[Mgs] 74 B acting fuel starved

wkilleffer at epbfi.com wkilleffer at epbfi.com
Sat May 19 16:01:28 MDT 2018


Hey everyone, 

I recently posted some things about my 1974 MGB with the 18GK engine. Yesterday, I decided to tune and balance the HS4 carbs as they haven't been adjusted since I got all the evaporative loss stuff hooked back up. After a bit of fine tuning today, I took the car for a couple of drives and all seemed quite well. However, I was taking the car out again, and just as I was exiting the neighborhood, after revving up to 3000 before shifting into 2nd gear, it started acting fuel starved. It seemed to snap back, but after about a minute, it bogged down, ceased responding to the accelerator, and stalled. 

Now, I've recently replaced the fuel tank, anti run-on valve, oil pressure switch, all of the rubber hoses involved with the evaporative loss system, including the ones to the vapor separator in the boot, and began using a non-vented oil filler cap. I've also added new rubber fuel lines under the boot, and a new fuel filter. The current fuel pump is a genuine SU and is less than a year old. The evaporative system seems to work as designed as the car will stall if I block off the bottom intake on the anti run-on valve, and there are no more fuel smells in the boot. 

When it first stalled, I remembered that checking the fuel cap was a good idea, but there was enough road noise nearby that if a whoosh of air came out of the neck, I didn't hear it. After that, the car started, but rather begrudgingly. It didn't want to idle at the speed where I'd set it. I thought maybe it was low on fuel and managed to make it to a gas station nearby, but it took less than half a tank. The full tank didn't make a difference. 

I went on to check the grounding point in the trunk, as well as all the connections on the fuse box and the fuses themselves. It started up faster after the fueling, but soon exhibited the same symptoms as before, and I had another stall on the way home. 

Something I couldn't help but notice is that the fuel pump was clicking like it was pumping out of an empty tank even though that wasn't the case at all. It wasn't clicking as quickly as I've heard it do before, but still not shutting off even though there was no reason for it to be pumping. There are no signs of leaks, no fuel smells. I also wonder if it could be as much a spark issue as a fuel one. 

Any advice would be appreciated. 

Thank you, 
-William 
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