my 740 had a stuck open injector so it would dump the fuel rail into cyl 3 upon each shutdown. upon startup a bit of a white cloud for a block or so until the cylinder cleared.

I didn't have the guage but found it by pulling the fuel rail, connecting it up unplug the coil high tension lead. , crank a it a bit then shut the key off and look. In my case injector 3 spewed a bunch of gas after key off which proved it was leaky. replaced 1 injector, all fine now. If you pull the fuel rail get new rubber O rings first. remember the safety risk since you will be spraying a bit of raw gas out from the injectors.

Regina is foreign to me, but it still has injectors so I don't see why this test would be much different. most shop manuals say to use the pressure gauge and assume you have one, That's safer because you don't need to spill any raw fuel out.

I think if you do this and apply safety precautions it will prove to you if all your injectors are shutting off and then you can forget about that if they do or fix it if they don't all shut off. It will prove either way then you can move forward to other troubleshooting. Knowing the actual fuel pressure measured with a gauge has some value, this only proves if they shut off or not.

the relay might have bad contact points, if so that could cause intermittent pump operation. I took an old relay and added a fuse and jumped the contacts so if I swap that relay in it powers up my fuel pump , only for testing.
in a pinch you can pop poen the cover of the relay and inspect or clean the contacts. if they look all burned, change the relay.

If I replace a fuel pump I also wire in a low watt bulb in parallel with the two pump wires. it gives me a easy way to monitor if the pump has power or not to help diagnose that easier. you can put the little indicator lamp where you want to. If I have any starting issue I can see if that lamp is on or not and that helps me with a more easy diagnosis especially if Im not near my tools and on the road somewhere. The last one I did I just shared the connector at the pmp since I had to solder new lugs ont he pump wires anyway, it might be neater to pick up those same two wires right at the relay, then its in the cabin. I just put mine under the hood near the brake reservoir.

a test for the older system , you can pull a fuse to omit the in tank pump. then open the fuel line and see if it fills a jar and how fast. you can do the same with the main pump running and see more flow.. I assume you can do a similar test with the regina but maybe it only has one pump..
if you do this realize the pump can move a lot of fuel quickly so dont flood the jar all over the place and do not cause a fire.

pressure requires resistance to flow, best to use a gauge for that. If you can find stats on the gallons per minute of flow then you can measure the flow rate. you can likely just guestimate..

the filter screens in the older ones often turn to plastic garbage. Im working on an car right now that sat a while and the bottom of the tank has a lot of thick tar-like goo. Its like molasses.. that stuff can sit in the tank and plug up filters and screens things. the pump might make considerable pressure but if the inlet gets blocked it can get stuck cavitating, and no flow then. in my case the screen will be plugged and Ill have to flush the tank with solvents so I plan to use the old fuel pump as my solvent flush pump to rinse this garbage out of my tank, and then I will replace the pump and the filter. Ill also clean the fuel line maybe by pulling a wire and then thin rope through it or similar. I don't want that molasses like goo in the injectors..


I'd suggest checking your fuel flow first, if you don't have fuel delivery issues you may not want to muck with the tank. on the earlier cars they had a filter screen and the pump in the tank and I'd change both if I go there..