carb in addition to the regular fuel filter that would be easily clogged by now on an 84. I seem to recall a spacer block between the pump and engine block that had to be the right dimension. An 84 Quadrajet carburetor was one of the most developed fuel delivery systems ever to come out of Detroit. If they were set correctly (and that was no mean feat) they worked amazingly well considering the emissions restrictions on engines of the day. As I recall a new carburetor was about $1500 at the time and that cost was one of the considerations in going to the less expensive fuel injection. Find a good GM tech that worked on these, probably retired by now, and ask him to help you out. You had to be there to understand these beasts and everything (engine condition, intake, exhaust, ignition, fuel delivery and fuel quality) was important. (Anyone remember clothespins on the fuel line?)
Yes I remember the clothes pins and Dad would pour water on the fuel pump at the rear of the valley on old Ford flathead... 'after a sudden stop" some have a sock filter in the fuel tank and it can be shifted out of place by strong braking and kink.. later normal driving will reposition the long sock filter and be OK. On modern elect fuel pump MUST replace sock and inline filter to have a replacement in tank pump warrenty valid.
I remember a long time back, GM had some fuel pumps that the pump arm or lever that went into the engine to be pushed up and down by the rod off the camshaft would hang and not make a full stroke when overheated. You ended up getting only half or less of the fuel supplied to the carburetor, so you would have fuel starvation for a while. I think that we only ran into this maybe a couple of times in my shop and it was a nightmare to find. This was back in the late 70's or early 80's. I think it also made a noise like a lifter was stuck.
There were some (lots of them) of the quadrajets that the plugs would fall out of the bottom of the float bowl and allow a lot of fuel to seep into the intake manifold. The only thing this caused is flooding and hard starting and using a lot of gasoline.
Offline
