I had a bit of work done on my 186, nothing major, total rewiring and a couple of Strombergs. Its been starting and running fantastic for over a year. The other day I ran around for 20 minutes and fueled up at a servo. When I left the servo it was running like a pig 100 metres down the road and I just managed to limp 5 mintues home. I thought dirty fuel or I used diesel. I went back to the servo and checked and it was 95. Next day it was reluctant to start so I splashed some fuel in the carbys like I have been doing for 40 years and it started and ran fine. I didn't go for a drive but I ran in the driveway for half an hour until the new electric fan came on. I figured dirt or vapour lock or something.

This morning it started instantly and ran perfectly. But I noticed a lot of bubbles in the glass fuel pump bowl (that was NOS), it was running so nice I took it for another drive and after 15 minutes I could tell it was starving for fuel and it cut out so I had to get a mate to tow me home (embarasment+).

Today I had a fiddle around and couldn't see anything wrong other thant the accelerator pumps not doing anything. I disconnected the fuel line and turned the motor over a few times and it didn't seem like much fuel pumped into a cup. So I filled the float bowls with a syringe and it started and ran perfectly, but there were all those bubbles in the the fuel pump glass bowl that caught my eye yesterday.

I'm wondering if the diaphragm is split. I had that a couple of times with red motor V8s that don't have th glass bowl fuel pump, but they leaked oil when they failed.

Does "The Knowledge" think its a split pump diaphragm, or could there be something wrong with the vey-old fuel tank pick-up?

https://photos.google.co...7eWrqhq4-yqP8BxzldirCgnC

Edited by user Sunday, 15 October 2023 8:21:13 PM(UTC)  | Reason: Not specified

You can pressure test the fuel pump. Some of the basic compression tester gauges can do this.
Just connect the gauge to the fuel pump using hose clamps and fuel hose/line.
HQ/HJ 202 book says 3-4psi.

I sometimes see a few bubbles under the glass but never very many and usually none.

The fuel pumps can last a long time. I bought a replacement fuel pump because I figured the old one had to be wearing out after so many decades. Nope, it tested fine. The replacement pump is still sitting on my shelf!

It might also be a soft hose somewhere. The hose can pull itself inward and cut or reduce the fuel flow. Usually more common when the hose is warm or hot, or when you accelerate or use high revs as more fuel gets used and it starves. The engine will usually idle fine when this is the problem.

Good luck.